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Chronic ketosis and cerebral metabolism.код для вставкиСкачать
Chronic Ketosis and Cerebral Metabolism Darryl C. DeVivo, MD, Mary P. Leckie, BS, James S. Ferrendelli, MD, and David B. McDougal, Jr, MD T h e effects of chronic ketosis on cerebral metabolism were determined in adult rats maintained on a high-fat diet for approximately three weeks and compared to a control group of animals. T h e fat-fed rats had statistically significantly lower blood glucose concentrations and higher blood p-hydroxybutyrate and acetoacetate concentrations; higher brain concentrations of bound glucose, glucose 6-phosphate, pyruvate, lactate, P-hydroxybutyrate, citrate, a-ketoglutarate, alanine, and adenosine triphosphate (ATP); lower brain concentrations of fructose 1,6-diphosphate, aspartate, adenosine diphosphate (ADP), creatine, cyclic nucleotides, succinyl coenzyme A (CoA), acid-insoluble CoA, and total CoA; and similar brain concentrations of glucose, malate, calculated oxaloacetate, glutamate, glutamine, adenosine monophosphate, phosphocreatine, reduced CoA, acetyl CoA, sodium, potassium, chloride, and water content. T h e metabolite data in the chronically ketotic rats demonstrate an increase in t h e cerebral energy reserve and energy charge. These data also suggest negative modification of the enzymes phosphofructokinase, pyruvic dehydrogenase, and a-ketoglutaric dehydrogenase; positive modification of glycogen synthase; and possible augmentation of the hexose transport system. There was no demonstrable difference in brain pH, water content, or electrolytes i n the two groups of animals. We speculate that the increased brain ATP/ADP ratio is central to most, if not all, the observed metabolic perturbations and may account for the increased neuronal stability that accompanies chronic ketosis. DeVivo DC, Leckie MP, Ferrendelli JS, et al: Chronic ketosis and cerebral metabolism. Ann Neurol 3:331-337, 1978 T h e anticonvulsant property of a ketogenic diet is well recognized, but t h e mechanism underlying the effect remains obscure. Our laboratory has reported previously on an experimental model using rats to study the high-fat diet El]. Using this animal model w e have demonstrated an increase in the convulsive threshold to minimal electroconvulsive shock. We report here the results of similar experiments designed to characterize various perturbations in cerebral intermediary metabolism. Some of these findings have been presented previously [7]. Materials and Methods All reagents used in the substrate assays were of the highest analytical grade available. Sprague-Dawley rats were maintained on high-fat feedings for 20 days as described previously [ 11. The control animals consumed Wayne Lab-Blox (Allied Mills, Chicago) ad libitum and were narcotized twice daily to simulate the gavage feeding conditions. All animals gained weight during the experiment. The control rats ranged in weight from 225 to 390 gm when killed. The high-fat-fed rats grew from 258 & 6 to 274 ? 3 gm during the feeding period. All rats were housed, 3 per cage, in air-conditioned animal quarters with alternating twelvehour periods of light and dark. Animals were allowed free access to water, and the cage bedding was changed daily. The animals were killed utilizing the freeze-blowing techFrom the Edward Mallinckrodt Department of Pediatrics and the Departments Of and Neurosurgery (Neurol"6Y) and Pharmacology, Washington University School of Medicine, and the Division of Neurology, St. Louis Children's Hospital, St. Louis, MO. nique described by Veech et a1 [36].The brain tissue was powdered in liquid nitrogen and stored at -80°C until extracted. Acid-methanol-perchlorate extracts were prepared from the brain powder [ 2 3 ] for direct enzymatic microfluorometric determination of glucose, glucose 6phosphate (G-6-P), fructose 1,G-diphosphate (F-1,6-P2), pyruvate, lactate, citrate, a-ketoglutarate (a-KG), malate, adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), phosphocreatine (PCr), creatine (Cr), and aspartate [19]; for glutamate and glutamine [ 2 5 ] ; for alanine [13]; and for phydroxybutyrate (P-OHB) [391. The residue from this perchloric acid extraction was acid hydrolyzed with 1 N hydrochloric acid to liberate glucose as an indirect measure of the glycogen content [9]. Cyclic nucleotides were extracted from frozen brain powder and assayed according to the method of Steiner et a1 [341. Coenzyme A (CoA) and several of its esters were measured using a modification of the phosphotransace tylase cycling method of Stadtman, Novelli, and Lipmann [24, 331 coupled with methods designed to destroy selected CoA esters and free CoA specifically (McDougal, DB Jr, Dargar R: unpublished data). The entire set of CoA assays requires only 20 to 30 mg of brain. Acetyl CoA is identified by its specific reaction with oxaloacetate and citrate synthase. Succinyl CoA is identified by its reaction with guanosine diphosphate and succinic thiokinase in the presence of arsenate. Acid-insoluble CoA includes (long-chain) fatty acyl-CoA esters which are insoluble in perchloric acid. Accepted for publication Nov 3. 1977. Address reprint requests Dr DeVjvo, St. Louis tal, 5oo Kingshighway, St. Louis, MO 6 3 178, ~ ~ 6 4 - 5 ~ 3 4 / ~ 8 / 0 ~ 0 3 - 0 4 0 9@ $ 0I978 ~ . 2 5by Darryl C. DeVivo Hasp,- 331 Blood samples were collected by cardiac puncture immediately after removal of the brain tissue, added to an equal volume of 3 M perchloric acid, and prepared for assay of glucose, /3-OHB, and acetoacetate (AcAc) as outlined previously [8]. Brain sodium, potassium, chloride, and water content also were determined on a fraction of the frozen brain powder. The brain powder was placed in a preweighed test tube, weighed, and placed in an oven at 105°C for 48 hours before being capped in a desiccator jar for 24 hours and reweighed. The process was repeated to ensure that a dry weight had been achieved. The dried tissue was digested with 10 vol Cwlv) of 0.75 N nitric acid as described previously [ 8 ] for determination of Na, K, and CI. Several equations were used to calculate substrate concentrations or metabolic parameters. Oxaloacetate (Oxal) concentrations were derived from the following equations: Oxaloacetate = K ~ , l ) i l [Malate] . Oxaloacetate = "AD+](. [NADH& [LY-KG][aspartate] I?;, )T [glu raniate] &,,,,. where KMDH = 278 X lo-' and = 6.01 at pH 7 . 0 [151. The cytoplasmic oxidation-reduction potential was calculated from Equation 3 LNAD+](. = [Pyruvate] K, 1 ) ~[lactate] ~ [NADH,],. (3) where KI.I)H= 111 x IO-" at p H 7.0 [15]. The cerebral energy charge [ 2 ] was calculated as follows: Energy charge = 0.5 ( 2 ATP + ADP) ATP + ADP + AMP According to this equation che hydrogen ion concentration is directly proportional to the mass action ratio. A rise in brain tissue p H therefore is associated with a fall in the mass action ratio. Results Ail animals remained in a n anabolic state t h r o u g h o u t t h e e x p e r i m e n t as judged by a gain in b o d y weight. C o n s u m p t i o n of a high-fat d i e t p r o d u c e d a significant ( p < 0.005) decrease in blood glucose and increases in t h e blood P-OHB and A c A c concentrations (Table 1). T h e brain electrolytes ( N a , K, C1) a n d water c o n t e n t w e r e the s a m e in t h e control and high-fat-fed g r o u p s (Table 2). Several significant differences in cerebral metabolites w e r e noted b e t w e e n t h e two groups, as s h o w n i n T a b l e 3. T h e b o u n d glucose (reflecting glycogen content), G-6-P, pyruvate, lactate, /3-OHB, citrate, a-KG, alanine, and ATP concentrations w e r e significantly increased in t h e high-fat-fed g r o u p ; F-1 ,6-P2, ADP, aspartate, succinyl CoA, acidinsoluble CoA, total CoA, a n d t h e cyclic nucleotides w e r e significantly decreased in t h e high-fat-fed g r o u p ; and f r e e glucose, malate, glutamate, glutamine, calculated oxaloacetate, A M P , P C r , r e d u c e d C o A , and acetyl CoA w e r e similar in t h e two g r o u p s ( s e e T a b l e 3). The cerebral lactate/pyruvate ratio a n d t h e cytoplasmic oxidation-reduction potential w e r e similar in t h e t w o g r o u p s of animals (Table 4). T h e cerebral energy charge a n d t h e ATPlADP ratio, cerebral Tuble 2. Efferts of Diet on Bruin Electrolytes and Water Content The cerebral energy reserve [ 2 0 ]was calculated from Equarion 5 : Energy reserve = (PCr + ADP) + 2 (ATP glucose) + + 2.9 (glycogen) (5) Brain pH was estimated from the mass action ratio of the creatine phosphokinase reaction [3 11 as derived from Equation 6: KVIVK = [Crl[ATPl [PCr] [ADP] 1 [H'] Determination Control (N = 22) High-Fat Diet ( N = 13) Sodium Potassium Chloride Water (%) 44.7 97.6 32.0 79.3 44.7 ? 0 . 5 N S 98.7 +- 0.8 N S 31.7 ? 0.3 N S 78.9 ? 0.2 NS 2 2 2 2 0.4 0.8 0.3 0.2 Significance Values represent mean 2 SEM for the dumber of animals indicated. Electrolytes are expressed as milliequivalents per kilogram of wet [issue. NS = not significant. Table I . Effpcts of Diet on Blood Gfucooseand Ketone Body Concentration.( Metabolite Control ( N = 22) High-Fat Diet ( N = 13) Significance Glucose /3-H ydroxy butyrate Acetoacetate 7,080 2 142 117 2 8 73 4 6,290 2 218 578 2 39 111 10 p < 0.005 p < 0.005 p < 0.00s * Values are in micromoles per liter and represent mean 332 Annals of Neurology Vol 3 No 4 % * SEM for the number of animals indicated. April 1978 Tablr 3 . Effects of Diet on Vurious Rrain Metabolites Metabolite Control (N= 2 2 ) High-Fat Diet (N = 1 3 ) Glucose [free) Glucose (bound) G-6-P F- 1,6-P2 Pyruvate Lactate 2,130 3,400 156 25.3 107 1,560 13.5 298 189 279 4.62 6.71 680 2,640 11,270 4,870 2,440 681 68 3,995 5,620 2.92 0.068 15.36 2.85 4.01 43.6 69.9 2,290 4,130 175 18.5 132 1,990 34.8 314 209 272 4.55 6.34 730 2,270 11,270 5,140 2,600 640 62 3,990 5,380 2.58 0.054 14.80 2.80 2.98 38.0 62.9 P-OHB Citrate a-KG Malate (OxalhDH !Oxal),,, Alanine Aspartate Glutamate Glutamine ATP ADP AMP PCr Cr Cyclic AMP Cyclic G M P Reduced CoA Aceryl CoA Succinyl CoA Acid-insoluble CoA Total CoA t 63 2 50 t t 2 1.2 3 2 39 t 3.0 2 2 t 2 t ? f 2 t 2 2 t 2 * f f ? t t f f t 5 2 4 0.17 0.12 20 60 130 110 22 14 3 35 70 0.11 0.008 0.41 0.10 0.28 1.2 1.8 Cerebral metabolites expressed as micromoles per kilogram of wet tissue ? Significance f 84 * 90 4 1.2 f 4 5 60 f 2.4 ? 3 t 4 _f * NS < 0.005 < 0.005 < 0.005 < 0.005 < 0.005 < 0.005 < 0.005 < 0.005 p p p p p p p p f NS NS * p < 0.05 p < 0.05 p < 0.005 7 t 0.16 f 0.17 f 30 50 2 90 f 150 t 14 f 14 2 3 f 65 t 30 t 0.08 f 0.003 t 0.72 t 0.08 f 0.18 t 1.0 f 1.3 NS NS p < 0.005 p < 0.05 NS NS p < 0.025 p < 0.025 p < 0.005 NS NS p < 0.005 p < 0.05 p < 0.005 SEM G-6-P = glucose 6-phosphate; F- 1,6-P2= fructose 1,B-diphosphate;P-OHB = P-hydroxybutyrate; u - K G = cr-ketoglutaratc; ( ~ x a l ) ~ , = ,,, oxaloacetate calculated from equation 1; (oxal),,,,,, = oxaloacetate calculated from equation 2; ATP = adenosine triphosphate; ADP = adenosine diphosphate; A M P = adenosine monophosphate; PCr = phosphocreatine; Cr = creatine; G M P = guanine monophosphate; CoA = coenzyme A; NS = not significant. Table 4. Effects of Diet 011 Cerebral Metabolism Determination (N Control = 22) tN Lactatelpyruvate ~NAD+l,./[NADH,I, Energy charge ATPl ADP Energy reserve Braidblood glucose [Crl [ATPI [PCrl [ADPI 14.8 t 0.3 617 2 14 0.872 t 0.003 3.63 2 0.10 t 0.2 23.6 0.303 2 0.011 601 0.884 4.08 26.4 0.367 5.20 t 0.17 High-Fat Diet = 13) 15.1 t 0.3 f 13 f 0.002 f 0.10 t 0.6 5 0.014 5.52 t 0.17 Significance NS NS p < 0.005 p < 0.005 p < 0.005 p < 0.005 NS "AD+], = nicotinamide-adenine dinucleotide; [NADH,],. = nicotinarnide-adenine dinucleotide, reduced state; ATP = adenosine triphosphate; ADP = adenosine diphosphate; C r = creatine; PCr = phosphocreatine; NS = not significant. DeVivo et al: Ketosis and Cerebral Metabolism 333 energy reserve, and brain glucose/blood glucose ratio were significantly higher (p < 0.005) in the high-fatfed group. The creatine phosphokinase mass action ratio was similar in the two groups of animals. Discussion Our observations in this study lend themselves t o several interpretations. First, we noted a significant elevation in the brain concentrations of glycogen (bound glucose) and G-6-P and a significant increase in the brain glucose/blood glucose ratio in the highfat-fed animals (see Table 3). G-6-P is the product of the reaction catalyzed by hexokinase (Figure). This enzyme reaction is subject to product inhibition, and as such it controls the flux of glucose into the brain pool of phosphorylated intermediates [4]. G-6-P also influences glycogen synthesis by acting as a positive modifier of the dependent (or active) form ofglycogen synthase, the rate-limiting reaction involving formation of glycogen [ 181. The increased concentrations of G-6-P and ATP therefore may partly explain the 22% increase in brain glycogen (see Table 3 ) that we observed in the high-fat-fed group. The increased brain glucose/blood glucose ratio in the high-fat-fed group is the consequence of a significantly lower blood glucose concentration (see Table 1) and a higher (although not statistically significant) brain glucose concentration (see Table 3). This altered ratio could be interpreted as evidence either for slower phosphorylation of brain glucose (for the reasons stated above) or for enhanced transport of glucose from the blood into the brain. Glucose transport across the bloodbrain barrier is known to be carrier mediated (facilitation), with a Michaelis-Menten constant (K,) of approximately 5 mM [26]. At the moment there is no evidence that the hexose transport system across the blood-brain barrier can be induced by nutritional states. However, augmentation of another transport system (for monocarboxylic acids) during fasting has recently been demonstrated [51. Movement of ketone bodies into the brain is dependent upon the monocarboxylic transport system. The design of our present study does not permit us to discriminate between these two possibilities as explanations for the elevated brain glucose/blood glucose ratio in the high-fat-fed group. The second set of observations focuses on the brain concentrations of G-6-P, F-l ,6-P2, pyruvate, lactate, alanine, acetyl CoA, citrate, a-KG, and succinyl CoA. These metabolites represent reactants of important regulatory enzymes controlling glycolysis and oxidative metabolism. G-6-P and fructose 6-phosphate are at equilibrium; as such, either metabolite reflects the activity of phosphofructokinase, the key regulatory enzyme in glycolysis. F-l,6-P2 is the product of this reaction (see the Figure). An increase in the G-6-P 334 Annals of Neurology Vol 3 No 4 April 1978 concentration and decrease in the F-1 ,6-Pz concentration as seen in the high-fat-fed group (Table 3) suggest negative modification of phosphofructokinase. The increased ATP and citrate concentrations we observed may be important in this regard since both intermediates are negative modifiers of this reaction [20, 301. The similarity between the creatine phosphokinase mass action ratios (see Table 4 ) suggests that a decrease in brain p H is not a plausible explanation for the observed inhibition of phosphofructokinase in the high-fat-fed group of animals. By similar reasoning, increased concentrations of pyruvate and a - K G suggest decreased activities of pyruvate dehydrogenase and a-ketoglutaric dehydrogenase, respectively (see the Figure). These two multienzyme reaction sequences are tightly regulated and share some biochemical similarities, as has been discussed recently [28, 3 2 , 371. The pyruvic dehydrogenase ( P D H ) complex is regulated by a phosphorylation-dephosphorylation mechanism [37]. The dephosphorylated (active) form of the complex is inactivated by a phosphorylation reaction catalyzed by the enzyme P D H kinase; conversely, dephosphoryla- The metabolic relationships betuwen glycolysis, the tricarboxylicacid cycle, and ketone body oxidation. Thepercentages in parentheses indicate significant increases (+) or decreases ( -) of the respectivebrain substrates in the high-fat-fed rats compared udth the control rats. Enzymes referred t o i n the text are indicated by the letters: (a) = hexokinase; (b) = phosphofructokinase; (c) = pyrucic dehydrogenase: (d) = glutamir-pyruiiic transaminase; ( e )= citvate synthase; ( f ) = a-ketoglutaric dehydrogenase; ( g )= 3-oxoacid-CoA transferase. GLYCOGEN ( + 2 2 % ) G LUCOS E -0 0 - G 6 - P ( + 12 %) F - 1 t, 6 - P 2 ( - 2 7 % ) (-14%) ASP CoA M ALATE CIT R ATE (+5% ) J a-KG (+I1%) t SUCCINATE t s UCC I N Y L - Co A (- 2 6 %) (+ I 57 % P O H B T tion of the inactive form is catalyzed by the enzyme P D H phosphatase. P D H kinase is inhibited by A D P and therefore is dependent upon the ATP/ADP ratio [37]. The higher ATP/ADP ratio which we observed in the high-fat-fed group may explain the apparent inhibition of the P D H complex. T h e acetyl CoA/CoA ratio also controls activity of the PDH complex. However, we observed no significant difference in this ratio between the two groups of animals. T h e acetyl CoA concentrations, in fact, were very similar. This observation probably reflects the alternate synthesis of acetyl CoA fromP-OHB and AcAc (see the Figure) to compensate for the presumed decreased synthesis of acetyl CoA from pyruvate. The higher alanine concentrations in the high-fat-fed group apparently represent a shift in the mass action ratio of the reaction catalyzed by glutamic-pyruvic transaminase associated with increased pyruvate concentrations (see the Figure). Similarly, lactate concentrations increased in parallel with pyruvate concentrations in the high-fatfed group, thereby maintaining a relatively constant lactate/pyruvate ratio. This observation also suggests that the cytoplasmic oxidation-reduction potential is not perturbed by chronic anabolically induced ketosis as opposed to acute starvation-induced ketosis [ 8 ] . The elevated a-KG and decreased succinyl CoA concentrations imply a block at the enzymatic step catalyzed by cu-ketoglutaric dehydrogenase (see the Figure). Recent evidence suggests that the succinyl CoA/CoA ratio is the major regulating mechanism for this reaction, with little o r no influence being exerted by the guanine or adenine nucleotides [32]. In our study the succinyl CoA/CoA ratio was lower in the high-fat-fed group (0.203 & 0.02 1 vs 0.248 2 0.017;p < 0.10) and cannot be invoked as the mechanism of enzyme inhibition under these experimental conditions. The pyridine nucleotide ratio also exerts a regulatory effect upon this reaction. Unfortunately, the cerebral intramitochondrial oxidation-reduction potential is difficult to estimate for reasons that have been reviewed recently [2 13. The undetectable brain concentrations of AcAc preclude estimation of the intramitochondrial redox potential using the P-hydroxybutyric dehydrogenase reaction. One might anticipate that the mitochondria1 redox potential could shift to a more oxidized state if pyruvate is partially replaced by /3-OHB or AcAc as a fuel source for oxidative metabolism [8]. Such a redox shift, however, would favor rather than inhibit a-ketoglutaric dehydrogenase activity. O u r inability to suggest a mechanism that might inhibit the a-ketoglutaric dehydrogenase complex might imply that the statistically significant elevation of a-KG (see Table 3) is biologically unimportant. The identical concentrations of brain glutamate and similar concentrations of brain y-aminobutyric acid [ 11 observed in the two groups of rats are consistent with this formulation. The relatively greater decrease in the mean succinyl CoA concentration might reflect greater conversion of this metabolite to succinate via the reaction catalyzed by the enzyme 3-oxoacid-CoA transferase during chronic ketosis. As shown in the Figure, succinyl CoA is essential for the metabolism of AcAc. An increased availability of NAD+ might facilitate the pyridine nucleotide-dependent reactions in the citric acid cycle involved in the oxidation of various intermediates. The potential advantage of this speculation in relation to malic dehydrogenase is to further counter the unfavorable kinetics of malate oxidation to oxaloacetate, thereby augmenting intramitochondrial oxaloacetate formation and the malate-aspartate shuttle. Availability of oxaloacetate as a cosubstrate probably is the most important mechanism controlling the velocity of citrate synthase [17, 381. The K,,, for oxaloacetate varies from approximately 1 to 1 6 p M in most biological systems. The velocity of the reaction therefore is probably linearly related to the concentration of oxaloacetate, and in view of the similarities in the calculated concentrations of oxaloacetate, this rate might be expected not to differ greatly in the two groups of animals. Clearly, appropriate experiments need to be designed to assess the credibility of these speculations. The third set of observations focuses on the energy state of the tissue. We noted no change in the PCr concentrations, a significant increase in ATP, and a significant decrease in A D P (see Table 3). Expressed as energy charge or as ATP/ADP ratio, these observations can be translated into a favorable shift in the cellular energy state as shown in Table 4. Perhaps more meaningful (in the sense that the calculations also include glycogen and PCr) is the observed significant increase in cerebral energy reserve (Table 4). This observation suggests that the brain may be metabolically more stable from moment to moment and less easily compromised by subtle fluctuations in glucose availability or body temperature. For this reason we suggest that the anticonvulsant property of a ketogenic diet derives from the observed increase in cerebral energy reserve, which in turn reflects the higher ATP/ADP ratio in the high-fat-fed group. The anticonvulsant effect of a ketogenic diet evolves slowly over several days but can be obliterated in three hours [35]o r one to two days [ 11with resumption of an antiketogenic regimen. The metabolic adaptation after a ketogenic diet is begun also parallels the augmentation of the monocarboxylic acid transport system [51, further supporting our contention that ketone body utilization is fundamental to the anticonvulsant effect of a ketogenic diet. W e presume that the temporal profile describing the rise in convulsive threshold after the onset of ketosis reflects cerebral DeVivo et al: Ketosis and Cerebral Metabolism 335 metabolic adaptation to ketone body utilization. The biochemical mechanism or mechanisms underlying the increased ATP/ADP ratio, however, remain to be defined. It should be noted that similar metabolic perturbations have been defined in other tissues during ketosis, including heart [27] and diaphragm [3], and that this intracellular change may underlie the carbohydrate intolerance that develops during starvation o r high-fat feeding [ l o , 161. Relevant studies have also been carried out using cerebral slices from animals [12, 291. Rolleston and Newsholme [29] demonstrated that j3-OHB decreased the rate of glucose oxidation without influencing the rate of glucose utilization by guinea pig cerebral cortex slices. The increased lactate production by the tissue under these conditions was equivalent to a glucose-sparing effect. Similar effects of P-OHB on glucose metabolism by rat cerebral slices were observed by Ide et a1 [121. Our findings can be compared with the observed biochemical effects of various anticonvulsants including phenobarbital [ 141 and trimethadione, ethosuximide, and chlordiazepoxide [22]. In general, these anticonvulsant medications have similar apparent effects on cerebral glucose transport, glycogen synthesis, and glycolysis. However, these agents appear to behave like sedatives by depressing some citric acid cycle intermediates. This latter effect is the opposite of our observations in the high-fat-fed group, in which we noted increased cerebral concentrations of citrate and a-KG and similar levels of malate and calculated oxaloacetate. The animals maintained on the high-fat diet did not have a significant alteration in brain p H as determined by the reactants involved in the reaction catalyzed by creatine phosphokinase (see Table 4); nor did we see any important changes in the brain tissue content of water, sodium, potassium, o r chloride (see Table 2). It would appear therefore that presumed alterations of brain tissue p H , electrolytes, or water content cannot be invoked to explain the anticonvulsant effect of a high-fat diet. Whether ketosis affects the rate of cerebral metabolism remains unanswered. The decreased concentrations of cyclic nucleotides (see Table 3 ) and the increased ATP/ADP ratio could be interpreted as evidence for depression of cerebral metabolism. However, a recent study of rat brain metabolism during fasting demonstrated no major differences in cerebral blood flow or cerebral oxygen consumption [6].Experimental studies designed to evaluate the profile of citric acid cycle intermediates under various metabolic conditions have revealed some distinctive changes [ 111. Hyperthermia was associated with elevated brain concentrations of pyruvate, a-KG, and malate; ether anesthesia was associated with decreased levels of pyruvate, a-KG, and malate; and anoxic ischemia was 336 Annals of Neurology Vol 3 No 4 April 1978 associated with elevated concentrations of pyruvate and malate and a reduced concentration of a-KG. The cerebral metabolic profile we observed in the chronically ketotic rats (elevated pyruvate and a-KG and unchanged malate concentrations) differs from each of these three metabolic conditions, allowing us to suggest that chronic ketosis neither increases nor decreases cerebral metabolic oxygen consumption. Further studies are in progress to clarify the effect of ketosis on brain metabolism in the rat model used in the present study. In any event, it appears that a rise in the ATP/ADP ratio is central to most, if not all, of the metabolic perturbations described in our study and might provide a reasonable explanation for the increased neuronal stability that develops during chronic ketosis. Supported in part by Public Health Service Grants NS09808, NS06800, and NS13104. References 1. Appleton DB, DeVivo DC: An animal model for the ketogenic diet. Epilepsia 15:2 11-227, 1974 2. Atkinson DE, Walton GM: Adenosine triphosphate conservation in metabolic regulation: rat liver citrate cleavage enzyme. J Biol Chem 242:3239-3241, 1967 3. Bringolf M, Zaragoza N , Rivier D, et al: Studies in the metabolic effects induced in the rat by a high-fat diet. Eur J Biochem 26:360-367, 1972 4. Buschiazzo PM, Terrell EG, Regen D M Sugar transport across the blood-brain barrier. 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Novelli G D Methods for determination of coenzyme A. Methods Biochem Anal 2:189-213, 1955 25. Pagliara AS, Karl IE, DeVivo DC, et al: Hypoalaninemia: a concomitant of hypoglycemia. J Clin Invest 5 1:1440-1449, 1972 26. Pardridge WM, Oldendorf WH: Transport of metabolic substrates through the blood-brain barrier. J Neurochem 28:5- 12, 1977 27. Randle PJ, Garland PB, Hales CN, et al: Interactions of metabolism and the physiological role of insulin. Rec Prog Hormone R ~ 2211-48, s 1966 28. Reed LJ, Linn TC, Pettit FH, et al: Pyruvate dehydrogenase complex: structure, function and regulations, in Mehlmann MA, Hanson RW (,eds): Energy Metabolism and the Regula- tion of Metabolic Processes in Mitochondria. New York, Academic Press, 1972, pp 253-270 29. Rolleston FS, Newsholme EA: Effects of fatty acids, ketone bodies, lactate and pyruvate on glucose utilization by guineapig cerebral cortex slices. Biochem J 104:519-523, 1967 30. Shen LC, Fall L, Walton GM, et al: Interaction between energy charge and metabolite modulation in the regulation of enzymes of amphibolic sequences: phosphofructokinase and pyruvate dehydrogenase. Biochemistry 7:4041-4045, 1968 31. Siesjo BK, Folbergrova J, MacMillan V: Effect of hypercapnia upon the intracellular p H in brain evaluated by bicarbonatecarbonic acid method and from the creatine phosphokinase equilibrium. J Neurochem 19:2483-2495, 1972 32. Smith CM, Bryla J, Williamson JR: Regulation of mitochondrial a-ketoglutarate metabolism by product inhibition at a-ketoglutarate dehydrogenase. J Biol Chem 249: 1497-1505, 1974 33. Stadtman ER, Novelli GD, Lipmann F: Coenzyme A function in and acetyl transfer by the phosphotransacetylase system. J Biol Chem 191:365-376, 1951 34. Steiner AL,Ferrendelli J A , Kipnis DM: Radioimmunoassay for cyclic nucleotides: 111. J Biol Chem 247:1121-1124, 1972 35. Uhlemann ER, Neims AH: Anticonvulsant properties of the ketogenic diet in mice. J Pharmacol Exp Ther 180:231-238, 1972 36. Veech RL, Harris RL, Veloso D, et al: Freeze-blowing: a new technique for the study of brain in vivo. J Neurochem 20:183-188, 1973 37. Walajtys El, Gottesman DP, Williamson JR: Regulation of pyruvate dehydrogenase in rat liver mitochondria by phosphorylation-dephosphorylation.J Biol Chem 249: 18571865, 1974 38. Weitzman PDJ, Danson MJ: Citrate synthase, in Horecker BL, Stadtman ER (eds): Current Topics in Cellular Regulation. New York, Academic Press, 1976, vol 10, pp 161-204 39. Williamson D H , Mellanby J, Krebs HA: Enzymic determination of D(-)-P-hydroxybutyric acid and acetoacetic acid in blood. Biochem J 82:90-98, 1962 DeVivo et al: Ketosis and Cerebral Metabolism 337


text:
Six years ago my lovely mother was diagnosed with terminal cancer. She died seven months later.
Two things I will never forget from that horrible time – her bravery and the care she received at Velindre.
A former nurse who taught nursing, Mam knew the staff at this Cardiff cancer hospital were something special. We had been given a hint of what was to come from another patient.
"Have you been to Velindre yet?" she asked as we sat chatting in a waiting room at Royal Glamorgan.
"I know this might sound a strange thing to say," the lady continued, "but it's the happiest hospital you'll ever go to."
I was grateful for this optimistic heads-up. Velindre was a word that made my stomach flip, associated with all sorts of frightening scenarios. And that was indeed the darkest time we have ever endured as a family.
But the one thing that made it more bearable was the approach of the Velindre staff – their warmth, their concern and their humour. The latter proved the perfect ice-breaker when my mother arrived for her first appointment.
The radiographer explained he would be making a tattoo to line up the radiotherapy machine for each treatment.
"Now June I know what you valley girls are like but you don't have to take all your clothes off," he quipped.
Granted, not the most politically correct introduction but it made us burst out laughing, immediately defusing the tension.
And as my mother attended daily radiotherapy sessions over the subsequent weeks, she formed a wonderful bond with the nurses and insisted on getting presents for them all at the end of her treatment. With her experience of years caring for others throughout her own NHS career, she really appreciated the care she received, explaining that it was pastoral as well as practical.
When we lost my mother, we had a collection for Velindre and after I delivered the cheque to the hospital the Head of Fundraising Andrew Morris asked if I would like to become involved as an ambassador, and more recently as a patron.
I found the connection a comfort. Channelling all that grief and sadness into something so positive was a huge help.
Over the past few years, the connection has also given me a broader insight into what a remarkable place Velindre is on the research front as well as patient care.
And over the next few weeks, the viewing public have the chance to see this too as the cameras go behind the scenes of Wales' leading cancer centre for a new four-part series on ITV Wales – Velindre: Hospital of Hope.
Narrated by Ruth Wignall, the series aims to highlight the human stories behind the cancer statistics and diagnostics, focusing on the patients and staff who make Velindre such a comforting place to be treated.
From the uplifting and emotive stories of the patients as they undergo treatment to the pioneering work of the medical staff, each 30-minute programme will capture the highs and lows inside this very special centre.
Llinos Griffin-Williams, executive producer for Green Bay Media, who made the series for ITV Wales said: "As cancer rates improve in Wales, we're proud to be making a series that will capture the exceptional sense of courage and commitment from patients and staff alike."
She added: "From pioneering medical research and treatment to the personal effect of cancer on patients and their families, we'll see first-hand the impact of life changing decisions and how in the darkest of times patients are given hope for dignity and choice, even in end of life care.
"Following porters, consultants and specialist nurses, viewers will get to know the army of skilled professionals supporting patients. We hope to show how life, laughter and love continues through the most challenging of circumstances and how medical development is increasing the number of cancer survivors."
Andrea Hague, director of cancer services at Velindre Cancer Centre, said: "Velindre is a very special place, full of dedicated staff. Every day we see the challenges our patients and their families face with such strength. I am sure a lot of people who watch the series might be affected by cancer themselves or know someone who has had cancer. We hope this series will give people a helpful insight into the day-to-day work of a busy cancer centre."
In the first programme we meet Rosa, an elderly lady finding it difficult to speak after treatment to remove cancer from her cheekbone. But despite her ordeal she has nothing but praise for Velindre: "This is a miracle place," she says. "You can feel the hope within the walls."
Episode two follows patients Carol and Michael as deal with the effects of their different cancers. They both form bonds with medical students Elin and Aileen who have been paired up with them as part of a pioneering oncology project from Cardiff University School of Medicine. Over a period of five months the students attend clinics, consultations and visit them at home to get a better understanding of what it's like from the patients' perspective.
It was heartening to see that empathy is now being considered as valuable a skill as medical expertise in the training of tomorrow's doctors. As the young medics hang round in waiting rooms and share the families' anxiety and emotions, patients cease to be just a casefile full of notes. "They've made me want to be a better doctor," Aileen reflects.
In the third episode we follow two patients at two different stages of their cancer journeys. Rebecca, a vibrant young mother who's been having chemotherapy for two years for incurable abdominal cancer and Pauline who's coming to terms with her diagnosis of anal cancer and the stigma surrounding it. "Everyone's got a backside haven't they?" laughs Pauline, as she discusses how people find it much easier to talk about other types of cancer.
Throughout the series there are good outcomes for the patients featured but the final episode focuses on Allyson, who has terminal bowel cancer and is yearning to make it to a very special summer party, her 30th wedding anniversary.
We witness sensitive and frank conversations between Allyson and Velindre's palliative care consultant Dr Mark Taubert about her end of life path.
It is at this point that the title of the series – Hospital of Hope – may feel cruel. Yet Allyson stresses the hope Velindre has given her in making her precious final years and months as fulfilling as they can be, as together they manage her choice of treatment and she decides to forgo any more chemotherapy.
Her courage and positivity remind me of the strength my mother showed in her final months. When that end comes people talk about their about loved ones "losing their battle" with cancer but I hate that metaphor because cancer isn't a fair fight.
But what I do know is that when you have it, Velindre will fight for you. They will fight to get you the best possible treatment. They will fight to fund the best possible research. They will fight to give you the best possible chance. And that is why this very special place truly is a Hospital of Hope.
* Velindre: Hospital of Hope begins next Friday on ITV Wales at 8pm. Following the final episode, Ruth Wignall will be hosting a Facebook Live with specialists and staff from the cancer centre to discuss some of the issues from the series and to give advice to those patients and families living through a cancer diagnosis.

subset: commoncrawl


text:
LAME is a library that enables a few packages to fix MP3 recordsdata. LAME is , but in some countries you may need to reward a license charge with a purpose to legally MP3 information.
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What year did vehicles start coming out by means of MP3s?
MP3acquire doesnotjust do culmination normalization ,as diverse normalizers do. instead, it does somestatistical analysisto decide how rolling the editorial actuallysoundsto the human ear.additionally, the adjustments MP3gain makes are completely lossless. there isn't any quality lost in the vary as a result of this system adjusts the mp3 post directly,with out decoding and re-encoding.
MP3GAIN by the side of ModuleDIY LaptopDuinoInternet of ThingsRobot partsSoldering KitsFPGAARMAVRMAXQMSP4three0PICDSPEEGPower SupplyUEXT Modules InterfaceAdaptersSensorsLCDLEDIOVideoRFRFIDEthernetTimeGPSMPthreeBiofeedback USB ModulesBreadboardingCompbyentsToolsSwagProducts value ListTweetProductsUEXT ModulesMPthree MP3 MOD-MP3This item can not shelter ordered but! MOD-MPthree-Xprice29.ninety five EUR10 - forty nine pcs26.96 EUR50 - a thousand0 pcs2three.96 EUR boost basketMOD-MP3-X-maceworththree9.95 EUR10 - 49 pcs35.ninety six EUR50 - 10000 pcs31.ninety six EUR bump up basketMOD-MP3-X-LITEworth22.ninety five EUR10 - forty nine pcs20.sixty six EUR50 - a thousand0 pcs1eight.36 EUR bump up basket
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text:
tag:theconversation.com,2011:/au/topics/theory-of-everything-5831/articles Theory of Everything – The Conversation 2018-08-15T15:17:11Z tag:theconversation.com,2011:article/101622 2018-08-15T15:17:11Z 2018-08-15T15:17:11Z Anthill 28: On nothing

shutterstock

Why is it so hard for us to just sit and do nothing? We don't mean mindlessly scrolling through social media, while you watch TV. Actually sitting still and letting your mind wander.

Busyness seems to be a status symbol of our time. Everybody everywhere is busy – busy with work, busy with family, busy exercising, busy meditating. Busy being busy. Busyness is associated with success and fulfilment in most societies, so we view busyness as something to aspire to.

But what if you could achieve more by doing less? Psychologist Giulia Poerio shares some of her research about the benefits of daydreaming.

We also explore what it's like when this is taken to the extreme and all you have are your own thoughts for company. Solitary confinement has been used systematically in prisons since the 19th century. Historian Hilary Marland explains the thinking behind what was called the "separate system" and how time alone was meant to give prisoners room to reflect on their crimes and repent of their sins. But as prison memoirs of the time reveal, solitary confinement was blamed for huge numbers of mental breakdowns, and its purpose as a tool for rehabilitation began to be questioned.

Peter Scharff Smith then talks us through how and why solitary confinement is still used in prisons around the world today, despite clear evidence of its negative health effects. And neuroscientist Ross Vanderwert explains why our brains react the way they do when we are deprived of meaningful social contact for long periods.

Finally, we explore the physics of nothing with astronomer royal, Martin Rees. By explaining how physicists are trying to understand what empty space is, he takes us on a journey from the beginning of the universe to the end.

The Anthill theme music is by Alex Grey for Melody Loops. Music in the daydreaming segment is Ant! Stop Daydreaming! by Just Plain Ant. Music in the solitary confinement segment is Falling into Darkness by Ascetic. And music in the physics of nothing segment is The Idea of Space by Lee Rosevere

Click here to listen to more episodes of The Anthill, on themes including Twins, Intuition, and Confidence. And browse other podcasts from The Conversation here.

Thank you to City, University of London's Department of Journalism for letting us use their studios to record The Anthill.
 A podcast all about nothing. From the importance of doing nothing to the ill-effects of time spent in solitary confinement and what nothing means in space. Annabel Bligh, Business + Economy Editor, The Conversation UK Gemma Ware, Society Editor, The Conversation UK Miriam Frankel, Science Editor, The Conversation UK Holly Squire, Commissioning Editor, The Conversation UK Licensed as Creative Commons – attribution, no derivatives. tag:theconversation.com,2011:article/50057 2015-11-24T17:08:28Z 2015-11-24T17:08:28Z Will we have to rewrite Einstein's theory of general relativity?

The fathers of modern physics, including Einstein, Millikan, Planck and others, in debate. Materialscientist/wikimedia

Einstein famously laboured hard to create the theory of general relativity, but it is less well known that he also helped to launch quantum mechanics, which he didn't much care for. These two views of the world are the very foundation stones of modern physics – without them we would not have things such as space travel, medical imaging, GPS systems or nuclear energy.

General relativity is unparalleled when it comes to describing the world on a large scale, such as planets and galaxies, while quantum mechanics perfectly describes physics on the smallest scale, such as the atom or even parts of the atom. Uniting the two into a consistent "theory of everything" is the single biggest challenge in physics today – and progress is slow.

The birth of modern physics

Our knowledge of the universe is based on a sequence of "natural laws". With time many laws become morphed into new ones as a result of experimental evidence or changing conceptual prejudices. Einstein's rejection of the concept of universal time was one of the most radical shifts in the history of physics. Its consequences have proved crucial to shaping some of the most profound developments in our understanding of nature.

By fusing the three dimensions of space (height, width and depth) with that of a time direction to construct a "spacetime structure", a new symmetry of nature could be uncovered. When Einstein later added gravitation to his theories, it led to experimentally verifiable predictions as well as the prediction of gravitational waves and black holes, beyond the natural scope of Newton's existing law of gravitation.

But Einstein didn't just work on relativity. A big problem at the time was the fact that Maxwell's laws, describing electromagnetic phenomena, were unable to explain why faint ultraviolet light falling on metallic electrodes could induce sparks more easily than bright red light. Einstein suggested that this could be understood if the energy in the light wave wasn't continuously distributed as a wave but rather as a shower of individual "light bullets" (photons – also known as "light quanta"), each with an energy proportional to the colour (frequency) of the light. Many scientists were sceptical of this groundbreaking thought, as so many experiments had already shown that light was a wave.

 <img alt="" src="https://images.theconversation.com/files/102884/original/image-20151123-18230-bbj53b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/102884/original/image-20151123-18230-bbj53b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=849&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102884/original/image-20151123-18230-bbj53b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=849&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102884/original/image-20151123-18230-bbj53b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=849&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102884/original/image-20151123-18230-bbj53b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1066&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102884/original/image-20151123-18230-bbj53b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1066&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102884/original/image-20151123-18230-bbj53b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1066&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
 Millikan proved Einstein right. Nobel foundation/wikipedia, CC BY-SA

One of them was Robert Millikan, who ironically eventually ended up experimentally verifying Einstein's theory. Millikan also discovered that charged particles known as electrons have wave-like properties. Together with Einstein's discovery, this pointed to a duality where both matter and light could be described as a particle or as a wave – an idea which led to the development of quantum mechanics by a number of scientists.

This theory has had wide applicability on the smallest of scales, where gravity can often be neglected as it is so weak compared to the other forces affecting particles. Not only has it led to a consistent description of matter and radiation observed in everyday life, it has also made predictions of new particles and processes that are now observed in high-energy accelerator experiments on Earth or cosmic events in space.

The contenders

To unify the description of matter and radiation quanta with gravitation it became natural to contemplate "gravitational quanta" that carry the force of gravitation. String theory has emerged as a candidate to do this. It states that matter is made up of vibrating extended structures, like tiny strings or membranes, rather than point-like particles. Each type of vibration of these structures corresponds to a particular state of matter.

One type of vibration also corresponds to a gravitational quantum. However, for the resulting quantum description to be consistent it becomes necessary to boost the dimension of spacetime by introducing additional space dimensions that are unobservable to the eye and current technology. To date, there has been no firm experimental confirmation of string theory.

By contrast, in domains where gravitation appears irrelevant, quantum mechanics remains unchallenged, despite describing a very strange world. It states that particles can be in a number of different possible states at once. While the theory can predict a set of probabilities for the particle to be in a particular state, it cannot, in general, predict which probability will actually occur.

In such cases, one must take a large number of observations and then calculate average measurements. Furthermore, such averages depend on what properties are to be measured and when such measurement decisions are made. This peculiar world picture sits uncomfortably alongside Einstein's world view of causal events and frozen histories in spacetime.

What's more, according to quantum mechanics, one particle's state can be correlated with another particle's state, even if it is in a distant location. Einstein didn't like this because it seemed to imply that correlations could occur over events that could not be connected by a beam of light, thereby breaking a rule that says nothing can travel faster than the speed of light. He felt that such "spooky action at a distance" was proof for the incompleteness of the theory, although experimental evidence since points to the contrary.

 <img alt="" src="https://images.theconversation.com/files/102885/original/image-20151123-18257-fypsul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102885/original/image-20151123-18257-fypsul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102885/original/image-20151123-18257-fypsul.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102885/original/image-20151123-18257-fypsul.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102885/original/image-20151123-18257-fypsul.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102885/original/image-20151123-18257-fypsul.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102885/original/image-20151123-18257-fypsul.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
 Could the International Space Station be the key to probe the effects of gravity on quantum entanglement? NASA/wikipedia

However, new experiments are underway to see whether gravitational interactions might influence such eerie action in unexpected ways. A research group in Vienna proposes to use the International Space Station to see how gravity might influence this action. A collection of entangled photon pairs will be created on Earth before one member of each pair is sent to the orbiting space station. There, a state known as polarisation will be recorded and compared with the state of its partner on Earth.

It is unclear whether quantum mechanics or general relativity will need either mathematical or conceptual modification in response to future experimental probing. But while the outcome is difficult to predict, Einstein's influence has been and remains pivotal in this quest.

Robin Tucker receives funding from EPSRC and STFC.
 Physicists are working hard to unite Einstein's theory of relativity with quantum mechanics. It's no easy task. Robin Tucker, Professor in mathematical physics, Lancaster University Licensed as Creative Commons – attribution, no derivatives. tag:theconversation.com,2011:article/34676 2014-12-03T10:49:42Z 2014-12-03T10:49:42Z Theory of Everything debunks myth of Hawking as disembodied mind
Early in The Theory of Everything, the student Stephen Hawking strides across the grounds at Cambridge University in the 1960s, his face dreamy. He is lost in thought about the nature of time.

Then he trips and smacks his head on the concrete, cracking his glasses and bruising his face.

It's a pivotal incident in the film, as it triggers the battery of tests that lead to his diagnosis of Lou Gehrig's disease and the prediction that he had only two years to live.

The rest of the film follows the British cosmologist as he confounded that grim forecast. It dramatizes how he achieved renown within physics because of his ground-breaking 1970s work on black holes.

In less detail, the movie goes on to show how he became a pop culture star after A Brief History of Time, his 1988 explanation of cosmology for nonspecialists, became the bestselling general science book ever.

As he's grown older, Hawking has become progressively weaker as his condition wasted his muscles, but his brilliant mind continued to whir. In the process, a dominant myth took shape around him, a myth that presented to wider society a misleading view of the physicist and his research.

The myth was best articulated by Hélène Mialet in her book Hawking Incorporated. She noted that the cosmologist is overwhelmingly presented in popular culture as an intellect "liberated from his body and seemingly emancipated from everything that clutters the mundane mind (such as emotions, values, and prejudices)."

This image of Hawking as disembodied mind has crystallized in public opinion. It's reproduced in photographs and articles and the BBC documentary The Hawking Paradox. Moreover, the latest published biography of him was named Stephen Hawking: An Unfettered Mind.

Missing in these images are the vast networks of support systems that allow Hawking to live and work. Research students support him as he writes his papers and delivers his presentations. Nurses tend to his daily needs. Technological staff ensures he can communicate with the world. And, crucially, his family have provided decades of care and emotional support.

Yet as Mialet writes, when Hawking is presented in popular culture, these collective support systems "'magically' disappear." All that remains is Hawking as a lone researcher, a pure intellect, an unfettered mind.

But The Theory of Everything debunks this myth. By showing Hawking cracking his head on the concrete, it inverts the central idea of the myth: Hawking's mind is not free of his body, but is instead bound inextricably to it.

Moreover, the film makes Hawking's support systems visible and vivid. His wife Jane Hawking dresses him, feeds him and cares for him. She and, later, nurse Elaine Mason teach him to communicate after a tracheotomy takes away his ability to speak. A system of technology then grants him a new, robotic voice. With these systems, his science has flourished.

The film also anchors Hawking in the physical world. Far from being a purely cerebral creature, he is shown choking on food, coughing up blood and trying in vain to count on his fingers as his muscles waste. His physical attraction to Elaine is obvious. He breaks down in tears as he tells Jane he is leaving her for Elaine.

It is not surprising that these images dominate, as the film's source material is Jane Hawking's biographical account of their life together, Travelling to Infinity, itself a 500-page debunking of any notion of Hawking as totally cerebral genius.

The film challenges this notion from the start. One of its first scenes shows Hawking in 1963 speeding on a bike around Cambridge. As Rolling Stone wrote in its review, the scene "will be a revelation to those stuck with the image of Hawking shackled to a motorized wheelchair, his head lolling, his muscles limp, his voice computer-generated."

I've traced Stephen Hawking's development as a world famous scientist in my forthcoming book. I believe The Theory of Everything gives the most rounded picture of the man since the first sustained coverage of him in the late 1970s and early 1980s after his most significant finding: that black holes leak heat. At the time, a series of long profiles in a range of magazines from New Scientist and Reader's Digest to Vanity Fair explored his science and his family and his collaboration with colleagues.

The film has been criticized for leaving out or glossing over important scientific details. But, for me, it illuminates a deeper truth about the work of Hawking and all scientific researchers: the creation of knowledge is an ongoing collaborative endeavor that involves vast networks of researchers, each with their own lives, each with their own systems of support.

Dramatizing this idea, the film underlined a prescient point made in the early 1990s by the late novelist Anthony Burgess when he reviewed two early biographies of the physicist. Burgess did not identify Hawking as the books' real star. Jane, he wrote, was "the true heroine of his story, sustained in her care of [Hawking] and their children by a profound belief in God."

Declan Fahy does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
 Early in The Theory of Everything, the student Stephen Hawking strides across the grounds at Cambridge University in the 1960s, his face dreamy. He is lost in thought about the nature of time. Then he… Declan Fahy, Assistant Professor of Communication, American University School of Communication Licensed as Creative Commons – attribution, no derivatives. tag:theconversation.com,2011:article/14998 2013-06-06T20:41:50Z 2013-06-06T20:41:50Z Einstein to Weinstein: the lone genius is an exception to the rule

Albert Einstein was considered to be a 'lone genius' – but this was not the case, and it's certainly not the norm. tsweden

Developing a Theory of Everything is physics' Holy Grail. So could it have been completed in recent weeks? And by an outsider, working alone?

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 Eric Weinstein - the new Einstein? Wikimedia Commons

American mathematical physicist-turned-hedge-fund-consultant Eric Weinstein is in the (very) early stages of revealing to the public his homemade theory of everything, developed over two decades, alone, in his spare time.

I haven't attended Weinstein's lectures and I haven't seen his work (very few people have so far), so I'm not going to comment on its genius or lack thereof. Nor will I comment on the media attention per se, as others have done plenty of that.

But I will say the Weinstein lone-genius model of theoretical physics is in stark contrast to how theoretical physics is nearly always done.

But … Einstein!

One of the reasons Einstein carries such a hefty cultural weight is that he, like Newton a few centuries before him, appears to have basically single-handedly invented a fundamentally new view of the universe.

Newton did it over the course of 18 months, starting in 1665 while isolated to avoid the Plague, revolutionising optics and gravity, and inventing calculus along the way.

 <img alt="" src="https://images.theconversation.com/files/25143/original/5nbvqwgg-1370498381.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/25143/original/5nbvqwgg-1370498381.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=899&fit=crop&dpr=1 600w, https://images.theconversation.com/files/25143/original/5nbvqwgg-1370498381.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=899&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/25143/original/5nbvqwgg-1370498381.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=899&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/25143/original/5nbvqwgg-1370498381.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/25143/original/5nbvqwgg-1370498381.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/25143/original/5nbvqwgg-1370498381.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
  Recuerdos de Pandora

Einstein's turn came in his "Annus Mirabilus" (miracle year) in 1905, when he published four groundbreaking papers and a PhD thesis, touching on optics, the size and motions of atoms, and the theory of special relativity.

Einstein is frequently depicted as having been completely cut off from the academic establishment during this time – and being "just a patent clerk".

But, although he was certainly not a working academic physicist, he still had connections with the community, people to bounce ideas off and a (stalled) PhD-in-progress at the University of Zurich.

He is, I will grant, probably the best example in the modern era of a theoretical physicist revolutionising science from outside "the establishment". In fact, he's the only one I can think of.

"Hey, who invented quantum mechanics?"

I asked this question of a colleague of mine while writing this, not because I thought he'd have a single answer, but because I was curious what the list might look like. There are a few people who should probably get some credit:

Maxwell, who first formulated the basic equations of electromagnetism

Hertz, an experimentalist who helped demonstrate the photoelectric effect

Planck, who was so important to quantum theory that its most fundamental constant is named after him

Einstein, who first explained the photoelectric effect from a theoretical point of view

or Pauli, or Heisenberg, or Bohr, or Nernst, or Schrödinger …

Quantum mechanics is a great illustration of the fact that it doesn't take a lone iconoclast to revolutionise our understanding of the universe.

 <img alt="" src="https://images.theconversation.com/files/25146/original/dmyt7hht-1370499334.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/25146/original/dmyt7hht-1370499334.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/25146/original/dmyt7hht-1370499334.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/25146/original/dmyt7hht-1370499334.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/25146/original/dmyt7hht-1370499334.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/25146/original/dmyt7hht-1370499334.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/25146/original/dmyt7hht-1370499334.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
  Kennedy Goodkey

Even huge breakthroughs that fundamentally change how we see and do physics can – and do – come about in a series of incremental steps. Experimentalists see something odd in their experiments, theorists propose possible explanations, experimentalists go back and test the consequences of each theory, and the cycle begins again.

This has happened a number of times since Einstein's era. In addition to quantum mechanics, we've seen the appearance of the Standard Model of Particle Physics, quantum field theory, the concordance model of cosmology (including dark matter and dark energy), and the as-yet purely theoretical frameworks of supersymmetry and string theory.

None of these advances could be attributed to one person, nor did they generally involve people working in isolation on theories of their very own.

So how does it usually work?

Physics is, these days, an immensely collaborative field. There are a lot of conferences as well as institutes and workshops and collaboration visits; there are endless seminars and dissections of research papers.

Newly-built physics institutes tend to have hallways lined with blackboards or dry-erase-glass cubicles to get people out of their offices to collaborate. We talk to each other, not because we are inherently very social (though a lot of us are), but because it's a really productive way to proceed.

 <img alt="" src="https://images.theconversation.com/files/25147/original/qz2q6wyx-1370500318.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/25147/original/qz2q6wyx-1370500318.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=804&fit=crop&dpr=1 600w, https://images.theconversation.com/files/25147/original/qz2q6wyx-1370500318.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=804&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/25147/original/qz2q6wyx-1370500318.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=804&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/25147/original/qz2q6wyx-1370500318.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1011&fit=crop&dpr=1 754w, https://images.theconversation.com/files/25147/original/qz2q6wyx-1370500318.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1011&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/25147/original/qz2q6wyx-1370500318.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1011&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
  Fellowship of the Rich

Personally, I find I think better when I'm explaining my ideas to someone. Some people, after staring at the same equations for days, just need to get the math written down and show it to other people to make sure it really makes sense. Even more importantly, we're not all experts on all areas of physics.

One person might have spent four years working on a particular quantum mechanical process in the early universe while another might be an expert on strong-field gravitation, and together they can create a much clearer picture of how, say, how gravitational waves might be produced right after the Big Bang.

And here I'm just talking about pure theory - if you want to actually test theories, you have to be in touch with experimentalists and observers and find out what kind of tools they have available.

So why are we hearing about Weinstein's (still unpublished) ideas now, for the first time? I don't know. Maybe he had a really good reason not to talk to other physicists about his work.

Perhaps he was worried it might be wrong and didn't want to embarrass himself, or perhaps he was worried it might be right and he'd be scooped or not get all the credit. Or maybe he just doesn't like to talk to physicists all that much.

It's even possible he thought his ideas were so revolutionary that no one else would understand. But I kind of doubt that.

We physicists love finding new ways to think. We love stretching our minds and seeing things from another point of view. It's why we do the work we do - and it's why we spend so much time talking to each other about it.

 A version of this article appeared on The Universe, in Theory.

Katherine J Mack receives funding from the Australian Research Council in the form of a Discovery Early Career Researcher Award.
 Developing a Theory of Everything is physics' Holy Grail. So could it have been completed in recent weeks? And by an outsider, working alone? American mathematical physicist-turned-hedge-fund-consultant… Katherine J Mack, DECRA Fellow, Astrophysics, University of Melbourne Licensed as Creative Commons – attribution, no derivatives.


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05:00PM, Tuesday 31 January 2017
Opposition to plans for hundreds of new home sin Wooburn and Bourne End has been given a boost after campaigners were told they had a strong legal case.
Members of the Keep Bourne End Green group have been fighting proposals in the Wycombe District Local Plan to build up to build 750 new homes in the villages.
There is concern this could cause knock-on effects to roads, services and destroy greenbelt land.
Penny Drayton, one of the founders of the campaign, which was originally called Don't Destroy Bourne End, said a meeting with solicitors on Wednesday, January 25, has gone well.
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A fundraising fashion show is due to be held on Friday, February 24, and a ball has been planned for Saturday, March 4.
Visit www.keepbourneendgreen.org to find out more about the campaign and upcoming events.
Visit www.wycombe.gov.uk to find out more about the Wycombe District Local Plan.
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Beyonce looked stunning as she showed off her busty figure during date night with Jay-Z.
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Overview Detail Legend Zoom: ?? Overlay features legend For more map options click on any overview map area or any detail map feature. Detail Map Features Showing 13 items: Mweelrea 814m, Ben Lugmore 803m, Ben Bury 795m, Ben Lugmore West Top 790m, Ben Lugmore East Top 790m, Mweelrea SE Spur 495m, Carricklea 95m, Tracks: 3357, 15km 3579, 13km 1999, 13km 3853, 10km 3854, 9km 2858, 7km Find Suggested WalksOpen walks finder Find hill, mountain, island, coastal feature. Videos Recent Contributions 1 2 3 .. 28 Next page >> Slieve Beg: Southern plunge Summit Comment simon3 3 hours ago The famous side of Slieve Beg is the NE, gashed by the Devils Coachroad. However the SE side also has its drama.Taken on a frosty slippy day from Cove. Chimney Rock Mountain: Rock, cloud and sea. Summit Comment simon3 3 hours ago Chimney Rock photographed from between Slievelamagan an Cove. Pic de Cresp Track 4031 David-Guenot 20 hours ago walk, Len: 12.9km, Climb: 1190m, Area: France, Occitanie () James Forrest - VLs in 2 months man - talks Forum: General simon3 a day ago Date: 23rd/24th/25th January 2019Venue: 23rd Jan Dublin24th Jan Thurles25th Jan NewryDetails here: https://mountaineering.ie/events/2013/default.aspx?iid=2214The Vandeleur-Lynams, a list now maint... Dromderalough NE Top: VL Number 273 bagged.... Summit Comment Colin Murphy 2 days ago My final Vandeleur-Lynam! Unfortunately No. 273 wasn't the most distinctive summit (when I came off Mangerton I couldn't even pick it out on the landscape) , but the views from the top are tremend... Dromderalough NE Top: Long route from the south. Summit Summary Collaborative entry Last edit by: Colin Murphy 2 days ago Not normally done in isolation, this top usually forms part of a walk involving Dromderalough itself or Mangerton. One approach is from the north, which has the advantage of a gently rising track ... Dromderalough NE Top: Odd-looking formations Summit Comment Colin Murphy 2 days ago On my approach to the summit I came across a large field of hundreds of these rather striking formations, which I think are are moss-covered boulders, but which looked like giant green ant-hills o... Mullaghdoo: Winter has arrived in the Sperrins Summit Comment eamonoc 2 days ago Visited Mullaghdoo today, as part of a 16.4km tek over the Mullaghs, followed Onzy`s track 2570 and added on the walk out to Mullaghdoo and back from Mullaghclogha, much retracing of steps require... Mullaghdoo: Winter has arrived in the Sperrins Summit Comment eamonoc 2 days ago View back over route taken from Mullaghclogha to Mullaghdoo Slievenaglogh: Pleasant 90 Minute Stroll Summit Comment Pepe 5 days ago A blanket of cloud covered the higher Cooleys from Foxe's Rock to Foye but Slievenagloch was in the clear - happy days! Lots of logging activity at 9.30 of a Monday morning, so no space to park at... Mangerton: The Lake District Summit Comment TommyV 6 days ago Scapania's directions to the start are perfect. It's possible to make a looped walked taking in Stoompa and Mangerton which will allow for great views of so many lakes I won't list them. It's a fa... Naweeloge Top: Meh Summit Comment magnumpig 6 days ago I followed Sandmans instructions - thanks for those - it's a bit of a time consuming and boring climb, and the views from the top arent great. I wouldnt prioritise it if you have time constraints ... Most Recent Monthly Newsletter. Conditions and Info Use of MountainViews is governed by conditions. General information about the site is here. Opinions in material here are not necessarily endorsed by MountainViews. Hillwalking is a risk sport. Information in comments, walks or shared GPS tracks may not be accurate for example as regards safety or access permission. You are responsible for your safety and your permission to walk see conditions. Credits and list definitions are listed here Credits RSS Feed for Recent Items. Visit our Facebook page. Video display Mweelrea Mountains Area More detail Place count in area: 9, OSI/LPS Maps: 37, MSW Highest place: Mweelrea, 814m Maximum height for area: 814 metres, Maximum prominence for area: 779 metres, Places in area Mweelrea Mountains:Ben Bury 795mBen Lugmore 803mBen Lugmore East Top 790mBen Lugmore West Top 790mCorrymailley Hill 286mMweelrea 814mMweelrea SE Spur 495mTawnydoogan 312mTeevnabinnia 379m Note: this list of places includes island features such as summits, but not islands as such. Centre on map. Ben Bury Mountain Ucht an Chreagáin A name in Irish also Oughty Craggy an extra name in English (Ir. Ucht an Chreagáin [logainm.ie], 'breast of the little crag') Mayo County, in Arderin, Vandeleur-Lynam, Irish Best Hundred Lists, Sandstone & conglomerate, ignimbrite Bedrock Height: 795m OS 1:50k Mapsheet: 37 Grid Reference: L80244 68290 Place visited by 337 members. Recently by: david bourke, Patbrdrck, MagdaK, billh999, Atlanticstar, jamesmforrest, pgrondier, conorjob, Liamob, Seamus-hills, ilenia, Richtea, Haulie, FrankMc1964, PaulaMc I have visited this place: NO (You need to be a logged-in member to change this.) More detail Longitude: -9.811829, Latitude: 53.650821 , Easting: 80244, Northing: 268290 Prominence: 60m, Isolation: 0.7km ITM: 480223 768308, GPS IDs, 6 char: BnBry, 10 char: Ben BuryBedrock type: Sandstone & conglomerate, ignimbrite, (Mweelrea Formation) Also known as Oughty Craggy. Ben Bury is the third highest mountain in the Mweelrea Mountains area and the 44th highest in Ireland. Trackback: https://mountainviews.ie/summit/43/?PHPSESSID=62bi3fc81utnf7rdbsrigu8tk6 Rate Gallery COMMENTS for Ben Bury << Prev page 1 2 3 Next page >> This is a great starting point for walks to all t .. by ankaby (Show all for Ben Bury) After all the excitement of the Ben Lugmore ridge .. by madfrankie (Show all for Ben Bury) Benbury was the first top I reached on the way to .. by gerrym (Show all for Ben Bury) Panoramic view from north end of Doo Lough - Ben .. by stevefe (Show all for Ben Bury) Picture from murphysw : Near the top of the ramp in awful conditions Picture: Near the top of the ramp in awful conditions murphysw on Ben Bury, 2008 by murphysw 6 Dec 2008 I recently returned to Mweelrea with a few mates who were keen to complete their 4 province high points. I had already done Mweelrea back in March, so made the detour to Ben Bury in order to at least get a new peak for myself. It was good we did so as the rain was terrible, visibility was nearly nil, and the wind between Ben Bury and Mweelrea was nearly strong enough to knock you off your feet. Having to be precise on the ramp is actually a help in conditions like this as it is hard to get lost. Its a different matter above as without the GPS we would never have found the summits of Ben Bury and Mweelrea. We were talking to a barman from the west side of the mountain, who was really surprised to hear we did it from the 'backside' as he put it! Trackback: https://mountainviews.ie/summit/43/comment/3467/ Your Score: Very useful << >>Average Parked at North of Doo Lough, and we head SW into .. by Geo (Show all for Ben Bury) COMMENTS for Ben Bury << Prev page 1 2 3 Next page >> (End of comment section for Ben Bury.) Some mapping: Open Street Map (Various variations used.) British summit data courtesy: Database of British & Irish Hills (Creative Commons Licence) MountainViews.ie, a Hill-walking Website for the island of Ireland. 11 Million Visitors Per Year. 1300 Contributors.


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