Tuberous sclerosis complex (TSC) is a rare multisystem autosomal dominant genetic disease that causes non-cancerous tumours to grow in the brain and on other vital organs such as the kidneys, heart, liver, eyes, lungs and skin. A combination of symptoms may include seizures, intellectual disability, developmental delay, behavioral problems, skin abnormalities, lung disease, and kidney disease.

TSC is caused by a mutation of either of two genes, TSC1 and TSC2, which code for the proteins hamartin and tuberin, respectively, with TSC2 mutations accounting for the majority and tending to cause more severe symptoms. These proteins act as tumor growth suppressors, agents that regulate cell proliferation and differentiation.

Prognosis is highly variable and depends on the symptoms, but life expectancy is normal for many.

The prevalence of the disease is estimated to be 7 to 12 in 100,000. The disease is often abbreviated to tuberous sclerosis, which refers to the hard swellings in the brains of patients, first described by French neurologist Désiré-Magloire Bourneville in 1880.

Signs and symptoms
The physical manifestations of TSC are due to the formation of hamartia (malformed tissue such as the cortical tubers), hamartomas (benign growths such as facial angiofibroma and subependymal nodules), and very rarely, cancerous hamartoblastomas. The effect of these on the brain leads to neurological symptoms such as seizures, intellectual disability, developmental delay, and behavioral problems.

Neurological

Three types of brain tumours are associated with TSC:
 Giant cell astrocytoma: (grows and blocks the cerebrospinal fluid  flow, leading to dilatation of ventricles causing headache and vomiting)
 Cortical tubers: after which the disease is named
 Subependymal nodules: form in the walls of ventricles

Classic intracranial manifestations of TSC include subependymal nodules and cortical/subcortical tubers.

The tubers are typically triangular in configuration, with the apex pointed towards the ventricles, and are thought to represent foci of abnormal neuronal migration. The T2 signal abnormalities may subside in adulthood, but will still be visible on histopathological analysis. On magnetic resonance imaging (MRI), TSC patients can exhibit other signs consistent with abnormal neuron migration such as radial white matter tracts hyperintense on T2WI and heterotopic grey matter.

Subependymal nodules are composed of abnormal, swollen glial cells and bizarre multinucleated cells which are indeterminate for glial or neuronal origin. Interposed neural tissue is not present. These nodules have a tendency to calcify as the patient ages. A nodule that markedly enhances and enlarges over time should be considered suspicious for transformation into a subependymal giant cell astrocytoma, which typically develops in the region of the foramen of Monro, in which case it is at risk of developing an obstructive hydrocephalus.

A variable degree of ventricular enlargement is seen, either obstructive (e.g. by a subependymal nodule in the region of the foramen of Monro) or idiopathic in nature.

Neuropsychiatric
About 90% of people with TSC develop a range of neurodevelopmental, behavioural, psychiatric, and psychosocial difficulties. The "TSC‐associated neuropsychiatric disorders" are abbreviated TAND. These difficulties are less frequently identified and thus undertreated when compared with the neurological symptoms. Most problems are associated with more severe intellectual delay or associated with childhood and adolescence, and some (for example depressed mood) may be unreported if the person is unable to communicate. TAND can be investigated and considered at six levels: behavioural, psychiatric, intellectual, academic, neuropsychological, and psychosocial.

Behavioural problems most commonly seen include overactivity, impulsivity and sleeping difficulties. Also common are anxiety, mood swings, and severe aggression. Less common are depressed mood, self-injury, and compulsive behaviours.

People with TSC are frequently also diagnosed with psychiatric disorders: autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), anxiety disorder and depressive disorder. TSC is one of the most common genetic causes of autism spectrum disorder, which affects nearly half of people with TSC. ASD is more common in TSC2 than TSC1 and more common with earlier and more severe epilepsy, and with lower intellectual ability. ADHD is nearly as frequently seen in TSC as ASD (up to half of all people with TSC). Anxiety and depressive disorders, when they occur, are typically diagnosed in early adulthood and among those intellectually able to express their moods.

The intellectual ability of people with TSC varies enormously. About 40–50% have a normal IQ. A normal IQ is much more commonly seen in TSC1 than TSC2, and profound intellectual disability seen in 34% of TSC2 compared with 10% of TSC1 in one study. Many studies have examined whether early onset, type and severity of epilepsy associates with intellectual ability. Academic issues occur even in people with TSC who have normal intellectual ability. These are often specific learning disorders such as dyscalculia (understanding mathematics), but also include other aspects affecting school life such as anxiety, lack of social skills or low self-esteem.

About half of people with TSC, when assessed for neuropsychological skills, are in the bottom 5th percentile in some areas, which indicates a severe impairment. These include problems with attention (for example, being able to concentrate on two separate things like looking and listening), memory (particularly recall, verbal and spatial working memory) and executive function (for example, planning, self-monitoring, cognitive flexibility).

The psychosocial impacts of TSC include low self-esteem and self-efficacy in the individual, and a burden on the family coping with a complex and unpredictable disorder.

Kidneys

Between 26% and 80% of TSC patients have benign tumors of the kidneys called angiomyolipomas, with hematuria being the most frequent presenting symptom.   TSC angiomyolipomas differ from non-TSC angiomyolipomas in age of presentation (31.5 years vs 53.6 years), mean tumor size (8.2 cm vs 4.5 cm), and percentage of cases requiring surgical intervention (50% vs 28%).  Although benign, an angiomyolipoma larger than 4 cm is at risk for a potentially catastrophic hemorrhage, either spontaneously or with minimal trauma.

Lungs
Patients with TSC can develop progressive replacement of the lung parenchyma with multiple cysts, known as lymphangioleiomyomatosis (LAM). Recent genetic analysis has shown that the proliferative bronchiolar smooth muscle in TSC-related lymphangioleiomyomatosis is monoclonal metastasis from a coexisting renal angiomyolipoma. Cases of TSC-related lymphangioleiomyomatosis recurring following lung transplant have been reported.

Heart
Small tumours of the heart muscle, called cardiac rhabdomyomas, are rare in the general population (perhaps 0.2% of children) but very common in people with TSC. Around 80% of children under two-years-old with TSC have at least one rhabdomyoma, and about 90% of those will have several. The vast majority of children with at least one rhabdomyoma, and nearly all children with multiple rhabdomyomas will be found to have TSC. Prenatal ultrasound, performed by an obstetric sonographer specializing in cardiology, can detect a rhabdomyoma after 20 weeks. Rhabdomyoma vary in size from a few millimetres to several centimetres, and are usually found in the lower chambers (ventricles) and less often in the upper chambers (atria). They grow in size during the second half of pregnancy, but regress after birth, and are seen in only around 20% of children over two years old.

Most rhabdomyomas cause no problems but some may cause heart failure in the foetus or first year of life. Rhabdomyomas are believed to be responsible for the development of heart arrhythmia later in life, which is relatively common in TSC. Arrhythmia can be hard to spot in people with TSC, other than by performing routine ECG. For example, arrhythmia may cause fainting that is confused with drop seizures, and symptoms of arrhythmia such as palpitations may not be reported in an individual with developmental delay.

Skin

Some form of dermatological sign is present in 96% of individuals with TSC. Most cause no problems, but are helpful in diagnosis. Some cases may cause disfigurement, necessitating treatment. The most common skin abnormalities include:
 Hypomelanic macules ("ash leaf spots") are present in about 90% of people with TSC. These small white or lighter patches of skin may appear anywhere on the body, and are caused by a lack of melanin. They are usually the only visible sign of TSC at birth. In fair-skinned individuals, a Wood's lamp (ultraviolet light) may be required to see them. On the scalp, the effect may be a white patch of hair (poliosis). Patches smaller than 3mm are known as "confetti" skin lesions.
 Facial angiofibromas are present in about 75% of people with TSC. These are a rash of reddish spots or bumps on the nose and cheeks in a butterfly distribution, which consist of blood vessels and fibrous tissue. This potentially socially embarrassing rash starts to appear during childhood.
 Ungual fibromas: Also known as Koenen's tumors, these are small fleshy tumors that grow around and under the toenails or fingernails. These are rare in childhood, but common by middle age. They are generally more common on toes than on fingers, develop at 15–29 years, and are more common in women than in men.
 Fibrous cephalic plaques are present in about 25% of people with TSC. These are raised, discoloured areas usually found on the forehead, but sometimes on the face or elsewhere on the scalp.
 Shagreen patches are present in about half of people with TSC, appearing in childhood. They are areas of thick leathery skin that are dimpled like an orange peel, and pigmented, they are usually found on the lower back or nape of the neck, or scattered across the trunk or thighs. The frequency of these lesions rises with age.
 Dental enamel pits are found in almost all adults with TSC.
 Intraoral fibromas are small surface-tumours found in the gums, inside the cheeks or tongue. Gum (gingival) fibromas are found in about 20-50% of people with TSC, more commonly in adults.

Eyes
Retinal lesions, called astrocytic hamartomas (or "phakomas"), which appear as a greyish or yellowish-white lesion in the back of the globe on the ophthalmic examination. Astrocytic hamartomas can calcify, and they are in the differential diagnosis of a calcified globe mass on a CT scan.

Nonretinal lesions associated with TSC include:
 Coloboma
 Angiofibromas of the eyelids
 Papilledema (related to hydrocephalus)

Pancreas
Pancreatic neuroendocrine tumours have been described in rare cases of TSC.

Variability
Individuals with TSC may experience none or all of the clinical signs discussed above. The following table shows the prevalence of some of the clinical signs in individuals diagnosed with TSC.

Genetics

TSC is a genetic disorder with an autosomal dominant pattern of inheritance, variable expressivity, and incomplete penetrance. Two-thirds of TSC cases result from sporadic genetic mutations, not inheritance, but their offspring may inherit it from them. Current genetic tests have difficulty locating the mutation in roughly 20% of individuals diagnosed with the disease. So far, it has been mapped to two genetic loci, TSC1 and TSC2.

TSC1 encodes for the protein hamartin, is located on chromosome 9 q34, and was discovered in 1997. TSC2 encodes for the protein tuberin, is located on chromosome 16 p13.3, and was discovered in 1993. TSC2 is contiguous with PKD1, the gene involved in one form of polycystic kidney disease (PKD). Gross deletions affecting both genes may account for the 2% of individuals with TSC who also develop polycystic kidney disease in childhood. TSC2 has been associated with a more severe form of TSC. However, the difference is subtle and cannot be used to identify the mutation clinically. Estimates of the proportion of TSC caused by TSC2 range from 55% to 90%.

TSC1 and TSC2 are both tumor suppressor genes that function according to Knudson's "two hit" hypothesis. That is, a second random mutation must occur before a tumor can develop. This explains why, despite its high penetrance, TSC has wide expressivity.

Pathophysiology
Hamartin and tuberin function as a complex which is involved in the control of cell growth and cell division. The complex appears to interact with RHEB GTPase, thus sequestering it from activating mTOR signalling, part of the growth factor (insulin) signalling pathway. Thus, mutations at the TSC1 and TSC2 loci result in a loss of control of cell growth and cell division, and therefore a predisposition to forming tumors. TSC affects tissues from different germ layers. Cutaneous and visceral lesions may occur, including angiofibroma, cardiac rhabdomyomas, and renal angiomyolipomas. The central nervous system  lesions seen in this disorder include hamartomas of the cortex, hamartomas of the ventricular walls, and subependymal giant cell tumors, which typically develop in the vicinity of the foramina of Monro.

Molecular genetic studies have defined at least two loci for TSC. In TSC1, the abnormality is localized on chromosome 9q34, but the nature of the gene protein, called hamartin, remains unclear. No missense mutations occur in TSC1. In TSC2, the gene abnormalities are on chromosome 16p13. This gene encodes tuberin, a guanosine triphosphatase–activating protein. The specific function of this protein is unknown. In TSC2, all types of mutations have been reported; new mutations occur frequently. Few differences have yet been observed in the clinical phenotypes of patients with mutation of one gene or the other.

Cells from individuals with pathogenic mutations in the TSC2 gene display abnormal accumulation of glycogen that is associated with depletion of lysosomes and autophagic impairment. The defective degradation of glycogen by the autophagy-lysosome pathway is, at least in part, independent of impaired regulation of mTORC1 and is restored, in cultured cells, by the combined use of PKB/Akt and mTORC1 pharmacological inhibitors.

Diagnosis
Tuberous sclerosis complex is diagnosed with clinical and genetic tests. There are many different mutations in the TSC1 and TSC2 genes that have been identified in individuals with TSC. A pathogenic mutation in the gene prevents the proteins from being made or inactivates the proteins. If such a pathogenic mutation is found then this alone is sufficient to diagnose TSC. However, some mutations are less clear in their effect, and so not sufficient alone for diagnosis. Between 1 in 10 and 1 in 4 of individuals with TSC have no mutation that can be identified. Once a particular mutation is identified in someone with TSC, this mutation can be used to make confident diagnoses in other family members.

For clinical diagnosis, there isn't one sign that is unique (pathognomonic) to TSC, nor are all signs seen in all individuals. Therefore, several signs are considered together, classed as either major or minor features. An individual with two major features, or one major feature and at least two minor features can be given a definite diagnosis of TSC. If only one major feature or at least two minor features are present, the diagnosis is only regarded as possibly TSC.

TSC can be first diagnosed at any stage of life. Prenatal diagnosis is possible by chance if heart tumours are discovered during routine ultrasound. In infancy, epilepsy, particularly infantile spasms, or developmental delay may lead to neurological tests. The white patches on the skin may also first become noticed. In childhood, behavioural problems and autism spectrum disorder may provoke a diagnosis. During adolescence, the skin problems appear. In adulthood, kidney and lung problems may develop. An individual may also be diagnosed at any time as a result of genetic testing of family members of another affected person.

Management

Tuberous sclerosis complex affects multiple organ systems so a multidisciplinary team of medical professionals is required.

In suspected or newly diagnosed TSC, the following tests and procedures are recommended by 2012 International Tuberous Sclerosis Complex Consensus Conference.
 Take a personal and family history covering three generations. Genetic counselling and tests determine if other individuals are at risk.
 A magnetic resonance imaging (MRI) of the brain to identify tubers, subependymal nodules (SEN) and sub-ependymal giant cell astrocytomas (SEGA).
 Children undergo a baseline electroencephalograph (EEG) and family educated to identify seizures if/when they occur.
 Assess children for behavioural issues, autism spectrum disorder, psychiatric disorders, developmental delay, and neuropsychological problems.
 Scan the abdomen for tumours in various organs, but most importantly angiomyolipomata in the kidneys. MRI is superior to CT or ultrasound. Take blood pressure and test renal function.
 In adult women, test pulmonary function and perform a high-resolution computed tomography (HRCT) of the chest.
 Examine the skin under a Wood's lamp (hypomelanotic macules), the fingers and toes (ungual fibroma), the face (angiofibromas), and the mouth (dental pits and gingival fibromas).
 In infants under three, perform an echocardiogram to spot rhabdomyomas, and electrocardiogram (ECG) for any arrhythmia.
 Use a fundoscope to spot retinal hamartomas or achromic patches.

The various symptoms and complications from TSC may appear throughout life, requiring continued surveillance and adjustment to treatments. The following ongoing tests and procedures are recommended by 2012 International Tuberous Sclerosis Complex Consensus Conference.
 In children and adults younger than 25 years, a magnetic resonance imaging (MRI) of the brain is performed every one to three years to monitor for subependymal giant cell astrocytoma (SEGA). If a SEGA is large, growing or interfering with ventricles, the MRI is performed more frequently. After 25 years, if there are no SEGAs then periodic scans may no longer be required. A SEGA causing acute symptoms are removed with surgery, otherwise either surgery or drug treatment with an mTOR inhibitor may be indicated.
 Repeat screening for TSC-associated neuropsychiatric disorders (TAND) at least annually. Sudden behavioural changes may indicate a new physical problem (for example with the kidneys, epilepsy or a SEGA).
 Routine EEG determined by clinical need.
 Infantile spasms are best treated with vigabatrin and adrenocorticotropic hormone used as a second-line therapy. Other seizure types have no TSC-specific recommendation, though epilepsy in TSC is typically difficult to treat (medically refractory).
 Repeat MRI of abdomen every one to three years throughout life. Check renal (kidney) function annually. Should angiomyolipoma bleed, this is best treated with embolisation and then corticosteroids. Removal of the kidney (nephrectomy) is strongly to be avoided. An asymptomatic angiomyolipoma that is growing larger than 3 cm is best treated with an mTOR inhibitor drug. Other renal complications spotted by imaging include polycystic kidney disease and renal cell carcinoma.
 Repeat chest HRCT in adult women every five to 10 years. Evidence of lymphangioleiomyomatosis (LAM) indicates more frequent testing. An mTOR inhibitor drug can help, though a lung transplant may be required.
 A 12-lead ECG should be performed every three to five years.

The mTOR inhibitor everolimus was approved in the US for treatment of TSC-related tumors in the brain (subependymal giant cell astrocytoma) in 2010 and in the kidneys (renal angiomyolipoma) in 2012.  Oral everolimus (rapalog) reduces tumour size, is effective in terms of response to skin lesions and does not increase the risk of adverse events. Everolimus also showed evidence of effectiveness at treating epilepsy in some people with TSC. In 2017, the European Commission approved everolimus for treatment of refractory partial-onset seizures associated with TSC.

Neurosurgical intervention may reduce the severity and frequency of seizures in TSC patients. Embolization and other surgical interventions can be used to treat renal angiomyolipoma with acute hemorrhage. Surgical treatments for symptoms of lymphangioleiomyomatosis (LAM) in adult TSC patients include pleurodesis to prevent pneumothorax and lung transplantation in the case of irreversible lung failure.

Other treatments that have been used to treat TSC manifestations and symptoms include a ketogenic diet for intractable epilepsy and pulmonary rehabilitation for LAM. Facial angiofibromas can be reduced with laser treatment and the effectiveness of mTOR inhibitor topical treatment is being investigated. Laser therapy is painful, requires anaesthesia, and has risks of scarring and dyspigmentation.

Prognosis
The prognosis for individuals with TSC depends on the severity of symptoms, which range from mild skin abnormalities to varying degrees of learning disabilities and epilepsy to severe intellectual disability, uncontrollable seizures, and kidney failure. Those individuals with mild symptoms generally do well and live long, productive lives, while individuals with the more severe form may have serious disabilities. However, with appropriate medical care, most individuals with the disorder can look forward to normal life expectancy.

A study of 30 TSC patients in Egypt found, "...earlier age of seizures commencement (<6 months) is associated with poor seizure outcome and poor intellectual capabilities. Infantile spasms and severely epileptogenic EEG patterns are related to the poor seizure outcome, poor intellectual capabilities and autistic behavior. Higher tubers numbers is associated with poor seizure outcome and autistic behavior. Left-sided tuber burden is associated with poor intellect, while frontal location is more encountered in ASD [autism spectrum disorders]. So, close follow up for the mental development and early control of seizures are recommended in a trial to reduce the risk factors of poor outcome. Also early diagnosis of autism will allow for earlier treatment and the potential for better outcome for children with TSC."

Leading causes of death include renal disease, brain tumour, lymphangioleiomyomatosis of the lung, and status epilepticus or bronchopneumonia in those with severe intellectual disability. Cardiac failure due to rhabdomyomas is a risk in the fetus or neonate but is rarely a problem subsequently. Kidney complications such as angiomyolipoma and cysts are common and more frequent in females than males and in TSC2 than TSC1. Renal cell carcinoma is uncommon. Lymphangioleiomyomatosis  is only a risk for females with angiomyolipomas. In the brain, the subependymal nodules occasionally degenerate to subependymal giant cell astrocytomas. These may block the circulation of cerebrospinal fluid around the brain, leading to hydrocephalus.

Detection of the disease should be followed by genetic counselling. It is also important to realize that though the disease does not have a cure, symptoms can be treated symptomatically. Hence, awareness regarding different organ manifestations of TSC is important.

Epidemiology
TSC occurs in all races and ethnic groups, and in both sexes. The live-birth prevalence is estimated to be between 10 and 16 cases per 100,000. A 1998 study estimated total population prevalence between about 7 and 12 cases per 100,000, with more than half of these cases undetected. Prior to the invention of CT scanning to identify the nodules and tubers in the brain, the prevalence was thought to be much lower, and the disease associated with those people diagnosed clinically with learning disability, seizures and facial angiofibroma. Whilst still regarded as a rare disease, TSC is common when compared to many other genetic diseases, with at least 1 million individuals affected worldwide.

History

TSC first came to medical attention when dermatologists described the distinctive facial rash (1835 and 1850). A more complete case was presented by von Recklinghausen (1862), who identified heart and brain tumours in a newborn who had only briefly lived. However, Bourneville (1880) is credited with having first characterized the disease, coining the name "tuberous sclerosis", thus earning the eponym Bourneville's disease. The neurologist Vogt (1908) established a diagnostic triad of epilepsy, idiocy, and adenoma sebaceum (an obsolete term for facial angiofibroma).

Symptoms were periodically added to the clinical picture. The disease as presently understood was first fully described by Gomez (1979). The invention of medical ultrasound, CT and MRI has allowed physicians to examine the internal organs of live patients and greatly improved diagnostic ability.

In 2002, treatment with rapamycin was found to be effective at shrinking tumours in animals. This has led to human trials of rapamycin as a drug to treat several of the tumors associated with TSC.

See also
 Characteristics of syndromic ASD conditions

References

External links

 GeneReview/NCBI/NIH/UW entry on Tuberous Sclerosis Complex

Autosomal dominant disorders
Genodermatoses
Rare diseases
Biology of attention deficit hyperactivity disorder
Intellectual disability
Biology of obsessive–compulsive disorder
Disorders causing seizures

Tuberous sclerosis


The Macquarie River or Wambuul is part of the Macquarie–Barwon catchment within the Murray–Darling basin, is one of the main inland rivers in New South Wales, Australia.

The river rises in the central highlands of New South Wales near the town of Oberon and travels generally northwest past the towns of Bathurst, Wellington, Dubbo, Narromine, and Warren to the Macquarie Marshes. The Macquarie Marshes then drain into the Darling River via the lower Barwon River.

Lake Burrendong is a large reservoir with capacity of  located near Wellington which impounds the waters of the Wambuul Macquarie River and its tributaries the Cudgegong River and the Turon River for flood control and irrigation.

Name
The Wiradjuri are the people of the three rivers, Wambuul, Kalare (Lachlan) and the Murrumbidjeri (Murrumbidgee). Wambuul means winding river, and included the tributary Fish River. It has also been spelt Wambool.

The river was first documented for the British crown near Bathurst by European explorer, George Evans in 1812, who named the river in honour of Lieutenant-Colonel Lachlan Macquarie, who served as Governor of the Colony of New South Wales from 1810 to 1821.

In December 2021, Wambuul was recognised as an official dual name by the Geographical Names Board of New South Wales after support from a local movement and the Bathurst Local Aboriginal Land Council. Either or both names may be used and both are given equal status.

Geography
From its origin the Wambuul Macquarie River flows for  and drops around  over its length. Lake Burrendong at  is the only dam along the length of the river. Windamere dam, on the Cudgegong River, is operated in conjunction with Burrendong.

Sources
The Macquarie River starts below the locality of White Rock near Bathurst at an elevation of . It is a combination of two water systems which are the overflow from Chifley Dam which is fed by the Campbells River, and the Fish River which flows into and out of the Oberon Dam.

Tributaries
A number of rivers and creeks flow into the Wambuul Macquarie River, with descending elevation as follows:

Communities and bridge crossings along the river

Catchment

The Macquarie system covers an area of more than . Over 72% of land is flat, with an additional 17% undulating to hilly. The remainder is steep to mountainous, rising progressively to elevations above . To the east the boundary is formed by the Great Dividing Range. This boundary extends from near Oberon in the south to Coolah in the north. A well defined ridge extends north-west from the Great Dividing Range for around , then the boundary turns north.

From Bathurst, near the formation of the river, it passes through the following geographic areas:
 Bathurst Plains, undulating country of  elevation surrounded by high tablelands on all sides. This includes an extensive floodplain around Bathurst
past Hill End Plateau, where it is joined from the east by the Turon River, the river drains a plateau extending from near Portland to Sofala. The elevation is around  in the south and  in the north. This area is predominantly rugged slopes.
Burrendong Dam, the Macquarie River is joined from the east by the Cudgegong River, which rises in the hills around Rylstone with a general elevation around
through Wellington and Dubbo where the river is joined by the Bell and Little Rivers. The Bell River rises in flat to undulating country of the Orange plateau, which has a general elevation of  with the highest point being the extinct volcanic peak of Mount Canobolas at roughly . Between Wellington and Dubbo extensive flat areas are evident.
north of Dubbo, the Talbragar River joins the Macquarie. The Talbragar is the most important downstream tributary. This river rises in mountainous country at the junction of the Great Dividing Range and the Liverpool Range. The country through which the Talbragar River runs is broad and flat, bordered by undulating hills that disperse as the river nears Dubbo.
north of Dubbo, the river passes through flat plains flowing north-west through Narromine and Warren. A complex series of effluent creeks connect the Macquarie, Darling and Bogan Rivers.
Macquarie Marshes lie at the end of the river channel proper. Near Carinda, the Macquarie is joined by Marthaguy Creek which drains an area  and carries spill-over water from the Macquarie and Castlereagh Rivers during floods.

Rainfall
Rainfall varies across the catchment of the Macquarie River. Generally the peaks and tablelands receive higher rainfall due to the shadowing effects of the surrounding ranges. The Great Dividing Range area receives between  and  annual median rainfall. This is distributed relatively uniformly throughout the year. Where breaks in the Dividing Range allow the intrusion of moist easterly air streams inland, annual median rainfall of  or more is experienced further westward. Further north-west in the Castlereagh and middle portions of the Macquarie valleys the annual median rainfall is  to .

Rainfall can vary dramatically over several years. For example, records show a variation from >200% to <50% of the average annual figure. Evaporation varies from less than  south-east of Bathurst up to more than  at Bourke.

Statistics

History

Aboriginal history
The Wiradjuri people are the original inhabitants of the area that includes the Macquarie River catchment. The Wiradjuri knew the river as the Wambool, which means "winding river". The noted Wiradjuri warrior Windradyne came from the upper Macquarie River region, and was fatally wounded from a gun shot after a man hunt was commissioned by the crown in 1829. Near Carinda, between the Macquarie River and Marra Creek, the oldest evidence of bread making in the world (approximately 30,000 years old) was found at an ancient lake known as Cuddie Springs.

European history
The upper reaches of the Macquarie River were first seen by Europeans in 1813 and the river was named in honour of the then Governor of the Colony of New South Wales, Lieutenant-Colonel (later Major-General) Lachlan Macquarie. In 1813 Deputy Surveyor of Lands and explorer, George Evans wrote in his journal:
30 November 1813: I have at length reached the Ridge I so much wished to do after walking about 2 Miles, where I had a prospect to the North for a great distance; A Mist arises from a part I suppose to be a River or a large Lagoon about 20 Miles Off; and on 9 December 1813: I have called the Main Stream "Macquarie River".

Two years later Governor Macquarie inspected the country surrounding Bathurst and the Macquarie River and wrote on 10 June 1815, on his return to Government House in Sydney:
At the distance of seven miles from the bridge over the Campbell River, Bathurst Plains open to the view, presenting a rich tract of campaign country of 11 miles in length, bounded on both sides by gently rising and very beautiful hills, thinly wooded. The Macquarie River, which is constituted by the junction of the Fish and Campbell River, takes a winding course through the plains, which can be easily traced from the high lands adjoining by the particular verdure of the trees on its bank, which are likewise the only trees throughout the extent of the plains. The level and clear surface of these plains gives them at first view very much the appearance of lands in a state of cultivation. It is impossible to behold this grand scene without a feeling of admiration and surprise, whilst the silence and solitude, which reign in a space of such extent and beauty as seems designed by nature for the occupancy and comfort of man, create a degree of melancholy in the mind which may be more easily imagined than described.

During 1817 and 1818, explorer John Oxley was commissioned to explore the course of the Lachlan and Macquarie rivers respectively. Writing in his journal, published in 1820, Oxley described the junction of the two rivers:
The river in Wellington Valley had been swelled by the late rains, insomuch that the water below its junction with the Macquarie was quite discoloured. From the fineness of the soil, the rain had made the ground very soft, rendering it difficult for the horses to travel.....  Our day's journey lay generally over an open forest country, with rich flats on either side of the river .... The river had many fine reaches, extending in straight lines from one to three miles, and of a corresponding breadth. The rapids, although frequent, offered no material obstruction to the boats. The current in the long reaches was scarcely perceptible .... The river expanded into beautiful reaches, having great depth of water, and from two to three hundred feet broad, literally covered with water-fowl of different kinds: the richest flats bordered the river, apparently more extensive on the south side. The vast body of water which this river must contain in times of flood is confined within exterior banks, and its inundations are thus deprived of mischief..... The trees were of the eucalyptus (apple tree), and on the hills a few of the callitris macrocarpa [Note: Callitr. Vent decad.] were seen.... The main bed of the river was much contracted, but very deep, the waters spreading to the depth of a foot or eighteen inches over the banks, but all running on the same point of bearing. After going about twenty miles, we lost the land and trees: the channel of the river, which lay through reeds, and was from one to three feet deep, ran northerly. This continued for three or four miles farther, when although there had been no previous change in the breadth, depth, and rapidity of the stream for several miles, and I was sanguine in my expectations of soon entering the long sought for Australian sea, it all at once eluded our farther pursuit by spreading on every point from north-west to north-east, among the ocean of reeds which surrounded us, still running with the same rapidity as before. There, was no channel whatever among those reeds, and the depth varied from three to five feet. This astonishing change (for I cannot call it a termination of the river), of course left me no alternative but to endeavour to return to some spot, on which we could effect a landing before dark.... To assert positively that we were on the margin of the lake or sea into which this great body of water is discharged, might reasonably be deemed a conclusion which has nothing but conjecture for its basis; but if an opinion may be permitted to be hazarded from actual appearances, mine is decidedly in favour of our being in the immediate vicinity of an inland sea, or lake, most probably a shoal one, and gradually filling up by immense depositions from the higher lands, left by the waters which flow into it. It is most singular, that the high-lands on this continent seem to be confined to the sea-coast, or not to extend to any great distance from it.

By 1828, explorer Charles Sturt was commissioned to ascertain "the limits of the Colony" by following the Macquarie River "for the express purpose of ascertaining the nature and extent of that basin into which the Macquarie was supposed to fall, and whether any connection existed between it and the streams falling westerly". Navigating the marshes (later named in honour of Lachlan Macquarie), Sturt was the first European to visit the Darling River, named in honour of General Ralph Darling.

Water management

Irrigation
The Macquarie River catchment is a regulated Water Management Area and includes private irrigation as well as several public irrigation schemes located at Narromine – Trangie, Buddah Lakes, Tenandra, Trangie – Nevertire, Nevertire, and Marthaguy.

The River is classified as over-subscribed

Flooding

The Macquarie River has a history of flooding. Some significant events are listed below. After major floods, water can flow past the Macquarie Marshes and into the Barwon-Darling river system upstream of Brewarrina.
1867devastating floods wash away the first Denison Bridge at Bathurst and also debris damages Ranken's Bridge
1955serious flooding of Macquarie River amongst other river systems
1979 heavy flooding of the low lying sections along the river
1986severe localised flooding in Bathurst
1990severe localised flooding in Bathurst
1998there was a large flood that affected the farming of cotton and vegetables. Bathurst was severely affected
2010November/December saw major flooding of the lower Macquarie River following heavy rainfall events throughout Eastern Australia
2016August/September saw moderate to major flooding along the entire river.

Recreation
Recreational activities are popular along the length of the river particularly in the communities it passes by.

FishingThe following species of fresh water fish can be caught: brown trout, carp, eel-tailed catfish, golden perch, murray cod, rainbow trout, redfin, silver perch, trout cod and yabbies.
Lake Burrendonga large dam very popular with water sports enthusiasts activities include skiing, jet skis, sailing, and general boating.
Parksin Bathurst along the bank of the river is Bi-Centennial Park. This park is used for recreation purposes, picnics, events, bicycle riding, etc. In Warren, Macquarie Park, off Burton St, has English-style formal gardens and a monument in honour of Oxley and Sturt who traced the course of the Macquarie River. Oxley camped near Warren in 1818 and is further commemorated in the naming of Oxley Park on the other side of the river. Sturt passed by just to the north-east in 1828 and the bridge over the river is named after him. Hundreds of galahs roost in the red gums at sunset. The adjacent Red River Gum Walk follows the riverbank around to a 500-year-old river gum adjacent the Warren Hole, a natural and permanent waterhole once used for swimming and fishing.

References

External links

 Daily river reportsNSW Government

Further reading

Tributaries of the Darling River
Newell Highway

Macquarie River


Futbolo Klubas Šiauliai var en fodboldklub fra den litauiske by Šiauliai.

Historie
Klubben blev stiftet i 2004 og gik konkurs i 2016.

2004 – 2014, FK Šiauliai
2015 – FC Šiauliai

Klub farver

Bane farver

Historiske slutplaceringer

Trænere
  Vytautas Jančiauskas, 2004–2005
  Saulius Vertelis, 2006
  Darius Magdišauskas, 2006
  Rytis Tavoras, 2008
  Fabio Lopez, 2008
  Deivis Kančelskis, 2009
  Valdas Ivanauskas, 2010
  Saulius Širmelis, 2010–2011
  Deivis Kančelskis, 2011–2012
  Gediminas Jarmalavičius, 2012
  Tomas Kančelskis, 2013
  Audrius Paškevičius, 2013
  Gediminas Jarmalavičius 2014
  Tomas Ražanauskas 2015
  Deivis Kančelskis 2015

Noter

Eksterne kilder/henvisninger
 futbolinis.lt
 uefa.com
 foot.dk
 weltfussballarchiv.com
 soccerway

Šiauliai
Fodboldklubber i Litauen
Etableret i 2004
Ophørt i 2016
Tidligere fodboldklubber i Litauen

FC Šiauliai


Wansbeck fue un distrito no metropolitano del condado de Northumberland (Inglaterra).

Fue constituido el 1 de abril de 1974 bajo la Ley de Gobierno Local de 1972 como una fusión de los distritos urbanos de Ashington, Bedlingtonshire y Newbiggin-by-the-Sea. El distrito fue abolido el 1 de abril de 2009 y su ayuntamiento disuelto tras entrar en vigor una serie de cambios estructurales en el gobierno local de Inglaterra, transfiriendo sus responsabilidades al ayuntamiento del condado.

Wansbeck tenía una superficie de 66,76 km². Según el censo de 2001, había 61 138 personas residiendo en el distrito.

En 1996, la ciudad fue laureada con el Premio de Europa, una distinción otorgada anualmente por el Consejo de Europa, desde 1955, a aquellos municipios que hayan hecho notables esfuerzos para promover el ideal de la unidad europea.

Referencias

Antiguos distritos no metropolitanos
Northumberland
Localidades laureadas con el Premio de Europa

Wansbeck


Dan Dubină (n. 28 iulie 1950, Fierbinți, județul Dâmbovița) este un inginer român, membru titular al Academiei Române din 2015.

Note

Legături externe
 Membrii Academiei Române din 1866 până în prezent – D

Nașteri în 1950
Ingineri români în viață
Membri titulari ai Academiei Române
Ingineri constructori români
Oameni din județul Dâmbovița

Dan Dubină


Articulația talocalcaneonaviculară  (Articulatio talocalcaneonavicularis) sau articulația astragalocalcaneoscafoidiană este o articulație cu mare importanță în mișcările piciorului, care unește trei oase: talusul, pe de o parte, și calcaneul plus navicularul, pe de altă parte. Este o articulație sinovială sferoidală (o enartroză), deci o articulație triaxială. Mijloacele de unire sunt reprezentate de o capsulă articulară subțire și de 4 ligamente: ligamentul calcaneonavicular plantar, ligamentul talocalcanean interosos (planul său anterior), ligamentul calcaneonavicular (fasciculul medial al ligamentului bifurcat), ligamentul talonavicular. Articulația talocalcaneonaviculară face parte din articulația transversală a tarsului. Articulația transversală a tarsului (Articulatio tarsi transversa) numită și articulația mediotarsiană sau articulația lui Chopart, este o articulație dispusă transversal, care unește patru oase ale tarsului: talusul cu navicularul și calcaneul cu cuboidul. Ea se compune din două articulații distincte: articulația talocalcaneonaviculară  medial și articulația calcaneocuboidiană lateral.

Suprafețele articulare
Suprafețele articulare sunt reprezentate printr-un cap convex (suprafața articulară a talusului) și o cavitate de recepție concavă.

Suprafața articulară a talusului
Suprafața articulară a talusului, este sferoidă și împărțită în 4 fețișoare articulare separate prin proeminențe netede, una pe capul talusului (fața articulară naviculară) și celelalte trei pe fața inferioară a talusului (fața articulară a ligamentului calcaneonavicular plantar, fața articulară calcaneană anterioară și fața articulară calcaneană mijlocie). Fața articulară naviculară, situată  anterior pe capul talusului, este ovalară și convexă; ea corespunde cu fața posterioară a osului navicular. Axul mare al ei este îndreptat oblic în jos și medial, formând cu axul orizontal un unghi de 45°, numit unghiul de rotație. Fața articulară a ligamentului calcaneonavicular plantar, situată pe fața inferioară a capului talusului, este triunghiulară și corespunde cu fibrocartilajul triunghiular de pe fața superioară a ligamentului calcaneonavicular plantar. Fața articulară calcaneană anterioară a talusului este plană și aproape patrulateră sau ovală. Ea corespunde cu fața articulară talară anterioară a calcaneului. Fața articulară calcaneană mijlocie a talusului este ovalară și ușor convexă. Ea corespunde cu fața articulară talară mijlocie a calcaneului.

Cavitatea de recepție
Cavitatea de recepție concavă este formată din navicular (fața lui posterioară) și calcaneu (fețele articulare talare anterioară și mijlocie a calcaneului) unite între ele printr-un ligament puternic, numit ligamentul calcaneonavicular plantar. Osul navicular prezintă pentru articulație fața lui posterioară, care este concavă și eliptică. Ea corespunde cu capul talusului. Calcaneul prezintă pentru articulație două fețișoare articulare situate pe fața sa superioară: fața articulară talară anterioară a calcaneului, care corespunde cu fața articulară calcaneană anterioară a talusului, și fața articulară talară mijlocie a calcaneului, care corespunde cu fața articulară calcaneană mijlocie a talusului. Aceste două fețișoare articulare de pe calcaneu sunt alungite, concave antero-posterior și adesea unite între ele; ele prezintă un ax mare îndreptat oblic înainte, lateral și în jos. Fața articulară superioară a ligamentului calcaneonavicular plantar este triunghiulară și acoperită cu fibrocartilaj, ea corespunde cu fața articulară a ligamentului calcaneonavicular plantar de pe fața inferioară  a capului talusului. .

Capsula articulară
Capsula articulară se inseră pe marginea suprafețelor articulare cu excepția părții superioare și mediale, unde ea se îndepărtează puțin de această margine. Este formată dintr-un strat extern fibros și dintr-un strat intern sinovial. Sinoviala nu prezintă nimic deosebit, tapetând capsula pe fața interioară. Nu comunică de obicei cu cavitățile articulațiilor învecinate; uneori comunică cu cavitatea articulației subtalare.

Ligamentele

Ligamentul calcaneonavicular plantar
Ligamentul calcaneonavicular plantar (Ligamentum calcaneonaviculare plantare) este un ligament gros, lat, rezistent, format din țesut fibros, aflat pe partea plantară a tarsului piciorului; el unește navicularul și calcaneul. Este numit și ligament glenoidian, ligament resort (spring ligament), ligament calcaneoscafoidian inferior, ligament calcaneoscafoidian intern Barkow (H. Barkow, 1798-1873, anatomist polonez), trohlea articulară Weitbrecht (J. Weitbrecht, 1702-1747, anatomist german). Este un ligament puternic și bine dezvoltat, fiind unul dintre cele mai importante ligamente ale piciorului. El se întinde de la marginea anterioară a Sustentaculum tali la față plantară a navicularului până la tuberozitatea acestuia. Are o formă trapezoidală. Pe fața lui superioară (dorsală) se dezvoltă un fibrocartilaj triunghiular denumit navicular (sau fața articulară superioară a ligamentului calcaneonavicular plantar), pe care se sprijină capul talusului; acest fibrocartilaj apare datorită frecării ligamentului cu capul talusului. Greutatea corpului este astfel transmisă ligamentului și prin el bolții plantare. Ligamentului calcaneonavicular plantar susține arcul longitudinal medial din bolta plantară a piciorului. Prin relaxarea acestui ligament capul talusului coboară, iar bolta plantară se reduce treptat putând chiar să dispară (piciorul plat). Ligamentul calcaneonavicular plantar completează spațiul triunghiular rămas între Sustentaculum tali de pe calcaneu și navicular. Pe sub fața plantară a ligamentului calcaneonavicular trece medial tendonul mușchiului tibial posterior (Musculus tibialis posterior), iar lateral trec tendoanele mușchilor flexor lung al halucelui (Musculus flexor hallucis longus) și flexor lung al degetelor (Musculus flexor digitorum longus pedis), care contribuie în mod activ la susținerea capului talusului și menținerea boltei plantare. Pe marginea sa medială liberă se inseră ligamentul deltoidian al articulației talocrurale. Ligamentul calcaneonavicular plantar are un rol mare la formarea cavității concave de recepție a articulației, formată din navicular și calcaneu. Rolul acestuia în formarea cavității de recepție devine foarte evident pe o piesă osoasă a piciorului de la care s-a extras talusul. Ligamentul calcaneonavicular plantar este constituit, de fapt, din două părți una infero-laterală fibroasă, iar alta supero-medială fibrocartilaginoasă.

Ligamentul talocalcanean interosos
Ligamentul talocalcanean interosos (Ligamentum talocalcaneum interosseum) este o lamă fibroasă transversală scurtă, groasă, rezistentă și foarte puternică, situată oblic și lateral în sinusul tarsului; el separă articulația subtalară de cea talocalcaneonaviculară. Se inserează sus în șanțul talusului și jos în șanțul calcaneului. Ligamentul talocalcanean interosos este format din două planuri (lame sau fascicule): unul posterior și altul anterior, separate prin țesut adipos, uneori, printr-o bursa sinovială. Planul posterior aparține articulației subtalare, pe când cel anterior articulației talocalcaneonaviculare. Planul anterior întărește capsula articulară; acest plan se inserează sus în șanțul talusului și jos în șanțul calcaneului.

Ligamentul cervical
Ligamentul cervical al sinusului tarsului (neomologat de Terminologia Anatomica), numit și ligamentul talocalcanean extern, ligamentul talocalcanean anterolateral, ligamentul talocalcanean anterior, ligamentul interosos anterolateral este un ligament puternic și rezistent situat în segmentul anteromedial al sinusului tarsului. După unii autori el corespunde cu fasciculul anterior al ligamentului talocalcanean interosos. Are originea jos în șanțul calcaneului aflat pe față superioară a calcaneului, medial de inserția mușchiului extensor scurt al degetelor (Musculus extensor digitorum brevis pedis), de unde se îndreaptă oblic în sus, înainte și medial și se inseă pe fața inferolaterală a colului talusului. Are un rol important în stabilizarea piciorului și este singurul ligamentul al articulației subtalare care frânează inversiunea piciorului.

Ligamentul bifurcat
Ligamentul bifurcat sau ligamentul în Y (Ligamentum bifurcatum) este un ligament foarte rezistent și puternic în formă V sau Y al articulației transversale a tarsului (articulația mediotarsiană), aflat pe fața dorsală a piciorului. Acest ligament prezintă o mare importanță în solidarizarea oaselor tarsului, în special în articulația mediotarsiană. Este denumit ligamentul bifurcat, ligamentul în Y al piciorului sau ligamentul în V al piciorului, datorită formei sale, fiind format din două ramuri divergente (în V sau Y). Datorită marii lui importanțe chirurgicale a fost numit de către chirurgi cheia articulației lui Chopart sau ligamentul lui Chopart, deoarece pentru dezarticularea mediotarsiană a oaselor tarsului era absolut necesară secționarea ligamentului bifurcat (F. Chopart, 1743-1795, chirurg francez). Se inseră jos și posterior pe partea anterioară a feței superioare (dorsale) a calcaneului,  lângă marginea laterală a feței articulare talare anterioare, de unde se îndreaptă ascendent anterior împărțindu-se în două fascicule, unul medial, ligamentul calcaneonavicular și altul lateral, ligamentul calcaneocuboidian,  care se prind pe oasele omonime: navicular și cuboid. Numai ligamentul calcaneonavicular face parte din articulația talocalcaneonaviculară, în timp ce ligamentul calcaneocuboidian aparține articulației calcaneocuboidiene. Ligamentul calcaneonavicular (Ligamentum calcaneonaviculare), fasciculul medial al ligamentului bifurcat, numit în trecut și ligamentul calcaneoscafoidian intern, fasciculul intern al ligamentului bifurcat se fixează pe fața superioară (dorsală) și laterală a navicularului. El întărește partea laterală a articulației talocalcaneonaviculare. Ligamentul calcaneocuboidian (Ligamentum calcaneocuboideum), fasciculul lateral al ligamentului bifurcat, numit în trecut și ligamentul calcaneoscafoidian extern, fasciculul extern al ligamentului bifurcat, se prinde pe fața superioară (dorsală) și medială a cuboidului, medial de ligamentul calcaneocuboidian dorsal. El întărește partea medială a articulației calcaneocuboidiene.

Ligamentul talonavicular
Ligamentul talonavicular sau ligamentul astragaloscafoidian superior (Ligamentum talonaviculare) este un ligament lat și subțire, așezat pe partea dorsală a tarsului piciorului.  Se inseră posterior pe fața superioară (dorsală) a colului talusului, de unde se îndreaptă înainte și se prinde pe fața superioară (dorsală) a navicularului; este acoperit de tendoanele mușchilor extensori ai piciorului.

Note

Articulații
Anatomia membrelor inferioare

Articulația talocalcaneonaviculară


آي آر سي إكس  أو اختصارا IRCX, هي إضافة لشبكة الآي آر سي طورقت من قبل شركة مايكروسوفت.

هذه الإضافة تحسن من قدرات خادوم الآي آر سي وتضيف له مزايا كثيرة كإمكانية أن يجد المستخدم قنوات بلغته ويضيف رتب إضافة إلى القنوات.

تم دعم هذه الإضافة من قبل مايكروسوفت إكسشانج بدلا عن البروتوكول القديم مايكروسوفت تشات, وهذا الإصدار الجديد أصبح متاحا في إكسشانج لعام 2000.

مراجع

إم إس إن
بروتوكول الدردشة عبر الإنترنت

آي آر سي إكس


Le nom Sno-Cat s'applique à une série de véhicules à chenilles conçus pour circuler sur la neige et fabriqués par la société Tucker à Medford, Oregon.

Le Sno-Cat se distingue par son utilisation de quatre chenilles. Certains ont été utilisés pour des expéditions dans l'Antarctique au cours de la seconde moitié du .

Développement

Évolution
Emmitt M. Tucker (1892-1964) a d'abord expérimenté au début des années 1920 avec un véhicule entrainé par deux pontons à vis pour finalement produire un modèle à une vis et trois skis en 1926 appelé «snow motor sled».

Vers 1935, Tucker fabrique un véhicule léger, à trois skis avec une chenille d'acier et un moteur refroidi par air, qui peut transporter trois passagers en ligne, le Sno-Cycle. Les recherches continuent et, en 1938, Tucker invente la chenille d'acier qui tourne autour d'un ponton (comme les premiers chars d'assaut) et fabrique le Sno-Cat à 2 chenilles et 2 skis avant qui deviendra le modèle No 423. La manœuvrabilité étant très limitée par la direction primitive à essieu pivotant et à skis sans suspension, Tucker continue le développement. En 1948, le Sno-cat est muni de 4 chenilles lorsque Tucker invente le premier véhicule à chenilles, avec servo-direction articulée, inspiré du «bob sleigh» un type de traîneau à patins tiré par des chevaux.

Il existe au moins deux modèles de production qui n'utilisaient que deux chenilles: le petit Tucker Kitten No 222 (sans ski, muni d'un moteur de 10 cv, une variante à portes carrées et l'autre à portes arrondies) et la série 320 quasi-expérimentale avec l'avant de la chenille de plus grand diamètre (No 322 et No 323).

Servo-direction articulée

Les Sno-Cats à quatre chenilles sont considérés comme des classiques de l'histoire américaine. Ils se distinguent par le système de servo-direction articulée inventé par Tucker. Deux robustes plaques en X oscillantes (fifth wheel) sont fixées sous le châssis par deux chevilles ouvrières; les ponts sont boulonnés aux plaques par l'intermédiaire des ressorts de suspension à lames (note, le brevet et le prototype n'ont pas de lames). Un levier de direction en H (steering swing) est fixé sur pivot à un point central du châssis et peut basculer vers l'avant ou l'arrière sous la poussée du cylindre hydraulique de servo-direction. Le levier de direction en H transfert le mouvement oscillant aux plaques avant et arrière (en direction opposée) via une barre de direction. Les joints de cardan des arbres de transmission permettent la faible rotation.

Chenille sur ponton (brevet Tucker)

Le train chenillé est de type triangulaire. Les modèles classiques utilisaient tous une chenille en acier munie de roulements à bille et qui révolutionnait sur un ponton rigide tout en acier formant traineau (dont les côtés ont été remplacés ultérieurement par des panneaux en fibre de verre pour contrer la corrosion). Les chenilles, en forme de chaîne, sont entraînées par un pignon double situé en haut, au centre du ponton. La chenille, très ajourée, sert principalement à la traction alors que la base du ponton agit comme patin et assure la plus grande partie de la portance sur la neige. La flexibilité du châssis et de la suspension à lames combinée aux pontons pivotants permettaient une traction exceptionnelle en terrains accidentés (sauf au-dessus des crevasses en Antarctique). Le Sno-Cat est devenu populaire même si les chenilles d'acier usaient rapidement et que leurs 240 roulements à bille (et plus) nécessitaient une lubrification aux  (avec pose et dépose du raccord à graisser). C'est dû principalement à sa grande manœuvrabilité en neige profonde grâce à la servo-direction qui fait pivoter les deux essieux (en direction opposée, sans blocage de chenille ni ripage), ainsi qu'à sa mécanique de camion à 4 roues motrices très fiable, sa haute garde au sol, sa stabilité assurée par l'écartement des chenilles, sa grande capacité de remorquage et son faible rayon de braquage malgré le petit angle de rotation des essieux (rayon de braquage de  pour le No 443 par rapport à plus de  pour le No 423 à 2 skis qui était encore moins efficace en neige profonde).

Le système de direction articulé de Tucker ne permettait pas l'usage d'une lame chasse-neige à l'avant, à moins de risquer de graves avaries aux joints à rotule des barres de direction et aux chevilles ouvrières. La défaillance des roulements de chenille était la seule véritable faiblesse du Sno-Cat. Pourtant, une excellente chenille (à travers d'acier boulonnés sur courroies de caoutchouc) existait déjà, celle des autoneiges de Bombardier qui a été utilisée avec succès par d'autres grands manufacturiers comme Foremost Nodwell, et Thiokol. Il semble que Tucker et ses clients attribuaient les performances exceptionnelles du Sno-Cat, en neige profonde, aux chenilles sur ponton sans reconnaître l'importance de la direction articulée. Aujourd'hui, l'usage de chenilles de caoutchouc sur les Sno-Cats a démontré le contraire.

Évolution des chenilles
Tucker invente la chenille d'acier sur ponton en 1938; elle sera disponible jusqu'en 1980 et Tucker en fabrique encore pour la rénovation de Sno-Cats anciens. Vers 1973, les Sno-Cats adoptent la chenille à travers d'acier boulonnés sur quatre courroies de caoutchouc renforcées. Vers 1996, la chenille moulée d'une seule pièce (Terra) est utilisée.

Modèles classiques (à pontons) et utilisation

Utilisation
Les premiers semi-chenillés de Tucker ont principalement servi aux skieurs et aux propriétaires de chalets en montagne pour accéder à des sites dont les chemins étaient ensevelis sous la neige en hiver. Il y a eu quelques essais pour faire de l'arpentage ou pour aller faire de l'entretien d'équipements situés en des endroits inaccessibles en hiver. Ce n'est qu'avec le Sno-Cat à quatre chenilles et ses capacités exceptionnelles que les utilisations commerciales se sont multipliées.

Les Sno-Cats ont été utilisés dans des domaines variés: l'exploration de l'antarctique, l'entretien d'équipements situés dans les montagnes enneigées, l'entretien des pistes de ski et des sentiers de motoneige ainsi que l'usage industriel, entre autres, pour la suppression des incendies, la prospection de gaz et de pétrole.

Modèles
Le premier chiffre désigne la série, le deuxième le nombre de chenilles (2 ou 4) et le dernier le nombre de portes (0, 1, 2 ou 3); 0 pour aire ouverte sans cabine, 1 avec toit seulement (sans porte), 2 avec cabine courte à 2 portes, 3 avec cabine allongée dont la troisième porte est à l'arrière (qui peut accueillir une civière dans les grands modèles comme les fourgons de l'expédition antarctique). Plusieurs configurations étaient disponibles: berline (sedan), fourgon à espace de chargement fermé et plateforme ouverte (flat deck); certains ont été fabriqués sur mesure pour des clients particuliers. Dans les anciens pamphlets publicitaires, la série 400 est appelée «utility» et la série 700 «freighter».

 220, 221, 222: Appelé «Kitten» (chaton), petit Sno-Cat à 2 chenilles (virage par blocage d'une chenille), il existe un modèle à portes rondes (plutôt que carrées) et celui du fils d'Emmitt Tucker (aussi à portes rondes), muni de 2 pontons de la série 400.
 321, 322, 322-A (tank), 323: Série expérimentale à 2 chenilles (châssis trapézoïdal plutôt que rectangulaire comme le Kitten, ou triangulaire comme tous les autres). Le prototype de 1956 (appelé tank) est un 322-A à moteur central et cabine avancée. Tous les autres sont de type sedan et n'ont été produits qu'à peu d'exemplaires. Conçus vers 1965, les modèles 342 et 343 (à 4 chenilles) sont une version compacte des 442 et 443; leur cabine exiguë a limité les ventes.
 420, 421, 422, 423, 424, 440, 442,443, 443 (châssis tubulaire): Série originale dérivée du prototype de 1938 avec l'invention de la chenille sur ponton, dont le sedan 423 avec skis à l'avant et le modèle 442 à 4 chenilles et plateau arrière.
 523, 524, 540, 542, 542CF, 543, 544: La série 500, conçue à la même époque, se veut une version robuste de la série 400 et se distingue par ses larges chenilles de 28" au lieu de 18" (71 cm vs 45,7 cm); elle est aussi disponible en cabine sur moteur (cab over).
 623, 643: Sur Internet, la photo d'un modèle à 2 skis et cabine allongée, serait un 623.
 722, 740CF, 742, 743: La série 700 est originellement appelée «freighter». Vers 1957, des modèles 743 avec cabine sur moteur ont été fabriqués pour accueillir 20 passagers (style autocar).
 800: Les modèles de cette série sont les plus gros et sont équipés d'un moteur diesel Cummins 6 cylindres. En 1959, la série 800 reprend le style autocar, mais aux angles de carrosserie carrés, qui sera surnommé «boîte à chaussure», sur un châssis encore plus gros (chenille 32" x 125" ou 813 mm x 3175 mm); la plupart des Sno-Cats série 800 ont probablement été vendus au U. S. Antarctic Research Program.
 942: Vers 1969, la série 900 est ajoutée comme une version utilitaire (plus courte) de la série 700, très semblable à la série 500 mais avec des chenilles moins larges.
 Les pamphlets des années cinquante listaient une série de remorques portant les numéros 925, 926, 927, 948 et 949; cette dernière pouvait accueillir 25 passagers.

Concurrents historiques
Tucker est toujours en activité avec ses «Sno-Cat» à quatre chenilles. Parmi ses premiers concurrents qui fabriquaient tous des véhicules à deux chenilles, Thiokol, KRISTI (Snowcat) et le fabricant suédois Aktiv (Snow Trac) ont cessé leurs activités. Bombardier s'est diversifié et Foremost s'est spécialisé dans les véhicules de transport tout-terrain de grande capacité.

Bombardier

La compagnie poursuit toujours ses activités mais a radicalement modifié son modèle d'affaires et sa sélection de produits en devenant un important fabricant de produits récréatifs (la motoneige Ski-Doo et sa chenille moulée en caoutchouc, inventée en 1959), ainsi que de matériel de transport aérien et ferroviaire. En 1935 (brevet obtenu en 1937), Bombardier a inventé la chenille à travers d'acier boulonnés sur courroies de caoutchouc (à convoyeur) et entrainée par un barbotin caoutchouté (engrenage). Il a vendu plus de  B-12 pour le transport de passagers (12 passagers) dont certaines sont toujours utilisées aujourd'hui et qui sont très en demande par les collectionneurs. Cette autoneige, avec deux skis avant, est limitée en manœuvrabilité dans la neige profonde des hautes montagnes mais peut atteindre  dans les plaines ou sur les lacs gelés ( pour le Sno-Cat original de Tucker; mais en pratique, il est très coûteux de dépasser ). En 1961, Bombardier invente la «dameuse» avec le Snowpacker dont un exemplaire est utilisé pendant plusieurs années au centre de ski du Mont Offord en Estrie, au Québec. En 1982, Bombardier a vendu son entreprise de fabrication de chenilles de caoutchouc renforcées à Camoplast. En 1995, la compagnie Bombardier se sépare de sa division de produits récréatifs qui devient BRP (Bombardier Produits récréatifs). En 2004, Camoplast achète de Bombardier la division de dameuses puis, en 2005, la revend à Leitner Group/Prinoth.

Thiokol
«Au début des années soixante, la Fondation Scientifique de l'Utah transfert la production de ses autoneiges à la compagnie Thiokol Chemical Corporation, qui a modifié les modèles existants et développé d'autres modèles. La principale modification a trait au mécanisme de direction (très rudimentaire avec un ski) qui est remplacé par un système à différentiel pour permettre d'effectuer un virage en freinant une chenille»(Gray p. 539). Thiokol se diversifia ensuite dans la production de dameuses pour les centres de ski mais en 1978 vendit cette division à John DeLorean qui la renomma DeLorean Motor Company (DMC). Elle devint Logan Machine Company (LMC) en 1988 et cessa ses opérations en 2000.  DMC a poursuivi la production des véhicules les plus populaires de Thiokol, Imp, Super-Imp et Spryte, qui ont été des succès commerciaux mais sans pouvoir compenser pour les autres pertes de l'entreprise. Beaucoup de ces modèles sont encore utilisés aujourd'hui sur le marché commercial et sont populaires en tant que chenillettes privées. La compagnie Thiokol est devenue un fournisseur de matériel aérospatial et a fusionné avec d'autres compagnies.

Foremost (Nodwell)

À partir de 1948, Bruce Nodwell a construit quelques véhicules d'exploration pétrolière appelés «North Kings» pour la compagnie Imperial Oil en Alberta. Les véhicules sont peu manœuvrables et peu durables. En 1950, Bombardier fabrique pour Imperial Oil des camions à double chenille et skis à l'avant (pouvant être remplacée par des chenilles non motrices); la chenille est semblable à celle de ses autoneiges mais plus large, à trois courroies, double roue et entrainée par un barbotin double. En 1953, Bombardier produit le Muskeg monoplace à chenille large qui a beaucoup de succès. Nodwell s'en inspire et, en 1955, il invente le «wide track», une chenille large à deux courroies et simple roue mais dont l'alignement est assuré par l'usage d'un barbotin à chaque extrémité. Familier avec l'exploration pétrolière, il fabrique une chenillette de grande capacité, d'abord appelé «Tracked Truck», et qui deviendra le Nodwell 110 (capacité de 110 x 100 lbs ou 11 000 lbs). Aujourd'hui, Foremost possède trois divisions, des usines en 5 endroits, 400 employés et fabrique aussi des véhicules sur chenilles de très grande capacité.

Kristi Snowcat

La compagnie Kristi de l'État du Colorado (États-Unis), produisit environ 180 Snowcats de 1956 à 1968. Ces petits véhicules, pour le transport de quelques personnes, se distinguaient par la possibilité d'ajuster en hauteur les chenilles et par leurs portes latérales à ouverture verticale (albatros). Le «ski action» permettait de relever une chenille de telle sorte que la cabine demeurait horizontale en traversant des dénivelés; de plus, la suspension hydraulique des chenilles leur permettait de suivre le profil des bosses. Kristi a été acheté par un groupe d'ingénieurs de Boeing qui a déménagé la production à Washington, laquelle a cessé au début des années 1970.

Aktiv (Snow-Trac)

En 1954, l'ingénieur chef de AB Westerasmaskiner, une compagnie suédoise d'équipement de ferme, développe un véhicule à chenilles pour aller avec son frère à la pêche blanche en hiver. La compagnie reprend son idée et met en production sa première autoneige Snow Trac (en) en 1957. Il s'agit d'un petit véhicule à deux chenilles de la grosseur d'une auto compacte. Une des nouveautés est l'utilisation d'un volant au lieu de leviers pour le diriger. Ce volant est relié à un variateur de courant qui répartit la vitesse de déroulement des chenilles selon la position du volant. Le conducteur est le seul à faire face vers l'avant, les six passagers sont assis de chaque côté et l'entrée est à l'arrière. Aktiv a fabriqué plus de . Mais en 1982 son fournisseur (Volkswagen) a cessé la fabrication de moteurs refroidis par air en Europe. Le Snow-Trac a été exporté à travers le monde dont en Alaska et dans le nord du Canada pour le transport des équipes de réparation et d'entretien des télécommunications et des routes. Le Snow-Trac est toujours d'usage courant.

Galerie

Aujourd'hui
Le Sno-Cat a de nombreux concurrents modernes pour le damage des pentes enneigées dans les stations de ski et le surfaçage des sentiers de motoneige: Kässbohrer Geländefahrzeug /PistenBully, Prinoth, Soucy, VMC/UTV International, Scot-Trac ainsi que Sure Trac conversions de tracteurs agricoles pour damer la neige. Le bras articulé au-dessus de certaines dameuses européennes, sert à guider le câble du treuil arrière pour permettre de gravir les pentes raides.

Exploration de l'Antarctique

L'explorateur anglais Sir Vivian Fuchs a utilisé 4 Tucker Sno-Cats spécialement préparés dans l'expédition transantarctique de 1957-1958. Un Sno-Cat 743 a été expédié au Royaume-Uni et est actuellement exposé au Science Museum de Wroughton . Un autre Sno-Cat de la même expédition est exposé dans la section antarctique du musée de Canterbury à Christchurch, en Nouvelle-Zélande. Un troisième est exposé au Antique Gas and Steam Engine Museum de Vista, en Californie, aux États-Unis.

Références

Articles connexes

Articles connexes

 Sno-Cat est aussi le nom d'un jeu pour le Commodore 64, dans lequel l'un de ces véhicules devait gravir une montagne pour sauver un groupe de skieurs perdus.

Liens externes

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Expédition en Antarctique
Autoneige
Véhicule tout-terrain
Chenillette
Semi-chenillé
Camion

Chenillette Sno-Cat de Tucker