The use of at least one diazonium salt bearing an initiator function, for forming an undercoat obtained by grafting a graft derived from the diazonium salt and bearing an initiator function at the surface of a conductive or semiconductive material on the undercoat, and for forming on the undercoat a polymeric layer obtained by polymerization, in particular free radical polymerization, in situ of at least one monomer, initiated from the initiator function.

1. Field of the Invention
A subject of the present invention is a material, in particular metallic, the surface of which is modified, as well as its preparation method. The present invention also relates to the uses of said material, in particular for the preparation of implants, stents or prostheses.
2. Description of the Related Art
The covering of metallic surfaces by organic layers constitutes a set of significant industrial methods (Plankaert, 1994; Biethan et al., 1991; Hochberg, 1979). These methods involve the deposition of a polymer on a metal sheet, either from a liquid, or from a solid polymer sheet or also by cataphoresis. In these methods, only weak bonds are formed between the metal and the organic layer. Other methods have been described, they also involve weak bonds for example during the deposition of polyphenols on Pt (McCarley, 1990), in the electrochemical deposition of conductive polymers in particular on iron (Lu et al., 1988; Cheung et al., 1988; Troch-Nagels et al., 1992; Schirmeisen et al., 1989; Beck et al., 1994; Otero et al., 1992; Ferreira et al., 1990; Ferreira et al., 1996; Krstajić et al., 1997; Su et al., 1997; Fraoua et al., 1999).
Two types of methods exist for creating stronger bonds between the metal and the organic layer: in the first type a bond is formed between the organic layer and an oxide on the surface of the metal (Biethan, 1991; Hochberg, 1979; Boenig, 1984; d'Agostino, 2000; Vautrin-Ul et al., 2000), and in the second type, bonds are formed between the metal itself and the organic layer.
Several electrochemical methods already exist which make it possible to attach polymers to metallic surfaces using covalent bonds. Polymer layers can be attached to platinum by oxidation of N-vinylpyrrolidone (Doneux et al., 1997; Calberg et al., 1998). Moreover, the electrochemical oxidation of amines leads to the grafting of —NHR units onto the platinum. By using ω-diamines such as ethylenediamine, it is possible to attach polyethyleneimine to Au, Pt or Al (Herlem et al., 1997; Herlem et al., 2000; Fahys et al., 2002; Herlem et al., 2003; Lakard et al., 2002). However, it should be noted that the methods using the electrochemical oxidation of organic substrates are not applicable to industrial metals which are in general very easy to oxidize. Methods using electrochemical reduction are therefore particularly desirable. One of these methods (Lécayon et al., 1982; Deniau et al., 1992; Viel et al., 1993; Bureau et al., 1994; Tanguy et al., 1993; Tanguy et al., 1994; Tanguy et al., 1996; Deniau et al., 1997; Bureau et al., 1997; Deniau et al., 1998; Charlier et al., 1999; Viel et al., 1999; Jérome et al., 2001; Baute et al., 1999; Mertens et al., 1998; Calberg et al., 1997) involves reducing an active acrylic monomer onto a metallic surface (for example of nickel or iron). The radical-anion formed under anhydrous conditions is responsible for the reaction with the metal and for the continuation of polymerization. A fine layer of polymer (2 to 10 nm) is attached in a covalent manner onto the surface. At the same time, a thicker layer of polymer is only deposited, it can be eliminated by rinsing.
Several methods for grafting preformed polymers onto a functionalized surface ("grafting onto") have already been described making it possible to attach polymers to a polyaryl under-layer obtained by the electrochemical reduction of diazonium salts. The first method consists of grafting onto the metal a benzophenone unit which reacts with the polystyrene under photochemical irradiation; the second method consists of grafting a benzoic acid unit, which can react with magnesium ions and the free carboxylic groups of a polyester deposited mechanically onto the surface (Adenier et al., 2002). A method which is similar to the first two has also been described (Lou et al., 2002), involving grafting polyesters comprising pendant acrylate groups by electrochemistry. The poly-ε-caprolactone thus grafted being miscible with poly(vinyl chloride), the PVC layers thus obtained are strongly adherent.
Several "grafting-from" type methods have been developed which make it possible to make polymers grow from a functionalized surface. On an iron surface, it is possible to carry out the electrochemical grafting of a polyacrylate with a low molar mass the acrylate unit of which contains a chemical function allowing the subsequent polymerization of another monomer. For example, ethyl 2-chloropropionate acrylate allows the initiation of polymerization of the styrene by Atom Transfer Radical Polymerization (ATRP) (Claes et al., 2003), norbornenylmethylene acrylate offers the possibility of polymerizing norbornene by ring opening metathesis polymerization (ROMP) (Detrembleur et al., 2001) and 2-phenyl-2-(2,2,6,6-tetramethyl-piperidin-1-yloxy)-ethylacrylate (PTEA) makes the polymerization of styrene possible, thanks to the presence of alkoxyamine (polymerization initiator) according to the nitroxide mediated process (NMP) (Voccia et al., 2003).

Modified surface material, method for preparing same and uses thereof


Nuclear spin tomography (synonym: magnetic resonance tomography, MRT) is applied in medicine for the purpose of examining patients. A method is proposed for improving the image homogeneity of image data from phase-cycled steady state sequences in magnetic resonance tomography. In the method, both the sum of squares (SOS) and the maximum intensity projection (MIP) are calculated, pixel-wise, from the image data of the participating sequences. Further, a result image optimized with regard to image homogeneity is obtained by pixel-wise combination of the sum-of-squares image and MIP image.

MRT is based on the physical phenomenon of nuclear spin resonance and has been used successfully as an imaging method for over 20 years in medicine and in biophysics. In this examination method, the object is exposed to a strong, constant magnetic field. This aligns the nuclear spins of the atoms in the object, which were previously irregularly oriented. High frequency waves can now excite these "ordered" nuclear spins to a specific oscillation.
In MRT, this oscillation produces the actual measurement signal, which is picked up by use of suitable receiving coils. It is possible in this case by using inhomogeneous magnetic fields produced by gradient coils to code the measurement object in the respective region of interest—also called FOV (Field Of View)—in three dimensions in all three spatial directions, something which is generally denoted as "location coding".
In MRT, the data are picked up in the so-called k domain (synonym: frequency domain). The MRT image in the so-called image domain is linked to the MRT data in the k domain by use of Fourier transformation. The location coding of the object, which defines the k domain, is performed by using gradients in all three spatial directions. A distinction is made here between slice selection (determines a recording slice in the object, usually the z-axis), frequency coding (determines a direction in the slice, usually the x-axis) and phase coding (determines the second dimension inside the slice, usually the y-axis).
Thus, the first step is to excite a slice selectively—for example in the z-direction. The coding of the location information in the slice is performed by a combined phase and frequency coding by way of these two abovementioned orthogonal gradient fields that are produced, in the example of a slice excited in the z-direction, by the gradient coils, likewise already mentioned, in the x- and y-directions.
A possible way of picking up the data in an MRT experiment is based on the so-called true FISP sequence, which is illustrated in FIG. 2. FISP stands for "Fast Imaging with Steady Precession" and is the special form of a gradient echo sequence.
As with conventional imaging sequences, rephasing also takes place here with reference to a slice selection gradient GS, as does preliminary dephasing with reference to a readout gradient GR. This gradient switching compensates the dephasing of the transverse magnetization caused by the gradients, thus producing an echo signal that is denoted as gradient echo. The basic idea is thus that the transverse magnetization is restored after the signal readout and can be used for the next sequence pass.
The echo signal is generated exclusively by gradient reversal.
The repetition time TR is the time after which one HF excitation pulse follows the other. The echo signal follows after time
      T    E    =            T      R        2  and can be acquired by use of a readout gradient GR.
The true FISP signal is distinguished by total symmetry in the time domain, that is to say the gradient profiles are completely balanced
      (                            ∑          i                                              G            i                                                                                t            i                              =      0        )    .All the magnetization components are refocussed again owing to the total symmetry of the gradient profiles in the time domain, and so the ideal steady state signal is produced after a short settling time.
During phase coding, a gradient field is switched on for a fixed time before the acquisition of the steady state signal and after the acquisition, the strength of said gradient field being lowered (↓) or raised (↑) stepwise by an amount ΔGp with each sequence pass.
The true FISP sequence can be carried out with the aid of different HF excitation schemes that differ from one another in a different phase angle of the succeeding high frequency pulse α. The simplest HF excitation scheme is an HF pulse sequence without a phase difference in the HF pulse:. . . α0°−TR−α0°−TR−α0° . . . .
A further HF excitation scheme within the framework of a true FISP sequence is represented by a phase alternation of the HF pulses:. . . α0°−TR−α180°−TR−α0° . . . .
Such a scheme is illustrated by way of example in FIG. 2, the alternation being symbolized by positive and negative amplitudes of the HF pulses. HF pulses with a phase angle of 0° are marked (α+) with a plus sign, while HF pulses with a phase angle of 180° are provided (α−) with a minus sign. Further possible HF excitation schemes would be combinations of HF pulses with phase angles of 0°, 90°, 180°, 270° and/or any desired further values between 0° and 360°, and/or integral multiples thereof.
In the case of relatively complex combinations, the HF pulse (flip angle α) is provided with an index exposing the respective phase angle, for example . . . α0°−TR−α90°−TR−α180°−TR−α270°−TR−α0°− . . . .
True FISP measurements with different HF excitation pulse schemes are also denoted as "phase-cycled steady state sequences" and generally deliver different data records.
The direct sequence of a number of phase-cycled steady state sequences is denoted as a CISS (Constructive Interference in Steady State) sequence. The CISS sequence is used for high-resolution T2 imaging by means of which it is possible, in particular, to measure liquids with very high intensity on the basis of the favorable small T1/T2 ratio.
In general, the CISS sequence is therefore based on the n-fold measurement of a 2D or 3D true FISP data record with a changed HF excitation scheme in each case. A maximum of four different schemes (n=4) are currently used.
The combination of phase-alternating HF pulses with non-phase-alternating HF pulses (n=2) constitutes the simplest case of a CISS sequence. This delivers two different data records S plus-minus (Spm) and S plus-plus (Spp):Spm[ . . . α+−TR−α−−TR−α+− . . . ]Spp[ . . . α+−TR−α+−TR−α+− . . . ],each of these data records per se generally having the typical strip artifacts (signal minima) of a true FISP sequence.
The true FISP sequence alone places high demands on the calibration of hardware and software. Even a slight maladjustment or else local B0-field inhomogeneities lead to disturbing unacceptable interference strips (strip artifacts) in the reconstructed image. The interference (signal extinctions) results in this case from the fact that after being flipped by the excitation pulse α, the magnetization vector precesses by an off-resonance angle β in the rotating reference system during the repetition time TR at various points of the tissue. Depending on the HF excitation scheme, the α pulse is capable of flipping the magnetization vector such that the steady state is maintained, or else the α pulse reduces the steady state to a very small value.
FIG. 3 illustrates this state of affairs for a precession angle β=180° (=π). The magnetization vector {right arrow over (M)} is flipped from point A to point B in the xz-plane by an α+ excitation pulse, for example. During the repetition time, the magnetization vector {right arrow over (M)} precesses back again to A along the dotted circular segment. The vector {right arrow over (M)} can therefore be flipped to B at A by means of a new subsequent α+ excitation pulse. An α− excitation pulse would bring the vector {right arrow over (M)} from point A on the great circle to a position C, and thus lead to an oscillatory behavior with very low equilibrium magnetization.
It is therefore necessary to distinguish as follows:
In a true FISP sequence with phase alternation ( . . . α+−TR−α−− . . . ), signal extinctions occur at the points i, j where the precession angle of the transverse magnetization Mxy={right arrow over (B)}1 yields an angleβij=2πγ·ΔB0ij·TR=πwithin the TR time.
In a true FISP sequence without phase alternation ( . . . α+−TR−α+− . . . ), signal extinctions occur at the points i, j where the precession angle of the transverse magnetization Mxy={right arrow over (B)}1 yields an angleβij=2πγ·ΔB0ij·TR=n·2πwithin the TR time (with n=0, 1, 2, . . . ).
The situation for the two cases is illustrated in FIGS. 4a and 4b. FIG. 4a shows the interference pattern of a true FISP sequence with phase alternation, and FIG. 4b the same without phase alternation. The negative interference (signal extinction black) is produced by a resonance offset β=nπ or β=n2π (n=0, 1, 2, . . . ) relative to the resonant frequency in the rotating reference system during the time TR because of hardware imperfections and/or B0-field inhomogeneities. As can be seen, both patterns are displaced relative to one another by nπ (n=0, 1, 2, . . . ).
The profile of the signal intensity as a function of the off-resonance angle β is illustrated in FIG. 5. The continuous line shows the signal profile of a true FISP sequence without phase alternation with signal extinctions at n 2π (n=0, 1, 2, . . . ). The dashed line shows the signal profile of a true FISP sequence with phase alternation, the signal extinctions exhibiting a periodicity of n π (n=0, 1, 2, . . . ) here.
These "off-resonance artifacts" can be reduced with the aid of suitable manipulation of the complex raw data (for example complex addition and/or subtraction with subsequent fast Fourier transformation FFT, absolute-value generations and renewed addition).
However, the calculation of the sum of squares (SOS) from the respective absolute-value generators Spp and Spm has proved to be simpler and yet still similarly effective:SOSij:=√{square root over ((Sppij)2+(Spmij)2)}{square root over ((Sppij)2+(Spmij)2)}.
A further method is based on the pixel-wise calculation of the maximum intensity projection (MIP) between the two absolute-value generators Spp and Spm:
      MIP    ij    :=      {                                        Spp            ij                                    if                                                    Spm              ij                        ≤                          Spp              ij                                                                        Spm            ij                                    if                                                    Spm              ij                        >                          Spp              ij
The intensity profile of the SOSij values is illustrated in FIG. 6a, and the intensity profile of the MIPij values is illustrated in FIG. 6b (pixel values SOSij and MIPij as a function of β).
Nevertheless, in each case a relatively high residual ripple remains with reference to amplitude (ripple Δ) and location variation δr in the respective result image.

Method for improving the image homogeneity of image data from phase-cycled steady state sequences


As a novel biodegradable metallic material the degradation speed of which in vivo can be controlled over a broad scope while achieving desired mechanical properties such as strength, work hardening and ductility without restricting the shape of an implant device, it is intended to provide a magnesium-based biodegradable metallic material which comprises Mg containing Mg as the major composition and having a concentration of inevitable impurities equal to or less than 0.05 atomic %, is free from precipitates or intermetallic compounds, and has an average grain size being regulated to equal to or less than ¼ of the minimum part of the material.

Conventionally used metal biomedical devices in the medical field are often used for the part of the body that need strength, such as bone and tooth.
The reason is that the metal biomaterials used for such devices have superior mechanical properties to polymeric materials and ceramic materials.
Conventional metallic biomedical devices, such as dental implants, total hip prosthesis, fracture fixation systems, stents, etc. will remain inside of the body until removal thereof by operation etc. after being implanted in the living body, and it is desirable that some of the devices are promptly removed after the restoration of peripheral tissues.
For example, in the case of coronary stents, they become unnecessary after the restoration of damaged vascular tissues by opening of the narrowed area.
However, since the removal needs an open chest surgery and gives large physical, mental, temporal, and financial burden to the patient the coronary stents are left behind inside of the body in most cases.
In such a case, the difference in the mechanical properties between the metallic materials that form the device and the living tissue causes mechanical stimulation at every pulsation of the heart to surrounding vascular tissues of the device, resulting in possible induction of the restinosis by the intimal thickening.
Moreover, removal of the device by reoperation is not often performed in fracture fixation systems. Therefore, metal fixtures having a strength superior to that of the bones will support most of the load and sufficient loads are not applied for the bones, leading to insufficient restoration of the bones.
Under these conditions, biodegradable polymeric or ceramic materials have been proposed.
In some cases, however, the biodegradable polymeric and ceramic materials cannot serve as substitute for metallic biomedical devices in respect of their mechanical properties.
Meanwhile, implant devices composed by biodegradable metallic materials in the living body have been proposed (for example, refer to Patent Documents 1 and 2).    Patent Document 1: PCT National Publication No. 2001-511049    Patent Document 2: Japanese Patent Application Laid-Open No. 2004-160236

Magnesium-based biodegradable metallic material

National Institute for Materials Science


A method of determining the sequence of amino acids that constitute peptides, polypeptides or proteins by mass spectrometry and especially by tandem mass spectrometry is disclosed without the use of any additional data concerning the nature of the peptide and without any limit to the number of possible sequences considered. The method can be implemented on a personal computer typically used for data acquisition on the tandem mass spectrometer even in the case of peptides comprising 10 or more amino acids. The method does not rely on exhaustive comparison of the spectra predicted from every possible amino acid sequence with any molecular weight constraint, but instead uses mathematical techniques to simulate the effect of such a complete search without actually carrying it out.

1. Field of the Invention
This invention relates to methods of determining the sequence of amino acids that constitute peptides, polypeptides or proteins by mass spectrometry and especially by tandem mass spectrometry or MS/MS. In particular it relates to methods whereby the sequence can be determined from the mass spectral data alone and which do not require the use of existing libraries of protein sequence information. Methods according to the invention require no information concerning the nature of the peptide other than a library of the amino acid residues that may occur in proteins weighted according to natural abundance.
2. Discussion of the Prior Art
Although several well-established chemical methods for the sequencing of peptides, polypeptides and proteins are known (for example, the Edman degradation), mass spectrometric methods are becoming increasingly important in view of their speed and ease of use. Mass spectrometric methods have been developed to the point at which they are capable of sequencing peptides in a mixture without any prior chemical purification or separation, typically using electrospray ionization and tandem mass spectrometry (MS/MS). For example, see Yates III (J. Mass Spectrom, 1998 vol. 33 pp. 1-19), Papayannopoulos (Mass Spectrom. Rev. 1995, vol. 14 pp. 49-73), and Yates III, McCormack, and Eng (Anal. Chem. 1996 vol. 68 (17) pp. 534A-540A). Thus, in a typical MS/MS sequencing experiment, molecular ions of a particular peptide are selected by the first mass analyzer and fragmented by collisions with neutral gas molecules in a collision cell. The second mass analyzer is then used to record the fragment ion spectrum that generally contains enough information to allow at least a partial, and often the complete, sequence to be determined.
Unfortunately, however, the interpretation of the fragment spectra is not straightforward. Manual interpretation (see, for example, Hunt, Yates III, et al, Proc. Nat. Acad. Sci. USA, 1986, vol. 83 pp 6233-6237 and Papayannopoulos, ibid) requires considerable experience and is time consuming. Consequently, many workers have developed algorithms and computer programs to automate the process, at least in part. The nature of the problem, however, is such that none of those so far developed are able to provide in reasonable time complete sequence information without either requiring some prior knowledge of the chemical structure of the peptide or merely identifying likely candidate sequences in existing protein structure databases. The reason for this will be understood from the following discussion of the nature of the fragment spectra produced.
Typically, the fragment spectrum of a peptide comprises peaks belonging to about half a dozen different ion series each of which correspond to different modes of fragmentation of the peptide parent ion. Each typically (but not invariably) comprises peaks representing the loss of successive amino acid residues from the original peptide ion. Because all but two of the 20 amino acids from which most naturally occurring proteins are comprised have different masses, it is therefore possible to establish the sequence of amino acids from the difference in mass of peaks in any given series which correspond to the successive loss of an amino acid residue from the original peptide. However, difficulties arise in identifying to which series an ion belongs and from a variety of ambiguities that can arrive in assigning the peaks, particularly when certain peaks are either missing or unrecognized. Moreover, other peaks are typically present in a spectrum due to various more complicated fragmentation or rearrangement routes, so that direct assignment of ions is fraught with difficulty. Further, electrospray ionization tends to produce multiply charged ions that appear at correspondingly resealed masses, which further complicates the interpretation of the spectra. Isotopic clusters also lead to proliferation of peaks in the observed spectra. Thus, the direct transformation of a mass spectrum to a sequence is only possible in trivially small peptides.
The reverse route, transforming trial sequences to predicted spectra for comparison with the observed spectrum, should be easier, but has not been fully developed. The number of possible sequences for any peptide (20n, where n is the number of amino acids comprised in the peptide) is very large, so the difficulty of finding the correct sequence for, say, a peptide of a mere 10 amino acids (2010=1013 possible sequences) will be appreciated. The number of potential sequences increases very rapidly both with the size of the peptide and with the number (at least 20) of the residues being considered.
Details of the first computer programs for predicting probable amino acid sequences from mass spectral data appeared in 1984 (Sakurai, Matsuo, Matsuda, Katakuse, Biomed. Mass Spectrom, 1984, vol. 11 (8) pp 397-399). This program (PAAS3) searched through all the amino acid sequences whose molecular weights coincided with that of the peptide being examined and identified the most probable sequences with the experimentally observed spectra. Hamm, Wilson and Harvan (CABIOS, 1986 vol. 2 (2) pp 115-118) also developed a similar program.
However, as pointed out by Ishikawa and Niwa (Biomed. and Environ. Mass Spectrom. 1986, vol. 13 pp 373-380), this approach is limited to peptides not exceeding 800 daltons in view of the computer time required to carry out the search. Parekh et al in UK patent application 2,325,465 (published November 1998) have resurrected this idea and give an example of the sequencing of a peptide of 1000 daltons which required 2xc3x97106 possible sequences to be searched, but do not specify the computer time required. Nevertheless, despite the increase in the processing speed of computers between 1984 and 1999, a simple search of all possible sequences for a peptide of molecular weights greater than 1200 daltons is still impractical in a reasonable time using the personal computer typically supplied for data processing with most commercial mass spectrometers.
This problem has long been recognized and many attempts have been made to render the problem more tractable. For example, the MS/MS spectrum may be correlated with amino acid sequences derived from a protein database rather than every possible sequence. Such methods are taught in PCT patent application 95/25281, by Taylor and Johnson (Rapid Commun. in Mass Spectrom. 1997 vol. 11 pp 1067-1075, by Eng. McCormack, Yates in J. Am. Mass Spectrom. 1994 vol. 5 pp 976-989, by Figeys, Lock et al. (Rapid Commun. in Mass Spectrom. 1998 vol. 12 pp 1435-1444), and by Mortz, O""Connor et al (Proc. Nat. Acid Sci. USA 1996 vol. 93 pp 8264-8267). Alternatively, MS/MS experiments can be carried out on both the original peptide and a derivative of it, and the results from both experiments combined to establish at least a partial sequence without reference to a database. (See, for example, the isotopic labeling method taught by Shevchenko, Chernushevich et al in Rapid Commun. in Mass Spectrom, 1997 vol. 11 pp 1015-24, or the esterification method taught by Yates III, Griffin and Hood in Techniques in Protein Chem. II, ch 46 (1991) pp 477-485), and the H2/D2 exchange method taught by Septov, Issakova et al in Rapid Commun. in Mass Spectrom. 1993 vol. 7 pp 58-62. Johnson and Walsh (Protein Science, 1992 vol. 1 pp 1083-1091) teach a similar method, combining Edman degradation data and MS/MS data.
Of the prior programs which attempt to predict sequence information using only MS/MS data and without reference to existing databases, a variety of methods have been suggested to facilitate the prediction of sequence information. Siegel and Bauman (Biomed. Environ. Mass Spectrom. 1998 vol. 15 pp 333-343) describe an algorithm which builds up the sequence information stepwise from the mass difference between neighbouring ions in ion series recognized in the spectrum, but good results were obtained only with peptides of a few amino acids. Zidarov, Thibault et al. (Biomed. and Environ. Mass Spectrom, 1990 vol. 19 pp 13-26) proposed an algorithm which first attempted to derive the amino acid composition of the peptide from molecular weight and isotopic ratio data, and subsequently to sequence the peptide using a stepwise approach considering all possible sequences for the amino acids so identified. The program SEQPEP (Johnson and Biemann, Biomed and Environ. Mass Spectros. 1989 vol. 18 pp 945-957) identified short sub-sequences of amino acids in a peptide and then extended the sequence outwards from the ends of the sequence, attempting to correlate other peaks in the spectra with more amino acid residues, until the molecular weight of the peptide was reached. Bartels (Biomed. and Environ. Mass Spectrom, 1990 vol. 19 pp 363-368) recognized this search strategy as a problem in graph theory, and the method was further developed by Fernandez-de-Cossio et al (CABIOS, 1995 vol. 11 (4) pp 427-434). These methods calculated a score for trial sequences based on the number of peaks in the experimental spectrum that they fit. Unfortunately, peptides fragment in idiosyncratic fashion, and global scores such as theirs do not perform well. Hines, Falik, et al (J. Am. Soc. Mass Spectrom 1992 vol. 3 pp 326-336) have described a sequencing program which uses pattern recognition techniques to identify groups of peaks in an observed spectrum and subsequently to predict the amino acid sequence. Delgada and Pulfer (J. Chem. Inf. Computer Sci. 1993 vol. 33 pp 332-337) describe a similar pattern recognition algorithm which uses learning machine techniques, also applied to observed spectra. Scarberry, Zhang and Knapp (J. Am. Soc. Mass Spectrom, 1995 vol. 6 pp 936-946) report the application of artificial neural networks to classify the peaks in observed peptide MS/MS spectra followed by sequence determination of the series of peaks so identified.
The following difficulties are inherent in these prior sequencing algorithms. Those that are limited to searching existing databases to identify a peptide or protein will clearly fail if the sequence is in fact unknown at the time. Those that attempt to sequence in a stepwise manner will fail if the spectrum does not contain a significant peak at a mass corresponding to a particular amino acid loss, and the likelihood of this increases rapidly as the number of amino acids comprised in the peptide increases. Those that require the analysis of derivatives of the peptides to resolve ambiguities are clearly less desirable than those which purport to provide the sequence without such derivatives. Those that eliminate groups of possible sequences early on in the sequencing process on the basis of a single test in order to rapidly reduce the number of possibilities to a more manageable level frequently fail to suggest even a low probability for the correct sequence because it has been incorrectly eliminated due to failure of that test. This may arise due to an incorrect assignment of a peak to a series, a smaller than expected peak intensity, or slightly inaccurate mass measurement. Those that require additional information, such as a partial sequence, will fail if that information is in fact incorrect or unavailable. Those that attempt to recognize patterns in the observed data are heavily dependent on a precise understanding of the fragmentation mechanisms which determine the nature of the spectrum, and the complexity of the processes involved is such that universally applicable rules cannot at present be formulated. Thus, the resurrection in GB 2,325,465 of the xe2x80x9cde-novoxe2x80x9d approach of Sakurai et al, Ishikawa, et al and Hamm et al (ibid.) whereby all possible sequences are compared with the observed data without eliminating any possibilities nor relying on a machine interpretation of chemical rules is clearly desirable. However, GB 2,325,465 does not advance the art in practice and merely restates the earlier techniques.
Thus, there is no prior teaching of a xe2x80x9cde-novoxe2x80x9d peptide sequencing method for MS/MS spectra which is capable of handling the data from peptides of more than about ten amino acids. Full searches take too long on the computer typically used to process data generated by the mass spectrometer used to obtain the MS/MS data.
It is an object of the present invention to provide a method of sequencing a peptide either individually or comprised in a mixture of peptides, by tandem mass spectrometry without the use of any additional data concerning the nature of the peptide and without any limit to the number of possible sequences considered. It is a further object to provide such a method which can be implemented on a personal computer typically used for data acquisition on the tandem mass spectrometer, even in the case of peptides comprising 10 or more amino acids. It is another object to provide such a method which does not rely on exhaustive comparison of the spectra predicted from every possible amino acid sequence consistent with any molecular weight constraint, but instead uses mathematical techniques to simulate the effect of such a complete search without actually carrying it out.
In accordance with these objectives the invention provides a method of identifying the most likely amino acid sequences which would account for a mass spectrum obtained from a peptide of unknown sequence, said method comprising the steps of:
a) Producing a processable mass spectrum from said peptide;
b) Choosing a limited number of trial amino-acid sequences which are consistent with a prior probability distribution;
c) Iteratively modifying said trial sequences through a terminated Markov Chain Monte Carlo (MCMC) algorithm to generate new trial sequences, using at each stage modifications which lie within said prior probability distribution, calculating the probability of each of said trial sequences accounting for said processable mass spectrum, and accepting or rejecting each of said trial sequences according to said probability and the mathematical principle of detailed balance.
In preferred methods, the probability of a particular trial sequence accounting for the processable mass spectrum is estimated using Bayes"" theorem. A prior probability is assigned to the sequence and is multiplied by a likelihood factor that reflects the degree of agreement between a spectrum predicted for that sequence and the processable mass spectrum. This process is represented by the equation
Probability (trial sequence AND processable spectrum)=Prior (trial sequence)xc3x97Probability (processable spectrum GIVEN trial sequence)
Conveniently, the term
Prior (trial sequence)
may be determined from the natural (or other) abundance of each of the amino acid residues comprised in the trial sequence. The term
Probability (processable spectrum GIVEN trial sequence)
is the likelihood factor and may be determined using a fragmentation model that sums probabilistically over all the ways in which a trial sequence might fragment and give rise to peaks in the processable mass spectrum.
In one preferred embodiment, the limited number of trial amino-acid sequences chosen in step b) may comprise about 100 members chosen pseudo-randomly from the prior probability distribution. This distribution may comprise sequences based on a library of the 20 most common amino acid residues, but it is within the scope of the invention to include less common or presently unknown residues. The distribution embodies rough preliminary information about the nature of the unknown peptide sample, but its determination may require only minimal information about the sample. For example, it may be sufficient that trial sequences chosen from it are chemically plausible and not of such length that they obviously could not represent the sample. The amino acid composition of the sample, if known, may also suffice. In preferred methods, however, the distribution may be constrained by the approximate molecular weight of the sample, for example within xc2x15 daltons, or most preferably within xc2x10.5 daltons if it is known sufficiently accurately. In general, the more constraints that can be placed on the prior probability distribution, the faster will be the computation and the more tightly constrained will be the most probable sequences for the unknown peptide.
It will be understood that in the initial stages of the process the trial sequences may bear little resemblance to the actual sequence of the unknown peptide. In order to ensure a gentle convergence to the most probable sequences, in further preferred methods the contribution of the likelihood factor to the probability score may be controlled by simulated annealing. Typically, the likelihood factor may be raised to a fractional power which is initially zero and is gradually increased as the algorithm progresses so that the experimental data is given gradually increasing significance.
A further advantage in the use of simulated annealing is that the algorithm employed can indicate when a sufficient number of trial sequences have been tested, so that the generation of trial sequences may be terminated automatically. The simulated annealing algorithm may itself, on the basis of the probabilities assigned to previously tested sequences, determine the fractional power to be currently applied to the likelihood factors of the current trial sequences. Thus in further preferred embodiments of the invention the generation and testing of new trial sequences is continued until the simulated annealing algorithm sets to the correct value (unity) the power to which the likelihood factors are raised.
According to the invention, a Markov Chain Monte Carlo algorithm generates new trial amino-acid sequences. Use of such an algorithm allows the most probable sequences to be identified without the need to test every possible sequence of amino acids that might, for example, account for the observed molecular weight range of the unknown peptide. In order to achieve maximum efficiency, the changes made to the trial sequences should preferably be made in a chemically meaningful manner, rather than purely randomly. Thus, in further preferred embodiments of invention, the Markov Chain Monte Carlo algorithm may modify a trial sequence in at least some, and preferably all, of the following ways:
a) Reversing a contiguous sub-sequence with randomly chosen end points, for example a sequence . . . ARQEIK . . . may be changed to . . . KIEQRA . . .
b) Cycling a contiguous sub-sequence with randomly chosen end points, for example . . . ARQEIK . . . may be changed to . . . QEIKAR . . .
c) Permuting a contiguous sub-sequence with randomly chosen end points, for example a sequence . . . ARQEIK . . . may be changed to . . . IQRKAE . . .
d) Replacing a contiguous sub-sequence with randomly chosen end points with another sub-sequence of approximately the same nominal mass, for example . . . NEQ . . . may be replaced by . . . EKGG . . .
e) Exchanging the C-terminus and N-terminus ends of two sequences to preserve nominal mass, for example the sequences EKGG-DQCYKR and NEH-YKDQCR may be changed to NEH-DQCYKR and EKGG-YKDQCR.
It will be appreciated that this list of possible mutations is not exclusive and many others may be included in the Markov Chain Monte Carlo algorithm. However, to minimize the danger of the algorithm failing to explore all the regions of high probability of the trial sequences accounting for the processable mass spectrum, it is desirable that at least one xe2x80x9cgenetic algorithmxe2x80x9d, as exemplified by the mutation e) above, is included. In accordance with the Markov Chain Monte Carlo method, the choice of which mutations to make to a particular sequence may be determined by a pseudo-random number generator.
In still further preferred methods, a novel fragmentation model, which sums probabilistically over all the ways in which a trial sequence might fragment to give rise to peaks in the processable mass spectrum, is employed. Such a model may be based on the production of at least two series of ions, the b series (which comprises ions representing the N-terminal residue of the trial sequence and the loss of C-terminal amino acid residues), and the yxe2x80x3 series (which comprises ions representing the C-terminal residue and the loss of N-terminal amino acid residues). Each family of ions behaves as a coherent series, with neighbouring ions likely to be either both present or both absent. This behaviour may be described by a Markov chain, in which the probability of an ion being observed is influenced by whether or not its predecessor was observed. The parameters of the chain may be adjusted to take account of the proton affinities of the residues and their physical bond strengths. The fragmentation model may be refined by including other ion series, particularly the a series (b ions which have lost CO), the zxe2x80x3 series (yxe2x80x3 ions which have lost NH3), and the more general loss of NH3 or H2O, again taking account of the probability of the chemical processes involved. Immonium ions equivalent to the loss of CO and H from the various amino acid residues may also be included. Further, the fragmentation model may comprise the generation of sub-sequences of amino acids, that is, sequences that begin and end at amino acid residues internal to the unknown peptide. It will be appreciated that the more realistic is the fragmentation model, the better will be the accuracy and speed of the computation of the most probable sequences. It is theirfore envisaged that different fragmentation models may be employed if advances are made in understanding the chemical mechanism by which the mass spectrum of the petide is produced.
Using Marov chains to model the fragmentation process allows the sum over all the possible fragmention patterns to be calculated in liner time (ie, in a time proportional to the number of animo acid residues in the peptide) rather than in a time proportional to the exponentially large number of fragmentation patterns themselves. This allows the time taken for the prediction of the most probable sequences to be reduced to a practical value (that is, a minute or so), even for peptides of 10 or more amino acids, using a typical personal computer. However, it will be appreciated that the invention is not limited to the particular fragmentation model described above, but includes any probabilistic fragmentation model that can be integrated computationally in polynomial time. The result of applying such a model is a probabilistic likelihood factor
Probability(processable spectrum GIVEN trial sequence)
that can be used in the Markov Chain Monte Carlo algorithm.
Although in certain simple cases the processable mass spectrum may simply be the observed mass spectrum, it is generally preferable to convert the observed spectrum into a more suitable form before attempting to sequence the peptide. Preferably, the processable spectrum is obtained by converting multiply-charged ions and isotopic clusters of ions to a single intensity value at the mass-to-charge ratio corresponding to a singly-charged ion of the lowest mass isotope, and calculating an uncertainty value for the actual mass and the probability that a peak at that mass-to-charge ratio has actually been observed. Conveniently, the uncertainty value of a peak may be based on the standard deviation of a Gaussian peak representing the processed peak and the probability that a peak is actually observed may be related to the signal-to-noise ratio of the peak in the observed spectrum. The program xe2x80x9cMaxEnt3(trademark)xe2x80x9d available from Micromass UK Ltd. may be used to produce the processable spectrum from an observed spectrum.
It will be appreciated that a fragmentation model as described may be used to calculate the probability of any trial sequence of amino acids accounting for a given mass spectrum, irrespective of how that trial sequence has been derived. Viewed from another aspect, therefore, the invention comprises a method of calculating the probability that an experimentally determined mass spectrum of a peptide or a similar molecule may be accounted for by a given sequence of amino acids by the use of a fragmentation model which sums probabilistically over all the ways that said given sequence might fragment. Preferably, the fragmentation model may model the fragmentation of the sequence by means of Markov chains in the manner described above. Also preferably, the experimentally determined mass spectrum is a processable spectrum, obtained in the manner described above. For example, a fragmentation model according to the invention may be used to calculate the probability of amino acid sequences comprised in an existing protein or peptide database accounting for an experimentally observed mass spectrum of a peptide. In this way the peptide, and/or the protein from which it is derived, may be identified. Conveniently, in such a method, only sequences or partial sequences having a molecular weight in a given range are selected from the database for input to the fragmentation model.
In order to carry out the methods of the invention a sample comprising one or more unknown peptides may be introduced into a tandem mass spectrometer and ionized using electrospray ionization. The molecular weights of the unknown peptides may typically be determined by observing the molecular ion groups of peaks in a mass spectrum of the sample. The first analyzer of the tandem mass spectrometer may then be set to transmit the molecular ion group of peaks corresponding to one of the unknown peptides to a collision cell, in which the molecular ions are fragmented by collision with neutral gas molecules. The second mass analyzer of the tandem mass spectrometer may then be used to record an observed fragmentation mass spectrum of the peptide. A processable mass spectrum may then be derived from the observed spectrum using suitable computer software, as explained. If the sample comprises a mixture of peptides, for example as might be produced by a tryptic digest of a protein, further peptides may be analyzed by selecting the appropriate molecular ion group using the first mass analyzer.
Viewed from another aspect the invention provides apparatus for identifying the most likely sequences of amino acids in an unknown peptide, said apparatus comprising a mass spectrometer for generating a mass spectrum of a said unknown peptide and data processing means programmed to:
a) Process data generated by said mass spectrometer to produce a processable mass spectrum;
b) Choose a limited number of trial amino acid sequences that are consistent with a prior probability distribution;
c) Iteratively modify said trial sequences through a terminated Markov Chain Monte Carlo algorithm to generate further trial sequences which are consistent with said prior probability distribution, to calculate the probability of each of said trial sequences accounting for said processable mass spectrum and to accept or reject each of said trial sequences according to said probability and the mathematical principle of detailed balance.
In preferred embodiments, apparatus according to the invention comprises a tandem mass spectrometer, and most preferably a tandem mass spectrometer that comprises a Time-of-Flight mass analyzer at least as its final stage. A Time-of-Flight mass analyzer is preferred because it is generally capable of greater mass measurement accuracy than a quadrupole analyzer. Preferably also the mass spectrometer comprises an electrospray ionization source into which an unknown peptide sample may be introduced.

Method of determining peptide sequences by mass spectrometry


An information distribution method for sending similar information from a sending node to all of receiving nodes in a given state in a dense wireless network. The sending node sends, only one time, information including status data directly to all of receiving nodes in an area where communication with the sending node is possible, not via a node other than the respective receiving nodes. Thereafter, the sending node determines whether or not any record corresponding to a receiving node to which the information should be sent is left in a distribution list. Only when it is determined that any record corresponding to a receiving node is left in the distribution list, the sending node sends information similar in content to the information sent in the directly sending step to the receiving node corresponding to the record left in the distribution list by using a unicast protocol.

1. Field of the Invention
The present invention relates to a method of distributing information in a wireless network, and more particularly to a technique for reducing the load on a wireless network in sending similar information to a number of nodes.
2. Description of the Related Art
In conventional wireless networks, a number of nodes located in the coverage area send and receive information to and from each other. When a sending node sends information to receiving nodes in a given state (for example, nodes that are moving at a speed of more than 80 km per hour) in such a wireless network, the sending node generally sends the information to each of the receiving nodes by using a unicast protocol, i.e., by specifying the respective addresses of the receiving nodes. However, where there are a large number of receiving nodes in the given state in the wireless network, the above method requires the sending node to repeat sending of the information the number of times corresponding to the number of the receiving nodes in the given state. This may cause increased traffic in the wireless network, thus resulting in increased load on the wireless network.
Multicast protocols (such as DVMRP, MOSPF, and so on) common in wired networks tend to involve a large number of packets for path control and involve long data headers. Therefore, if such a multicast protocol is used for sending and receiving information in a dense wireless network (having one hundred or more nodes in the coverage area), the wireless network may be congested due to the path control packets to have a heavy load. Accordingly, using the multicast protocols cannot solve the above described problem.
Japanese laid-open patent publication 2003-158548 discloses a packet sending/receiving system that achieves flexible and effective multicast when a terminal knows the logical device addresses of all other terminals that can communicate with the terminal itself as well as knowing the logical device address of the terminal itself. However, even with this technique, the above described problem cannot be solved.

Wireless network information distribution method


A content management apparatus includes a content storage section configured to store a piece of content together with a content unique identifier; a content transmitter configured to transmit the piece of content together with the content unique identifier to a Web server; an intra-server management identifier receiver configured to receive an intra-server management identifier corresponding to the content unique identifier from the Web server; a management table for storing the content unique identifier and the intra-server management identifier; a content information updating message receiver configured to receive content information on the piece of content and a content information updating message containing the intra-server management identifier from the Web server; an identifier converter configured to convert the intra-server management identifier contained in the content information updating message into the content unique identifier; and a content management section configured to allow the content storage section to store the content information.

1. Field of the Invention
The present invention relates to a content management apparatus. More particularly, the present invention relates to a content management apparatus for managing searches for information on content, to a Web server and a network system, which are used with the content management apparatus, to a processing method for use with the content management apparatus, the Web server, and the network system, and to a program for enabling a computer to perform such a processing method.
2. Description of the Related Art
In digital still cameras in recent years, comments regarding impressions, recollections, and the like of a user can be attached to many captured images so that they can be classified. An apparatus for managing content of such images is referred to as a content management apparatus. Examples of the content management apparatus include, in addition to a digital still camera, a personal computer, and the like.
It is possible for the content management apparatus to search for a keyword in a comment and extract target content. Usually, in such a case, it is assumed that a user has already input a comment in advance for each piece of content. As an example of such an apparatus of the related art, an album creation apparatus using a comment that has been input by a user has been proposed (refer to, for example, Japanese Unexamined Patent Application Publication No. 2003-85265 (FIG. 1)).

This patent is subject to a terminal disclaimer.

Content management apparatus, web server, network system, content management method, content information management method, and program


A pressure sensor apparatus having capability of preventing invasion of foreign materials into a pressure sensor with a simplified structure includes the pressure sensor (1) for detecting pressure of a fluid for measurement, and a sensor container (2) for housing therein the pressure sensor (1). The sensor container (2) is connected to a pressure intake port (13) formed in a pipe (12) through which the fluid for measurement flows. The sensor container (2) includes a wall (17) for defining a second compartment (16) located in opposition to the pressure intake port (13) and a first compartment (15) having a pressure introducing port (14) for introducing the fluid for measurement extracted through the pressure intake port (13) to the pressure sensor (1).

1. Field of the Invention
The present invention relates to a pressure sensor apparatus for detecting or measuring a pressure of an object or fluid whose pressure is to be detected or measured such as, for example, a pressure sensor apparatus mounted on an intake manifold of an intake system of an internal combustion engine for detecting the intake air pressure. Hereinafter, the object or fluid whose pressure is to be detected or measured will be referred to as the fluid for measurement only for the convenience of description.
2. Description of Related Art
Heretofore, such pressure sensor apparatus is known in which invasion of foreign materials into a pressure sensor constituting a major part of the pressure sensor apparatus is prevented by providing a barrier plate for causing the foreign materials to flow around the pressure sensor. In this connection, reference may have to be made to, for example, Japanese Patent Application Laid-Open Publication No. 30535/1999 (JP-A-1999-30535) (FIG. 1).
In the pressure sensor apparatus mentioned above, invasion of the foreign materials into the pressure sensor can certainly be prevented by providing the barrier plate. However, to this end, it is required to prepare a dedicated barrier plate, which gives rise to a problem that the manufacturing cost of the pressure sensor apparatus is correspondingly increased, to a disadvantage.

Multi-compartment pressure sensor housing apparatus


An optical transmission system and optical transmission devices in the optical transmission system that can achieve a high quality transmission using considerably simple arrangements are disclosed. At a transmitting-end optical transmission device, encoding means having n outputs, forms k data by aligning phases of data on k channels with each other and for generating (n−k) error correction bits for said k data and adding said (n−k) error correction bits to said k data, and wavelength-multiplexing means connected to the encoding means, converts both said k data and said (n−k) error correction bits to n optical signals having different wavelengths and for wavelength-multiplexing said n optical signals so as to be delivered to the optical transmission line. At a receiving-end optical transmission device, wavelength-demultiplexing means separates the wavelength-multiplexed optical signals from the optical transmission line into n optical signals, each corresponding to one of the different wavelengths, and decoding means connected to the wavelength-multiplexing means, generates k error corrected data by correcting error bits using the (n−k) error correction bits contained in said n separated optical signals.

1. Field of the Invention
The present invention generally relates to an optical transmission system that can be applicable to a long distance, high capacity transmission.
The present invention also relates to optical transmission devices, such as a transmitter and a receiver for the optical transmission system.
Such types of high capacity transmission systems using optical signals have been developed and designed so as to be adapted to multimedia applications. Many TDM (Time Division Multiplexing) transmission systems or WDM (Wavelength Division Multiplexing) transmission systems have been known. Typically, those systems have been intended to efficiently make use of a transmission line. In these high capacity transmission systems, it is particularly demanded that a reliable transmission can be achieved.
Therefore, the present invention relates to, in particular, the optical transmission system that has their transmission reliability been improved and the optical transmission device used in this system.
2. Description of the Related Art
A conventional wavelength-multiplexing transmission system includes an optical transmitter 201, an optical transmission line 203 and an optical receiver 202, as schematically shown in FIG. 1, and the system is in conformity with SDH (Synchronous Digital Hierarchy) that is a set of international, digital transmission standards. The optical transmitter 201 has, for each of k channels CHi (i=1, . . . , k), individually an SOH (Section Over Head) inserting unit 204 for inserting an SOH, an electrical-optical converter (OS) 205 and a wavelength-multiplexer 206. The optical receiver 202 also has, for each of the k channels, individually a wavelength-demultiplexer 207, an optical-electrical converter (OR) 208 and an SOH terminating unit 209.
The SOH inserting unit 204 at the optical transmitter 201 inserts the SOH into an electrical signal for one of the corresponding channels CHi. Each electrical signal for the every channel is then provided to the optical-electrical converter 205 and converted to an optical signal with a wavelength λi corresponding to the channel CHi. The optical signals having the wavelength of λi are multiplexed by the wavelength-multiplexer 206 and resulting wavelength-multiplexed signals are transmitted to the optical transmission line 203.
The wavelength demultiplexer 207 at the optical receiver 202 separates the multiplexed signals received from the optical transmitter 201 through the optical transmission line 203 into the signals corresponding to the wavelengths λ1 to λk, respectively. These optical signals having the wavelength of λ1 to λk, respectively, are converted to corresponding electrical signals by the optical-electrical converter 208, and then the SOH of the electrical signals is terminated by the SOH terminating unit 209. The electrical signals having their SOH terminated are transmitted to a further stage (not shown in FIG. 1) on an each i.e., (individual) channel basis. Thus, the data comprising the electrical signals for each of the channels CH1 to CHk can be transmitted from the optical transmitter 201 to the optical receiver 202 over the signal optical transmission line 203.
Several error correction techniques have been also proposed in order to improve a transmission quality by correcting transmission errors involved in the transmitted data. For example, one of the known techniques, also called an "FEC (Forward Error Correction)" method, consists in generating and adding an error correction bit to the data representing one frame or the data of a predetermined length and performing the error correction at a receiver side.
Adding a parity bit to the transmitted data is also a common technique used for determining a presence/absence of the transmission error within the transmitted data. In this case, the SOH may be also provided with error monitoring bits, named B1 and B2.
The earlier described error correction techniques consist in, for every frame or every block of the transmission data, generating an error correction bit and adding it to each frame or block. Therefore, in contrast with a transmission system without correcting transmission errors, the conventional transmission system provided with the error correction technique has to increase a transmission rate, because a number of bits to be transmitted are increased. Alternatively, if the transmission rate is set to a predetermined value, the transmission system should reduce an amount of the transmission data so that the error correction bit can be transmitted together with the transmission data within the predetermined transmission rata.
Furthermore, in some of the conventional transmission systems, erroneous bits included in the transmission data cannot be corrected when parity bits are contained in the data. One solution for improving a capability of correcting the erroneous bits in the data is to increase the number of the error correction bits added to the transmission data. However, this solution may be not practical, because a considerably high transmission rate is required for increasing the number of error correcting redundant bits to be added to the transmission data.
Another possible solution is to insert the error correction bits into reserved bits within the SOH. The reserved bits means that those bits are reserved for a variety of future applications. In this case, since a lot of redundant bits are to be inserted into some particular locations in the SOH, a problem may occur that a size of a circuit comprising a transmission device, such as the transmitter 201 and the receiver 202, is enlarged. This solution has a further drawback in that the error correction bits, which have been already assigned to the reserved bits, cannot be made use of, if the reserved bits are decided to be used for one of the future appiications.

Optical transmission system and optical transmission device


A system for forming a looped suture having a tapered cut is provided. The system includes a base for selectively retaining a portion of thread, a clamping device for receiving a first end of the thread, a tensioning device for receiving a second end of the thread, a welding assembly configured to join a first and second section of the thread to form a loop, and a cutting assembly configured to form a tapered end on the first section of the thread.

1. Technical Field
The present disclosure relates to a method of forming a looped suture. More particularly, the present disclosure relates to a method of forming a looped suture having a tapered surface.
2. Background of Related Art
A method for forming a loop in a suture during a wound closing procedure (surgery) is known. It would be beneficial to have a system and method for more effectively forming a loop on a suture prior to engagement of tissue with the suture. It would be further beneficial if the system and method could form a tapered end on the loop.

System and method of making tapered looped suture


A transparent mobile handset housing with graphical elements such as alphanumeric characters, icons, and logos positioned directly onto the housing with visibility enhanced through backlighting. The transparent housing is covered with an opaque coating and omitted portions of the opaque coating form a negative image of the graphical elements, or the housing is left transparent and opaque graphical elements are coated onto the housing. A backlighting source from within the housing, such as an array of light emitting diodes or an electroluminescent panel, provides illumination to the housing. In the case of negatively imaged graphical elements, the graphical elements are illuminated. In the case of opaque graphical elements, the surrounding transparent housing is illuminated.

1. Field of the Invention (Technical Field)
The present invention relates to accentuating graphical elements on a housing, in particular to icons, alphanumeric characters, and logos located on a mobile handset housing.
2. Background Art
Mobile telephone handsets typically comprise a rigid housing enclosing a printed circuit board, the associated electronic and electro-acoustic components, and an antenna, through which radio frequency (RF) signals are transmitted and received. The telephone user interfaces with the circuitry and microprocessor of the telephone through a keypad located on the front outer surface of the housing. This keypad is often located on the same face of the housing as the microphone and speaker through which the user speaks and listens during communication. Keys on the keypad are pressed by the user to temporarily close an internal switch and send a signal to the microprocessor of the telephone where an appropriate routine processes the input and performs the desired function. Graphical elements, including alphanumeric characters and icons, are located on or adjacent the keys to guide the user in interfacing with the telephone. For example, the numbers 0-9 may be located on the keys, as well as letters of the alphabet, the pound and asterisk signs, and a variety of menu navigation symbols. A display above the keypad on the telephone housing often provides menus, messaging, and readouts of data input by the user. Further, the manufacturer of the telephone or the service provider may provide one or more logos on the housing to build brand awareness. Accordingly, it is important that the logo be prominently positioned to increase user perception. However, due to the physical space constraints on a mobile handset, the logo or logos may be of limited size and perceptibility. Also, the logos are merely printed on or attached to the housing, so are not visible in a darkened environment.
In order to enhance visibility of the alphanumeric characters or icons located on the keys of the keypad, lighting is often provided from behind the keypad and within the telephone housing to illuminate either the graphical elements on the keys or the keys themselves. Backlighting is typically provided from an array of light emitting diodes (LEDs) or an electroluminescent (EL) panel located directly behind the keypad. Each LED may be located behind a particular key or the array may be located generally behind the keypad to provide diffuse lighting. This type of backlighting illuminates the keypad material surrounding the graphics in the case where the graphics are more opaque than the keys of the keypad, for example, when the graphics are black and the keys are white. Alternatively the backlighting illuminates the graphics in the case where the keys are opaque in comparison to the graphics, for example, when the graphics are white and the keys are black. The LED array is powered from the power supply for the telephone electronics, which is typically a battery, and is illuminated upon activation of the telephone, such as when the user turns on the telephone, when a call is made, or when a call is answered.
The prior art method of placing graphics on the keys of a telephone limits the graphics configuration available to the telephone manufacturer to that on the keypad designed for its telephones. For example, only a very limited amount of information may be positioned on a typical key. Further, when graphics are located on the keypad, they are constantly being contacted by the user's fingertips when interfacing with the telephone potentially causing wear and fading of the graphics. This inhibits the user's ability to view the graphics and limits the useful life of the telephone. Also, when user interface graphics are located only on the keys, the keys must be made of a material than can be illuminated to enhance the visibility of the graphics.

Method and apparatus for accentuating graphical elements on a mobile handset housing


Improved apparatuses and methods are provided for ionizing samples and analyzing the samples with mass spectrometry.

Mass spectrometry is an important tool in the analysis of components (or "analytes") in a sample. In a mass spectrometric analysis, a sample has to be ionized to generate ions of the analytes; the ions are then separated based on their mass-to-charge ratios by a mass analyzer, and detected by a detector. There are many different techniques for ionizing samples, such as electrospray ionization (ESI), chemical ionization (CI), photoionization (PI), inductively coupled plasma (ICP) ionization, and matrix assisted laser desorption ionization (MALDI). Although all the techniques listed above share a common aspect, that a solid or liquid sample must be converted to a plume of molecules, atoms or ions, their mechanisms of ionization differ. As a result, the compounds that can be ionized by each of these techniques are not identical.
In the earliest implementation of electrospray, a sample plume was sprayed into a high electrical field without pneumatic or ultrasonic nebulization. This is referred to as "pure electrospray." Pure electrospray had the problem of low flow capabilities (0.1 to 10 μl per minute). Therefore, it was difficult to use pure electrospray with liquid chromatography (LC), which has a much higher flow rate (typically up to 2 ml per minute). When the electrospray flow rate is above 100 μl per minute, it is usually impossible to maintain a sample plume, due to unstable spray formation. The ionization efficiency of pure electrospray thus decreases at higher flow rates, and sensitivity is completely lost at typical chromatographic flow rates. Therefore, the interface between LC and pure electrospray routinely splits the sample flow by a factor of 10 or more, sacrificing sensitivity, resolution and reproducibility.
The development of pneumatically assisted electrospray (or "ion spray"; see, e.g., U.S. Pat. No. 4,861,988) alleviated the flow limitation to some extent. This technique employs a concentric nebulizing gas around the central liquid delivery capillary, and enables a flow rate up to several hundred micro liters per minute, with a moderate loss of sensitivity. As discussed below, various improvements have been made to this technique.
A few years after U.S. Pat. No. 4,861,988, a heater was mounted directly on the pneumatic sprayer to assist ionization with heat and heated gas. This thermally assisted electrospray interface improved sensitivity by three times, and a flow rate of up to 500 μl per minute was demonstrated (U.S. Pat. No. 4,935,624). However, the heated nebulizer was prone to sample degradation and clogging, due to difficulty of regulating the temperature at the tip of the nebulizer.
Another implementation (Vestal, 1992) used moderately heated concentric air to assist ion formation within the electrospray plume, but, because the sprayer was deeply buried inside the concentric heated chamber, adjustment or service of the sprayer region was difficult.
At about the same time, U.S. Pat. No. 5,352,892 disclosed another way of heating the spray plume, wherein a heated disk with a central opening was placed in between a pneumatically assisted electrospray nebulizer and the ion sampling inlet to a mass analyzer. In this arrangement, a fraction of the nebulizing gas would be preheated at the opening of the heated disk body. This heated gas was then remixed with the central portion of the spray plume prior to the ion sampling inlet. In this device, heat transfer was sufficient to achieve ion formation at flow rates as high as 2 ml per minute, but the drawback was contamination of the heated disk, which required frequent cleaning.
In a design described in U.S. Pat. No. 5,412,208, the nebulization and ion sampling process was assisted by preheated gas that intersected the flow of the nebulized sample. This turbulent mixing helped to evaporate droplets of the sample, as well as push the electrospray plume in the direction of the ion sampling inlet. The main disadvantage of this design is non-uniform and limited heat exchange between the heated gas flow and the ESI plume. A newer design, described in U.S. Pat. No. 6,759,650, used two heated gas flows that intersected with the sample flow to promote turbulent mixing, but the design was complicated and less cost effective.
U.S. Pat. No. 5,495,108 discloses an ion source in which a heated drying gas is directed to a spray plume that is orthogonal to the ion sampling inlet. For example, the ion sampling inlet 236 may be positioned at 90 degrees with respect to the direction of nebulization (FIG. 2). A liquid sample 224 is delivered though a stainless steel grounded tube 226, while nebulizing gas 222 is supplied through a concentric grounded tube 228. A heated drying gas 234 is partially diverted through a special conduit 235 to deliver about 1 liter per minute of highly heated gas into the pneumatically assisted electrospray plume 237, with an overlapping ark section 243 to assist droplet evaporation and ion formation at higher sample liquid flow rates (up to 1 ml/min). The main opening 241 for the heated drying gas, defined by spray shield 238, delivers the gas at a flow rate up to 12 liters per minute. A Faraday cage electrode 239 provides a high voltage electrical field.
Another design, described in U.S. Pat. No. 7,199,364, includes a second, laminar gas flow that is heated, wherein the nozzle for the second gas flow is behind the nebulization nozzle in a semi-circular pattern. This design achieved limited heat transfer and only a moderate improvement in sensitivity.
In summary, there is a constant need for further improvements in ion source design and higher ionization efficiency.


A cabinet drawer is configured to fully extend from within a cabinet case, tilting downward and outward when fully extended to allow personnel to access items located at the rear of the drawer. Mating channels and slots in the drawer and associated support structure allow for full movement of the drawer, while preventing its disengagement from the cabinet. The inclusion of a downward tiltable drawer provides easy access to the contents of the drawer, regardless of its height.

Many conventional types of supply/storage cabinets have only a few shelves, since many people would otherwise have difficulty in accessing items stored at heights above about six feet or so. Indeed, even in conventional designs, the top shelf may be inaccessible to some users, or at least is located at a height where individuals tend to climb on chairs, etc., to reach items stored on the top shelf. Moreover, even shelves at reasonable heights may have an appreciable amount of wasted space in a rear area that is not readily accessible to most individuals. Another concern is that supplies located toward the rear of the shelves may be "lost" or forgotten, a real concern when a supply cabinet is used to store items (such as medicines or medical supplies) with an expiration date.
A specific implementation of a supply cabinet used in a hospital or medical office setting may not include a back wall. Instead, the cabinet is configured to open along both its "front" face and "rear" face (this type of cabinet referred to at times as a "nurse server", or a "pass-through" cabinet). The nurse server allows for staff to re-stock shelves from the one open side, as medical personnel remove items from the opposite open side. The need for both sides of a nurse server to be fully accessible, including the ability to reach items along the top-most shelf, is an important concern in the design of such cabinets.


Disclosed is a method for efficiently scanning a frequency of a new broadcasting area when a DVB-H receiving terminal moves. To this end, the DVB-H terminal stores in advance in a table DVB-H frequency changes according to the broadcasting area based on each cell whenever it moves. Then, the DVB-H receiving terminal preliminarily scans the DVB-H frequency previously stored in response to the current cell when the DVB-H receiving terminal moves in the future. If there exist one or more DVB-H frequencies stored in response to each cell, the DVB-H receiving terminal scans the stored DVB-H frequencies one by one in order to find a DVB-H frequency having an intensity higher than a predetermined intensity. The DVB-H receiving terminal quickly and efficiently scans the DVB-H frequencies according to the priority without scanning within all the DVB-H frequency ranges so that it can effectively minimize power consumption.

1. Field of the Invention
The present invention relates to a Digital Video Broadcasting-Handheld (DVB-H receiving terminal and a method for frequency scanning in the (DVB-H receiving) terminal. More particularly, the present invention relates to a DVB-H receiving terminal and a method for frequency scanning in the (DVB-H receiving) terminal. The terminal detects a frequency change in the broadcasting area according to the movement of the DVB-H receiving terminal and automatically converts the frequency into a frequency of new broadcasting area.
2. Description of the Related Art
DVB-H refers to a technology standard established in Europe for improving ground wave Digital TV (DTV) reception rate during movement, wherein H stands for 'Handheld'. DVB-H is a mobile multimedia standard supporting high quality voice and video service anytime and anywhere even when driving or walking.
The configuration of a service model using DVB-H will be described below. First, the transmitter side includes a network for interaction between a broadcasting provider and a communication provider based on a DVB-UMTS (DVB-Universal Mobile Telecommunication System) standard, in which the broadcasting provider transfers compressed data to the terminal in the transfer mode of DVB-H based on the DVB-AVC (DVB-ADVANCE VIDEO CODING) standard. Then, the terminal communicates with a mobile communication provider again by using a communication standard, such as DVB-UMTS/GSM (DVB-UMTS/Global System for Mobile) etc., and transfers receiving side information to the broadcasting provider through a communication network in real time.
In order to receive and reproduce broadcasting as described above, the DVB-H receiving terminal should receive signals from a broadcasting server and a repeater. First, the DVB-H receiving terminal must find a frequency including an actual signal in an area where a DVB-H signal exists, in order to receive the signal. When the frequency is found, the DVB-H receiving terminal should receive Service Information/Program Specific Information (SI/PSI) from the server on the basis of the found frequency.
SI/PSI includes Network Information Table (NIT) as well as information related to programs. In order to perform such operations as described above, when DVB-H applications are started or the DVB-H receiving terminal boots-up, the DVB-H receiving terminal should automatically start scanning for the existence of a DVB-H signal in the area where the terminal itself is located.
Generally, due to the common frequency interference, a DVB-H broadcasting network assigns different frequencies to the areas. Accordingly, the DVB-H receiving terminal scans the area at regularly spaced intervals according to its location so as to find a DVB-H frequency in an area where there is no DVB-H signal. When the DVB-H receiving terminal enters an area where there is a DVB-H signal, it checks whether the DVB-H frequency exists in the area.
In order to perform such an operation, it is necessary to continuously keep the RF module in an ON state, which influences the power consumption of the DVB-H receiving terminal.
As described above, since the conventional DVB-H receiving terminal assigns a different frequency to each of the cells when the conventional DVB-H receiving terminal starts DVB-H applications or moves from a shadow area of a DVB-H signal to a receivable area, the conventional DVB-H receiving terminal performs frequency scanning in order to find a DVB-H signal. To this end, the conventional DVB-H receiving terminal should individually scan various frequencies in the UFH signal band, i.e., DVB-H signal band, in order to find a DVB-H signal. That is, the frequency scanning efficiency of the conventional DVB-H receiving terminal decreases, because it repeats the process of frequency scanning in all of UHF signal bands according to each movement between cells. In addition, because it is necessary to continuously keep RF modules inside the DVB-H receiving terminal in an ON state in order to perform the operations above, the active state of the DVB-H receiving terminal also causes major battery consumption.

DVB-H receiving terminal and method for frequency scanning in DVB-H receiving terminal


In an automated data storage library, selective encryption for data stored or to be stored on removable media is provided. One or more encryption policies are established, each policy including a level of encryption, one or more encryption keys and the identity of one or more data cartridges. The encryption policies are stored in a policy table and the encryption keys are stored in a secure key server. A host requests access to a specified data cartridge and the cartridge is transported from a storage shelf in the library to a storage drive. Based on the identity of the specified cartridge, the corresponding encryption policy is selected from the table and the appropriate encryption key is obtained from the key server. The storage drive encrypts data in accordance with the key and stores the data on the media within the specified data cartridge.

Automated data storage libraries are known for providing cost effective storage and retrieval of large quantities of data. The data in automated data storage libraries is stored on data storage media that are, in turn, stored on storage shelves or the like inside the library in a fashion that renders the media, and its resident data, accessible for physical retrieval. Such media is commonly termed "removable media." Data storage media may comprise any type of media on which data may be stored and which may serve as removable media, including but not limited to magnetic media (such as magnetic tape or disks), optical media (such as optical tape or disks), holographic media (such as holographic tape or disks), electronic media (such as PROM, EEPROM, flash PROM, MRAM, Compactflash ™, Smartmedia ™, Memory Stick ™, etc.), or other suitable media. Typically, the data stored in automated data storage libraries is resident on data storage media that is contained within a cartridge and referred to as a data storage media cartridge. An example of a data storage media cartridge that is widely employed in automated data storage libraries for mass data storage is a magnetic tape cartridge.
In addition to data storage media, automated data storage libraries typically contain one or more data storage drives that store data to, and/or retrieve data from, the data storage media. Transporting data storage media between data storage shelves and data storage drives is typically accomplished by one or more robot accessors (hereinafter termed "accessors"). Such accessors have grippers for physically retrieving the selected data storage media from the storage shelves within the automated data storage library and transport such media to the data storage drives by moving in the X and/or Y directions.
In many applications, it is important to ensure that data stored on removable media is secure. In addition to the inconvenience and expense of having to replicate, reconstruct or re-obtain data lost to theft, accidents, etc., there can be tremendous fallout, including legal liability, if confidential information is misappropriated. However, it may not be necessary to secure all data or to secure all data to the same level.
Consequently, a need exists for a system and method for selectively securing data, such as stored on removable media in automated storage libraries, which is reliable, is sufficiently flexible to permit data on different data cartridges to be secured at different levels (or to remain unsecure) and does not adversely affect performance of the library or any of its components.

Selective encryption of data stored on removable media in an automated data storage library

INTERNATIONAL BUSINESS MACHINES CORPORATION


A head for a floor cleaning machine has a plate rotatable about an upright plate axis and formed offset therefrom with a plurality of downwardly open pockets, respective bearings seated in the pockets, and respective rods rotatable in the bearings about respective tool axes intersecting and forming a very small acute angle with the plate axis. Respective mounting sleeves fixed on the rods are each formed with a plurality of axially downwardly extending and radially deflectable retaining fingers each in turn having an outwardly directed barb and respective tool elements each have an upper side turned toward the plate and an opposite lower side and are each formed with a central throughgoing hole in turn formed with a downwardly directed shoulder and receiving the respective mounting sleeve with the respective barbs engaged over the shoulder and retaining the respective element on the respective mounting sleeve. Respective seal assemblies on the plate and elements annularly surround each rod. Respective caps hermetically close the holes in the elements at the respective lower sides.

As described in commonly owned German patent document 195 22 019 a head for a floor cleaning machine has a plate rotatable about an upright plate axis and formed offset therefrom with a plurality of downwardly open pockets, respective bearings seated in the pockets, and respective rods rotatable in the bearings about respective tool axes intersecting and forming a very small acute angle with the plate axis. Respective mounting sleeves fixed on the rods are each formed with a plurality of axially downwardly extending and radially deflectable retaining fingers each in turn having an outwardly directed barb. Respective tool elements each have an upper side turned toward the plate and an opposite lower side and are each formed with a central throughgoing hole in turn formed with a downwardly directed shoulder and receiving the respective mounting sleeve with the respective barbs engaged over the shoulder and retaining the respective element on the respective mounting sleeve. Respective seal assemblies on the plate and elements annularly surround each rod.
In such an arrangement it is necessary to periodically replace the tool elements, which can be brushes, polishing disks, or the like. This is done by inverting the tool and pushing in the deflectable fingers so that the tools can be pulled off the rods. Such an operation is carried out in the field normally by the janitorial staff using the equipment.
After some use of the floor machine, however, it is likely that wax, for instance, will fill the hole in the bottom of each tool, packing it tight with a relatively hard substance. Such fouling makes it very difficult to remove the tools, as the retaining fingers have to be pushed inward against this mass. Thus the person changing the tools must clean out the centers of the tools before removing them, making the changeover operation fairly onerous.

Motor-driven plate with cleaning tools for floor machine


A method includes operating in a normal mode to receive and transmit packets, where the network device is one of multiple network devices that operate as a virtual chassis, where the virtual chassis corresponds to a single logical network device, and detecting when the network device crashes. The method further includes initiating a resetting process and operating in a pass through mode, during the resetting process, where the pass through mode permits packets to be received and transmitted to the network devices of the virtual chassis.

In a network environment, a virtual chassis may be implemented by allowing a group (e.g., two or more) of routers or switches to behave as a single router or a single switch. In this type of network environment, the group of routers or switches may be grouped or connected together using cables. In order for the routers or switches to communicate with one another, each router or each switch needs to be up and running (versus being down due to a failure). That is, if one of the routers or one of the switches crashes, then routers or switches on one side of the crashed router or the crashed switch will lose connectivity to the other routers or to the other switches connected on the other side of the crashed router or the crashed switch. In such instances, this results in a split.
One solution to this problem is to connect the group of routers or switches in a ring fashion. However, this solution may resolve the issue when only a single router or a single switch crashes. This solution may not resolve the issue when multiple routers or multiple switches crash. Additionally, this solution requires that the routes associated with the crashed router or the crashed switch be reconfigured. In either case, traffic loss may occur.

No split virtual chassis based on pass through mode


A probe tip of a scanning probe microscope or a profilometer is scanned across a surface in a contact, non-contact, or intermittent contact mode to sense the presence of a feature to be located. The probe tip may be scanned along substantially parallel paths, spiral paths or in a sequence of random positions to locate the feature. After the feature has been located, a different searching sequence is employed in order to locate a center of the feature if such is desired. Then, the probe tip is scanned across the surface over the center of the feature in order to perform a measurement of the feature. For some particular features such as tungsten plugs, metal clusters or metal filled via holes of a surface, an electrical or magnetic parameter of the feature may be used for locating the feature after which the same or a different characteristic of the feature, such as geometric profile, can be measured.

This invention relates in general to systems for inspecting surfaces and in particular, to a system for locating features of a surface.
Stylus profilometers and/or scanning probe microscopes have been used for inspecting features of surfaces, where such features may include the topography, dimensional information, electrical resistance or capacitance or magnetic characteristics, frictional properties, van der Waals forces, light emission or transmission behavior and other physical properties.
In order to locate one or more of such features, optical techniques using video cameras, objective lenses, and pattern recognition have conventionally been employed. These techniques are limited by the resolution of the optics and of the camera, the optical magnification power of the optics, the illumination angle and pattern recognition software algorithms. Even with a high power objective lens and using the most robust pattern recognition software available at present, an object can still fail to be located optically to a desired degree of accuracy. After the feature has been located optically, the stylus tip of the scanning probe microscope or of the profilometer is then moved to a desired location relative to the feature in order to measure the feature. If optical techniques are used to position the feature relative to the stylus tip, the stylus may hinder the path of view of the optics for precise positioning of the feature under the stylus. If the positioning of the feature is performed using a "coarse stage", the repeatability of the positioning of large stages, such as wafer or disk handling stages, is somewhat limited to about 0.25 microns so that the object cannot be positioned to an accuracy better than 0.25 microns.
Due to the uncertainties inherent in the positioning procedure described above, the user cannot be certain as to the position of the stylus tip relative to the feature to be measured. For this reason, in conventional methods, even after the stylus tip has been located roughly close to the feature to be measured, more accurate positioning still needs to be achieved. One must first designate a window or area of interest that contains the feature and acquire high resolution two-dimensional or three-dimensional data of the feature within such window or target area. The stylus tip and sensor are used to acquire high resolution two-dimensional or three-dimensional data in an area containing the feature of interest. The data is then examined for an indication of the feature of interest, and the data is used to position the stylus tip at the exact location of interest. It is only at such point that the user is then ready to use the stylus tip to measure the feature.
The above-described technique for positioning the stylus tip in position to measure the feature has several shortcomings. If the feature is not one that can be located optically, the above-described optical technique cannot be used. Even for features that can be optically located, the above-described procedure is time consuming and wasteful of resources. Due to the uncertainty inherent in the optical technique, conventional positioning techniques require the acquisition of the full image within a target area in the manner described above. For example, if a scanning probe microscope is used to acquire a 256.times.256 data point full image, such data acquisition typically requires four to five minutes. Most of these data points will be discarded after the feature is located. Therefore, the above-described process is limited in throughput and is wasteful of the user's resources. It is, therefore, desirable to provide an improved system for locating and then measuring a feature of interest, where the system can be used even when the feature is not optically detectable.

System for locating a feature of a surface


A cover plate device for covering a wall mounted wiring device having no visible fasteners when installed. An attachment plate is attached over and to a wiring device which has been mounted in and to a ganged box mounted adjacent an aperture in a wall. Latch pawls are arranged at the opposite longitudinal ends of the attachment plate. A cover plate member overlies the wiring device and ganged box and provides a series of recesses to receive the associated pawls in locking arrangement. Because of the number of recesses available at each pawl location, the cover plate can still be installed even if the wall is not flat or even. The attachment plate and cover plate member can be provided with various types and numbers of apertures, and the number of pawls and groups of recesses employed depend on the size of the attachment and cover plate members.

1. Field of the Invention
The invention is directed to the field of installing wiring devices to ganged boxes mounted in building walls and more particularly to the provision of cover plate devices which can be used to cover such wiring devices to prevent unwanted access to such wiring devices and at the same time provide a finished look without exposed fasteners.
2. Description of the Prior Art:
At present when it is desired to install a wiring device such as a switch, a receptacle, a duplex receptacle, a combination receptacle and switch, etch, in a wall of a building, whether public, commercial or residential, it is necessary to cut a hole into such wall and install a ganged box adjacent the hole by attaching such box to a stud or the like. The ganged box is hollow to receive such wiring devices and provides pairs of mounting ears for mounting the wiring devices within and to the box. The size of the box is selected to accept all the wiring devices required at that location and the number of pairs of mounting ears will be equal to the number of possible wiring devices which the box can receive. Once the wiring device is connected to the various conductors it will service, the wiring device is screwed to at least one pair of ears to mount the wiring device in and to the box. When all wiring devices are in place a cover plate having suitable apertures through it will be installed over the exposed wiring devices and the ganged box. The method of fastening the cover plate to the wiring devices is to use screws which pass through the cover plate and are received in threaded apertures in such wiring devices. The usual arrangement of mounting screws is one between each duplex receptacle and two, one to each side, for a switch. Thus, when a prior art wiring system containing two duplex receptacles and a switch was completes one could see four exposed mounting screws. This made the completed job unsightly and could expose the user to a shock hazard if the correct insulation were not used during assembly.
One prior art approach to hide these unsightly and potentially hazardous fasteners is shown in U.S. Pat. No. 4,873,396 issued Oct. 10, 1988 to Guity-Mehr. The cover plate was fashioned with an M-shaped groove near the bottom of the plate's back surface which could be positioned under the head of the lower fastening screw used to anchor the wiring device to the ganged box mounting ear. This mounting screw would have to be mounted so that the proper length of its body remained outside of the wiring device to be gripped by the M-shaped groove. If the screw was not sufficiently installed the cover plate would be free to rattle and if the screw was installed too deeply the M-shape groove could not be positioned under the screw head.
Once the cover plate was positioned with the M-groove under the mounting screw, the cover plate is positioned so that the second mounting screw can be installed in a recessed groove in the front of the cover plate and screwed into the wiring device. Then a screw groove cover is fitted over the screw groove to hide the screw head and the screw groove.