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1

Regression of cerebellar tonsillar descent and hydrocephalus after endoscopic third ventriculostomy in a patient with a quadrigeminal arachnoid cyst  

PubMed Central

Background: Posterior fossa arachnoid cysts, including quadrigeminal cistern arachnoid cysts, can occasionally cause compression of the quadrigeminal plate, leading to Sylvian aqueduct stenosis and induction of cerebellar tonsillar descent into the foramen magnum. This, in turn, can result in obstructive hydrocephalus. In such cases, the characteristic of hydrocephalus is generally considered to be hypertensive. Case Description: We present the case of a 28-year-old female complaining of chronic and progressively worsening headaches following the delivery of her first child. Magnetic resonance imaging revealed marked tri-ventriculomegaly, the arachnoid cyst located in the quadrigeminal cistern, and cerebellar tonsillar descent. Ophthalmoscopy revealed bilateral papilledema indicating a long-standing elevation of intracranial pressure. Endoscopic third ventriculostomy (ETV) was performed successfully and resulted in complete recovery from her headaches and papilledema. Postoperative MRI revealed resolution of ventriculomegaly and cerebellar tonsillar descent, suggesting that the fourth ventricle outlet obstruction was associated with the development of the hydrocephalus in this patient. Conclusion: Our case is the first report that a quadrigeminal arachnoid cyst associated with both cerebellar tonsillar descent and hydrocephalus was well treated with ETV. It was indicated that the patient's hydrocephalus and cerebellar tonsillar descent were secondary and synergistic events, caused by the arachnoid cyst located in the quadrigeminal cistern. PMID:24232572

Arakawa, Yasuaki; Kita, Daisuke; Ezuka, Isamu; Hayashi, Yutaka; Hamada, Jun-ichiro; Hayashi, Yasuhiko

2013-01-01

2

Management of Cerebellar Tonsillar Herniation following Lumbar Puncture in Idiopathic Intracranial Hypertension  

PubMed Central

Lumbar puncture is performed routinely for diagnostic and therapeutic purposes in idiopathic intracranial hypertension, despite lumbar puncture being classically contraindicated in the setting of raised intracranial pressure. We report the case of a 30-year-old female with known idiopathic intracranial hypertension who had cerebellar tonsillar herniation following therapeutic lumbar puncture. Management followed guidelines regarding treatment of traumatic intracranial hypertension, including rescue decompressive craniectomy. We hypothesize that the changes in brain compliance that are thought to occur in the setting of idiopathic intracranial hypertension are protective against further neuronal injury due to axonal stretch following decompressive craniectomy.

Hoffman, Kenneth R.; Chan, Sean W.; Hughes, Andrew R.; Halcrow, Stephen J.

2015-01-01

3

Relationship of syrinx size and tonsillar descent to spinal deformity in Chiari malformation Type I with associated syringomyelia  

PubMed Central

Object Chiari malformation Type I (CM-I) is a developmental abnormality often associated with a spinal syrinx. Patients with syringomyelia are known to have an increased risk of scoliosis, yet the influence of specific radiographically demonstrated features on the prevalence of scoliosis remains unclear. The primary objective of the present study was to investigate the relationship of maximum syrinx diameter and tonsillar descent to the presence of scoliosis in patients with CM-I–associated syringomyelia [AQ? Edit okay? If not, please advise. JG: edit correct]. A secondary objective was to explore the role of craniovertebral junction (CVJ) characteristics for additional risk factors for scoliosis. Methods The authors conducted a retrospective review of pediatric patients evaluated for CM-I with syringomyelia at a single institution in the period from 2000 to 2012. Syrinx morphology and CVJ parameters were evaluated with MRI, whereas the presence of scoliosis was determined using standard radiographic criteria. Multiple logistic regression was used to analyze radiological features that were independently associated with scoliosis. Results Ninety-two patients with CM-I and syringomyelia were identified. The mean age was 10.5 ± 5 years. Thirty-five (38%) of 92 patients had spine deformity; 23 (66%) of these 35 were referred primarily for deformity, and 12 (34%) were diagnosed with deformity during workup for other symptoms. Multiple regression analysis revealed maximum syrinx diameter > 6 mm (OR 12.1, 95% CI 3.63–40.57, p < 0.001) and moderate (5–12 mm) rather than severe (> 12 mm) tonsillar herniation (OR 7.64, 95% CI 2.3–25.31, p = 0.001) as significant predictors of spine deformity when controlling for age, sex, and syrinx location. Conclusions The current study further elucidates the association between CM-I and spinal deformity by defining specific radiographic characteristics associated with the presence of scoliosis. Specifically, patients presenting with larger maximum syrinx diameters (> 6 mm) have an increased risk of scoliosis. PMID:24527859

Godzik, Jakub; Kelly, Michael P.; Radmanesh, Alireza; Kim, David; Holekamp, Terrence F.; Smyth, Matthew D.; Lenke, Lawrence G.; Shimony, Joshua S.; Park, Tae Sung; Leonard, Jeffrey; Limbrick, David D.

2014-01-01

4

Clinical aspects of tonsillar tuberculosis.  

PubMed

A clinical analysis of 6 patients with pathologically confirmed tonsillar tuberculosis was carried out retrospectively. The subjects comprised three men and three women, ranging in age from 20 to 74 years. All of the patients presented with a sore throat and 5 had lymphadenopathy. Ulcerations, masses and white patches characterized the tonsillar lesions; the pathological findings included caseous granuloma with positive acid-fast bacilli (AFB) in 5 patients and chronic granulomatous inflammation with negative AFB in one patient. Four of the six patients had pulmonary tuberculosis. The three patients who received complete treatment responded well. The presenting symptoms and abnormal tonsillar findings associated with tonsillar tuberculosis are similar to those of malignant tumors and therefore it is difficult to differentiate the two pathologies; moreover, tonsillar tuberculosis often occurs with pulmonary tuberculosis and AIDS and therefore, a chest X-ray and HIV-screening are recommended for all patients with tonsillar tuberculosis. PMID:12118442

Srirompotong, Somchai; Yimtae, Kwanchanok; Srirompotong, Supaporn

2002-03-01

5

Cerebellar seizures.  

PubMed

Epilepsy, especially with refractory seizures, is thought to arise only from cortical lesions or substrate. The authors report on 2 patients with refractory epilepsy and cerebellar lesions. Depth electrodes were placed within the cerebellar lesions in both patients, and intracranial electroencephalographic recordings showed seizure origin from the cerebellar lesions. One patient eventually attained seizure control with antiepileptic drugs. The other case involved a child with generalized myoclonic epilepsy associated with a pilocytic astrocytoma of the cerebellum. This patient obtained seizure control following gross-total resection of the tumor. PMID:23808728

Boop, Sarah; Wheless, James; Van Poppel, Katherine; McGregor, Amy; Boop, Frederick A

2013-09-01

6

Cerebellar Degeneration  

MedlinePLUS

... the spinal cord, medulla oblongata, cerebral cortex, and brain stem. Cerebellar degeneration may be the result of inherited ... in ongoing loss of neurons in the cerebellum, brain stem, and spinal cord transmissible spongiform encephalopathies (such as ...

7

Ascent/Descent Software  

NASA Technical Reports Server (NTRS)

The Ascent/Descent Software Suite has been used to support a variety of NASA Shuttle Program mission planning and analysis activities, such as range safety, on the Integrated Planning System (IPS) platform. The Ascent/Descent Software Suite, containing Ascent Flight Design (ASC)/Descent Flight Design (DESC) Configuration items (Cis), lifecycle documents, and data files used for shuttle ascent and entry modeling analysis and mission design, resides on IPS/Linux workstations. A list of tools in Navigation (NAV)/Prop Software Suite represents tool versions established during or after the IPS Equipment Rehost-3 project.

Brown, Charles; Andrew, Robert; Roe, Scott; Frye, Ronald; Harvey, Michael; Vu, Tuan; Balachandran, Krishnaiyer; Bly, Ben

2012-01-01

8

Recapitulation and Descent  

Microsoft Academic Search

IN NATURE of October 14 my friend and colleague, Mr. L. T. Hogben, contributes a thoughtful letter on ``Recapitulation and Descent,'' on which you will, perhaps, allow me to make one or two comments. Mr. Hogben traverses the position taken up by Dr. Bather in his address to the Geological Section of the British Association that ``recapitulation'' in the development

E. W. MacBride

1920-01-01

9

Descent and Divergence  

Microsoft Academic Search

IN Sir Arthur Keith's presidential address to the British Association at Leeds (Supplement to NATURE, Sept. 3, 1927), reference is made to ``the zigzag line of man's descent.'' It seemed desirable, if possible, to have some graphic method of crystallising, as in a nutshell, the views of the present moment as deduced from the results attained by leading investigators in

Arthur Willey

1927-01-01

10

Production of lymphotoxin by isolated human tonsillar B lymphocytes and B lymphocyte cell lines.  

PubMed Central

The expression of lymphotoxin (LT) mRNA and cytokine in human tonsillar B cells and B cell lines was examined by Northern blots and cytotoxicity assays, respectively. In tonsillar B cells, phorbol myristate acetate (PMA) or Staphylococcus aureus Cowan l (SAC) alone induced low levels of LT mRNA accumulation. However, SAC and anti-mu were strongly synergistic with PMA in this induction. Peak LT mRNA expression in tonsillar B cells stimulated by PMA plus SAC occurred between 48 and 72 h and was approximately half as much as that in PMA plus anti-CD3-stimulated T cells. Cyclosporine A was not effective in inhibiting LT mRNA accumulation by stimulated tonsillar B cells. A number of B cell lines could also be stimulated by PMA to express LT mRNA. Peak accumulation of LT mRNA in the cell line RPMI 1788 stimulated with PMA peaked about 8 h. A23187 in combination with PMA caused this accumulation to increase slightly and to peak earlier. The cytotoxic effects in the supernatants of stimulated B cells were contributed mostly by LT. The results indicate that tonsillar B cells are important in LT production and that there are important differences in the stimulation requirements for LT production and in LT mRNA expression kinetics between tonsillar B cells and B cell lines. Images PMID:2786889

Sung, S S; Jung, L K; Walters, J A; Jeffes, E W; Granger, G A; Fu, S M

1989-01-01

11

Cytokines and immunoglobulin in rheumatic heart disease: production by blood and tonsillar mononuclear cells.  

PubMed

Rheumatic fever and rheumatic heart disease are considered to result from abnormal immune responses after Group A streptococcal pharyngitis. Production of interleukin 1 (IL-1), tumor necrosis factor-alpha (TNF), interleukin 2 (IL-2) and immunoglobulin (Ig) by blood and tonsillar mononuclear cells from rheumatic or healthy children was measured after stimulation in vitro by pokeweed mitogen (PWM) or the streptococcal extracellular product, blastogen A (BLA). Tonsillar cells from patients with rheumatic heart disease produced significantly less IL-1, TNF, IL-2, and Ig than control tonsillar cells. In contrast, blood mononuclear cell cultures from rheumatic children produced more TNF and IL-2 than controls. Our findings suggest that abnormal regulation of cytokine and Ig production may contribute to the pathogenesis of acute rheumatic fever and rheumatic heart disease. PMID:2600943

Miller, L C; Gray, E D; Mansour, M; Abdin, Z H; Kamel, R; Zaher, S; Regelmann, W E

1989-11-01

12

Preclinical diagnosis of chronic wasting disease in captive mule deer (Odocoileus hemionus) and white-tailed deer (Odocoileus virginianus) using tonsillar biopsy  

Microsoft Academic Search

The usefulness of tonsillar biopsy on live deer for preclinical diagnosis of the transmissible spongiform encephalopathy chronic wasting disease (CWD) was evaluated. Disease was tracked in a CWD-endemic herd using serial tonsillar biopsies collected at 6 to 9 month intervals from 34 captive mule deer (Odocoileus hemionus) and five white-tailed deer (O. virginianus). Tonsillar biopsies were examined for accumulation of

Margaret A. Wild; Terry R. Spraker; Christina J. Sigurdson; Katherine I. O'Rourke; Michael W. Miller

13

Entry, Descent, Landing Animation (Animation)  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Click on the image for Entry, Descent, Landing animation

This animation illustrates the path the Stardust return capsule will follow once it enters Earth's atmosphere.

2005-01-01

14

[Cerebellar cognitive affective syndrome secondary to a cerebellar tumour].  

PubMed

Cerebellar cognitive affective syndrome is characterized by disturbances of executive function, impaired spatial cognition, linguistic difficulties, and personality change. The case of an 11year old boy is presented, with behavior problems, learning difficulties and social interaction problems. In the physical examination he had poor visual contact, immature behavior, reduced expressive language and global motor disability with gait dyspraxia, with no defined cerebellar motor signs. In the neuropsychological evaluation he has a full scale overall intellectual quotient of 84, with signs of cerebellar cognitive affective syndrome. A tumour affecting inferior cerebellar vermis was observed in the magnetic resonance imaging, which had not significantly grown during 5years of follow up. The cerebellum participates in controlling cognitive and affective functions. Cerebellar pathology must be considered in the differential diagnosis of children with cognitive or learning disorder with associated behavioral and emotional components. PMID:24954915

Domínguez-Carral, J; Carreras-Sáez, I; García-Peñas, J J; Fournier-Del Castillo, C; Villalobos-Reales, J

2015-01-01

15

Tonsillar focal infectious disease involving IgA nephropathy, pustulosis, and ossification  

Microsoft Academic Search

We report a rare case of IgA nephropathy (IgAN), that was considered as showing tonsillar focal infection, involving pulmoplantar\\u000a pustulosis (PPP), and sternocostoclavicular hyperosteosis (SCCH). A 53-year-old man with a 3-year history of PPP had hematuria\\u000a and proteinuria, and he sometimes had anterior chest pain. He was also diagnosed with IgAN and SCCH. We performed tonsillectomy\\u000a as a treatment. The

Kenji Noda; Satoru Kodama; Satoshi Suenaga; Masashi Suzuki

2007-01-01

16

Small Lymphocytic Lymphoma Obscuring Microscopic Tonsillar Squamous Cell Carcinoma: an Unknown Occurrence with a Known Primary  

Microsoft Academic Search

Head and neck squamous cell carcinoma (HNSCC) often presents with cervical lymph node metastases and at times the primary\\u000a tumor cannot be identified despite extensive workup. Lymphoma is the second most common neoplasm in the head and neck region\\u000a but is seldom synchronous with HNSCC and rarely involves regional mucosal sites. We report herein a rare occurrence of tonsillar\\u000a involvement

Eugen C. Minca; Saurin R. Popat; Manpreet K. Chadha; Mihai Merzianu

17

Molecular mapping to species level of the tonsillar crypt microbiota associated with health and recurrent tonsillitis.  

PubMed

The human palatine tonsils, which belong to the central antigen handling sites of the mucosal immune system, are frequently affected by acute and recurrent infections. This study compared the microbiota of the tonsillar crypts in children and adults affected by recurrent tonsillitis with that of healthy adults and children with tonsillar hyperplasia. An in-depth 16S rRNA gene based pyrosequencing approach combined with a novel strategy that included phylogenetic analysis and detection of species-specific sequence signatures enabled identification of the major part of the microbiota to species level. A complex microbiota consisting of between 42 and 110 taxa was demonstrated in both children and adults. This included a core microbiome of 12 abundant genera found in all samples regardless of age and health status. Yet, Haemophilus influenzae, Neisseria species, and Streptococcus pneumoniae were almost exclusively detected in children. In contrast, Streptococcus pseudopneumoniae was present in all samples. Obligate anaerobes like Porphyromonas, Prevotella, and Fusobacterium were abundantly present in children, but the species diversity of Porphyromonas and Prevotella was larger in adults and included species that are considered putative pathogens in periodontal diseases, i.e. Porphyromonas gingivalis, Porphyromonas endodontalis, and Tannerella forsythia. Unifrac analysis showed that recurrent tonsillitis is associated with a shift in the microbiota of the tonsillar crypts. Fusobacterium necrophorum, Streptococcus intermedius and Prevotella melaninogenica/histicola were associated with recurrent tonsillitis in adults, whereas species traditionally associated with acute tonsillitis like pyogenic streptococci and Staphylococcus aureus were scarce. The findings suggest that recurrent tonsillitis is a polymicrobial infection in which interactions within consortia of taxa play an etiologic role. The study contributes to the human microbiome data, to the understanding of the etiology of infections affecting the tonsils, and forms a basis for further insight into the consequences of the intense microbe-host interactions that take place in the tonsils. PMID:23437130

Jensen, Anders; Fagö-Olsen, Helena; Sørensen, Christian Hjort; Kilian, Mogens

2013-01-01

18

Molecular Mapping to Species Level of the Tonsillar Crypt Microbiota Associated with Health and Recurrent Tonsillitis  

PubMed Central

The human palatine tonsils, which belong to the central antigen handling sites of the mucosal immune system, are frequently affected by acute and recurrent infections. This study compared the microbiota of the tonsillar crypts in children and adults affected by recurrent tonsillitis with that of healthy adults and children with tonsillar hyperplasia. An in-depth 16S rRNA gene based pyrosequencing approach combined with a novel strategy that included phylogenetic analysis and detection of species-specific sequence signatures enabled identification of the major part of the microbiota to species level. A complex microbiota consisting of between 42 and 110 taxa was demonstrated in both children and adults. This included a core microbiome of 12 abundant genera found in all samples regardless of age and health status. Yet, Haemophilus influenzae, Neisseria species, and Streptococcus pneumoniae were almost exclusively detected in children. In contrast, Streptococcus pseudopneumoniae was present in all samples. Obligate anaerobes like Porphyromonas, Prevotella, and Fusobacterium were abundantly present in children, but the species diversity of Porphyromonas and Prevotella was larger in adults and included species that are considered putative pathogens in periodontal diseases, i.e. Porphyromonas gingivalis, Porphyromonas endodontalis, and Tannerella forsythia. Unifrac analysis showed that recurrent tonsillitis is associated with a shift in the microbiota of the tonsillar crypts. Fusobacterium necrophorum, Streptococcus intermedius and Prevotella melaninogenica/histicola were associated with recurrent tonsillitis in adults, whereas species traditionally associated with acute tonsillitis like pyogenic streptococci and Staphylococcus aureus were scarce. The findings suggest that recurrent tonsillitis is a polymicrobial infection in which interactions within consortia of taxa play an etiologic role. The study contributes to the human microbiome data, to the understanding of the etiology of infections affecting the tonsils, and forms a basis for further insight into the consequences of the intense microbe-host interactions that take place in the tonsils. PMID:23437130

Jensen, Anders; Fagö-Olsen, Helena; Sørensen, Christian Hjort; Kilian, Mogens

2013-01-01

19

Redistribution of crossed cerebellar diaschisis  

SciTech Connect

Crossed cerebellar diaschisis refers to a functional decrease in blood flow to the cerebellar hemisphere contralateral to the infarcted or ischemic cerebral hemisphere. This phenomenon can be depicted using PET as well as using SPECT. This condition, seen on early I-123 IMP brain scans, can show redistribution on the three hour delayed scan, presumably due to normal non-specific amine receptor sites of the affected cerebellum. One such case is reported.

Kim, S.M.; Park, C.H.; Intenzo, C.M.; Bell, R.

1989-04-01

20

Massive cerebellar infarction: "conservative" management.  

PubMed

Eleven patients with large cerebellar infarctions were admitted recently to our service. Eight of them showed evidence of hydrocephalus on the CT scan examination. Five were treated with controlled external ventricular drainage and six were managed conservatively. One death, most likely due to progressive brainstem infarction, occurred. The outcome was favorable in the other patients. It is suggested that prompt treatment of the acute obstructive hydrocephalus may obviate the need for posterior fossa decompression in patients with massive cerebellar infarction. PMID:6658959

Khan, M; Polyzoidis, K S; Adegbite, A B; McQueen, J D

1983-01-01

21

Ectopic Oral Tonsillar Tissue: A Case Series with Bilateral and Solitary Presentations and a Review of the Literature  

PubMed Central

An ectopic tonsil is defined as tonsillar tissue that develops in areas outside of the four major tonsil groups: the palatine, lingual, pharyngeal, and tubal tonsils. The occurrence of tonsillar tissue in the oral cavity in ectopic locations, its prevalence, and its developmental mechanisms that belong to its formation remain unclear. In this report, we describe a rare case of bilateral symmetric ectopic oral tonsillar tissue located at the ventral surface of the tongue along with two solitary cases arising from the floor of the mouth. The role of immune system and its aberrant response leading to ectopic deposits desires further studies. As an ectopic tonsil may simulate a benign soft tissue tumor, this case series highlights the importance of this entity in our clinical differential diagnosis of oral soft tissue masses.

Kimura, Masashi; Nagao, Toru; Saito, Terumi; Warnakulasuriya, Saman; Ohto, Hiroyuki; Takahashi, Akihito; Komaki, Kanji; Naganawa, Yoshiyuki

2015-01-01

22

Cultured tonsillar lymphocytes excrete [3H]thymidine labeled DNA and revert to resting state.  

PubMed

Large tonsillar lymphocytes labeled with [3H]thymidine reverted to small lymphocytes with concomitant loss of [3H]DNA upon culturing. The decrease of labeled DNA content and size of large lymphocytes was demonstrated by flow cytometry and cell sorting. These observations suggest that stimulated lymphocytes may revert from their proliferative phase to resting phase by shedding 'extra'DNA under cell culture conditions. This released DNA is not due to cell damage and can be hybridized to chromosomal DNA. PMID:6517940

Sasvari-Szekely, M; Staub, M; Taljanidisz, J; Szabo, G; Takacs, J; Antoni, F

1984-12-28

23

Consert during the Philae Descent  

NASA Astrophysics Data System (ADS)

The CONSERT experiment on board Rosetta and Philae is to perform the tomography of the 67P/CG comet nucleus measuring radio waves transmission from the Rosetta S/C to the Philae Lander and using the 67P nucleus rotation to cover different geometries. CONSERT will operate during the Philae descent. This geometry strongly differs from the "nominal" bistatic tomography where the orbiter is on the opposite side of the nucleus by regard to the lander. During the descent, CONSERT will measure direct wave propagating from orbiter to lander and waves reflected / scattered by the 67P surface and subsurface. This signal will provide information of the greatest interest for both scientific investigations of 67P and technical operations of Philae. The landing site position is known a priori with a large ellipse of dispersion due to uncertainties on the Rosetta velocity and Rosetta/Philae separation strength. This dispersion is increased by the difference between nominal and emergency separation strength. An accurate estimation of the landing position as soon as possible after landing is of the greatest interest to optimize Philae operation during FSS. So propagation delay of the direct and reflected waves measured by CONSERT will help to reconstruct the descent geometry in order to more precisely estimate the landing position. The reflected signal is determined by the surface properties: its dielectric permittivity, its roughness and layering. The signal power inversion will allow to map surface properties especially in the vicinity of the landing site. This paper details the measurement configuration. It presents the data retrieval based on Monte-Carlo simulation using Metropolis-Hastings algorithm and expected performances for both science and operations.

Herique, Alain; Berquin, Yann; Blazquez, Alejandro; Antoine Foulon, Marc; Hahnel, Ronny; Hegler, Sebastian; Jurado, Eric; Kofman, Wlodek; Plettemeier, Dirk; Rogez, Yves; Statz, Christoph; Zine, Sonia

2014-05-01

24

Descent theory for semiorthogonal decompositions  

SciTech Connect

We put forward a method for constructing semiorthogonal decompositions of the derived category of G-equivariant sheaves on a variety X under the assumption that the derived category of sheaves on X admits a semiorthogonal decomposition with components preserved by the action of the group G on X. This method is used to obtain semiorthogonal decompositions of equivariant derived categories for projective bundles and blow-ups with a smooth centre as well as for varieties with a full exceptional collection preserved by the group action. Our main technical tool is descent theory for derived categories. Bibliography: 12 titles.

Elagin, Alexei D

2012-05-31

25

Cognition and Emotion in Cerebellar Disorders  

MedlinePLUS

... ATAXIA FOUNDATION Are problems in the areas of cognition and emotion related to the cerebellar damage in ... minimal or no ataxia. FREQUENTLY ASKED QUESTIONS ABOUT... Cognition and Emotion in Cerebellar Disorders National Ataxia Foundation ...

26

Predictability of Top of Descent Location for Operational Idle-Thrust Descents  

NASA Technical Reports Server (NTRS)

To enable arriving aircraft to fly optimized descents computed by the flight management system (FMS) in congested airspace, ground automation must accurately predict descent trajectories. To support development of the trajectory predictor and its uncertainty models, commercial flights executed idle-thrust descents at a specified descent speed, and the recorded data included the specified descent speed profile, aircraft weight, and the winds entered into the FMS as well as the radar data. The FMS computed the intended descent path assuming idle thrust after top of descent (TOD), and the controllers and pilots then endeavored to allow the FMS to fly the descent to the meter fix with minimal human intervention. The horizontal flight path, cruise and meter fix altitudes, and actual TOD location were extracted from the radar data. Using approximately 70 descents each in Boeing 757 and Airbus 319/320 aircraft, multiple regression estimated TOD location as a linear function of the available predictive factors. The cruise and meter fix altitudes, descent speed, and wind clearly improve goodness of fit. The aircraft weight improves fit for the Airbus descents but not for the B757. Except for a few statistical outliers, the residuals have absolute value less than 5 nmi. Thus, these predictive factors adequately explain the TOD location, which indicates the data do not include excessive noise.

Stell, Laurel L.

2010-01-01

27

The compartmental restriction of cerebellar interneurons  

PubMed Central

The Purkinje cells (PC's) of the cerebellar cortex are subdivided into multiple different molecular phenotypes that form an elaborate array of parasagittal stripes. This array serves as a scaffold around which afferent topography is organized. The ways in which cerebellar interneurons may be restricted by this scaffolding are less well-understood. This review begins with a brief survey of cerebellar topography. Next, it reviews the development of stripes in the cerebellum with a particular emphasis on the embryological origins of cerebellar interneurons. These data serve as a foundation to discuss the hypothesis that cerebellar compartment boundaries also restrict cerebellar interneurons, both excitatory [granule cells, unipolar brush cells (UBCs)] and inhibitory (e.g., Golgi cells, basket cells). Finally, it is proposed that the same PC scaffold that restricts afferent terminal fields to stripes may also act to organize cerebellar interneurons. PMID:23346049

Consalez, G. Giacomo; Hawkes, Richard

2013-01-01

28

Tonsillar focal infectious disease involving IgA nephropathy, pustulosis, and ossification.  

PubMed

We report a rare case of IgA nephropathy (IgAN), that was considered as showing tonsillar focal infection, involving pulmoplantar pustulosis (PPP), and sternocostoclavicular hyperosteosis (SCCH). A 53-year-old man with a 3-year history of PPP had hematuria and proteinuria, and he sometimes had anterior chest pain. He was also diagnosed with IgAN and SCCH. We performed tonsillectomy as a treatment. The tonsillectomy was done with the patient under general anesthesia, and this treatment was followed by steroid therapy. Interestingly, all the symptoms of IgAN, PPP, and SCCH were alleviated 6 months after the tonsillectomy. Thus, tonsillectomy and steroid therapy may be effective and could be considered as treatment for these diseases. PMID:17385006

Noda, Kenji; Kodama, Satoru; Suenaga, Satoshi; Suzuki, Masashi

2007-03-01

29

Linking oscillations in cerebellar circuits  

PubMed Central

In many neuroscience fields, the study of local and global rhythmicity has been receiving increasing attention. These network influences could directly impact on how neuronal groups interact together, organizing for different contexts. The cerebellar cortex harbors a variety of such local circuit rhythms, from the rhythms in the cerebellar cortex per se, or those dictated from important afferents. We present here certain cerebellar oscillatory phenomena that have been recorded in rodents and primates. Those take place in a range of frequencies: from the more known oscillations in the 4–25 Hz band, such as the olivocerebellar oscillatory activity and the granule cell layer oscillations, to the more recently reported slow (<1 Hz oscillations), and the fast (>150 Hz) activity in the Purkinje cell layer. Many of these oscillations appear spontaneously in the circuits, and are modulated by behavioral imperatives. We review here how those oscillations are recorded, some of their modulatory mechanisms, and also identify some of the cerebellar nodes where they could interact. A particular emphasis has been placed on how these oscillations could be modulated by movement and certain neuropathological manifestations. Many of those oscillations could have a definite impact on the way information is processed in the cerebellum and how it interacts with other structures in a variety of contexts. PMID:23908606

Courtemanche, Richard; Robinson, Jennifer C.; Aponte, Daniel I.

2013-01-01

30

Speech Prosody in Cerebellar Ataxia  

ERIC Educational Resources Information Center

Persons with cerebellar ataxia exhibit changes in physical coordination and speech and voice production. Previously, these alterations of speech and voice production were described primarily via perceptual coordinates. In this study, the spatial-temporal properties of syllable production were examined in 12 speakers, six of whom were healthy…

Casper, Maureen A.; Raphael, Lawrence J.; Harris, Katherine S.; Geibel, Jennifer M.

2007-01-01

31

Cerebellar Control of Robot Arms  

Microsoft Academic Search

Decades of research into the structure and function of the cerebellum have led to a clear understanding of many of its cells, as well as how learning takes place. Furthermore, there are many theories on what signals the cerebellum operates on, and how it works in concert with other parts of the nervous system. Nevertheless, the application of computational cerebellar

P. Patrick Van Der Smagt

1998-01-01

32

GENERALIZED HARISH-CHANDRA DESCENT AND APPLICATIONS TO GELFAND PAIRS  

E-print Network

GENERALIZED HARISH-CHANDRA DESCENT AND APPLICATIONS TO GELFAND PAIRS AVRAHAM AIZENBUD AND DMITRY of the paper we generalize a descent technique due to Harish- Chandra to the case of a reductive group acting Harish-Chandra descent 8 3.1. Generalized Harish-Chandra descent 8 3.2. A stronger version 10 4

33

Downregulation of the &Bgr;1,3- Galactosyltransferase Gene in Tonsillar B Lymphocytes and Aberrant Lectin Bindings to Tonsillar IgA as a Pathogenesis of IgA Nephropathy  

Microsoft Academic Search

IgA is a glycoprotein with multiple O-glycans. Under-O-glycosylation of the hinge in IgA in patients with IgA nephropathy (IgAN) is reported. The development of IgAN is frequently preceded by episodes of upper respiratory tract infections such as tonsillitis. Therefore, the tonsils may be related to the pathogenesis of IgAN. However, the mechanism of underglycosylation in tonsillar IgA has not yet

T. Inoue; H. Sugiyama; Y. Kikumoto; N. Fukuoka; Y. Maeshima; H. Hattori; K. Fukushima; K. Nishizaki; Y. Hiki; H. Makino

2007-01-01

34

Feature Clustering for Accelerating Parallel Coordinate Descent  

SciTech Connect

We demonstrate an approach for accelerating calculation of the regularization path for L1 sparse logistic regression problems. We show the benefit of feature clustering as a preconditioning step for parallel block-greedy coordinate descent algorithms.

Scherrer, Chad; Tewari, Ambuj; Halappanavar, Mahantesh; Haglin, David J.

2012-12-06

35

Transabdominal testicular descent is really ovarian ascent.  

PubMed

Some investigators have suggested that testicular descent relative to the ovary is actually caused by the relative upward growth of the structures adjacent to the testis and that in the early phase of descent the testis is anchored to the inguinal region as the embryo enlarges. This concept was founded on results from the dissection of human fetuses. In this study the development of the urogenital system in fetal mice is examined using scanning electron microscopy to determine the distance between the bladder neck and the lower pole of the gonad. The results of this study confirm that transabdominal descent of the testis relative to the ovary is in one sense really ascent of the ovary in the fetal mouse, while the testis is anchored to the inguinal region by the developed gubernaculum. The testis shows real movement at the beginning of the inguinoscrotal phase of testicular descent at birth. PMID:8022013

Shono, T; Ramm-Anderson, S; Hutson, J M

1994-08-01

36

Lunar descent using sequential engine shutdown  

E-print Network

The notion of sequential engine shutdown is introduced and its application to lunar descent is motivated. The concept calls for the utilization of multiple fixed thrust engines in place of a single continuously throttleable ...

Springmann, Philip N

2006-01-01

37

Descent relations in cubic superstring field theory  

NASA Astrophysics Data System (ADS)

The descent relations between string field theory (SFT) vertices are characteristic relations of the operator formulation of SFT and they provide self-consistency of this theory. The descent relations langleV2|V1rangle and langleV3|V1rangle in the NS fermionic string field theory in the ? and discrete bases are established. Different regularizations and schemes of calculations are considered and relations between them are discussed.

Aref'eva, I. Y.; Gorbachev, R.; Medvedev, P. B.; Rychkov, D. V.

2008-01-01

38

Optimal spline regression utilizing steepest descent  

E-print Network

OPTIMAL SPLINE REGRESSION UTILIZING STEEPEST DESCENT A Thesis ERIC SHIRLEY FLORA Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May l975 Major Sub...]ect: Mathematics OPTIMAL SPLINE REGRESSION UTILIZING STEEPEST DESCENT A Thesis ERIC SHIRLEY FLORA Approved as to style and content by; (Chai an of Committee) (Head of Department) ~' (Member) (Member ) May 1975 ABSTRACT Optimal Spline Regression Utilizing...

Flora, Eric Shirley

1975-01-01

39

X-linked disorders with cerebellar dysgenesis  

Microsoft Academic Search

X-linked disorders with cerebellar dysgenesis (XLCD) are a genetically heterogeneous and clinically variable group of disorders\\u000a in which the hallmark is a cerebellar defect (hypoplasia, atrophy or dysplasia) visible on brain imaging, caused by gene mutations\\u000a or genomic imbalances on the X-chromosome. The neurological features of XLCD include hypotonia, developmental delay, intellectual\\u000a disability, ataxia and\\/or other cerebellar signs. Normal cognitive

Ginevra Zanni; Enrico S Bertini

2011-01-01

40

[Molecular and anatomical studies of testicular descent].  

PubMed

The mechanism of testicular descent is multifactorial, and the process is known to occur in two steps accompanied by different anatomies and hormonal regulation. In the first step, the testis descends from the lower pole of the kidney to the pelvic cavity near the bladder neck as a result of the swelling reaction of the gubernaculum. Next, in the second step, the testis descends into the scrotum through the inguinal canal via the gubernacular migration. The first step is androgen-independent, whereas the second step depends on the androgen action. Recently, several molecular studies on testicular descent have been reported. Several factors, such as androgen, calcitonin gene-related peptide (CGRP), epidermal growth factor (EGF), Hoxa-10 and insulin-like factor 3 (INSL3) have been suggested to be possible regulators of testicular descent. Because cryptorchidism has been frequently shown in androgen-insensitive human and mice (TFM-mice), androgen has been thought to play an important role in testicular descent. CGRP, which is released from the genitofemoral nerve, has been suggested to mediate the inguinoscrotal testicular descent. The epidermal growth factor (EGF) may promote both testosterone-induced wollfian duct differentiation and testicular descent by activating the androgen responsive systems. In male mice, a targeted disruption of the HOXA 10 gene causes cryptorchidism and the cryptorchid testes in these mutant mice are located in the lower abdominal cavity, whereas the cryptorchid testes in male mice lacking the INSL3 gene or its receptor Lgr8 were located in the abdominal cavity high. Recently, estrogens or environmental endocrine disruptors have also been suspected to induce a down-regulated INSL3 expression and thus disturb testicular descent. PMID:17702188

Shono, Takeshi

2007-07-01

41

Tonsillar biopsy and PrPSc detection in the preclinical diagnosis of scrapie.  

PubMed

Preliminary findings have indicated that in naturally infected sheep, fully susceptible to scrapie (VRQ-homozygous), PrPSc can be detected in the tonsils approximately one year before the expected onset of clinical disease, whereas no immunostaining can be detected in animals with a semi-resistant genotype. This paper describes the technique for taking tonsillar biopsies from sheep and gives the results of the completed experiment. In another experiment PrPSc was detected even earlier in comparable VRQ-homozygous sheep born and raised in different surroundings. At three-and-a-half months of age no PrPSc could be detected in three homozygous susceptible sheep (VRQ/VRQ), but PrPSc was detected at four months in one similar sheep. At eight months of age all seven sampled VRQ/VRQ sheep showed positive immunostaining in the biopsies, but none of the biopsies from three VRQ/ARQ heterozygotes showed any immunostaining; they were positive when sampled at 14 to 15 months of age. Biopsies from VRQ/ARR sheep were negative throughout this period. On the basis of the established or expected incubation period, PrPSc could thus be detected in the tonsils of live susceptible animals at between one-third and a half of the incubation period, more than one-and-a-half years before clinical signs normally appear in both these genotypes. PMID:9634704

Schreuder, B E; van Keulen, L J; Vromans, M E; Langeveld, J P; Smits, M A

1998-05-23

42

Heterozygous Alterations of TNFRSF13B/TACI in Tonsillar Hypertrophy and Sarcoidosis  

PubMed Central

TNFRSF13B/TACI defects have been associated with CVID pathogenesis and/or phenotype, especially the development of benign lymphoproliferation and autoimmunity. Our purpose was to investigate the role of TNFRSF13B/TACI defects in the pathogenesis of two common lymphoproliferative disorders, namely, sarcoidosis and tonsillar hypertrophy (TH). 105 patients (71 with sarcoidosis and 34 with TH, including 19 without infectious causative and 15 due to Haemophilus influenzae) were analyzed for TNFRSF13B/TACI defects. Two out of 19 TH patients without infectious cause (10.5%) and 2 patients with sarcoidosis (2.8%) displayed rare TNFRSF13B/TACI defects (I87N, L69TfsX12, E36L, and R202H, resp.). Both mutations identified in TH patients have been assessed as deleterious for protein function, while the patient with the R202H mutation and sarcoidosis exhibited also sIgG4D. Our study further supports the notion that TNFRSF13B/TACI defects alone do not result in CVID but may be also found frequently in distinct clinical phenotypes, including benign lymphoproliferation and IgG subclass deficiencies. PMID:23956760

Florou, Zoe; Petinaki, Efthimia; Daniil, Zoe; Bardaka, Fotini; Gourgoulianis, Konstantinos I.; Skoulakis, Charalampos; Germenis, Anastasios E.

2013-01-01

43

Epstein–Barr virus infection negatively impacts the CXCR4-dependent migration of tonsillar B cells  

PubMed Central

The primary Epstein–Barr virus (EBV) infection occurs in the oropharynx, where the virus infects B cells and subsequently establishes latency in the memory B-cell compartment. EBV has previously been shown to induce changes in the cell surface expression of several chemokine receptors in cell lines and the transfection of EBNA2 or LMP1 into a B-cell-lymphoma-derived cell line decreased the expression of CXCR4. We show that in vitro EBV infection reduces the expression of CXCR4 on primary tonsil B cells already 43 hr after infection. Furthermore, EBV infection affects the chemotactic response to stromal cell-derived factor (SDF-1)?/CXCL12, the ligand for CXCR4, with a reduction of SDF-1?-induced migration. To clarify whether this reduced migration is EBV-specific or a consequence of cell activation, tonsillar B cells were either infected with EBV, activated with anti-CD40 and interleukin-4 (IL-4) or kept in medium. Activation by anti-CD40 and IL-4 decreased the CXCR4 expression but the CD40 + IL-4-stimulated cells showed no reduction of chemotactic efficacy. Our finding suggests that changing the SDF-1? response of the EBV-infected B cells may serve the viral strategy by directing the infected cells into the extrafollicular areas, rather than retaining them in the lymphoepithelium. PMID:16476057

Ehlin-Henriksson, Barbro; Mowafi, Frida; Klein, George; Nilsson, Anna

2006-01-01

44

Consensus paper: management of degenerative cerebellar disorders.  

PubMed

Treatment of motor symptoms of degenerative cerebellar ataxia remains difficult. Yet there are recent developments that are likely to lead to significant improvements in the future. Most desirable would be a causative treatment of the underlying cerebellar disease. This is currently available only for a very small subset of cerebellar ataxias with known metabolic dysfunction. However, increasing knowledge of the pathophysiology of hereditary ataxia should lead to an increasing number of medically sensible drug trials. In this paper, data from recent drug trials in patients with recessive and dominant cerebellar ataxias will be summarized. There is consensus that up to date, no medication has been proven effective. Aminopyridines and acetazolamide are the only exception, which are beneficial in patients with episodic ataxia type 2. Aminopyridines are also effective in a subset of patients presenting with downbeat nystagmus. As such, all authors agreed that the mainstays of treatment of degenerative cerebellar ataxia are currently physiotherapy, occupational therapy, and speech therapy. For many years, well-controlled rehabilitation studies in patients with cerebellar ataxia were lacking. Data of recently published studies show that coordinative training improves motor function in both adult and juvenile patients with cerebellar degeneration. Given the well-known contribution of the cerebellum to motor learning, possible mechanisms underlying improvement will be outlined. There is consensus that evidence-based guidelines for the physiotherapy of degenerative cerebellar ataxia need to be developed. Future developments in physiotherapeutical interventions will be discussed including application of non-invasive brain stimulation. PMID:24222635

Ilg, W; Bastian, A J; Boesch, S; Burciu, R G; Celnik, P; Claaßen, J; Feil, K; Kalla, R; Miyai, I; Nachbauer, W; Schöls, L; Strupp, M; Synofzik, M; Teufel, J; Timmann, D

2014-04-01

45

Altered cerebellar feedback projections in Asperger syndrome  

Microsoft Academic Search

It has been proposed that the biological basis of autism spectrum disorder includes cerebellar ‘disconnection’. However, direct in vivo evidence in support of this is lacking. Here, the microstructural integrity of cerebellar white matter in adults with Asperger syndrome was studied using diffusion tensor magnetic resonance tractography. Fifteen adults with Asperger syndrome and 16 age–IQ–gender-matched healthy controls underwent diffusion tensor

Marco Catani; Derek K. Jones; Eileen Daly; Nitzia Embiricos; Quinton Deeley; Luca Pugliese; Sarah Curran; Dene Robertson; Declan G. M. Murphy

2008-01-01

46

Cellular and molecular basis of cerebellar development  

PubMed Central

Historically, the molecular and cellular mechanisms of cerebellar development were investigated through structural descriptions and studying spontaneous mutations in animal models and humans. Advances in experimental embryology, genetic engineering, and neuroimaging techniques render today the possibility to approach the analysis of molecular mechanisms underlying histogenesis and morphogenesis of the cerebellum by experimental designs. Several genes and molecules were identified to be involved in the cerebellar plate regionalization, specification, and differentiation of cerebellar neurons, as well as the establishment of cellular migratory routes and the subsequent neuronal connectivity. Indeed, pattern formation of the cerebellum requires the adequate orchestration of both key morphogenetic signals, arising from distinct brain regions, and local expression of specific transcription factors. Thus, the present review wants to revisit and discuss these morphogenetic and molecular mechanisms taking place during cerebellar development in order to understand causal processes regulating cerebellar cytoarchitecture, its highly topographically ordered circuitry and its role in brain function. PMID:23805080

Martinez, Salvador; Andreu, Abraham; Mecklenburg, Nora; Echevarria, Diego

2013-01-01

47

Cerebellar evolution in Darwin's Finches  

E-print Network

and continuous with the fourth ventricle is the cerebellar ventricle, a narrow cleft formed by the dorsal arching of i:he cerebellum during ontogeny. After turning caudalward shortly after its origin, it contirues upwards between the posterior medullary sheet... in the medullary sheet at the base of lobule IX. Above this the ventricle continues as a thin cleft into the fiber sheet of the median lobe. The relatively slender and short lobule I is directed ventrally at the base, but immediately turns rostral, becomes...

St. Jules, Robert Sherman

2012-06-07

48

Developmental Cerebellar Cognitive Affective Syndrome in Ex-preterm Survivors Following Cerebellar Injury.  

PubMed

Cerebellar injury is increasingly recognized as an important complication of very preterm birth. However, the neurodevelopmental consequences of early life cerebellar injury in prematurely born infants have not been well elucidated. We performed a literature search of studies published between 1997 and 2014 describing neurodevelopmental outcomes of preterm infants following direct cerebellar injury or indirect cerebellar injury/underdevelopment. Available data suggests that both direct and indirect mechanisms of cerebellar injury appear to stunt cerebellar growth and adversely affect neurodevelopment. This review also provides important insights into the highly integrated cerebral-cerebellar structural and functional correlates. Finally, this review highlights that early life impairment of cerebellar growth extends far beyond motor impairments and plays a critical, previously underrecognized role in the long-term cognitive, behavioral, and social deficits associated with brain injury among premature infants. These data point to a developmental form of the cerebellar cognitive affective syndrome previously described in adults. Longitudinal prospective studies using serial advanced magnetic resonance imaging techniques are needed to better delineate the full extent of the role of prematurity-related cerebellar injury and topography in the genesis of cognitive, social-behavioral dysfunction. PMID:25241880

Brossard-Racine, Marie; du Plessis, Adre J; Limperopoulos, Catherine

2014-09-23

49

Time Estimation Deficits in Developmental Dyslexia: Evidence of Cerebellar Involvement  

Microsoft Academic Search

In addition to their language-related difficulties, dyslexic children suffer problems in motor skill, balance, automatization and speeded performance. Given the recent evidence for cerebellar involvement in the acquisition of language fluency, these problems suggest cerebellar deficit. To test the hypothesis of cerebellar dysfunction in dyslexia, a time estimation task considered to be a sensitive index of cerebellar function was administered

Roderick I. Nicolson; Angela J. Fawcett; Paul Dean

1995-01-01

50

TWIST1 promoter methylation is associated with prognosis in tonsillar squamous cell carcinoma.  

PubMed

Tonsillar squamous cell carcinomas (TSCC) frequently present with locally advanced diseases and cervical metastases, which are associated with poor prognoses. Epithelial-mesenchymal transition (EMT) is critical for tumor invasiveness and metastatic potential. Recent studies have shown that TWIST1-inducing EMT is overexpressed and hypermethylated in several cancers, indicating disease progression. The aim of the present study was to determine the clinical and prognostic significance of TWIST1 hypermethylation and EMT-related protein expression in TSCC. Methylation levels of TWIST1 promoter were analyzed by quantitative real-time methylation-specific polymerase chain reaction. Immunohistochemical analyses of TWIST1, Snail, and SMAD nuclear interacting protein-1 (SNIP1) were performed in 65 formalin-fixed, paraffin-embedded blocks of surgically resected specimens. TWIST1 promoter hypermethylation was found in 27.7% (18/65) of TSCCs. TWIST1 promoter hypermethylation was associated with poor differentiation (P = .012). Contralateral cervical lymph node metastasis was more frequently observed in TWIST1-methylated tumors (P = .029). High protein expressions of TWIST1, Snail, and SNIP1 were observed in 14 TSCC specimens (21.5%), 21 TSCC specimens (32.3%), and 38 TSCC specimens (58.5%), respectively. SNIP1 expression correlated significantly with TWIST1 methylation (P = .001), whereas TWIST1 protein expression did not. Contralateral cervical lymph node metastasis was an independent risk factor of the decreased overall survival rate (P = .002). TWIST1 methylation (P = .031) and pN stage (P = .037) were independent factors of poor prognoses affecting disease-free survival. TWIST1 promoter hypermethylation may be a useful molecular marker for predicting prognoses and contralateral cervical lymph node metastases in patients with TSCC. PMID:23664538

Kwon, Mi Jung; Kwon, Ji Hyun; Nam, Eun Sook; Shin, Hyung Sik; Lee, Dong Jin; Kim, Jin Hwan; Rho, Young Soo; Sung, Chang Ohk; Lee, Won Jae; Cho, Seong Jin

2013-09-01

51

Research study: STS-1 Orbiter Descent  

NASA Technical Reports Server (NTRS)

The conversion of STS-1 orbiter descent data from AVE-SESAME contact programs to the REEDA system and the reduction of raw radiosonde data is summarized. A first difference program, contact data program, plot data program, and 30 second data program were developed. Six radiosonde soundings were taken. An example of the outputs of each of the programs is presented.

Hickey, J. S.

1981-01-01

52

America's Descent into Madness  

ERIC Educational Resources Information Center

This article describes America's descent into madness under the regime of neoliberalism that has emerged in the United States since the late 1970s. In part, this is due to the emergence of a public pedagogy produced by the corporate-owned media that now saturates Americans with a market-driven value system that undermines those formative…

Giroux, Henry A.

2014-01-01

53

Ka-Band Radar Terminal Descent Sensor  

NASA Technical Reports Server (NTRS)

The terminal descent sensor (TDS) is a radar altimeter/velocimeter that improves the accuracy of velocity sensing by more than an order of magnitude when compared to existing sensors. The TDS is designed for the safe planetary landing of payloads, and may be used in helicopters and fixed-wing aircraft requiring high-accuracy velocity sensing

Pollard, Brian; Berkun, Andrew; Tope, Michael; Andricos, Constantine; Okonek, Joseph; Lou, Yunling

2007-01-01

54

Cerebellar Motor Function in Spina Bifida Meningomyelocele  

PubMed Central

Spina bifida meningomyelocele (SBM), a congenital neurodevelopmental disorder, involves dysmorphology of the cerebellum, and its most obvious manifestations are motor deficits. This paper reviews cerebellar neuropathology and motor function across several motor systems well studied in SBM in relation to current models of cerebellar motor and timing function. Children and adults with SBM have widespread motor deficits in trunk, upper limbs, eyes, and speech articulators that are broadly congruent with those observed in adults with cerebellar lesions. The structure and function of the cerebellum are correlated with a range of motor functions. While motor learning is generally preserved in SBM, those motor functions requiring predictive signals and precise calibration of the temporal features of movement are impaired, resulting in deficits in smooth movement coordination as well as in the classical cerebellar triad of dysmetria, ataxia, and dysarthria. That motor function in individuals with SBM is disordered in a manner phenotypically similar to that in adult cerebellar lesions, and appears to involve similar deficits in predictive cerebellar motor control, suggests that age-based cerebellar motor plasticity is limited in individuals with this neurodevelopmental disorder. PMID:20652468

Dennis, Maureen; Salman, Michael S.; Juranek, Jenifer; Fletcher, Jack M.

2010-01-01

55

X-linked disorders with cerebellar dysgenesis  

PubMed Central

X-linked disorders with cerebellar dysgenesis (XLCD) are a genetically heterogeneous and clinically variable group of disorders in which the hallmark is a cerebellar defect (hypoplasia, atrophy or dysplasia) visible on brain imaging, caused by gene mutations or genomic imbalances on the X-chromosome. The neurological features of XLCD include hypotonia, developmental delay, intellectual disability, ataxia and/or other cerebellar signs. Normal cognitive development has also been reported. Cerebellar dysgenesis may be isolated or associated with other brain malformations or multiorgan involvement. There are at least 15 genes on the X-chromosome that have been constantly or occasionally associated with a pathological cerebellar phenotype. 8 XLCD loci have been mapped and several families with X-linked inheritance have been reported. Recently, two recurrent duplication syndromes in Xq28 have been associated with cerebellar hypoplasia. Given the report of several forms of XLCD and the excess of males with ataxia, this group of conditions is probably underestimated and families of patients with neuroradiological and clinical evidence of a cerebellar disorder should be counseled for high risk of X-linked inheritance. PMID:21569638

2011-01-01

56

Relative Contributions of the Cerebellar Cortex and Cerebellar Nucleus to Eyelid Conditioning  

Microsoft Academic Search

We have presented data addressing the relative contributions of the cerebellar cortex and nuclei in the acquisition and expression\\u000a of conditioned eyelid responses. Data from a series of studies support the notion that while plasticity occurs in both the\\u000a cerebellar cortex and nucleus, the cerebellar cortex is essential for acquisition, extinction, and for the proper expression\\u000a of conditioned eyelid responses.

William L. Nores; Javier F. Medina; Philip M. Steele; Michael D. Mauk

57

Synchrony and neural coding in cerebellar circuits  

PubMed Central

The cerebellum regulates complex movements and is also implicated in cognitive tasks, and cerebellar dysfunction is consequently associated not only with movement disorders, but also with conditions like autism and dyslexia. How information is encoded by specific cerebellar firing patterns remains debated, however. A central question is how the cerebellar cortex transmits its integrated output to the cerebellar nuclei via GABAergic synapses from Purkinje neurons. Possible answers come from accumulating evidence that subsets of Purkinje cells synchronize their firing during behaviors that require the cerebellum. Consistent with models predicting that coherent activity of inhibitory networks has the capacity to dictate firing patterns of target neurons, recent experimental work supports the idea that inhibitory synchrony may regulate the response of cerebellar nuclear cells to Purkinje inputs, owing to the interplay between unusually fast inhibitory synaptic responses and high rates of intrinsic activity. Data from multiple laboratories lead to a working hypothesis that synchronous inhibitory input from Purkinje cells can set the timing and rate of action potentials produced by cerebellar nuclear cells, thereby relaying information out of the cerebellum. If so, then changing spatiotemporal patterns of Purkinje activity would allow different subsets of inhibitory neurons to control cerebellar output at different times. Here we explore the evidence for and against the idea that a synchrony code defines, at least in part, the input–output function between the cerebellar cortex and nuclei. We consider the literature on the existence of simple spike synchrony, convergence of Purkinje neurons onto nuclear neurons, and intrinsic properties of nuclear neurons that contribute to responses to inhibition. Finally, we discuss factors that may disrupt or modulate a synchrony code and describe the potential contributions of inhibitory synchrony to other motor circuits. PMID:23248585

Person, Abigail L.; Raman, Indira M.

2012-01-01

58

Reversible hypomagnesaemia-induced subacute cerebellar syndrome.  

PubMed

Magnesium is the second most abundant intracellular cation and is a fundamental cofactor in a multitude of cellular enzymatic reactions. Magnesium deficiency causes diverse clinical features predominantly due to cardio- and neurotoxicity. We describe a case of severe hypomagnesaemia associated with intermittent downbeat nystagmus, cerebellar ataxia, generalised convulsions and a supraventricular tachycardia. On MRI imaging, a transient lesion of the cerebellar nodulus was observed, which has not, to our knowledge, been previously described in isolated hypomagnesaemia. PMID:20607440

Sedehizadeh, Saam; Keogh, Michael; Wills, Adrian J

2011-08-01

59

Cerebellar Motor Function in Spina Bifida Meningomyelocele  

Microsoft Academic Search

Spina bifida meningomyelocele (SBM), a congenital neurodevelopmental disorder, involves dysmorphology of the cerebellum, and\\u000a its most obvious manifestations are motor deficits. This paper reviews cerebellar neuropathology and motor function across\\u000a several motor systems well studied in SBM in relation to current models of cerebellar motor and timing function. Children\\u000a and adults with SBM have widespread motor deficits in trunk, upper

Maureen Dennis; Michael S. Salman; Jenifer Juranek; Jack M. Fletcher

2010-01-01

60

Penicillin V, loracarbef and clindamycin in tonsillar surface fluid during acute group A streptococcal pharyngotonsillitis.  

PubMed

Patients with acute group A- strepotococcal pharyngotonsillitis were randomly assigned to treatment for 10 d with either phenoxymethylpenicillin (PcV), loracarbef or clindamycin. The concentrations of the drugs, respectively, were determined in tonsillar surface fluid (TSF), serum and the saliva in each patient on altogether 5 occasions; before, during and 4 d after end of therapy. On the same occasions blood was drawn for analysis of C-reactive protein (CRP) and orosomucoid. On the last d of treatment PcV could be detected in TSF in 1 of 6 patients only. Loracarbef had a slower decrease in TSF during therapy and measurable levels did occur 2 d after end of therapy corresponding to MIC 100 for GAS. This may be related to the somewhat better clinical results of the cephalosporins than of PcV, and possibly indicates that an extended therapy with these drugs in primary GAS pharyngotonsillitis for more than the arbitrarily chosen 10 d could reduce the number of recurrent episodes. PcV and loracarbef were not detected in serum after the end of treatment. The concentration of clindamycin in both TSF and the saliva was fairly longstanding during therapy and reached levels exceeding MIC 100 for GAS, in both TSF and serum 2 d after the end of treatment. Several investigations have shown that GAS, especially in the stationary phase may invade respiratory epithelial cells and are present intracellularly in patients with acute pharyngotonsillitis as well as in asymptomatic carriers. The same T-type, identical DNA fingerprints and arbitrarily primed patterns are found in GAS before and after treatment failure indicating that the primary episode and the failures are caused by the same strain. The longstanding concentrations of clindamycin in TSF, roughly independent of the degree of the local inflammation combined with its intracellular accumulation and activity against resting GAS seem to explain the efficiency of the drug in recurrent GAS pharyngotonsillitis. CRP and orosomucoid were of limited value in differing between bacterial and viral pharyngtonsillitis and a correlation between antibiotic concentration and CRP/orosomucoid levels was not found. PMID:16012002

Orrling, Arne; Kamme, Carl; Stjernquist-Desatnik, Anna

2005-01-01

61

Simulating Descent and Landing of a Spacecraft  

NASA Technical Reports Server (NTRS)

The Dynamics Simulator for Entry, Descent, and Surface landing (DSENDS) software performs high-fidelity simulation of the Entry, Descent, and Landing (EDL) of a spacecraft into the atmosphere and onto the surface of a planet or a smaller body. DSENDS is an extension of the DShell and DARTS programs, which afford capabilities for mathematical modeling of the dynamics of a spacecraft as a whole and of its instruments, actuators, and other subsystems. DSENDS enables the modeling (including real-time simulation) of flight-train elements and all spacecraft responses during various phases of EDL. DSENDS provides high-fidelity models of the aerodynamics of entry bodies and parachutes plus supporting models of atmospheres. Terrain and real-time responses of terrain-imaging radar and lidar instruments can also be modeled. The program includes modules for simulation of guidance, navigation, hypersonic steering, and powered descent. Automated state-machine-driven model switching is used to represent spacecraft separations and reconfigurations. Models for computing landing contact and impact forces are expected to be added. DSENDS can be used as a stand-alone program or incorporated into a larger program that simulates operations in real time.

Balaram, J.; Jain, Abhinandan; Martin, Bryan; Lim, Christopher; Henriquez, David; McMahon, Elihu; Sohl, Garrett; Banerjee, Pranab; Steele, Robert; Bentley, Timothy

2005-01-01

62

[Postpartum secondary cerebral venous sinus thrombosis with axial transtentorial and tonsillar herniation as a complication of intracranial hypotension syndrome after spinal anaesthesia].  

PubMed

We describe the case of a 28-year-old postpartum female patient who suffered from a secondary cerebral venous sinus thrombosis due to an intracranial hypotension syndrome with axial transtentorial and tonsillar herniation and the clinical signs of incarceration after spinal anaesthesia. PMID:25489758

Kraayvanger, L; Berlit, P

2014-12-01

63

Evidence of Bacterial Biofilms among Infected and Hypertrophied Tonsils in Correlation with the Microbiology, Histopathology, and Clinical Symptoms of Tonsillar Diseases  

PubMed Central

Diseases of the tonsils are becoming more resistant to antibiotics due to the persistence of bacteria through the formation of biofilms. Therefore, understanding the microbiology and pathophysiology of such diseases represent an important step in the management of biofilm-related infections. We have isolated the microorganisms, evaluated their antimicrobial susceptibility, and detected the presence of bacterial biofilms in tonsillar specimens in correlation with the clinical manifestations of tonsillar diseases. Therefore, a total of 140 palatine tonsils were collected from 70 patients undergoing tonsillectomy at University Malaya Medical Centre. The most recovered isolate was Staphylococcus aureus (39.65%) followed by Haemophilus influenzae (18.53%). There was high susceptibility against all selected antibiotics except for cotrimoxazole. Bacterial biofilms were detected in 60% of patients and a significant percentage of patients demonstrated infection manifestation rather than obstruction. In addition, an association between clinical symptoms like snore, apnea, nasal obstruction, and tonsillar hypertrophy was found to be related to the microbiology of tonsils particularly to the presence of biofilms. In conclusion, evidence of biofilms in tonsils in correlation with the demonstrated clinical symptoms explains the recalcitrant nature of tonsillar diseases and highlights the importance of biofilm's early detection and prevention towards better therapeutic management of biofilm-related infections. PMID:24454384

Alasil, Saad Musbah; Omar, Rahmat; Yusof, Mohd Yasim; Dhabaan, Ghulam N.

2013-01-01

64

21 CFR 882.5820 - Implanted cerebellar stimulator.  

Code of Federal Regulations, 2010 CFR

...cerebellar stimulator is a device used to stimulate electrically a patient's cerebellar cortex for the treatment of intractable epilepsy, spasticity, and some movement disorders. The stimulator consists of an implanted receiver with electrodes that are...

2010-04-01

65

Cerebellar modules operate at different frequencies  

PubMed Central

Due to the uniform cyto-architecture of the cerebellar cortex, its overall physiological characteristics have traditionally been considered to be homogeneous. In this study, we show in awake mice at rest that spiking activity of Purkinje cells, the sole output cells of the cerebellar cortex, differs between cerebellar modules and correlates with their expression of the glycolytic enzyme aldolase C or zebrin. Simple spike and complex spike frequencies were significantly higher in Purkinje cells located in zebrin-negative than zebrin-positive modules. The difference in simple spike frequency persisted when the synaptic input to, but not intrinsic activity of, Purkinje cells was manipulated. Blocking TRPC3, the effector channel of a cascade of proteins that have zebrin-like distribution patterns, attenuated the simple spike frequency difference. Our results indicate that zebrin-discriminated cerebellar modules operate at different frequencies, which depend on activation of TRPC3, and that this property is relevant for all cerebellar functions. DOI: http://dx.doi.org/10.7554/eLife.02536.001 PMID:24843004

Zhou, Haibo; Lin, Zhanmin; Voges, Kai; Ju, Chiheng; Gao, Zhenyu; Bosman, Laurens WJ; Ruigrok, Tom JH; Hoebeek, Freek E

2014-01-01

66

Metabolic anatomy of paraneoplastic cerebellar degeneration  

SciTech Connect

Eleven patients with acquired cerebellar degeneration (10 of whom had paraneoplastic cerebellar degeneration (PCD)) were evaluated using neuropsychological tests and /sup 18/F-fluorodeoxyglucose/positron emission tomography to (1) quantify motor, cognitive, and metabolic abnormalities; (2) determine if characteristic alterations in the regional cerebral metabolic rate for glucose (rCMRGlc) are associated with PCD; and (3) correlate behavioral and metabolic measures of disease severity. Eighteen volunteer subjects served as normal controls. Although some PCD neuropsychological test scores were abnormal, these results could not, in general, be dissociated from the effects of dysarthria and ataxia. rCMRGlc was reduced in patients with PCD (versus normal control subjects) in all regions except the brainstem. Analysis of patient and control rCMRGlc data using a mathematical model of regional metabolic interactions revealed two metabolic pattern descriptors, SSF1 and SSF2, which distinguished patients with PCD from normal control subjects; SSF2, which described a metabolic coupling between cerebellum, cuneus, and posterior temporal, lateral frontal, and paracentral cortex, correlated with quantitative indices of cerebellar dysfunction. Our inability to document substantial intellectual impairment in 7 of 10 patients with PCD contrasts with the 50% incidence of dementia in PCD reported by previous investigators. Widespread reductions in PCD rCMRGlc may result from the loss of cerebellar efferents to thalamus and forebrain structures, a reverse cerebellar diaschisis.

Anderson, N.E.; Posner, J.B.; Sidtis, J.J.; Moeller, J.R.; Strother, S.C.; Dhawan, V.; Rottenberg, D.A.

1988-06-01

67

Infection of primary human tonsillar lymphoid cells by KSHV reveals frequent but abortive infection of T cells.  

PubMed

The lymphotropic herpesvirus KSHV principally infects B cells in vivo and is linked to several human B cell lymphoproliferative syndromes. Here we examine the susceptibility of primary tonsillar lymphocytes to infection by a recombinant KSHV (rKSHV.219) that constitutively expresses GFP. At an MOI of ~1, ca. 5-10% of CD19+ B cells became GFP-positive. Surprisingly, in the same culture many more T cells became infected. However, in contrast to isolated B cells, isolated infected T cells did not support correct viral transcription and did not produce infectious virus, indicating the presence of one or more post-entry blocks to lytic KSHV replication in T cells. No immortalization or transformation has yet been observed in either B or T cells. These results affirm the feasibility of studying KSHV infection in primary lymphoid cells, and help to rationalize the detection of KSHV DNA in rare human T cell lymphomas in vivo. PMID:21353276

Myoung, Jinjong; Ganem, Don

2011-04-25

68

Severe Hypoglycemia Masquerading as Cerebellar Stroke  

PubMed Central

Hypoglycemia is a common presenting feature of diabetes in the emergency department. Cardiovascular and neuroglycopenia features are well documented in the literature. We here report a case of 55-year-old female who came to our emergency with clinical features suggestive of cerebellar stroke. Laboratory investigations revealed severe hypoglycemia. The cerebellar signs and symptoms improved completely with intravenous dextrose infusion. Her MR imaging and Doppler of carotid and vertebrobasilar arteries were noncontributory. Hypoglycemia causes behavioral changes, confusion, loss of consciousness, and seizures. It is also well known to cause hemiplegia and aphasia. Hypoglycemia presenting as cerebellar stroke is rarely reported in the literature. This case highlights an uncommon manifestation of a common clinical condition. Physician must rule out hypoglycemia in every stroke patients.

Agrawal, Naman; Jamshed, Nayer; Aggarwal, Praveen; Ekka, Meera

2014-01-01

69

Cerebellar contribution to feedforward control of locomotion  

PubMed Central

The cerebellum is an important contributor to feedforward control mechanisms of the central nervous system, and sequencing—the process that allows spatial and temporal relationships between events to be recognized—has been implicated as the fundamental cerebellar mode of operation. By adopting such a mode and because cerebellar activity patterns are sensitive to a variety of sensorimotor-related tasks, the cerebellum is believed to support motor and cognitive functions that are encoded in the frontal and parietal lobes of the cerebral cortex. In this model, the cerebellum is hypothesized to make predictions about the consequences of a motor or cognitive command that originates from the cortex to prepare the entire system to cope with ongoing changes. In this framework, cerebellar predictive mechanisms for locomotion are addressed, focusing on sensorial and motoric sequencing. The hypothesis that sequence recognition is the mechanism by which the cerebellum functions in gait control is presented and discussed. PMID:25009490

Pisotta, Iolanda; Molinari, Marco

2014-01-01

70

Marriage Networks, Descent Clusters and Native Title Claims Michael Houseman  

E-print Network

1 Marriage Networks, Descent Clusters and Native Title Claims Michael Houseman (Ecole Pratique des of empirical marriage patterns, with a view to its possible relevance for Native Title. Ethnographic accounts-related marriages. Descent, the key-stone genealogical principle of the 1976 Land Rights Act, is an excellent

Paris-Sud XI, Université de

71

Cerebellar tDCS: How to Do It.  

PubMed

Cerebellar transcranial direct current stimulation (cerebellar tDCS) is a non-invasive technique for inducing prolonged functional changes in the human cerebellum. Available data show that this simple and safe technique can modulate several motor and non-motor cerebellar functions in healthy humans. Also, preliminary data suggest that cerebellar tDCS is a possible therapeutic option in patients with cerebellar disorders. To provide a reference for those approaching this technique for the first time in healthy humans and patients, we here briefly and practically review the methodology for cerebellar tDCS, discussing electrode types, positions, DC duration and intensity. Recent modelling studies confirm that the electric field generated with the methodology reviewed here reaches the cerebellum at a strength within the range of values for modulating activity in the cerebellar neurons experimentally assessed. PMID:25231432

Ferrucci, Roberta; Cortese, Francesca; Priori, Alberto

2014-09-18

72

Cerebellar isolation, parcellation, and conformal surface mapping  

Microsoft Academic Search

The topographic organization of motor, sensory and cognitive functions in the human cerebellum is poorly understood, and, owing to its anatomical organization, most of the folial surface is hidden from view. In order to facilitate surface-based analysis of functional activation within the cerebellar cortex, we constructed a \\

Kelly Rehm; Monica Hurdal; Josh Stern; Kirt Schaper; De Witt Sumners; David Rottenberg

2001-01-01

73

Right side neglect in right cerebellar lesion  

PubMed Central

A patient is described who developed right side hemineglect after a right cerebellar lesion. This spatial disorder was interpreted as a secondary effect of a deficit of the motor organisation in the right hemispace due to left frontal diaschisis. The pathological base may be the interruption of a highly integrated system which includes the lateral cerebellum and the contralateral frontal lobe.?? PMID:11413276

Silveri, M; Misciagna, S; Terrezza, G

2001-01-01

74

Developmental dyslexia: the cerebellar deficit hypothesis  

Microsoft Academic Search

Surprisingly, the problems faced by many dyslexic children are by no means confined to reading and spelling. There appears to be a general impairment in the ability to perform skills automatically, an ability thought to be dependent upon the cerebellum. Specific behavioural and neuroimaging tests reviewed here indicate that dyslexia is indeed associated with cerebellar impairment in about 80% of

Roderick I Nicolson; Angela J Fawcett; Paul Dean

2001-01-01

75

Myoclonus epilepsy with cerebellar Lafora bodies  

PubMed Central

A case is reported of an 18 year old man with progressive myoclonus epilepsy. Histopathological examination revealed the presence of numerous Lafora bodies in the cerebellar granular layer, without other significant changes in the central nervous system or in other organs. Images PMID:932752

Scelsi, R.; Mazzella, G. L.; Lombardi, M.

1976-01-01

76

Rotorod sensorimotor learning in cerebellar mutant mice  

Microsoft Academic Search

Lurcher mutant mice, characterized by degeneration of cerebellar granule and Purkinje cells, were compared to normal littermate controls in a rotorod test, consisting of a wheel turning at constant speed which required on the part of the animal postural adjustments in order to maintain equilibrium. Identical baseline rates for the two grops were assured by changing the speed and size

R. Lalonde; A. N. Bensoula; M. Filali

1995-01-01

77

Effect of Methamidophos on cerebellar neuronal cells.  

PubMed

Methamidophos is a toxic organophosphorus compound that inhibits acetlycholinesterase activity, and induces neurotoxicity. It is a synthetic chemical commonly used as pesticides to limit pest damages to cultivated plants. Currently, there is serious public health concern over its safety and use due to its global nature, persistence and bioaccumulations. We have previously reported that methamidophos suppressed thyroid hormone receptor (TR)-mediated transcription, but did not dissociate the interaction between TR and its response element (thyroid hormone response element; TRE), neither did it interact with nuclear cofactors. In the present study, we investigated the effects of methamidophos on cerebellar neuronal cells. Using primary cerebellar culture from new born rats, We observed that Purkinje cell dendrite arborization were greatly impaired in the absence of thyroid hormone (TH), However, low dose methamidophos 10-6 M did not significantly impair dendrite arborization of cerebellar Purkinje cells in the presence of thyroid hormone (TH). However, using granule cell reaggregate culture, we observed that low dose methamidophos 10-6 M remarkably suppressed granule cell neurite extension in the presence of TH. Taken together, our study shows that low dose methamidophos may negatively impact TH-mediated cerebellar neuronal cell development and function, and consequently could interfere with TH-regulated neuronal events. PMID:24937384

Ibhazehiebo, K; Iyawe, V I; Koibuchi, Noriyuki

2013-01-01

78

Investigating Common Descent: Formulating Explanations and Models  

NSDL National Science Digital Library

This activity has students formulate explanations and models that simulate structural and biochemical data as they investigate the misconception that humans evolved from apes. Students should recognize that present-day species evolved from earlier species and the relatedness of organisms is the result of common ancestry. They will also discover that similarities among existing organisms provide evidence for evolution, anatomical similarities of living things reflect common ancestry, and all life forms use the same basic DNA building blocks. Basic concepts also include the fact that scientists pose, test, and revise multiple hypotheses to explain what they observe, our understanding of life through time is based upon multiple lines of evidence, the similarity of DNA nucleotide sequences can be used to infer the degree of kinship between species, and anatomical evidence is also used to infer lines of descent. This site includes a list of materials and all information required for this activity.

79

Distributed Control by Lagrangian Steepest Descent  

NASA Technical Reports Server (NTRS)

Often adaptive, distributed control can be viewed as an iterated game between independent players. The coupling between the players mixed strategies, arising as the system evolves from one instant to the next, is determined by the system designer. Information theory tells us that the most likely joint strategy of the players, given a value of the expectation of the overall control objective function, is the minimizer of a function o the joint strategy. So the goal of the system designer is to speed evolution of the joint strategy to that Lagrangian mhimbhgpoint,lowerthe expectated value of the control objective function, and repeat Here we elaborate the theory of algorithms that do this using local descent procedures, and that thereby achieve efficient, adaptive, distributed control.

Wolpert, David H.; Bieniawski, Stefan

2004-01-01

80

Nucleotide-binding and oligomerization domain-like receptors and retinoic acid inducible gene-like receptors in human tonsillar T lymphocytes.  

PubMed

Nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) and retinoic acid-inducible gene (RIG)-like receptors (RLRs) are recently discovered cytosolic pattern-recognition receptors sensing mainly bacterial components and viral RNA, respectively. Their importance in various cells and disorders is becoming better understood, but their role in human tonsil-derived T lymphocytes remains to be elucidated. In this study, we evaluated expression and functional relevance of NLRs and RLRs in human tonsillar CD3(+) T lymphocytes. Immunohistochemistry, real-time RT-PCR and flow cytometry revealed expression of NOD1, NOD2, NALP1, NALP3, NAIP, IPAF, RIG-1, MDA-5 and LGP-2 at mRNA and protein levels. Because of the limited number of ligands (iE-DAP, MDP, Alum, Poly(I:C)/LyoVec), functional evaluation was restricted to NOD1, NOD2, NALP3 and RIG-1/MDA-5, respectively. Stimulation with the agonists alone was not enough to induce activation but upon triggering via CD3 and CD28, a profound induction of proliferation was seen in purified CD3(+) T cells. However, the proliferative response was not further enhanced by the cognate ligands. Nonetheless, in tonsillar mononuclear cells iE-DAP, MDP and Poly(I:C)/LyoVec were found to augment the CD3/CD28-induced proliferation of tonsillar mononuclear cells. Also, iE-DAP and MDP were found to promote secretion of interleukins 2 and 10 as well as to up-regulate CD69. This study demonstrates for the first time a broad range of NLRs and RLRs in human tonsillar T cells and that NOD1, NOD2 and RIG-1/MDA-5 act synergistically with ?CD3 and ?CD28 to induce proliferation of human T cells. Hence, these results suggest that these receptors have a role in T-cell activation. PMID:21342182

Petterson, Terese; Månsson, Anne; Riesbeck, Kristian; Cardell, Lars O

2011-05-01

81

Nucleotide-binding and oligomerization domain-like receptors and retinoic acid inducible gene-like receptors in human tonsillar T lymphocytes  

PubMed Central

Nucleotide-binding and oligomerization domain (NOD) -like receptors (NLRs) and retinoic acid-inducible gene (RIG) -like receptors (RLRs) are recently discovered cytosolic pattern-recognition receptors sensing mainly bacterial components and viral RNA, respectively. Their importance in various cells and disorders is becoming better understood, but their role in human tonsil-derived T lymphocytes remains to be elucidated. In this study, we evaluated expression and functional relevance of NLRs and RLRs in human tonsillar CD3+ T lymphocytes. Immunohistochemistry, real-time RT-PCR and flow cytometry revealed expression of NOD1, NOD2, NALP1, NALP3, NAIP, IPAF, RIG-1, MDA-5 and LGP-2 at mRNA and protein levels. Because of the limited number of ligands (iE-DAP, MDP, Alum, Poly(I:C)/LyoVec), functional evaluation was restricted to NOD1, NOD2, NALP3 and RIG-1/MDA-5, respectively. Stimulation with the agonists alone was not enough to induce activation but upon triggering via CD3 and CD28, a profound induction of proliferation was seen in purified CD3+ T cells. However, the proliferative response was not further enhanced by the cognate ligands. Nonetheless, in tonsillar mononuclear cells iE-DAP, MDP and Poly(I:C)/LyoVec were found to augment the CD3/CD28-induced proliferation of tonsillar mononuclear cells. Also, iE-DAP and MDP were found to promote secretion of interleukins 2 and 10 as well as to up-regulate CD69. This study demonstrates for the first time a broad range of NLRs and RLRs in human tonsillar T cells and that NOD1, NOD2 and RIG-1/MDA-5 act synergistically with ?CD3 and ?CD28 to induce proliferation of human T cells. Hence, these results suggest that these receptors have a role in T-cell activation. PMID:21342182

Petterson, Terese; Månsson, Anne; Riesbeck, Kristian; Cardell, Lars O

2011-01-01

82

[Use of intubating laryngeal mask airway in combination with fiberoptic intubation in a patient with morbid obesity and unexpected lingual tonsillar hypertrophy].  

PubMed

Lingual tonsillar hyperplasia is rare, but may cause difficult or impossible tracheal intubation. We administered anesthesia to a female patient with a body mass index (BMI) of 47 kg x m(-2) with unexpected lingual tonsillar hyperplasia. A 32-year-old woman was scheduled for surgery to repair a ventral hernia under general anesthesia. After inducting anesthesia, three anesthesiologists were needed to ventilate via a facemask. At direct laryngoscopy, after achieving muscular relaxation, the arytenoids and epiglottis could not be identified because of markedly hypertrophied tissue. Next, we attempted to use Trachlight for tracheal intubation, but no light was seen through the anterior region of the neck. After inserting a laryngeal airway mask (LMA), ventilation could be continued. We replaced the LMA with an intubating laryngeal mask airway (ILMA) for the purpose of tracheal intubation. Finally, the patient's trachea was intubated by ILMA with fiberoptic bronchoscopy. Several methods for tracheal intubation for the patients with lingual tonsillar hypertrophy have been reported; the insertion of an ILMA might be considered for safe airway management in combination with a fiberscope. PMID:20420133

Kamada, Mineto; Kouno, Shinichi; Satake, Yoshiki; Kawashima, Shingo; Adachi, Yuji

2010-04-01

83

Neuro-Otological Aspects of Cerebellar Stroke Syndrome  

PubMed Central

Cerebellar stroke is a common cause of a vascular vestibular syndrome. Although vertigo ascribed to cerebellar stroke is usually associated with other neurological symptoms or signs, it may mimic acute peripheral vestibulopathy (APV), so called pseudo-APV. The most common pseudo-APV is a cerebellar infarction in the territory of the medial branch of the posterior inferior cerebellar artery (PICA). Recent studies have shown that a normal head impulse result can differentiate acute medial PICA infarction from APV. Therefore, physicians who evaluate stroke patients should be trained to perform and interpret the results of the head impulse test. Cerebellar infarction in the territory of the anterior inferior cerebellar artery (AICA) can produce a unique stroke syndrome in that it is typically accompanied by unilateral hearing loss, which could easily go unnoticed by patients. The low incidence of vertigo associated with infarction involving the superior cerebellar artery distribution may be a useful way of distinguishing it clinically from PICA or AICA cerebellar infarction in patients with acute vertigo and limb ataxia. For the purpose of prompt diagnosis and adequate treatment, it is imperative to recognize the characteristic patterns of the clinical presentation of each cerebellar stroke syndrome. This paper provides a concise review of the key features of cerebellar stroke syndromes from the neuro-otology viewpoint. PMID:19587812

2009-01-01

84

Surface erosion caused on Mars from Viking descent engine plume  

NASA Technical Reports Server (NTRS)

During the Martian landings the descent engine plumes on Viking Lander 1 (VL-1) and Viking Lander 2 (VL-2) eroded the Martian surface materials. This had been anticipated and investigated both analytically and experimentally during the design phase of the Viking spacecraft. This paper presents data on erosion obtained during the tests of the Viking descent engine and the evidence for erosion by the descent engines of VL-1 and VL-2 on Mars. From these and other results, it is concluded that there are four distinct surface materials on Mars: (1) drift materials, (2) crusty to cloddy material, (3) blocky material, and (4) rock.

Hutton, R. E.; Moore, H. J.; Scott, R. F.; Shorthill, R. W.; Spitzer, C. R.

1980-01-01

85

Identification of RNA Aptamers that Internalize into HPV-16 E6/E7 Transformed Tonsillar Epithelial Cells  

PubMed Central

Human papillomavirus type 16 (HPV-16) associated oropharyngeal cancers are on a significant increase and better therapeutic strategies are needed. The HPV-16 oncogenes E6 and E7 are expressed in HPV-associated cancers and are able to transform human tonsillar epithelial cells (HTECs). We used cell-SELEX (Systematic Evolution of Ligands by Exponential Enrichment) to select for RNA aptamers that entered into HPV-16 E6/E7-HTECs. After 12 rounds of cell-SELEX, a pool of aptamers was obtained that had significantly greater internalization capacity (~5-fold) into E6/E7-HTECs as compared to primary HTECs or fibroblasts. Analysis of individual aptamers from the pool indicated variable internalization into E6/E7-HTECs (1 to 8-fold as compared to a negative control). Most of the individual aptamers internalized into E6/E7 and primary HTECs with similar efficiency, while one aptamer exhibited ~3-fold better internalization into E6/E7-HTECs. Aptamers that internalize into cells may be useful for delivering therapeutic agents to HPV-16 associated malignancies. PMID:24074596

Gourronc, Francoise A.; Rockey, William M.; Thiel, William H.; Giangrande, Paloma H.; Klingelhutz, Aloysius J.

2013-01-01

86

From germinal matrix to cerebellar haemorrhage.  

PubMed

Abstract For many years cerebellar development after preterm birth has been poorly investigated and has been studied without taking germinal matrix-intraventricular haemorrhage into account. Advanced neuroimaging techniques like magnetic resonance imaging, as well as the use of various acoustic windows (mastoid fontanelle, occipital foramen) have allowed for in vivo diagnosis of acquired focal haemorrhagic lesions in the cerebellum of very preterm babies. The vulnerability of the cerebellum also seems to be related to specific gestational ages, i.e., between 23 and 27 weeks, when rapid growth in cerebellar volume occurs and at a much faster rate than mean brain volume increase. In this paper, the contribution of the cerebellum in long-term motor cognitive, learning and behavioural functions, including psychiatric ones, is discussed. PMID:23968333

Fumagalli, Monica; Bassi, Laura; Sirgiovanni, Ida; Mosca, Fabio; Sannia, Andrea; Ramenghi, Luca A

2013-08-23

87

Shortening reaction in patients with cerebellar ataxia.  

PubMed

During passive extension of the elbow, the triceps muscle normally shows a burst of electromyographic activity. This shortening reaction (SR) is known to be exaggerated in extrapyramidal disease states, but the effects of cerebellar disease are unknown. The SR was measured in both arms of a patient with hemiataxia, the unaffected arm serving as a matched control. In the ataxic arm, the SR was significantly larger and did not show the normal increase during "reinforcement." In a patient with bilateral ataxia, the SR was grossly exaggerated as compared with the SRs in a group of normal subjects. The present findings indicate an unexpected point of similarity between cerebellar and extrapyramidal disease states, which is discussed in terms of the anatomical connections of the cerebellum and basal ganglia. The techniques used in this work provide a quantitative approach to disorders of movement and muscle tone. PMID:7092180

Angel, R W

1982-03-01

88

Inverted (Reverse) Takotsubo Cardiomyopathy following Cerebellar Hemorrhage  

PubMed Central

Background. First described in 2005, inverted takotsubo is one of the four stress-induced cardiomyopathy patterns. It is rarely associated with subarachnoid hemorrhage but was not previously reported after intraparenchymal bleeding. Purpose. We reported a symptomatic case of inverted takotsubo pattern following a cerebellar hemorrhage. Case Report. A 26-year-old woman presented to the emergency department with sudden headache and hemorrhage of the posterior fossa was diagnosed, probably caused by a vascular malformation. Several hours later, she developed acute pulmonary edema due to acute heart failure. Echocardiography showed left ventricular dysfunction with hypokinetic basal segments and hyperkinetic apex corresponding to inverted takotsubo. Outcome was spontaneously favorable within a few days. Conclusion. Inverted takotsubo pattern is a stress-induced cardiomyopathy that could be encountered in patients with subarachnoid hemorrhage and is generally of good prognosis. We described the first case following a cerebellar hematoma. PMID:24826313

Piérard, Sophie; Vinetti, Marco

2014-01-01

89

Cerebellar secretin modulates eyeblink classical conditioning.  

PubMed

We have previously shown that intracerebellar infusion of the neuropeptide secretin enhances the acquisition phase of eyeblink conditioning (EBC). Here, we sought to test whether endogenous secretin also regulates EBC and to test whether the effect of exogenous and endogenous secretin is specific to acquisition. In Experiment 1, rats received intracerebellar infusions of the secretin receptor antagonist 5-27 secretin or vehicle into the lobulus simplex of cerebellar cortex immediately prior to sessions 1-3 of acquisition. Antagonist-infused rats showed a reduction in the percentage of eyeblink CRs compared with vehicle-infused rats. In Experiment 2, rats received intracerebellar infusions of secretin or vehicle immediately prior to sessions 1-2 of extinction. Secretin did not significantly affect extinction performance. In Experiment 3, rats received intracerebellar infusions of 5-27 secretin or vehicle immediately prior to sessions 1-2 of extinction. The secretin antagonist did not significantly affect extinction performance. Together, our current and previous results indicate that both exogenous and endogenous cerebellar secretin modulate acquisition, but not extinction, of EBC. We have previously shown that (1) secretin reduces surface expression of the voltage-gated potassium channel ?-subunit Kv1.2 in cerebellar cortex and (2) intracerebellar infusions of a Kv1.2 blocker enhance EBC acquisition, much like secretin. Kv1.2 is almost exclusively expressed in cerebellar cortex at basket cell-Purkinje cell pinceaus and Purkinje cell dendrites; we propose that EBC-induced secretin release from PCs modulates EBC acquisition by reducing surface expression of Kv1.2 at one or both of these sites. PMID:25403455

Fuchs, Jason R; Robinson, Gain M; Dean, Aaron M; Schoenberg, Heidi E; Williams, Michael R; Morielli, Anthony D; Green, John T

2014-12-01

90

Cerebellar dysregulation and heterogeneity of mood disorders  

PubMed Central

This paper discusses diverse studies to consider the hypothesis that cerebellar pathology supports the heterogeneous metabolic pathologies of mood disorders. The evidence presented includes studies selected from the following areas of scientific research: magnetic resonance imaging, histology, clinical syndromes, comparative anatomy, neuronal connections, and mitochondrial dysfunction. The gamut of different scientific study methods confirms the validity of the involvement of the cerebellum in mood disorders. PMID:25092983

Tobe, Edward H

2014-01-01

91

Reduction of Cerebellar Glucose Metabolism in Advanced Alzheimer's Disease  

Microsoft Academic Search

Although regional cerebral metabolism and blood flow in Alzhei mer's disease (AD) have been studied extensively with PET and SPECT, few reports have been concerned with cerebellar metabo lism or perfusion in Alzheimer's disease. To evaluate cerebellar glucose metabolism in Alzheimer's disease patients, we studied the cerebellar and cerebral metabolic rate for glucose (CMRglc) using 2(18F)fluoro-2-deoxy-D-glucose (18F-FDG)and PET. Methods: Six

Kazunari Ishii; Masahiro Sasaki; Hajime Kitagaki; Shigeru Yamaji; Setsu Sakamoto; Kant Matsuda; Etsuro Mori

92

Neurosurgical management of cerebellar haematoma and infarct.  

PubMed Central

The clinical features, treatment, and outcome were reviewed for 48 patients with a haematoma and 71 patients with an infarct in the posterior fossa in order to develop a rational plan of management. Clinical features alone were insufficient to make a diagnosis in about half of the series. Patients with a haematoma were referred more quickly to the neurosurgical unit, were more often in coma, and more often had CT evidence of brain stem compression and acute hydrocephalus. Ultimately, 75% of the patients with a haematoma required an operation. By contrast, most patients with an infarct were managed successfully conservatively. Early surgical management in both cerebellar haemorrhage and infarct (either external ventricular drainage or evacuation of the lesion), associated with early presentation and CT signs of brain stem compression and acute hydrocephalus, led to a good outcome in most patients. Of the patients with cerebellar haematoma initially treated by external drainage, over half subsequently required craniectomy and evacuation of the lesion; but, in some cases, this failed to reverse the deterioration. In patients with a cerebellar infarct, external drainage was more often successful. The guidelines, findings, and recommendations for future management of patients with posterior fossa stroke are discussed. Images PMID:7673958

Mathew, P; Teasdale, G; Bannan, A; Oluoch-Olunya, D

1995-01-01

93

Cerebellar-parietal connections underpin phonological storage.  

PubMed

Previous research has accumulated convincing evidence to show that the human cerebellum contributes to the short-term storage of verbal information, but its specific role in brain networks involved in phonological storage remains uncertain. In a randomized, crossover and sham-controlled design, we here combined transcranial direct current stimulation (tDCS), applied to the right cerebellum, with fMRI to investigate systematically the contribution of the human cerebellum to encoding, maintenance, and retrieval of verbal information. After anodal, but not cathodal, tDCS, we found a reduced item recognition capacity together with an attenuated neural signal from the right cerebellar lobule VIIb, specifically during the late encoding phase. Within this phase, tDCS furthermore affected task-associated functional connections between right cerebellar lobule VIIb and the posterior parietal cortex. These findings suggest that the right cerebellar lobule VIIb interacts with the posterior parietal cortex, specifically during the late stages of verbal encoding, when verbal information enters phonological storage. PMID:24695720

Macher, Katja; Böhringer, Andreas; Villringer, Arno; Pleger, Burkhard

2014-04-01

94

GENERALIZED HARISH-CHANDRA DESCENT, GELFAND PAIRS AND AN ARCHIMEDEAN ANALOG OF JACQUET-RALLIS' THEOREM  

E-print Network

GENERALIZED HARISH-CHANDRA DESCENT, GELFAND PAIRS AND AN ARCHIMEDEAN ANALOG OF JACQUET and Eitan Sayag Abstract. In the first part of the paper we generalize a descent technique due to Harish-Chandra 3. Generalized Harish-Chandra descent 9 3.1. Generalized Harish-Chandra descent 9 3.2. A stronger

95

Exogenous oestrogens prevent transabdominal testicular descent in mice with complete androgen resistance (testicular feminisation)  

Microsoft Academic Search

Testicular descent is believed to be hormonally mediated, but the precise mechanism remains unknown. Androgens have been proposed as the main stimulus for descent, based in part on the inhibition of descent by exogenous oestrogens, which supress fetal testosterone secretion by negative feedback on the hypothalamus. To test whether testosterone secretion was causally linked to descent, fetal male mice with

John M. Hutson

1987-01-01

96

Microglial activation underlies cerebellar deficits produced by repeated cannabis exposure  

PubMed Central

Chronic cannabis exposure can lead to cerebellar dysfunction in humans, but the neurobiological mechanisms involved remain incompletely understood. Here, we found that in mice, subchronic administration of the psychoactive component of cannabis, delta9-tetrahydrocannabinol (THC), activated cerebellar microglia and increased the expression of neuroinflammatory markers, including IL-1?. This neuroinflammatory phenotype correlated with deficits in cerebellar conditioned learning and fine motor coordination. The neuroinflammatory phenotype was readily detectable in the cerebellum of mice with global loss of the CB1 cannabinoid receptor (CB1R, Cb1–/– mice) and in mice lacking CB1R in the cerebellar parallel fibers, suggesting that CB1R downregulation in the cerebellar molecular layer plays a key role in THC-induced cerebellar deficits. Expression of CB2 cannabinoid receptor (CB2R) and Il1b mRNA was increased under neuroinflammatory conditions in activated CD11b-positive microglial cells. Furthermore, administration of the immunosuppressant minocycline or an inhibitor of IL-1? receptor signaling prevented the deficits in cerebellar function in Cb1–/– and THC-withdrawn mice. Our results suggest that cerebellar microglial activation plays a crucial role in the cerebellar deficits induced by repeated cannabis exposure. PMID:23934130

Cutando, Laura; Busquets-Garcia, Arnau; Puighermanal, Emma; Gomis-González, Maria; Delgado-García, José María; Gruart, Agnès; Maldonado, Rafael; Ozaita, Andrés

2013-01-01

97

Effects of cerebellar stimulation on processing semantic associations.  

PubMed

Current research in cerebellar cognitive and linguistic functions makes plausible the idea that the cerebellum is involved in processing temporally contiguous linguistic input. In order to assess this hypothesis, a lexical decision task was constructed to study the effects of cerebellar transcranial magnetic stimulation on semantic noun-to-verb priming based on association (e.g. 'soap-cleaning') or similarity (e.g. 'robbery-stealing'). The results demonstrated a selective increase in associative priming size after stimulation of a lateral cerebellar site. The findings are discussed in the contexts of a cerebellar role in linguistic expectancy generation and the corticocerebellar 'prefrontal' reciprocal loop. PMID:22752996

Argyropoulos, Giorgos P; Muggleton, Neil G

2013-02-01

98

Midbrain infarction causing oculomotor nerve palsy and ipsilateral cerebellar ataxia.  

PubMed

We herein report the case of an 81-year-old woman with midbrain infarction causing pupil-sparing oculomotor nerve palsy with ipsilateral cerebellar ataxia. The lesion was located at the rostral end of the decussation of the superior cerebellar peduncle touching the dorsal side, further caudal and dorsal to causal lesions of Claude's syndrome, which presented as oculomotor palsy and contralateral cerebellar ataxia. This is the third report of midbrain infarction causing partial oculomotor nerve palsy with ipsilateral cerebellar ataxia. It may be possible to establish this entity as a new syndrome following the accumulation of more cases. PMID:25224204

Tokunaga, Makoto; Fukunaga, Kimiko; Nakanishi, Ryoji; Watanabe, Susumu; Yamanaga, Hiroaki

2014-01-01

99

Descent Stage of Mars Science Laboratory During Assembly  

NASA Technical Reports Server (NTRS)

This image from early October 2008 shows personnel working on the descent stage of NASA's Mars Science Laboratory inside the Spacecraft Assembly Facility at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The descent stage will provide rocket-powered deceleration for a phase of the arrival at Mars after the phases using the heat shield and parachute. When it nears the surface, the descent stage will lower the rover on a bridle the rest of the way to the ground. The larger three of the orange spheres in the descent stage are fuel tanks. The smaller two are tanks for pressurant gas used for pushing the fuel to the rocket engines.

JPL, a division of the California Institute of Technology, manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington.

2008-01-01

100

Ascent/descent ancillary data production user's guide  

NASA Technical Reports Server (NTRS)

The Ascent/Descent Ancillary Data Product, also called the A/D BET because it contains a Best Estimate of the Trajectory (BET), is a collection of trajectory, attitude, and atmospheric related parameters computed for the ascent and descent phases of each Shuttle Mission. These computations are executed shortly after the event in a post-flight environment. A collection of several routines including some stand-alone routines constitute what is called the Ascent/Descent Ancillary Data Production Program. A User's Guide for that program is given. It is intended to provide the reader with all the information necessary to generate an Ascent or a Descent Ancillary Data Product. It includes descriptions of the input data and output data for each routine, and contains explicit instructions on how to run each routine. A description of the final output product is given.

Brans, H. R.; Seacord, A. W., II; Ulmer, J. W.

1986-01-01

101

Paul Tseng . Sangwoon Yun A Coordinate Gradient Descent  

E-print Network

sing duality , the%$ support vector regression'& model [5 .... vergence rate analysis involves new proof ideas to handle the nonsmoothness of ?° ... cY e denote by§% the identity matrix .... The descent condition ( Q ) is similar to those used in.

102

14 CFR 31.19 - Performance: Uncontrolled descent.  

Code of Federal Regulations, 2010 CFR

...be determined for the most critical uncontrolled descent that can result from any single failure of the heater assembly, fuel cell system, gas value system, or maneuvering vent system, or from any single tear in the balloon envelope between...

2010-01-01

103

Randomized coordinate descent methods for big data optimization   

E-print Network

This thesis consists of 5 chapters. We develop new serial (Chapter 2), parallel (Chapter 3), distributed (Chapter 4) and primal-dual (Chapter 5) stochastic (randomized) coordinate descent methods, analyze their complexity ...

Takac, Martin

2014-07-01

104

14 CFR 31.19 - Performance: Uncontrolled descent.  

Code of Federal Regulations, 2013 CFR

...be determined for the most critical uncontrolled descent that can result from any single failure of the heater assembly, fuel cell system, gas value system, or maneuvering vent system, or from any single tear in the balloon envelope between...

2013-01-01

105

14 CFR 31.19 - Performance: Uncontrolled descent.  

Code of Federal Regulations, 2012 CFR

...be determined for the most critical uncontrolled descent that can result from any single failure of the heater assembly, fuel cell system, gas value system, or maneuvering vent system, or from any single tear in the balloon envelope between...

2012-01-01

106

14 CFR 31.19 - Performance: Uncontrolled descent.  

Code of Federal Regulations, 2014 CFR

...be determined for the most critical uncontrolled descent that can result from any single failure of the heater assembly, fuel cell system, gas value system, or maneuvering vent system, or from any single tear in the balloon envelope between...

2014-01-01

107

14 CFR 31.19 - Performance: Uncontrolled descent.  

Code of Federal Regulations, 2011 CFR

...be determined for the most critical uncontrolled descent that can result from any single failure of the heater assembly, fuel cell system, gas value system, or maneuvering vent system, or from any single tear in the balloon envelope between...

2011-01-01

108

Orion Entry, Descent, and Landing Simulation  

NASA Technical Reports Server (NTRS)

The Orion Entry, Descent, and Landing simulation was created over the past two years to serve as the primary Crew Exploration Vehicle guidance, navigation, and control (GN&C) design and analysis tool at the National Aeronautics and Space Administration (NASA). The Advanced NASA Technology Architecture for Exploration Studies (ANTARES) simulation is a six degree-of-freedom tool with a unique design architecture which has a high level of flexibility. This paper describes the decision history and motivations that guided the creation of this simulation tool. The capabilities of the models within ANTARES are presented in detail. Special attention is given to features of the highly flexible GN&C architecture and the details of the implemented GN&C algorithms. ANTARES provides a foundation simulation for the Orion Project that has already been successfully used for requirements analysis, system definition analysis, and preliminary GN&C design analysis. ANTARES will find useful application in engineering analysis, mission operations, crew training, avionics-in-the-loop testing, etc. This paper focuses on the entry simulation aspect of ANTARES, which is part of a bigger simulation package supporting the entire mission profile of the Orion vehicle. The unique aspects of entry GN&C design are covered, including how the simulation is being used for Monte Carlo dispersion analysis and for support of linear stability analysis. Sample simulation output from ANTARES is presented in an appendix.

Hoelscher, Brian R.

2007-01-01

109

Design principles of descent vehicles with an inflatable braking device  

NASA Astrophysics Data System (ADS)

A new type of descent vehicle (DVs) is described: a descent vehicle with an inflatable braking device (IBD DV). IBD development issues, as well as materials needed for the design, manufacturing, and testing of an IBD and its thermal protection, are discussed. A list is given of Russian integrated test facilities intended for testing IBD DVs. Progress is described in the development of IBD DVs in Russia and abroad.

Alexashkin, S. N.; Pichkhadze, K. M.; Finchenko, V. S.

2013-12-01

110

Descent from the Summit of 'Husband Hill'  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Click on the image for Descent from the Summit of 'Husband Hill' (QTVR)

In late November 2005 while descending 'Husband Hill,' NASA's Mars Exploration Rover Spirit took the most detailed panorama so far of the 'Inner Basin,' the rover's next target destination. Spirit acquired the 405 individual images that make up this 360-degree view of the surrounding terrain using five different filters on the panoramic camera. The rover took the images on Martian days, or sols, 672 to 677 (Nov. 23 to 28, 2005 -- the Thanksgiving holiday weekend).

This image is an approximately true-color rendering using camera's 750-, 530-, and 430-nanometer filters. Seams between individual frames have been eliminated from the sky portion of the mosaic to better simulate the vista a person standing on Mars would see.

'Home Plate,' a bright, semi-circular feature scientists hope to investigate, is harder to discern in this image than in earlier views taken from higher up the hill. Spirit acquired this more oblique view, known as the 'Seminole panorama,' from about halfway down the south flank of Husband Hill, 50 meters (164 feet) or so below the summit. Near the center of the panorama, on the horizon, are 'McCool Hill' and 'Ramon Hill,' named, like Husband Hill, in honor of the fallen astronauts of the space shuttle Columbia. Husband Hill is visible behind the rover, on the right and left sides of the panorama. An arc of rover tracks made while avoiding obstacles and getting into position to examine rock outcrops can be traced over a long distance by zooming in to explore the panorama in greater detail.

Spirit is now significantly farther downhill toward the center of this panorama, en route to Home Plate and other enigmatic soils and outcrop rocks in the quest to uncover the history of Gusev Crater and the 'Columbia Hills.'

2005-01-01

111

Human Papillomavirus Prevalence and Cell Cycle Related Protein Expression in Tonsillar Squamous Cell Carcinomas of Korean Patients with Clinicopathologic Analysis  

PubMed Central

Background Human papillomavirus (HPV)-related tonsillar squamous cell carcinoma (TSCC) has recently been characterized as a distinct subset with a favorable prognosis. The prevalence and clinicopathologic significance of HPV-related TSCC in Koreans are not well known. Methods HPV in situ hybridization (ISH) accompanied by p53, p16, pRb, and cyclin D1 immunohistochemical staining were performed on 89 resection cases of TSCC from 2000 through 2010. Results HPV was detected by ISH in 59 of 89 cases (66.3%). HPV-positive TSCCs were more common in younger ages (p=0.005), and tumor sizes were smaller in the HPV-positive compared to the HPV-negative group (p=0.040). Positive HPV staining was significantly correlated with p16 expression (p<0.001), pRb inactivation (p=0.003), and cyclin D1 down-regulation (p<0.001) but not with p53 expression (p=0.334). Seventeen cases that showed p16-immunopositivity with HPV-negativity by ISH were retested by HPV typing; HPV DNA was not detected in all cases. There was no significant difference between HPV-positive and HPV-negative patients either in the disease-specific survival (DSS, p=0.857) or overall survival (p=0.910). Furthermore, pRb-inactivated cases showed better DSS (p=0.023), and p53-positive cases showed worse DSS (p=0.001). Conclusions Although high HPV prevalence was noted, it was not correlated with histopathologic findings or survival benefit. In addition to p53 expression, pRb inactivation along with p16 overexpression and down-regulation of cyclin D1 are thought to be important pathogenetic steps for developing TSCCs. PMID:23667374

Lee, Miji; Kim, Sung Bae; Lee, Sang-wook; Roh, Jong-Lyel; Choi, Seung-Ho; Nam, Soon Yuhl; Kim, Sang Yoon

2013-01-01

112

Cerebellar theta burst stimulation in stroke patients with ataxia  

PubMed Central

Summary Evidence for effective improvement of the symptoms of cerebellar stroke is still limited. Here, we investigated the effects of repetitive transcranial magnetic stimulation (rTMS) applied over the injured cerebellar hemisphere in six patients with posterior circulation stroke. We applied a two-week course of cerebellar intermittent theta burst stimulation (iTBS). Before and after the iTBS treatment, paired-pulse TMS methods were used to explore: i) the functional connectivity between the cerebellar hemisphere and the contralateral primary motor cortex (M1), by means of the cerebellar brain inhibition (CBI) protocol; and ii) the intracortical circuits in the contralateral M1, by means of the short intra-cortical inhibition (SICI) and intra-cortical facilitation (ICF) protocols. Patients were also evaluated using the Modified International Cooperative Ataxia Rating Scale (MICARS). Cerebellar iTBS induced a decrease in CBI and an increase in ICF at an interstimulus interval of 15 msec. These neurophysiological changes were paralleled by a clinical improvement, shown by the MICARS posture and gait subscale scores. Cerebellar iTBS could be a promising tool to promote recovery of cerebellar stroke patients. PMID:25014048

Bonnì, Sonia; Ponzo, Viviana; Caltagirone, Carlo; Koch, Giacomo

2014-01-01

113

Cerebellar interposed nucleus lesions suppress lymphocyte function in rats  

Microsoft Academic Search

We previously reported that the cerebellar fastigial nucleus, output nucleus of the spinocerebellum, modulates lymphocyte function. To further explore the role of the cerebellum in neuroimmunomodulation, we here lesioned bilaterally the cerebellar interposed nuclei (IN) of rats with kainic acid (KA) injections. On days 8, 16 and 32 after IN lesions, lymphocyte percentage in peripheral white blood cells was examined.

Yu-Ping Peng; Yi-Hua Qiu; Jian Qiu; Jian-Jun Wang

2006-01-01

114

Distinct Critical Cerebellar Subregions for Components of Verbal Working Memory  

ERIC Educational Resources Information Center

A role for the cerebellum in cognition has been proposed based on studies suggesting a profile of cognitive deficits due to cerebellar stroke. Such studies are limited in the determination of the detailed organisation of cerebellar subregions that are critical for different aspects of cognition. In this study we examined the correlation between…

Cooper, Freya E.; Grube, Manon; Von Kriegstein, Katharina; Kumar, Sukhbinder; English, Philip; Kelly, Thomas P.; Chinnery, Patrick F.; Griffiths, Timothy D.

2012-01-01

115

Cerebellar astrocytoma presenting as deterioration of handwriting in a child  

Microsoft Academic Search

Deterioration of handwriting in an 11-year-old boy over a 2 month period was found to be caused by a cerebellar astrocytoma. The clinical picture was characterised by a lack of the classic symptoms of increased intracranial pressure. The only positive neurological findings pointed to an isolated right cerebellar symptomatology expressed by mild intention tremor and decreased tone of the right

Shaul Harel; Moshe Holtzman; Uri Jurgenson; Irith Reider; Moshe Feinsod

1985-01-01

116

Parvovirus associated cerebellar hypoplasia in day-old chickens  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cerebellar hypoplasia and hydrocephalus were detected in day-old broiler chickens. Brains of chickens evaluated at necropsy appeared to be abnormal; some were disfigured and cerebellae appeared to be smaller than normal. Histopathologic examination of brains revealed cerebellar folia that were sho...

117

Composite cerebellar functional severity score: validation of a quantitative score of cerebellar impairment.  

PubMed

Reliable and easy to perform functional scales are a prerequisite for future therapeutic trials in cerebellar ataxias. In order to assess the specificity of quantitative functional tests of cerebellar dysfunction, we investigated 123 controls, 141 patients with an autosomal dominant cerebellar ataxia (ADCA) and 53 patients with autosomal dominant spastic paraplegia (ADSP). We evaluated four different functional tests (nine-hole pegboard, click, tapping and writing tests), in correlation with the scale for the assessment and rating of cerebellar ataxia (SARA), the scale of functional disability on daily activities (part IV of the Huntington disease rating scale), depression (the Public Health Questionnaire PHQ-9) and the EQ-5D visual analogue scale for self-evaluation of health status. There was a significant correlation between each functional test and a lower limb score. The performance of controls on the functional tests was significantly correlated with age. Subsequent analyses were therefore adjusted for this factor. The performances of ADCA patients on the different tests were significantly worse than that of controls and ADSP patients; there was no difference between ADSP patients and controls. Linear regression analysis showed that only two independent tests, the nine-hole pegboard and the click test on the dominant side (P < 0.0001), accounted for the severity of the cerebellar syndrome as reflected by the SARA scores, and could be represented by a composite cerebellar functional severity (CCFS) score calculated as follows: [Formula: see text]. The CCFS score was significantly higher in ADCA patients compared to controls (1.12 +/- 0.18 versus 0.85 +/- 0.05, P(c) < 0.0001) and ADSP patients (1.12 +/- 0.18 versus 0.90 +/- 0.08, P(c) < 0.0001) and was correlated with disease duration (P < 0.0001) but independent of self-evaluated depressive mood in ADCA. Among genetically homogeneous subgroups of ADCA patients (Spinocerebellar ataxia 1, 2, 3), SCA3 patients had significantly lower (better) CCFS scores than SCA2 (P(c) < 0.04) and the same tendency was observed in SCA1. Their CCFS scores remained significantly worse than those of ADSP patients with identified SPG4 mutations (P < 0.0001). The pegboard and click tests are easy to perform and accurately reflect the severity of the disease. The CCFS is a simple and validated method for assessing cerebellar ataxia over a wide range of severity, and will be particularly useful for discriminating paucisymptomatic carriers from affected patients and for evaluating disease progression in future therapeutic trials. PMID:18378516

du Montcel, Sophie Tezenas; Charles, Perrine; Ribai, Pascale; Goizet, Cyril; Le Bayon, Alice; Labauge, Pierre; Guyant-Maréchal, Lucie; Forlani, Sylvie; Jauffret, Celine; Vandenberghe, Nadia; N'guyen, Karine; Le Ber, Isabelle; Devos, David; Vincitorio, Carlo-Maria; Manto, Mario-Ubaldo; Tison, François; Hannequin, Didier; Ruberg, Merle; Brice, Alexis; Durr, Alexandra

2008-05-01

118

Up-regulation of CC chemokine receptor 6 on tonsillar T cells and its induction by in vitro stimulation with ?-streptococci in patients with pustulosis palmaris et plantaris  

PubMed Central

Pustulosis palmaris et plantaris (PPP) is a tonsil-related disease; tonsillectomy is somewhat effective in treating the condition. However, the aetiological association between the tonsils and PPP has not yet been elucidated fully. Recently, some chemokines and chemokine receptors, including CC chemokine receptor (CCR) 4, CCR6 and CX chemokine receptor (CXCR) 3, have been reported to play important roles in the development of psoriasis, a disease related closely to PPP. In this study, we found that CCR6 expression on both tonsillar and peripheral blood T cells was up-regulated more intensively in PPP patients than in non-PPP patients (P < 0·001 for both), but CCR4 and CXCR3 expressions were not. In vitro stimulation with ?-streptococcal antigen enhanced CCR6 expression significantly on tonsillar T cells in PPP patients (P < 0·05), but this was not observed in non-PPP patients. The chemotactic response of tonsillar T cells to the CCR6 ligand CC chemokine ligand (CCL) 20 was significantly higher in PPP patients than in non-PPP patients (P < 0·05). The percentage of CCR6-positive peripheral blood T cells decreased after tonsillectomy in PPP patients (P < 0·01); this decrease correlated with an improvement of skin lesions (P < 0·05, r = ?0·63). The numbers of CCR6-positive cells and the expression of CCL20 were increased significantly in pathological lesions compared with non-pathological lesions in PPP skin (P < 0·01, P < 0·05 respectively). These results suggest that a novel immune response to ?-streptococci may enhance CCR6 expression on T cells in tonsils and that CCR6-positive T cells may move to peripheral blood circulation, resulting in recruitment to target skin lesions expressing CCL20 in PPP patients. This may be one of the key roles in pathogenesis of the tonsil-related disease PPP. PMID:19659772

Yoshizaki, T; Bandoh, N; Ueda, S; Nozawa, H; Goto, T; Kishibe, K; Takahara, M; Harabuchi, Y

2009-01-01

119

A high and increasing HPV prevalence in tonsillar cancers in Eastern Denmark, 2000-2010: The largest registry-based study to date.  

PubMed

The aim was to explore whether the incidence of tonsillar squamous cell carcinomas (TSCCs) increased in Eastern Denmark, 2000-2010, and whether human papillomavirus (HPV) could explain the increase, and to assess the association of HPV prevalence with gender, age, and origin (i.e., the certainty of tonsillar tumor origin). We applied HPV DNA PCR and p16 immunohistochemistry to all TSCCs registered in the Danish Head and Neck Cancer Group (DAHANCA) and in the Danish Pathology Data Bank (n?=?632). Pathologists reviewed and subdivided the tumors into two groups: specified and nonspecified TSCCs. Approximately 10% of HPV-positive tumors was genotyped by amplicon next-generation sequencing. The overall crude incidence of TSCCs increased significantly (2.7% per year) and was explained by an increasing incidence of HPV-positive TSCCs (4.9% per year). The overall HPV prevalence was 58%, with HPV16 being the predominant HPV type. In multivariate analysis, the HPV prevalence was associated with age (<55 vs. >60 years) (OR, 1.72; 95% CI 1.13-2.63) and origin (nonspecified vs. specified TSCCs) (OR, 0.15; 95% CI 0.11-0.22). The association of HPV prevalence with origin increased over time in specified TSCCs (OR per year, 1.10; 95% CI 1.01-1.19), whereas no change over time was observed among nonspecified TSCCs (OR per year, 0.99; 95% CI 0.90-1.08). In conclusion, the observed increase in the number of HPV-positive TSCCs can explain the increasing number of TSCCs in Eastern Denmark, 2000-2010. HPV prevalence was associated with younger age (<55 years) and a high certainty of tonsillar tumor origin. PMID:25283302

Garnaes, Emilie; Kiss, Katalin; Andersen, Luise; Therkildsen, Marianne H; Franzmann, Maria B; Filtenborg-Barnkob, Bettina; Hoegdall, Estrid; Krenk, Lene; Josiassen, Michael; Lajer, Christel B; Specht, Lena; Frederiksen, Kirsten; Friis-Hansen, Lennart; Nielsen, Finn C; Kjaer, Susanne K; Norrild, Bodil; von Buchwald, Christian

2015-05-01

120

Remote Cerebral and Cerebellar Hemorrhage after Massive Cerebrospinal Fluid Leakage  

PubMed Central

Dural tears can occur during spinal surgery and may lead to cerebrospinal fluid (CSF) leakage which is rarely involved in remote cerebellar hemorrhage. Only a few of cases of simultaneous cerebral and cerebellar hemorrhage have been reported in the English literature. We experienced a case of multiple remote cerebral and cerebellar hemorrhages in a 63-year-old man who exhibited no significant neurologic deficits after spinal surgery. Magnetic resonance imaging (MRI) performed 4 days after the surgery showed a large amount of CSF leakage in the lumbosacral space. The patient underwent the second surgery for primary repair of the dural defect, but complained of headache after dural repair surgery. Brain MRI taken 6 days after the dural repair surgery revealed multifocal remote intracerebral and cerebellar hemorrhages in the right temporal lobe and both cerebellar hemispheres. We recommend diagnostic imaging to secure early identification and treatment of this complication in order to prevent serious neurologic deficits. PMID:22737308

You, Sung-Hye; Lee, Nam Joon; Suh, Jung-Keun

2012-01-01

121

Acute cerebellar ataxia following meningococcal group C conjugate vaccination.  

PubMed

Acute cerebellar ataxia is the most common cause of childhood ataxia, usually resulting from infections or vaccinations. Cases of acute cerebellar ataxia have been reported as a consequence of several viral and bacterial infections as well as immunizing agents, such as varicella, influenza, hepatitis B, and diphtheria-pertussis-tetanus vaccines. Although immunization with meningococcal group C conjugate vaccines has been associated with several neurological side effects, acute cerebellar ataxia has not been previously reported. The authors describe a case of a 12-year-old girl exhibiting acute cerebellar ataxia following meningococcal group C conjugate vaccination. In this patient, cerebellar symptoms started within 24 hours from the vaccination, and infective causes have been ruled out by serum and liquoral analyses. Magnetic resonance imaging findings were normal. Progressive clinical improvement was obtained after corticosteroid treatment. This case increases the small number of postvaccinal ataxias and contributes to further clarifying the complex pathogenesis of this disorder. PMID:23275434

Cutroneo, Paola Maria; Italiano, Domenico; Trifirò, Gianluca; Tortorella, Gaetano; Russo, Alessandra; Isola, Stefania; Caputi, Achille Patrizio; Spina, Edoardo

2014-01-01

122

[Dynamics of immunological characteristics and investigation of apoptosis of palatal tonsillar lymphocytes in patients presenting with chronic tonsillitis and treated by conservative therapy].  

PubMed

The enhanced amount of viable lymphocytes and the decreased number of apoptotic cells as well as the reduced levels of IgA and IgM and the elevated concentration of sIgA in lacunar secretion are considered to be the reliable criteria for the efficacy of the conservative treatment of chronic tonsillitis. Combined therapy of this condition including irrigation of the palatal tonsillar lacunae with a miramistin solution, their contact ultrasonic treatment, and application of imudon makes it possible to maintain the optimal ratio of viable to apoptotic lymphocytes during a period of up to 6-7 months. PMID:21720286

Mukhomedzianova, L V; Vakhrushev, S G; Polevshikov, A V; Andrianova, I V; Pozhilenkova, E A

2011-01-01

123

[Concurrence of Fahr's disease with cerebellar tumors].  

PubMed

Fara's disease or idiopathic calcification of the basal ganglia is a rare disease that is characterized by multiple petrificates in the area of the basal ganglia, caudate nucleus, and dentate nuclei of the cerebellum. As of now, only two cases of a concurrence of Fara's disease and brain tumors have been described. The authors present two more cases. Both cases are unique since the tumors occurred in the presence of Fara's disease symmetrically, as in the mirror, in the cerebellar hemispheres at the periphery of petrificates. This may be confirmed by the fact that astrocytic proliferation and hyperplasia around the calcified vessels are a cause of neoplasms. PMID:15724550

Ozerov, S S; Semenova, Zh B; Zuba?raev, M S; Pitskhelauri, D I; Ozerova, V I; Strebkova, N A

2004-01-01

124

Cerebellar liponeurocytoma--a case report.  

PubMed

Cerebellar liponeurocytomas have been included in the 2000 classification of tumours of the central nervous system, under the heading of glioneuronal tumours. The tumour has two populations of cells- one composed of cells with morphology of neurocytes and the other are lipidised cells which look like mature fat cells. The tumour occurs in adults and has a good prognosis. Less than fifteen cases have been reported in world literature. We report a case of this rare tumour entity in a 32 years old female patient. PMID:16758783

Tatke, Medha; Singh, A K

2005-01-01

125

[Venous angioma with associated cerebellar haemorrhage].  

PubMed

Venous angiomas are a developmental anomaly in which embryonic venous drainage is still present into adulthood. They are usually asymptomatic and benign course but they can cause seizures and less commonly bleeding, usually associated to cavernous malformation. Normally, treatment is not necessary although bleeding, severe clinical and lesions in which it is possible a favourable approach, we can consider treatment. We show a case of a 11 years old boy with acute decrease level of consciousness. We observed hematoma in the right cerebellar hemisphere with radial tubular structures consistent with developmental venous anomaly. The hematoma was evacuated without a demonstrable other reason justifying the bleeding. PMID:23218501

Sánchez Medina, Yanire; Pérez del Rosario, Pedro Antonio; Domínguez, Jaime; Millán, Ana

2013-01-01

126

Cerebellar Infarction Originating from Vertebral Artery Stenosis Caused by a Hypertrophied Uncovertebral Joint: A Case Report  

Microsoft Academic Search

We report a case of cerebellar infarction originating from vertebral artery stenosis caused by a hypertrophied uncovertebral joint. A 38-year-old male patient presented with sudden onset of headache, dizziness, and dysarthria. The brain MR image showed acute infarction in the right cerebellar hemisphere in the territory of the posterior inferior cerebellar artery (PICA) and superior cerebellar artery (SCA). The MR

Jong Mun Choi; Hyeok Jin Hong; Suk Ki Chang; Sung Han Oh

127

Cerebellar role in fear-conditioning consolidation  

PubMed Central

Some cerebellar structures are known to be involved in the memorization of several conditioned responses. The role of the interpositus nucleus (IN) and the vermis (VE) in fear-conditioning consolidation was investigated by means of a combined behavioral and neurophysiological technique. The IN and VE were subjected to fully reversible tetrodotoxin (TTX) inactivation during consolidation in adult male Wistar rats that underwent acoustic conditioned stimulus (CS) and context fear training. TTX was injected in different groups of rats at increasing intervals after the acquisition session. Memory was assessed as conditioned freezing duration measured during retention testing, always performed 72 and 96 h after the stereotaxic TTX administration. This schedule ensures that there is no interference with normal cerebellar function during either the acquisition or the retrieval phase so that any amnesic effect may be due only to consolidation disruption. Our results show that IN functional integrity is necessary for acoustic CS fear response memory formation up to the 96-h after-acquisition delay. VE functional integrity was shown to be necessary for memory formation of both context (up to the 96-h after-acquisition delay) and acoustic CS (up to the 192-h after-acquisition delay) fear responses. The present findings help to elucidate the role of the cerebellum in memory consolidation and better define the neural circuits involved in fear memories. PMID:12034877

Sacchetti, Benedetto; Baldi, Elisabetta; Lorenzini, Carlo Ambrogi; Bucherelli, Corrado

2002-01-01

128

Crew Procedures for Continuous Descent Arrivals Using Conventional Guidance  

NASA Technical Reports Server (NTRS)

This paper presents results from a simulation study which investigated the use of Continuous Descent Arrival (CDA) procedures for conducting a descent through a busy terminal area, using conventional transport-category automation. This research was part of the Low Noise Flight Procedures (LNFP) element within the Quiet Aircraft Technology (QAT) Project, that addressed development of flight guidance, and supporting pilot and Air Traffic Control (ATC) procedures for low noise operations. The procedures and chart were designed to be easy to understand, and to make it easy for the crew to make changes via the Flight Management Computer Control-Display Unit (FMC-CDU) to accommodate changes from ATC. The test runs were intended to represent situations typical of what exists in many of today's terminal areas, including interruptions to the descent in the form of clearances issued by ATC.

Oseguera-Lohr, Rosa M.; Williams, David H.; Lewis, Elliot T,

2007-01-01

129

Abnormal cerebellar morphometry in abstinent adolescent marijuana users  

PubMed Central

Background Functional neuroimaging data from adults have, in general, found frontocerebellar dysfunction associated with acute and chronic marijuana (MJ) use (Loeber & Yurgelun-Todd, 1999). One structural neuroimaging study found reduced cerebellar vermis volume in young adult MJ users with a history of heavy polysubstance use (Aasly et al., 1993). The goal of this study was to characterize cerebellar volume in adolescent chronic MJ users following one month of monitored abstinence. Method Participants were MJ users (n=16) and controls (n=16) aged 16-18 years. Extensive exclusionary criteria included history of psychiatric or neurologic disorders. Drug use history, neuropsychological data, and structural brain scans were collected after 28 days of monitored abstinence. Trained research staff defined cerebellar volumes (including three cerebellar vermis lobes and both cerebellar hemispheres) on high-resolution T1-weighted magnetic resonance images. Results Adolescent MJ users demonstrated significantly larger inferior posterior (lobules VIII-X) vermis volume (p<.009) than controls, above and beyond effects of lifetime alcohol and other drug use, gender, and intracranial volume. Larger vermis volumes were associated with poorer executive functioning (p’s<.05). Conclusions Following one month of abstinence, adolescent MJ users had significantly larger posterior cerebellar vermis volumes than non-using controls. These greater volumes are suggested to be pathological based on linkage to poorer executive functioning. Longitudinal studies are needed to examine typical cerebellar development during adolescence and the influence of marijuana use. PMID:20413277

Medina, Krista Lisdahl; Nagel, Bonnie J.; Tapert, Susan F.

2010-01-01

130

Contribution of Cerebellar Sensorimotor Adaptation to Hippocampal Spatial Memory  

PubMed Central

Complementing its primary role in motor control, cerebellar learning has also a bottom-up influence on cognitive functions, where high-level representations build up from elementary sensorimotor memories. In this paper we examine the cerebellar contribution to both procedural and declarative components of spatial cognition. To do so, we model a functional interplay between the cerebellum and the hippocampal formation during goal-oriented navigation. We reinterpret and complete existing genetic behavioural observations by means of quantitative accounts that cross-link synaptic plasticity mechanisms, single cell and population coding properties, and behavioural responses. In contrast to earlier hypotheses positing only a purely procedural impact of cerebellar adaptation deficits, our results suggest a cerebellar involvement in high-level aspects of behaviour. In particular, we propose that cerebellar learning mechanisms may influence hippocampal place fields, by contributing to the path integration process. Our simulations predict differences in place-cell discharge properties between normal mice and L7-PKCI mutant mice lacking long-term depression at cerebellar parallel fibre-Purkinje cell synapses. On the behavioural level, these results suggest that, by influencing the accuracy of hippocampal spatial codes, cerebellar deficits may impact the exploration-exploitation balance during spatial navigation. PMID:22485133

Passot, Jean-Baptiste; Sheynikhovich, Denis; Duvelle, Éléonore; Arleo, Angelo

2012-01-01

131

Flight Data Entry, Descent, and Landing (EDL) Repository  

NASA Technical Reports Server (NTRS)

Dr. Daniel Winterhalter, NASA Engineering and Safety Center Chief Engineer at the Jet Propulsion Laboratory, requested the NASA Engineering and Safety Center sponsor a 3-year effort to collect entry, descent, and landing material and to establish a NASA-wide archive to serve the material. The principle focus of this task was to identify entry, descent, and landing repository material that was at risk of being permanently lost due to damage, decay, and undocumented storage. To provide NASA-wide access to this material, a web-based digital archive was created. This document contains the outcome of the effort.

Martinez, Elmain M.; Winterhalter, Daniel

2012-01-01

132

Mars Smart Lander Simulations for Entry, Descent, and Landing  

NASA Technical Reports Server (NTRS)

Two primary simulations have been developed and are being updated for the Mars Smart Lander Entry, Descent, and Landing (EDL). The high fidelity engineering end-to-end EDL simulation that is based on NASA Langley's Program to Optimize Simulated Trajectories (POST) and the end-to-end real-time, hardware-in-the-loop simulation testbed, which is based on NASA JPL's (Jet Propulsion Laboratory) Dynamics Simulator for Entry, Descent and Surface landing (DSENDS). This paper presents the status of these Mars Smart Lander EDL end-to-end simulations at this time. Various models, capabilities, as well as validation and verification for these simulations are discussed.

Striepe, S. A.; Way, D. W.; Balaram, J.

2002-01-01

133

Entry, Descent and Landing Systems Analysis Study: Phase 1 Report  

NASA Technical Reports Server (NTRS)

NASA senior management commissioned the Entry, Descent and Landing Systems Analysis (EDL-SA) Study in 2008 to identify and roadmap the Entry, Descent and Landing (EDL) technology investments that the agency needed to make in order to successfully land large payloads at Mars for both robotic and human-scale missions. This paper summarizes the motivation, approach and top-level results from Year 1 of the study, which focused on landing 10-50 mt on Mars, but also included a trade study of the best advanced parachute design for increasing the landed payloads within the EDL architecture of the Mars Science Laboratory (MSL) mission

DwyerCianciolo, Alicia M.; Davis, Jody L.; Komar, David R.; Munk, Michelle M.; Samareh, Jamshid A.; Powell, Richard W.; Shidner, Jeremy D.; Stanley, Douglas O.; Wilhite, Alan W.; Kinney, David J.; McGuire, M. Kathleen; Arnold, James O.; Howard, Austin R.; Sostaric, Ronald R.; Studak, Joseph W.; Zumwalt, Carlie H.; Llama, Eduardo G.; Casoliva, Jordi; Ivanov, Mark C.; Clark, Ian; Sengupta, Anita

2010-01-01

134

Visually Guided Step Descent in Children with Williams Syndrome  

ERIC Educational Resources Information Center

Individuals with Williams syndrome (WS) have impairments in visuospatial tasks and in manual visuomotor control, consistent with parietal and cerebellar abnormalities. Here we examined whether individuals with WS also have difficulties in visually controlling whole-body movements. We investigated visual control of stepping down at a change of…

Cowie, Dorothy; Braddick, Oliver; Atkinson, Janette

2012-01-01

135

Bilaterally absent posterior inferior cerebellar artery: case report.  

PubMed

Posterior inferior cerebellar artery (PICA) is one of the cerebellar arteries which originates from the vertebral artery and has the most complex and variable course. The PICA usually originates from the vertebral artery intracranially as a single trunk, however, absent, double trunk, extracranial, and extradural PICA may also exist. In a collection of 50 cerebellar specimens (100 hemispheres) injected with colored gelatin, one case of bilaterally absent PICA was encountered, male aged 59 (causes of the death was not taken into consideration). PMID:23337996

Sharifi, Mansoor; Ciszek, Bogdan

2013-09-01

136

Ataxic hemiparesis with reductions of ipsilateral cerebellar blood flow  

SciTech Connect

Regional cerebellar blood flow was measured in a patient with left-sided ataxic hemiparesis, using single-photon emission computed tomography and N-isopropyl-p-(/sup 123/I)Iodoamphetamine. X-ray computed tomography revealed a small infarct in the paramedian portion of the right upper basis pontis. Blood flow was markedly reduced in the contralateral cerebellar hemisphere corresponding to the side of ataxia. The present study emphasizes the value of the three-dimensional functional imaging of the cerebellum to investigate the responsible lesion for ataxia and to study function of the cerebro-cerebellar circuits.

Sakai, F.; Aoki, S.; Kan, S.; Igarashi, H.; Kanda, T.; Tazaki, Y.

1986-09-01

137

Cerebellar haemorrhage after evacuation of an acute supratentorial subdural haematoma.  

PubMed

Recent reports have highlighted the unusual complication of distant cerebellar haemorrhage after supratentorial craniotomy, with only 25 previous cases reported in the literature. Nearly all reported cases occurred after craniotomy for temporal lobectomy or for deep seated intracerebral pathology requiring brain retraction and removal of CSF at surgery. Only one previous case of a cerebellar haemorrhage after evacuation of an extracerebral fluid collection has been reported. We describe the case of a cerebellar haemorrhage complicating the evacuation of an acute/subacute supratentorial subdural haematoma in a 83-year-old woman. The literature is reviewed and possible mechanisms of haemorrhage discussed. PMID:10562849

Kaplan, S S; Lauryssen, C

1999-06-01

138

Cerebellar Mutism Following Closed Head Injury in a Child  

PubMed Central

Cerebellar mutism is a rare occurrence following paediatric trauma. Although it is quite common after posterior fossa surgery in children, this phenomenon has rarely been reported following other insults, such as trauma, and its pathophysiology remains poorly understood. We report a seven-year-old child who presented to the casualty department of Sultan Qaboos University Hospital in Muscat, Oman, in May 2013 with a traumatic right cerebellar contusion. The child presented with clinical features of cerebellar mutism but underwent a rapid and spontaneous recovery. The possible mechanism of this occurrence is discussed.

Kariyattil, Rajeev; Rahim, Mohamed I. A.; Muthukuttiparambil, Unnikrishnan

2015-01-01

139

[Familial olivo-ponto-cerebellar atrophy with myoclonus. Limits of cerebellar myoclonic dyssynergia (Ramsay-Hunt syndrome)].  

PubMed

The case is described of a woman of 26 suffering (like her mother, a brother and a sister) from a progressively degenerating cerebellar syndrome, at first considered to be hereditary cerebellar ataxia, but which, after action myoclonus appeared, was diagnosed as dyssynergia cerebellaris myoclonica (D.C.M.). Anatomical verification however revealed a syndrome of olivo-ponto-cerebellar atrophy comprising massive demyelinisation of the white matter of the cerebellum and of the cerebellopontine fibres; atrophy of the pontine nuclei; the cerebellar cortex itself was severely affected; moderate nigral lesions; marked spinal lesions of the cerebellospinal fasciculi and of the posterior columns; lesions of the anterior horns and of the bulbar nuclei; cortical chromatolysis. The fact that the dentate system remained unaffected, also noted in some cases of olivo-ponto-cerebellar atrophy with myoclonus, whilst in a number of other cases the lesion remains clinically silent, emphasises the difficulty in establishing an accurate correlation between myoclonus and dentate nucleus. Discussion of the nosological limits of D.C.M.: confirmed cases generally displayed lesions of the dentate system and hereditary degenerative spino-cerebellar lesions. The same clinical symptoms can be observed in cases which do not come under this classification--or even under that of degenerative conditions of the cerebellar system--and D.C.M. appears to be only a syndrome, the Ramsay-Hunt syndrome. PMID:973068

Bonduelle, M; Escourolle, R; Bouygues, P; Lormeau, G; Gray, F

1976-02-01

140

A taxonomy of descent algorithms for nonlinear programs and variational inequalities  

E-print Network

A taxonomy of descent algorithms for nonlinear programs and variational inequalities Michael describes the problem and the choices of cost approximating mappings and merit functions. The taxonomy. Taxonomy, classification, nonlinear programs, variational inequalities, descent algo­ rithms, cost

Patriksson, Michael

141

[Relationship between insulin like hormone 3 and testicular descent and development].  

PubMed

Testicular descent is an essential step in the course of reproductive system development. The mechanisms involved in the regulation of testis descent is not distinct. Gubernaculum has a very close relationship with testis descent. Maldescent of testis can cause abnormalities of genital system such as testicular underwent (cryptorchidism), dysplasia, tumor, infertility and low sexuality. Recently insulin like hormone 3 is a hotspot of concerning affecting gubernacular development and testicular descent. This article briefly reviews the advances in these aspects. PMID:16483166

Xie, Xiao-jun; Jiang, Xue-Wu

2006-01-01

142

Cerebellar granule cells elaborate neurites before mitosis.  

PubMed

Neuronal birth and neurite outgrowth have been regarded as discrete, sequential stages of development. However, we recently found that sympathetic neuroblasts often elaborate axons before mitosis, in culture [E. Wolf, I.B. Black, E. DiCicco-Bloom, Mitotic neuroblasts determine neuritic patterning of progeny, J. Comp. Neurol. 367 (1996) 623-635] and in vivo [E. Wolf, I.B. Black, E. DiCicco-Bloom, Central and peripheral neuroblasts elaborate neurites prior to division in vivo and in vitro, Soc. Neurosci. Abstr. 21 (1995) 785; E. Wolf, I.B. Black, E. DiCicco-Bloom, Mitotic neuroblasts engage in axonal outgrowth and pathfinding in vivo, Soc. Neurosci. Abstr. 22 (1996) 525]. Here, we report that cerebellar granule cells often divide with heritable neurites in vitro. Therefore, mitotic CNS precursors, in addition to peripheral neuroblasts, simultaneously undergo proliferation and process formation. Potentially, neurites on dividing precursors may allow target fields to influence directly the course of neurogenesis. PMID:9352115

Wolf, E; Wagner, J P; Black, I B; DiCicco-Bloom, E

1997-09-20

143

Chronic THC intake modifies fundamental cerebellar functions.  

PubMed

Delta9-tetrahydrocannabinol (THC), the principal bioactive component in the Cannabis plant, is truly a captivating drug. Acute and chronic THC intake produces a spectrum of biological effects ranging from transient psychotropic effects to prolonged medicinal benefits, many of which have been fostered for centuries by our society. In the July 2013 issue of the JCI, Cutando et al. combined mouse genetics with classic mouse behavioral analysis to deepen our understanding of the physiological consequence of subchronic THC intake on eyeblink reflexes, a fundamental neuronal adaptive response, revealing that this regimen leads to downregulation of the cannabinoid CB1 receptor (referred to as CB1 in the Cutando et al. article) in cerebellar stress fibers and the activation of microglia, raising provocative new questions about the safety profile of regimented THC intake. PMID:23863631

Stella, Nephi

2013-08-01

144

Cytoplasmic organization in cerebellar dendritic spines.  

PubMed

Three sets of filamentous structures were found to be associated with synaptic junctions in slices of cerebellar tissue prepared by rapid-freezing and freeze-etch techniques. The electron-dense fuzz subjacent to postsynaptic membranes corresponds to a web of 4-6-nm-diam filaments that were clearly visualized in rapid-frozen, freeze-etched preparations. Purkinje cell dendritic spines are filled with a meshwork of 5-7-nm filaments that were found to contact the spine membrane everywhere except at the synaptic junction, and extend through the neck of the spine into the parent dendrite. In addition, 8-10-nm microfilaments, possibly actin, were seen to be associated with the postsynaptic web and to extend into the body and neck of the spine. The arrangements and attachments of the filamentous elements in the Purkinje cell dendritic spine may account for its shape. PMID:6684661

Landis, D M; Reese, T S

1983-10-01

145

Cortical network functional connectivity in the descent to sleep  

E-print Network

dreaming (7, 15, 16). REM sleep is also marked by atonia in skeletal muscles, reducing the ability stages of NREM and then REM sleep progressively disengage the self from the environment. It is now wellCortical network functional connectivity in the descent to sleep Linda J. Larson-Priora,1 , John M

Larson-Prior, Linda

146

Women of African Descent: Persistence in Completing Doctorates  

ERIC Educational Resources Information Center

This study examines the educational persistence of women of African descent (WOAD) in pursuit of a doctorate degree at universities in the southeastern United States. WOAD are women of African ancestry born outside the African continent. These women are heirs to an inner dogged determination and spirit to survive despite all odds (Pulliam, 2003,…

Iddrisu, Vannetta Bailey

2010-01-01

147

Simulation Results for Airborne Precision Spacing along Continuous Descent Arrivals  

NASA Technical Reports Server (NTRS)

This paper describes the results of a fast-time simulation experiment and a high-fidelity simulator validation with merging streams of aircraft flying Continuous Descent Arrivals through generic airspace to a runway at Dallas-Ft Worth. Aircraft made small speed adjustments based on an airborne-based spacing algorithm, so as to arrive at the threshold exactly at the assigned time interval behind their Traffic-To-Follow. The 40 aircraft were initialized at different altitudes and speeds on one of four different routes, and then merged at different points and altitudes while flying Continuous Descent Arrivals. This merging and spacing using flight deck equipment and procedures to augment or implement Air Traffic Management directives is called Flight Deck-based Merging and Spacing, an important subset of a larger Airborne Precision Spacing functionality. This research indicates that Flight Deck-based Merging and Spacing initiated while at cruise altitude and well prior to the Terminal Radar Approach Control entry can significantly contribute to the delivery of aircraft at a specified interval to the runway threshold with a high degree of accuracy and at a reduced pilot workload. Furthermore, previously documented work has shown that using a Continuous Descent Arrival instead of a traditional step-down descent can save fuel, reduce noise, and reduce emissions. Research into Flight Deck-based Merging and Spacing is a cooperative effort between government and industry partners.

Barmore, Bryan E.; Abbott, Terence S.; Capron, William R.; Baxley, Brian T.

2008-01-01

148

Irish descent, religion, and alcohol and tobacco use  

Microsoft Academic Search

The West of Scotland has traditionally been a focus for Irish migration. Using data from two studies carried out in this region, one quantitative, the other qualitative, this paper shows little difference in drinking and smoking between Scots of Irish descent and other Scots. It does, however, show significant differences in these behaviours according to religious affiliation in adulthood. Rather

KENNETH MULLEN; RORY WILLIAMS; KATE HUNT

1996-01-01

149

Men of African Descent and Carcinoma of the Prostate Consortium  

Cancer.gov

The Men of African Descent and Carcinoma of the Prostate (MADCaP) Consortium is collaborating on epidemiologic studies to address the high burden of prostate cancer among this population. These investigators are interested in understanding the complex multifactorial causes of prostate cancer etiology and outcomes among men of African ancestry worldwide.

150

Learning by Online Gradient Descent Michael Biehl \\Lambda  

E-print Network

Learning by Online Gradient Descent Michael Biehl \\Lambda CONNECT, The Niels Bohr Institute architecture. For this model the generalization error decays exponentially with the number of training examples model in this context is the so--called simple perceptron, a single binary threshold unit which realizes

Lunds Universitet,

151

Determining the Environmental Benefits of Implementing Continuous Descent Arrival Procedures  

Microsoft Academic Search

Several research and development efforts to date have been aimed at demonstrating that Continuous Descent Arrival (CDA) procedures have the potential for significant environmental benefits including reductions in noise, emissions, and fuel burn. The benefits evaluation portion of these efforts typically involves evaluating small numbers of CDA flights under idealized flight test conditions. This paper focuses on the development and

Eric P. Dinges

152

Elderhostels: Teaching and Learning with Americans of German Descent.  

ERIC Educational Resources Information Center

Describes three workshops designed for an Elderhostel program whose audience is largely Americans of German descent and the grandparents of today's students. The workshop topics include an introduction to the German-American experience and German-American studies; German American customs, beliefs, and traditions; and German-American genealogy,…

Reichmann, Eberhard; Reichmann, Ruth M.

1998-01-01

153

Monocular Hand Pose Estimation Using Variable Metric Gradient-Descent  

E-print Network

Monocular Hand Pose Estimation Using Variable Metric Gradient-Descent Martin de La Gorce - Nikos.de-la-gorce,nikos.paragios}@ecp.fr Abstract In this paper, we propose a novel model-based approach to recover 3D hand pose from 2D images through a compact articulated 3D hand model whose parameters are inferred in a Bayesian manner

Paragios, Nikos

154

Settling descent: place making and genealogy in Talas, Kyrgyzstan  

Microsoft Academic Search

This article explores how the inhabitants of two villages in northern Kyrgyzstan relate to one another and to their environment in terms of both place and genealogy. By performing relatedness, people make claims upon a physical landscape, while their relationships are simultaneously shaped by perceptions of the particular place they live in. The term ‘settling descent’ evokes this dialectic, in

Judith Beyer

2011-01-01

155

The Challenge of Mars EDL (Entry, Descent, and Landing)  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the some of the challenges of Martian atmospheric entry, descent and landing (EDL) on the surface of Mars. It reviews some of the technological difficulties, and some solutions that are being developed for future unmanned missions with larger payloads than previous landers, and ultimately human spacecraft landing.

Sostaric, Ronald

2010-01-01

156

Reference Airspeed Setting For Time Constrained Descent at Idle Thrust  

E-print Network

Nationale de l'Aviation Civile, Toulouse, France This paper addresses the issue of computing a reference and efficiency have become the two very important aspects in aviation industry after safety. Continuous Descent the arrival sequence and could be given for example through an Arrival Manager (AMAN). In addition

Boyer, Edmond

157

Role of fractional crystallization in the descent: Basalt ? trachyte  

Microsoft Academic Search

The role of fractional crystallization in the descent: basalt ? trachyte is critically examined. For each “simple basalt” magma type — alkaline, critically undersaturated, and oversaturated — there is a possible trachyte derived by way of fractional crystallization. Olivine removal is the main physical control that may interfere with trachytic trends at low pressure. Higher pressures widen the field of

Amalbikash Mukherjee

1967-01-01

158

Whole-body angular momentum during stair ascent and descent.  

PubMed

The generation of whole-body angular momentum is essential in many locomotor tasks and must be regulated in order to maintain dynamic balance. However, angular momentum has not been investigated during stair walking, which is an activity that presents a biomechanical challenge for balance-impaired populations. We investigated three-dimensional whole-body angular momentum during stair ascent and descent and compared it to level walking. Three-dimensional body-segment kinematic and ground reaction force (GRF) data were collected from 30 healthy subjects. Angular momentum was calculated using a 13-segment whole-body model. GRFs, external moment arms and net joint moments were used to interpret the angular momentum results. The range of frontal plane angular momentum was greater for stair ascent relative to level walking. In the transverse and sagittal planes, the range of angular momentum was smaller in stair ascent and descent relative to level walking. Significant differences were also found in the ground reaction forces, external moment arms and net joint moments. The sagittal plane angular momentum results suggest that individuals alter angular momentum to effectively counteract potential trips during stair ascent, and reduce the range of angular momentum to avoid falling forward during stair descent. Further, significant differences in joint moments suggest potential neuromuscular mechanisms that account for the differences in angular momentum between walking conditions. These results provide a baseline for comparison to impaired populations that have difficulty maintaining dynamic balance, particularly during stair ascent and descent. PMID:24636222

Silverman, Anne K; Neptune, Richard R; Sinitski, Emily H; Wilken, Jason M

2014-04-01

159

Cerebellar giant cell glioblastoma multiforme in an adult  

PubMed Central

Cerebellar glioblastoma multiforme (GBM) is a rare tumor that accounts for only 1% of all cases of GBM and its giant cell variant is even much rarely encountered in adults. A case of cerebellar giant cell GBM managed at our institution reporting its clinical presentation, radiological and histological findings, and treatment instituted is described. In conjunction, a literature review, including particular issues, clinical data, advances in imaging studies, pathological characteristics, treatment options, and the behavior of such malignant tumor is presented. It is very important for the neurosurgeon to make the differential diagnosis between the cerebellar GBM, and other diseases such as metastasis, anaplastic astrocytomas, and cerebellar infarct because their treatment modalities, prognosis, and outcome are different. PMID:25002780

Mishra, Sudhansu Sekhar; Behera, Sanjay Kumar; Dhir, Manmath Kumar; Senapati, Satya Bhusan

2014-01-01

160

A Case of Cerebellar Ataxia Associated with HIV Infection.  

PubMed

Cerebellar complications of HIV infection primarily manifested in ataxia, usually arise as the result of cerebellar lesions due to opportunistic infections, vasculitis or neoplastic processes. A 28 year old female known to have HIV infection for last four years, presented to our hospital with progressive unsteadiness in walking, slurring of speech and intention tremors for the last two months. There was no family history of similar complaints, and she was on Anti retroviral treatment for last one and a half years. The results of examination were notable for severe dysarthria, slow saccades, a conspicuous dysmetria and dysdiadokokinesia. She had no cognitive, sensory or motor deficits. MRI revealed diffuse cerebellar atrophy. Extensive laboratory work up failed to disclose a cause for subacute ataxia. Isolated cerebellar degeneration in an HIV patient is rare and should prompt a diagnostic work up. PMID:24759449

Anand, Kuljeet Singh; Wadhwa, Ankur; Garg, Jyoti

2014-09-01

161

RAPID COMMUNICATION Oscillatory Activity in the Cerebellar Hemispheres of  

E-print Network

-ously, in the absence of any observable sensory input or movement. tion animals were anesthetized with xylazine/ketamine-hydrochlo-Oscillations were synchronized both within and between cerebellar ride delivered intramuscularly (70 mg/kg ketamine

Hartmann, Mitra J. Z.

162

Hypocupremia: A Possible Association with Late Cortical Cerebellar Atrophy  

PubMed Central

Background We report a patient, diagnosed with late cortical cerebellar atrophy, who had persistent low serum copper levels. Case report A 48-year-old male developed progressive difficulty with balance, frequent falls, and dysarthric speech, which worsened over a short time span. He had an extensive ataxia work-up, which was unremarkable except for persistent low serum copper levels despite adequate supplementation. Magnetic resonance imaging of the brain showed marked cerebellar atrophy. The patient experienced progressive worsening of symptoms, which did not improve with either oral or parenteral copper supplementation. Discussion To our knowledge, ours is the first case report of late cortical cerebellar atrophy in the setting of low serum copper levels. The current report should trigger further research in mechanisms leading to copper deficiency and its possible role in cerebellar disease. PMID:25247109

Mittal, Shivam Om; Machado, Duarte G.

2014-01-01

163

Cerebellar giant cell glioblastoma multiforme in an adult.  

PubMed

Cerebellar glioblastoma multiforme (GBM) is a rare tumor that accounts for only 1% of all cases of GBM and its giant cell variant is even much rarely encountered in adults. A case of cerebellar giant cell GBM managed at our institution reporting its clinical presentation, radiological and histological findings, and treatment instituted is described. In conjunction, a literature review, including particular issues, clinical data, advances in imaging studies, pathological characteristics, treatment options, and the behavior of such malignant tumor is presented. It is very important for the neurosurgeon to make the differential diagnosis between the cerebellar GBM, and other diseases such as metastasis, anaplastic astrocytomas, and cerebellar infarct because their treatment modalities, prognosis, and outcome are different. PMID:25002780

Mishra, Sudhansu Sekhar; Behera, Sanjay Kumar; Dhir, Manmath Kumar; Senapati, Satya Bhusan

2014-07-01

164

Cerebellar theta-burst stimulation selectively enhances lexical associative priming.  

PubMed

Recent research in cerebellar cognitive and linguistic functions makes plausible the idea that the cerebellum is involved in processing temporally contiguous linguistic input. In order to assess this hypothesis, a simple lexical decision task was constructed to study whether the effect of transcranial magnetic stimulation on two different cerebellar sites would have a selective impact on associative as opposed to semantic priming. This is the first experiment applying transcranial magnetic stimulation of the cerebellum to a linguistic task. The results show a selective drop in lexical decision accuracy after stimulation of a medial cerebellar site in the first session of participation. Most importantly, they also demonstrate a selective increase of associative priming sizes after stimulation of the same site that cannot be attributed to changes in sensorimotor performance or in accuracy rates. The finding is discussed within the context of domain-general associative cerebellar computations. PMID:21451999

Argyropoulos, Giorgos P

2011-09-01

165

Development of quantitative tools for assessment of cerebellar dysfunction  

E-print Network

Two tools for the quantitative assessment of cerebellar dysfunction are developed and explored. One is based on a battery of laptop tests desgined for clinical use. Extensive analysis of one of the tests using a speed/accuracy ...

Garg, Aditi

2005-01-01

166

Non-invasive cerebellar stimulation--a consensus paper.  

PubMed

The field of neurostimulation of the cerebellum either with transcranial magnetic stimulation (TMS; single pulse or repetitive (rTMS)) or transcranial direct current stimulation (tDCS; anodal or cathodal) is gaining popularity in the scientific community, in particular because these stimulation techniques are non-invasive and provide novel information on cerebellar functions. There is a consensus amongst the panel of experts that both TMS and tDCS can effectively influence cerebellar functions, not only in the motor domain, with effects on visually guided tracking tasks, motor surround inhibition, motor adaptation and learning, but also for the cognitive and affective operations handled by the cerebro-cerebellar circuits. Verbal working memory, semantic associations and predictive language processing are amongst these operations. Both TMS and tDCS modulate the connectivity between the cerebellum and the primary motor cortex, tuning cerebellar excitability. Cerebellar TMS is an effective and valuable method to evaluate the cerebello-thalamo-cortical loop functions and for the study of the pathophysiology of ataxia. In most circumstances, DCS induces a polarity-dependent site-specific modulation of cerebellar activity. Paired associative stimulation of the cerebello-dentato-thalamo-M1 pathway can induce bidirectional long-term spike-timing-dependent plasticity-like changes of corticospinal excitability. However, the panel of experts considers that several important issues still remain unresolved and require further research. In particular, the role of TMS in promoting cerebellar plasticity is not established. Moreover, the exact positioning of electrode stimulation and the duration of the after effects of tDCS remain unclear. Future studies are required to better define how DCS over particular regions of the cerebellum affects individual cerebellar symptoms, given the topographical organization of cerebellar symptoms. The long-term neural consequences of non-invasive cerebellar modulation are also unclear. Although there is an agreement that the clinical applications in cerebellar disorders are likely numerous, it is emphasized that rigorous large-scale clinical trials are missing. Further studies should be encouraged to better clarify the role of using non-invasive neurostimulation techniques over the cerebellum in motor, cognitive and psychiatric rehabilitation strategies. PMID:23943521

Grimaldi, G; Argyropoulos, G P; Boehringer, A; Celnik, P; Edwards, M J; Ferrucci, R; Galea, J M; Groiss, S J; Hiraoka, K; Kassavetis, P; Lesage, E; Manto, M; Miall, R C; Priori, A; Sadnicka, A; Ugawa, Y; Ziemann, U

2014-02-01

167

Modulatory Effects of Theta Burst Stimulation on Cerebellar Nonsomatic Functions  

Microsoft Academic Search

Clinical and functional imaging studies suggest that the cerebellar vermis is involved in the regulation of a range of nonsomatic\\u000a functions including cardiovascular control, thirst, feeding behavior, and primal emotions. Cerebello-hypothalamic circuits\\u000a have been postulated to be a potential neuroanatomical substrate underlying this modulation. We tested this putative relationship\\u000a between the cerebellar vermis and nonsomatic functions by stimulating the cerebellum

Asli Demirtas-Tatlidede; Catarina Freitas; Alvaro Pascual-Leone; Jeremy D. Schmahmann

168

Cerebellar-Motor Dysfunction in Schizophrenia and Psychosis-Risk: The Importance of Regional Cerebellar Analysis Approaches  

PubMed Central

Motor abnormalities in individuals with schizophrenia and those at-risk for psychosis are well documented. An accumulating body of work has also highlighted motor abnormalities related to cerebellar dysfunction in schizophrenia including eye-blink conditioning, timing, postural control, and motor learning. We have also recently found evidence for motor dysfunction in individuals at ultra high-risk for psychosis (1–3). This is particularly relevant as the cerebellum is thought to be central to the cognitive dysmetria model of schizophrenia, and these overt motor signs may point to more general cerebellar dysfunction in the etiology of psychotic disorders. While studies have provided evidence indicative of motor cerebellar dysfunction in at-risk populations and in schizophrenia, findings with respect to the cerebellum have been mixed. One factor potentially contributing to these mixed results is the whole-structure approach taken when investigating the cerebellum. In non-human primates, there are distinct closed-loop circuits between the cerebellum, thalamus, and brain with motor and non-motor cortical regions. Recent human neuroimaging has supported this finding and indicates that there is a cerebellar functional topography (4), and this information is being missed with whole-structure approaches. Here, we review cerebellar-motor dysfunction in individuals with schizophrenia and those at-risk for psychosis. We also discuss cerebellar abnormalities in psychosis, and the cerebellar functional topography. Because of the segregated functional regions of the cerebellum, we propose that it is important to look at the structure regionally in order to better understand its role in motor dysfunction in these populations. This is analogous to approaches taken with the basal ganglia, where each region is considered separately. Such an approach is necessary to better understand cerebellar pathophysiology on a macro-structural level with respect to the pathogenesis of psychosis. PMID:25505424

Bernard, Jessica A.; Mittal, Vijay A.

2014-01-01

169

Analysis of various descent trajectories for a hypersonic-cruise, cold-wall research airplane  

NASA Technical Reports Server (NTRS)

The probable descent operating conditions for a hypersonic air-breathing research airplane were examined. Descents selected were cruise angle of attack, high dynamic pressure, high lift coefficient, turns, and descents with drag brakes. The descents were parametrically exercised and compared from the standpoint of cold-wall (367 K) aircraft heat load. The descent parameters compared were total heat load, peak heating rate, time to landing, time to end of heat pulse, and range. Trends in total heat load as a function of cruise Mach number, cruise dynamic pressure, angle-of-attack limitation, pull-up g-load, heading angle, and drag-brake size are presented.

Lawing, P. L.

1975-01-01

170

Defective cerebellar control of cortical plasticity in writer's cramp.  

PubMed

A large body of evidence points to a role of basal ganglia dysfunction in the pathophysiology of dystonia, but recent studies indicate that cerebellar dysfunction may also be involved. The cerebellum influences sensorimotor adaptation by modulating sensorimotor plasticity of the primary motor cortex. Motor cortex sensorimotor plasticity is maladaptive in patients with writer's cramp. Here we examined whether putative cerebellar dysfunction in dystonia is linked to these patients' maladaptive plasticity. To that end we compared the performances of patients and healthy control subjects in a reaching task involving a visuomotor conflict generated by imposing a random deviation (-40° to 40°) on the direction of movement of the mouse/cursor. Such a task is known to involve the cerebellum. We also compared, between patients and healthy control subjects, how the cerebellum modulates the extent and duration of an ongoing sensorimotor plasticity in the motor cortex. The cerebellar cortex was excited or inhibited by means of repeated transcranial magnetic stimulation before artificial sensorimotor plasticity was induced in the motor cortex by paired associative stimulation. Patients with writer's cramp were slower than the healthy control subjects to reach the target and, after having repeatedly adapted their trajectories to the deviations, they were less efficient than the healthy control subjects to perform reaching movement without imposed deviation. It was interpreted as impaired washing-out abilities. In healthy subjects, cerebellar cortex excitation prevented the paired associative stimulation to induce a sensorimotor plasticity in the primary motor cortex, whereas cerebellar cortex inhibition led the paired associative stimulation to be more efficient in inducing the plasticity. In patients with writer's cramp, cerebellar cortex excitation and inhibition were both ineffective in modulating sensorimotor plasticity. In patients with writer's cramp, but not in healthy subjects, behavioural parameters reflecting their capacity for adapting to the rotation and for washing-out of an earlier adaptation predicted the efficacy of inhibitory cerebellar conditioning to influence sensorimotor plasticity: the better the online adaptation, the smaller the influence of cerebellar inhibitory stimulation on motor cortex plasticity. Altered cerebellar encoding of incoming afferent volleys may result in decoupling the motor component from the afferent information flow, and also in maladjusted sensorimotor calibration. The loss of cerebellar control over sensorimotor plasticity might also lead to building up an incorrect motor program to specific adaptation tasks such as writing. PMID:23801734

Hubsch, Cecile; Roze, Emmanuel; Popa, Traian; Russo, Margherita; Balachandran, Ammu; Pradeep, Salini; Mueller, Florian; Brochard, Vanessa; Quartarone, Angelo; Degos, Bertrand; Vidailhet, Marie; Kishore, Asha; Meunier, Sabine

2013-07-01

171

Deoxycytidine is salvaged not only into DNA but also into phospholipid precursors. III. dCOP-diacylglycerol formation in tonsillar lymphocytes.  

PubMed

In addition to the water-soluble deoxyliponucleotides (Spasokukotskaja et al. (1988), Biochem. Biophys. Res. Commun. 155, 923), a lipid compound was shown to be labeled from external 3H-deoxycytidine (5-3H-CdR) in infant tonsillar lymphocytes. Chlorpromazine enhanced the labeling of this compound, identified by TLC as 3H-dCDP-diacylglycerol (3H-dCOP-DAG). The deoxynucleotide salvage pathway seems to be the main source for dCDP-DAG synthesis, as hydroxyurea increased its labeling from CdR. myo-Inositol induced the disappearance of 5-3H-dCOP-DAG, suggesting its utilization for phosphatidylinositol synthesis. 3H-Arabinosyl-Cytosine (araC) is also incorporated into the lipidic fraction at a rate comparable to its incorporation into DNA, supporting the effect of araC on membrane functions. PMID:1993063

Spasokukotskaja, T; Taljanidisz, J; Sasvári-Székely, M; Staub, M

1991-01-31

172

Flight Management System Execution of Idle-Thrust Descents in Operations  

NASA Technical Reports Server (NTRS)

To enable arriving aircraft to fly optimized descents computed by the flight management system (FMS) in congested airspace, ground automation must accurately predict descent trajectories. To support development of the trajectory predictor and its error models, commercial flights executed idle-thrust descents, and the recorded data includes the target speed profile and FMS intent trajectories. The FMS computes the intended descent path assuming idle thrust after top of descent (TOD), and any intervention by the controllers that alters the FMS execution of the descent is recorded so that such flights are discarded from the analysis. The horizontal flight path, cruise and meter fix altitudes, and actual TOD location are extracted from the radar data. Using more than 60 descents in Boeing 777 aircraft, the actual speeds are compared to the intended descent speed profile. In addition, three aspects of the accuracy of the FMS intent trajectory are analyzed: the meter fix crossing time, the TOD location, and the altitude at the meter fix. The actual TOD location is within 5 nmi of the intent location for over 95% of the descents. Roughly 90% of the time, the airspeed is within 0.01 of the target Mach number and within 10 KCAS of the target descent CAS, but the meter fix crossing time is only within 50 sec of the time computed by the FMS. Overall, the aircraft seem to be executing the descents as intended by the designers of the onboard automation.

Stell, Laurel L.

2011-01-01

173

Efficient Sensor Placement Optimization Using Gradient Descent and Probabilistic Coverage  

PubMed Central

We are proposing an adaptation of the gradient descent method to optimize the position and orientation of sensors for the sensor placement problem. The novelty of the proposed method lies in the combination of gradient descent optimization with a realistic model, which considers both the topography of the environment and a set of sensors with directional probabilistic sensing. The performance of this approach is compared with two other black box optimization methods over area coverage and processing time. Results show that our proposed method produces competitive results on smaller maps and superior results on larger maps, while requiring much less computation than the other optimization methods to which it has been compared. PMID:25196164

Akbarzadeh, Vahab; Lévesque, Julien-Charles; Gagné, Christian; Parizeau, Marc

2014-01-01

174

Helicopter optimal descent and landing after power loss  

NASA Technical Reports Server (NTRS)

An optimal control solution is obtained for the descent and landing of a helicopter after the loss of power in level flight. The model considers the helicopter vertical velocity, horizontal velocity, and rotor speed; and it includes representations of ground effect, rotor inflow time lag, pilot reaction time, rotor stall, and the induced velocity curve in the vortex ring state. The control (rotor thrust magnitude and direction) required to minimize the vertical and horizontal velocity at contact with the ground is obtained using nonlinear optimal control theory. It is found that the optimal descent after power loss in hover is a purely vertical flight path. Good correlation, even quantitatively, is found between the calculations and (non-optimal) flight test results.

Johnson, W.

1977-01-01

175

A conjugate gradient method with descent direction for unconstrained optimization  

NASA Astrophysics Data System (ADS)

A modified conjugate gradient method is presented for solving unconstrained optimization problems, which possesses the following properties: (i) The sufficient descent property is satisfied without any line search; (ii) The search direction will be in a trust region automatically; (iii) The Zoutendijk condition holds for the Wolfe-Powell line search technique; (iv) This method inherits an important property of the well-known Polak-Ribière-Polyak (PRP) method: the tendency to turn towards the steepest descent direction if a small step is generated away from the solution, preventing a sequence of tiny steps from happening. The global convergence and the linearly convergent rate of the given method are established. Numerical results show that this method is interesting.

Yuan, Gonglin; Lu, Xiwen; Wei, Zengxin

2009-11-01

176

Scaling Up Coordinate Descent Algorithms for Large ?1 Regularization Problems  

SciTech Connect

We present a generic framework for parallel coordinate descent (CD) algorithms that has as special cases the original sequential algorithms of Cyclic CD and Stochastic CD, as well as the recent parallel Shotgun algorithm of Bradley et al. We introduce two novel parallel algorithms that are also special cases---Thread-Greedy CD and Coloring-Based CD---and give performance measurements for an OpenMP implementation of these.

Scherrer, Chad; Halappanavar, Mahantesh; Tewari, Ambuj; Haglin, David J.

2012-07-03

177

Dynamic MR colpocystorectography assessing pelvic-floor descent  

Microsoft Academic Search

.   Magnetic resonance colpocystorectography (MR-CCRG) is presented in the evaluation of patients with pelvic-floor disorders.\\u000a Five healthy volunteers and 44 female patients with isolated or combined visceral descent underwent dynamic MRI and dynamic\\u000a fluoroscopy (DF). MR-CCRG was performed with the patient in a supine position using a True FISP sequence (1 image\\/1.2 s; in-plane\\u000a resolution 1.02 mm) during pelvic floor

A. Lienemann; C. Anthuber; A. Baron; P. Kohz; M. Reiser

1997-01-01

178

Directed Aerial Descent Behavior in African Canopy Ants (Hymenoptera: Formicidae)  

Microsoft Academic Search

Several species of neotropical ants direct their aerial descent toward tree trunks during a fall from the forest canopy. The\\u000a primary goal of this study was to determine if afrotropical arboreal ants exhibit similar gliding behavior. Ants were collected\\u000a from nine tree crowns in late secondary forest at a hydrocarbon extraction site near Gamba, Gabon. Of the 32 species tested,

S. P. Yanoviak; B. L. Fisher; A. Alonso

2008-01-01

179

Environmental effects on hormonal regulation of testicular descent.  

PubMed

Regulation of testicular descent is hormonally regulated, but the reasons for maldescent remain unknown in most cases. The main regulatory hormones are Leydig cell-derived testosterone and insulin-like factor 3 (INSL3). Luteinizing hormone (LH) stimulates the secretion of these hormones, but the secretory responses to LH are different: INSL3 secretion increases slowly and may reflect the LH dependent differentiated status of Leydig cells, whereas testosterone response to LH is immediate. Testosterone contributes to the involution of the suspensory ligament and to the inguinoscrotal phase of the descent, while INSL3 acts mainly in transabdominal descent by stimulating the growth of the gubernaculum. INSL3 acts through a G-protein coupled receptor LGR8. In the absence of either INSL3 or LGR8 mice remain cryptorchid. In humans only few INSL3 mutations have been described, whereas LGR8 mutations may cause some cases of undescended testis. Similarly, androgen insensitivity or androgen deficiency can cause cryptorchidism. Estrogens have been shown to down regulate INSL3 and thereby cause maldescent. Thus, a reduced androgen-estrogen ratio may disturb testicular descent. Environmental effects changing the ratio can thereby influence cryptorchidism rate. Estrogens and anti-androgens cause cryptorchidism in experimental animals. In our cohort study we found higher LH/testosterone ratios in 3-month-old cryptorchid boys than in normal control boys, suggesting that cryptorchid testes are not cabable of normal hormone secretion without increased gonadotropin drive. This may be either the cause or consequence of cryptorchidism. Some phthalates act as anti-androgens and cause cryptorchidism in rodents. In our human material we found an association of a high phthalate exposure with a high LH/testosterone ratio. We hypothesize that an exposure to a mixture of chemicals with anti-androgenic or estrogenic properties (either their own activity or their effect on androgen-estrogen ratio) may be involved in cryptorchidism. PMID:17049842

Toppari, J; Virtanen, H; Skakkebaek, N E; Main, K M

2006-12-01

180

A Variable Neighbourhood Descent Algorithm for the Redundancy Allocation Problem  

Microsoft Academic Search

This paper presents the first known application of a meta-heuristic algorithm, variable neighbour- hood descent (VND), to the redundancy allocation problem (RAP). The RAP, a well-known NP-hard problem, has been the subject of much prior work, generally in a restricted form where each subsystem must consist of identical components. The newer meta-heuristic methods overcome this limitation and offer a practical

Yun-Chia Liang; Chia-Chuan Wu

181

Development of synaptic junctions in cerebellar glomeruli.  

PubMed

In the glomerular synapses of developing mouse cerebellar cortex, 2 components of the synaptic junctions assemble independently in the immature granule cell dendrites, and then combine. 'Initial' junctions between mossy fiber axons and immature granule cell dendrites have presynaptic and postsynaptic electron-dense fuzz and a widened synaptic cleft, but lack the aggregate of intramembrane particles associated with the extracellular half of the postsynaptic membrane which characterizes mature synaptic junctions. In the vicinity of 'initial junctions' there are particle aggregates which resemble those at mature synaptic junctions, but which are less densely packed and which are not associated with the other features of a junction. The constituent particles of these aggregates move to the sites of 'initial junctions' to combine with them and form 'immature synaptic junctions'. Many of these immature junctions are larger in area than mature synaptic junctions. The immature junctions accumulate a fairly uniform complement of intramembrane particles, which increase in packing density as the junctions decrease in area and attain smaller, adult size. PMID:6871725

Landis, D M; Weinstein, L A; Halperin, J J

1983-06-01

182

Firing dynamics of cerebellar purkinje cells.  

PubMed

Knowledge of intrinsic neuronal firing dynamics is a critical first step to establishing an accurate biophysical model of any neuron. In this study we examined cerebellar Purkinje cells to determine the bifurcations likely to underlie firing dynamics within a biophysically realistic and experimentally supported model. We show that Purkinje cell dynamics are consistent with a system undergoing a saddle-node bifurcation of fixed points in the transition from rest to firing and a saddle homoclinic bifurcation from firing to rest. Our analyses account for numerous observed Purkinje cell firing properties that include bistability, plateau potentials, specific aspects of the frequency-current (F-I) relationship, first spike latency, and the ability for climbing fiber input to induce state transitions in the bistable regime. We also experimentally confirm new properties predicted from our model and analysis that include the presence of a depolarizing afterpotential (DAP), the ability to fire at low frequencies (<50 Hz) and with a high gain in the F-I relationship, and a bistable region limited to low-frequency firing. Purkinje cell dynamics, including bistability, prove to arise from numerous biophysical factors that include the DAP, fast refractory dynamics, and a long membrane time constant. A hyperpolarizing activated cation current (I(H)) is shown not to be directly involved in establishing bistable dynamics but rather reduces the range for bistability. A combined electrophysiological and modeling approach thus accounts for several properties of Purkinje cells, providing a firm basis from which to assess Purkinje cell output patterns. PMID:17493923

Fernandez, Fernando R; Engbers, Jordan D T; Turner, Ray W

2007-07-01

183

Lunar Surface Access Module Descent Engine Turbopump Technology: Detailed Design  

NASA Technical Reports Server (NTRS)

The need for a high specific impulse LOX/LH2 pump-fed lunar lander engine has been established by NASA for the new lunar exploration architecture. Studies indicate that a 4-engine cluster in the thrust range of 9,000-lbf each is a candidate configuration for the main propulsion of the manned lunar lander vehicle. The lander descent engine will be required to perform multiple burns including the powered descent onto the lunar surface. In order to achieve the wide range of thrust required, the engines must be capable of throttling approximately 10:1. Working under internal research and development funding, NASA Marshall Space Flight Center (MSFC) has been conducting the development of a 9,000-lbf LOX/LH2 lunar lander descent engine technology testbed. This paper highlights the detailed design and analysis efforts to develop the lander engine Fuel Turbopump (FTP) whose operating speeds range from 30,000-rpm to 100,000-rpm. The capability of the FTP to operate across this wide range of speeds imposes several structural and dynamic challenges, and the small size of the FTP creates scaling and manufacturing challenges that are also addressed in this paper.

Alvarez, Erika; Forbes, John C.; Thornton, Randall J.

2010-01-01

184

Inflammatory Bowel Disease in Children of Middle Eastern Descent  

PubMed Central

Increasing rates of inflammatory bowel disease (IBD) are now seen in populations where it was once uncommon. The pattern of IBD in children of Middle Eastern descent in Australia has never been reported. This study aimed to investigate the burden of IBD in children of Middle Eastern descent at the Sydney Children's Hospital, Randwick (SCHR). The SCHR IBD database was used to identify patients of self-reported Middle Eastern ethnicity diagnosed between 1987 and 2011. Demographic, diagnosis, and management data was collected for all Middle Eastern children and an age and gender matched non-Middle Eastern IBD control group. Twenty-four patients of Middle Eastern descent were identified. Middle Eastern Crohn's disease patients had higher disease activity at diagnosis, higher use of thiopurines, and less restricted colonic disease than controls. Although there were limitations with this dataset, we estimated a higher prevalence of IBD in Middle Eastern children and they had a different disease phenotype and behavior compared to the control group, with less disease restricted to the colon and likely a more active disease course. PMID:24987422

Naidoo, Christina Mai Ying; Leach, Steven T.; Day, Andrew S.; Lemberg, Daniel A.

2014-01-01

185

Biomechanical Analysis of Stair Descent in Patients with Knee Osteoarthritis  

PubMed Central

[Purpose] The purposes of this study were to investigate the lower extremity joint kinematics and kinetics of patients with the knee osteoarthritis (knee OA) during stair descent and clarify the biomechanical factors related to their difficulty in stair descent. [Subjects and Methods] Eight healthy elderly persons and four knee OA patients participated in this study. A 3-D motion analysis system and force plates were employed to measure lower extremity joint angles, ranges of motion, joint moments, joint powers, and ratios of contribution for the joint powers while descending stairs. [Results] Knee joint flexion angle, extension moment, and negative power during the early stance phase in the knee OA group were smaller than those in the healthy subjects group. However, no significant changes in these parameters in the ankle joint were observed between the two subject groups. [Conclusion] Knee OA patients could not use the knee joint to absorb impact during the early stance phase of stair descent. Hence, they might compensate for the roles played by the intact knee joint by mainly using ipsilateral ankle kinematics and kinetics. PMID:24926119

Igawa, Tatsuya; Katsuhira, Junji

2014-01-01

186

Hormonal control of testicular descent and the cause of cryptorchidism.  

PubMed

This paper briefly reviews the literature on testicular descent and presents new observations from the authors' laboratory which suggest new ways of looking at old problems. There is now good evidence that testicular descent occurs in two morphologically and hormonally distinct phases. Relative 'transabdominal migration' of the testis compared with the ovary occurs at 10-15 weeks of gestation in the human and 'inguinoscrotal' migration occurs at 26-35 weeks of gestation. We have proposed previously that the first phase is controlled by Müllerian inhibiting substance although this remains controversial. The second phase is androgen dependent and is possibly mediated indirectly through the release from the genitofemoral nerve (GFN) of the neuropeptide calcitonin gene-related peptide (CGRP). Recently we have used three different rodent models of undescended testis to determine the involvement of the GNF and/or CGRP. The testicular feminization mouse with complete androgen resistance and the rat exposed prenatally to the antiandrogen flutamide have a deficiency of CGRP in the GFN. In contrast, the mutant trans-scrotal rat which has normal androgen levels has an excess of CGRP in the GFN. All cryptorchidism models, despite their different primary cause, have in common an abnormality of the GNF and/or CGRP which is consistent with the hypothesis that normal testicular descent in the rodent may be mediated by the GFN. PMID:7991782

Hutson, J M; Baker, M; Terada, M; Zhou, B; Paxton, G

1994-01-01

187

Airborne Management of Traffic Conflicts in Descent With Arrival Constraints  

NASA Technical Reports Server (NTRS)

NASA is studying far-term air traffic management concepts that may increase operational efficiency through a redistribution of decisionmaking authority among airborne and ground-based elements of the air transportation system. One component of this research, En Route Free Maneuvering, allows trained pilots of equipped autonomous aircraft to assume responsibility for traffic separation. Ground-based air traffic controllers would continue to separate traffic unequipped for autonomous operations and would issue flow management constraints to all aircraft. To evaluate En Route Free Maneuvering operations, a human-in-the-loop experiment was jointly conducted by the NASA Ames and Langley Research Centers. In this experiment, test subject pilots used desktop flight simulators to resolve conflicts in cruise and descent, and to adhere to air traffic flow constraints issued by test subject controllers. Simulators at NASA Langley were equipped with a prototype Autonomous Operations Planner (AOP) flight deck toolset to assist pilots with conflict management and constraint compliance tasks. Results from the experiment are presented, focusing specifically on operations during the initial descent into the terminal area. Airborne conflict resolution performance in descent, conformance to traffic flow management constraints, and the effects of conflicting traffic on constraint conformance are all presented. Subjective data from subject pilots are also presented, showing perceived levels of workload, safety, and acceptability of autonomous arrival operations. Finally, potential AOP functionality enhancements are discussed along with suggestions to improve arrival procedures.

Doble, Nathan A.; Barhydt, Richard; Krishnamurthy, Karthik

2005-01-01

188

Cerebellar hemorrhage after embolization of ruptured vertebral dissecting aneurysm proximal to PICA including parent artery  

PubMed Central

Background: Some complications related to vertebral artery occlusion by endovascular technique have been reported. However, cerebellar hemorrhage after vertebral artery occlusion in subacute phase is rare. In this report, we describe a patient who showed cerebellar hemorrhage during hypertensive therapy for vasospasm after embolization of a vertebral dissecting aneurysm. Case Description: A 56-year-old female with a ruptured vertebral dissecting aneurysm proximal to the posterior inferior cerebellar artery developed cerebellar hemorrhage 15 days after embolization of the vertebral artery, including the dissected site. In this patient, the preserved posterior inferior cerebellar artery fed by retrograde blood flow might have been hemodynamically stressed during hypertensive and antiplatelet therapies for subarachnoid hemorrhage, resulting in cerebellar hemorrhage. Conclusion: Although cerebellar hemorrhage is not prone to occur in the nonacute stage of embolization of the vertebral artery, it should be taken into consideration that cerebellar hemorrhage may occur during hypertensive treatment. PMID:24872921

Tamase, Akira; Kamide, Tomoya; Mori, Kentaro; Kitamura, Yoshihisa; Shima, Hiroshi; Seki, Shunsuke; Nomura, Motohiro

2014-01-01

189

Does a basic deficit in force control underlie cerebellar ataxia?  

PubMed

Because damage to the cerebellum results in characteristic movement incoordination known as "ataxia," it has been hypothesized that it is involved in estimation of limb dynamics that occur during movement. However, cerebellar function may extend beyond movement to force control in general, with or without movement. Here we tested whether the cerebellum is involved in controlling force separate from estimating limb dynamics and whether ataxia could result from a deficit in force control. We studied patients with cerebellar ataxia controlling their arm force isometrically; in this condition arm dynamics are absent and there is no need for (or effect from an impairment in) estimations of limb dynamics. Subjects were required to control their force magnitude, direction, or both. Cerebellar patients were able to match force magnitude or direction similarly to control subjects. Furthermore, when controlling force magnitude, they intuitively chose directions (not specified) that required minimal effort at the joint level--this ability was also similar to control subjects. In contrast, cerebellar patients performed significantly worse than control subjects when asked to match both force magnitude and direction. This was surprising, since they did not exhibit significant impairment in doing either in isolation. These results show that cerebellum-dependent computations are not limited to estimations of body dynamics needed for active movement. Deficits occur even in isometric conditions, but apparently only when multiple degrees of freedom must be controlled simultaneously. Thus a fundamental cerebellar operation may be combining/coordinating degrees of freedom across many kinds of movements and behaviors. PMID:23175807

Charles, Steven K; Okamura, Allison M; Bastian, Amy J

2013-02-01

190

Crossed cerebellar diaschisis after status epilepticus in a young child.  

PubMed

We report on a 3.8-year-old girl who was born preterm. Due to a posthemorrhagic hydrocephalus she had a ventriculoperitoneal shunt. Magnetic resonance imaging (MRI) showed mild atrophy of the left cerebellum. She was found unresponsive in a febrile state. After the application of midazolam she regained consciousness. There were no epileptic discharges on electroencephalogram. MRI with diffusion-weighted sequences showed areas of hyperintensity in the right cerebrum. After the patient deteriorated again, MRI showed signs of increased intracranial pressure and high signal intensity throughout the right cerebral and left cerebellar hemispheres, suggesting crossed cerebellar diaschisis (CCD) most likely resulting from a nonconvulsive status epilepticus (SE). A follow-up MRI showed progressive brain atrophy. CCD after SE might be caused by cortical excitatory input through the cortico-pontine-cerebellar pathway. Alternatively, the cerebral edema in SE may decrease neuronal cell activity in the contralateral cerebellar hemisphere. The unilateral cerebellar atrophy before the onset of CCD might be attributed to impaired neuronal connections after peripartal cerebral injury. This case presents a young child with a combination of two CCDs, at first due to perinatal brain injury, and at second to SE. MRI with diffusion-weighted sequences can detect CCD at an early stage. PMID:22473242

Koy, Anne; Klee, Dirk; Weber, Artur-Aron; Karenfort, Michael; Mayatepek, Ertan

2012-04-01

191

Thalamic, brainstem, and cerebellar glucose metabolism in the hemiplegic monkey  

SciTech Connect

Unilateral ablation of cerebral cortical areas 4 and 6 of Brodmann in the macaque monkey results in a contralateral hemiplegia that resolves partially with time. During the phase of dense hemiplegia, local cerebral metabolic rate for glucose (1CMRG1c) is decreased significantly in most of the thalamic nuclei ipsilateral to the ablation, and there are slight contralateral decreases. The lCMRGlc is reduced bilaterally in most of the brainstem nuclei and bilaterally in the deep cerebellar nuclei, but only in the contralateral cerebellar cortex. During the phase of partial motor recovery, lCMRGlc is incompletely restored in many of the thalamic nuclei ipsilateral to the ablation and completely restored in the contralateral nuclei. In the brainstem and deep cerebellar nuclei, poor to moderate recovery occurs bilaterally. Moderate recovery occurs in the contralateral cerebellar cortex. The findings demonstrate that a unilateral cerebral cortical lesion strongly affects lCMRGlc in the thalamus ipsilaterally and in the cerebellar cortex contralaterally, but in the brainstem bilaterally. Partial recovery of lCMRGlc accompanies the progressive motor recovery. The structures affected include those with direct, and also those with indirect, connections to the areas ablated.

Shimoyama, I.; Dauth, G.W.; Gilman, S.; Frey, K.A.; Penney, J.B. Jr.

1988-12-01

192

Neurodevelopmental outcomes in children with cerebellar malformations: a systematic review.  

PubMed

Cerebellar malformations are increasingly diagnosed in the fetal period. Consequently, their consideration requires stressful and often critical decisions from both clinicians and families. This has resulted in an emergent need to understand better the impact of these early life lesions on child development. We performed a comprehensive literature search of studies describing neurodevelopmental outcomes of cerebellar malformations between January 1997 and December 2007. Overall, the data suggested that children with isolated inferior vermis hypoplasia (IVH) and mega cisterna magna (MCM) have a good developmental outcome, whereas children with molar tooth sign/Joubert syndrome, vermis hypoplasia, pontocerebellar hypoplasia (PCH) type II, and cerebellar agenesis experience moderate to severe global developmental delays. Reports for Dandy-Walker malformation (DWM) were conflicting; however, the presence of a normally lobulated vermis and the absence of associated brain anomalies were associated with a more favourable outcome. Finally, children with isolated cerebellar hypoplasia experienced fewer impairments. Important methodological limitations highlighted include a lack of standardized outcome measure use in 79% of studies and the predominant use of retrospective study designs (85%), with 40% limited to case reports or case-series. In summary, rigorous outcome studies describing the spectrum of disabilities in survivors are urgently needed to accurately delineate the long-term neurodevelopmental consequences of cerebellar malformations. PMID:19191827

Bolduc, Marie-Eve; Limperopoulos, Catherine

2009-04-01

193

Motor learning of mice lacking cerebellar Purkinje cells  

PubMed Central

The cerebellum plays a key role in the acquisition and execution of motor tasks whose physiological foundations were postulated on Purkinje cells' long-term depression (LTD). Numerous research efforts have been focused on understanding the cerebellum as a site of learning and/or memory storage. However, the controversy on which part of the cerebellum participates in motor learning, and how the process takes place, remains unsolved. In fact, it has been suggested that cerebellar cortex, deep cerebellar nuclei, and/or their combination with some brain structures other than the cerebellum are responsible for motor learning. Different experimental approaches have been used to tackle this question (cerebellar lesions, pharmacological agonist and/or antagonist of cerebellar neurotransmitters, virus tract tracings, etc.). One of these approaches is the study of spontaneous mutations affecting the cerebellar cortex and depriving it of its main input–output organizer (i.e., the Purkinje cell). In this review, we discuss the results obtained in our laboratory in motor learning of both Lurcher (Lc/+) and tambaleante (tbl/tbl) mice as models of Purkinje-cell-devoid cerebellum. PMID:23630472

Porras-García, M. Elena; Ruiz, Rocío; Pérez-Villegas, Eva M.; Armengol, José Á.

2013-01-01

194

Comparison of linear cephalometric dimensions in Americans of European descent (Ann Arbor, Cleveland, Philadelphia) and Americans of African descent (Nashville).  

PubMed

Eleven dimensions, extracted from four commercially available cephalometric atlases were compared. Three populations were American of European descent and one was American of African descent. The source data were carefully corrected for linear enlargement. The confounding effect of linear radiographic enlargement is exemplified by depicting the often-used distance, sella-nasion, before and after correction. Total face height was smallest in the Cleveland population and largest in the Nashville population. The difference was fully accounted for by differences in lower face height and that was the most variable of all dimensions studied. Upper face height was almost identical in all four populations. Posterior face height was largest in the Nashville population. The mandible in the Nashville population had an average ramus height, but a longer corpus. Mandibular dimensions were equal in the three other populations. The maxilla was clearly shortest in the Cleveland population and almost of equal length in the three others. PMID:12169032

Dibbets, Jos M H; Nolte, Kai

2002-08-01

195

Mars Science Laboratory: Entry, Descent, and Landing System Performance  

NASA Technical Reports Server (NTRS)

In 2010, the Mars Science Laboratory (MSL) mission will pioneer the next generation of robotic Entry, Descent, and Landing (EDL) systems, by delivering the largest and most capable rover to date to the surface of Mars. To do so, MSL will fly a guided lifting entry at a lift-to-drag ratio in excess of that ever flown at Mars, deploy the largest parachute ever at Mars, and perform a novel Sky Crane maneuver. Through improved altitude capability, increased latitude coverage, and more accurate payload delivery, MSL is allowing the science community to consider the exploration of previously inaccessible regions of the planet. The MSL EDL system is a new EDL architecture based on Viking heritage technologies and designed to meet the challenges of landing increasing massive payloads on Mars. In accordance with level-1 requirements, the MSL EDL system is being designed to land an 850 kg rover to altitudes as high as 1 km above the Mars Orbiter Laser Altimeter defined areoid within 10 km of the desired landing site. Accordingly, MSL will enter the largest entry mass, fly the largest 70 degree sphere-cone aeroshell, generate the largest hypersonic lift-to-drag ratio, and deploy the largest Disk-Gap-Band supersonic parachute of any previous mission to Mars. Major EDL events include a hypersonic guided entry, supersonic parachute deploy and inflation, subsonic heatshield jettison, terminal descent sensor acquisition, powered descent initiation, sky crane terminal descent, rover touchdown detection, and descent stage flyaway. Key performance metrics, derived from level-1 requirements and tracked by the EDL design team to indicate performance capability and timeline margins, include altitude and range at parachute deploy, time on radar, and propellant use. The MSL EDL system, which will continue to develop over the next three years, will enable a notable extension in the advancement of Mars surface science by delivering more science capability than ever before to the surface of Mars. This paper describes the current MSL EDL system performance as predicted by end-to-end EDL simulations, highlights the sensitivity of this baseline performance to several key environmental assumptions, and discusses some of the challenges faced in delivering such an unprecedented rover payload to the surface of Mars.

Way, David W.; Powell, Richard W.; Chen, Allen; Steltzner, Adam D.; San Martin, Alejandro M.; Burkhart, Paul D.; mendeck, Gavin F.

2006-01-01

196

Mars Science Laboratory: Entry, Descent, and Landing System Performance  

NASA Technical Reports Server (NTRS)

In 2010, the Mars Science Laboratory (MSL) mission will pioneer the next generation of robotic Entry, Descent, and Landing (EDL) systems, by delivering the largest and most capable rover to date to the surface of Mars. To do so, MSL will fly a guided lifting entry at a lift-to-drag ratio in excess of that ever flown at Mars, deploy the largest parachute ever at Mars, and perform a novel Sky Crane maneuver. Through improved altitude capability, increased latitude coverage, and more accurate payload delivery, MSL is allowing the science community to consider the exploration of previously inaccessible regions of the planet. The MSL EDL system is a new EDL architecture based on Viking heritage technologies and designed to meet the challenges of landing increasing massive payloads on Mars. In accordance with level-1 requirements, the MSL EDL system is being designed to land an 850 kg rover to altitudes as high as 1 km above the Mars Orbiter Laser Altimeter defined areoid within 10 km of the desired landing site. Accordingly, MSL will enter the largest entry mass, fly the largest 70 degree sphere-cone aeroshell, generate the largest hypersonic lift-to-drag ratio, and deploy the largest Disk-Gap-Band supersonic parachute of any previous mission to Mars. Major EDL events include a hypersonic guided entry, supersonic parachute deploy and inflation, subsonic heatshield jettison, terminal descent sensor acquisition, powered descent initiation, sky crane terminal descent, rover touchdown detection, and descent stage flyaway. Key performance metrics, derived from level-1 requirements and tracked by the EDL design team to indicate performance capability and timeline margins, include altitude and range at parachute deploy, time on radar, and propellant use. The MSL EDL system, which will continue to develop over the next three years, will enable a notable extension in the advancement of Mars surface science by delivering more science capability than ever before to the surface of Mars. This paper describes the current MSL EDL system performance as predicted by end-to-end EDL simulations, highlights the sensitivity of this baseline performance to several key environmental assumptions, and discusses some of the challenges faced in delivering such an unprecedented rover payload to the surface of Mars.

Way, David W.; Powell, Richard W.; Chen, Allen; SanMartin, A. Miguel; Burkhart, P. Daniel; Mendeck, Gavin F.

2007-01-01

197

Haemangioblastoma: a rare cause of a cerebellar mass in the elderly.  

PubMed

In the elderly, cerebellar lesions are commonly metastatic tumours with poor prognosis. We describe two octogenarians who presented with obstructive hydrocephalus, secondary to posterior fossa tumours that, on computed tomography, were thought to be cerebellar metastases. Both lesions were excised and the histology proved them to be cerebellar haemangioblastomas, primary benign tumours of the posterior fossa, which are rare in the elderly. PMID:14635754

Gnanalingham, K K; Apostolopoulos, V; Chopra, I; Mendoza, N; Peterson, D

2003-10-01

198

Cerebellar liponeurocytoma: a case report and review of the literature.  

PubMed

Cerebellar liponeurocytoma has recently been recognised by the 2000 World Health Organisation classification of tumours of the central nervous system as a distinct clinicopathologic entity. To our knowledge, 18 cases have been reported so far, under different names, such as "lipomatous medulloblastoma, lipidized medulloblastoma, neurolipocytoma, medullocytoma and lipomatous glioneurocytoma". The new classification included cerebellar liponeurocytoma in the category of glioneuronal tumours grade I or II because of its favourable clinical behaviour. The origin and nature of the lipomatous component have been matter of debate and make this tumour entity puzzling. We describe a new case of liponeurocytoma removed from the left cerebellar hemisphere of a 38-year-old-woman. The patient showed unspecific signs of intracranial hypertension and symptoms suggesting a posterior fossa lesion. PMID:15080526

Amina, M; Saadia, B; Kais, N; Hammouda Karim, B; Khadija, B; Slim, H; Moncef, Z; Nidhameddine, K

2003-12-01

199

Recurrent cerebellar architecture solves the motor-error problem.  

PubMed Central

Current views of cerebellar function have been heavily influenced by the models of Marr and Albus, who suggested that the climbing fibre input to the cerebellum acts as a teaching signal for motor learning. It is commonly assumed that this teaching signal must be motor error (the difference between actual and correct motor command), but this approach requires complex neural structures to estimate unobservable motor error from its observed sensory consequences. We have proposed elsewhere a recurrent decorrelation control architecture in which Marr-Albus models learn without requiring motor error. Here, we prove convergence for this architecture and demonstrate important advantages for the modular control of systems with multiple degrees of freedom. These results are illustrated by modelling adaptive plant compensation for the three-dimensional vestibular ocular reflex. This provides a functional role for recurrent cerebellar connectivity, which may be a generic anatomical feature of projections between regions of cerebral and cerebellar cortex. PMID:15255096

Porrill, John; Dean, Paul; Stone, James V.

2004-01-01

200

Modulatory Effects of Theta Burst Stimulation on Cerebellar Nonsomatic Functions  

PubMed Central

Clinical and functional imaging studies suggest that the cerebellar vermis is involved in the regulation of a range of nonsomatic functions including cardiovascular control, thirst, feeding behavior, and primal emotions. Cerebello-hypothalamic circuits have been postulated to be a potential neuroanatomical substrate underlying this modulation. We tested this putative relationship between the cerebellar vermis and nonsomatic functions by stimulating the cerebellum noninvasively via neuronavigated transcranial magnetic stimulation. In this randomized, counter-balanced, within-subject study, intermittent theta burst stimulation (TBS) was applied on three different days to the vermis and the right and left cerebellar hemispheres of 12 right-handed normal subjects with the aim of modulating activity in the targeted cerebellar structure. TBS-associated changes were investigated via cardiovascular monitoring, a series of emotionally arousing picture stimuli, subjective analog scales for primal emotions, and the Profile of Mood States test. All 36 sessions of cerebellar stimulation were tolerated well without serious adverse events. Cardiovascular monitoring pointed to a mild but significant decrease in heart rate subsequent to vermal stimulation; no changes were detected in systolic or diastolic blood pressure measurements. Subjective ratings detected a significant increase in Thirst and a trend toward increased Appetite following vermal stimulation. These observations are consistent with existing neurophysiological and neuroimaging data indicating a role for the cerebellum in the regulation of visceral responses. In conjunction with the modulatory function of the cerebellum, our results suggest a role for the vermis in somatovisceral integration likely through cerebello-hypothalamic pathways. Further research is warranted to elucidate the potential mechanisms underlying the cerebellar modulation of nonsomatic functions. PMID:21132574

Demirtas-Tatlidede, Asli; Freitas, Catarina; Pascual-Leone, Alvaro; Schmahmann, Jeremy D.

2011-01-01

201

STS-1 operational flight profile. Volume 5: Descent, cycle 3. Appendix C: Monte Carlo dispersion analysis  

NASA Technical Reports Server (NTRS)

The results of three nonlinear the Monte Carlo dispersion analyses for the Space Transportation System 1 Flight (STS-1) Orbiter Descent Operational Flight Profile, Cycle 3 are presented. Fifty randomly selected simulation for the end of mission (EOM) descent, the abort once around (AOA) descent targeted line are steep target line, and the AOA descent targeted to the shallow target line are analyzed. These analyses compare the flight environment with system and operational constraints on the flight environment and in some cases use simplified system models as an aid in assessing the STS-1 descent flight profile. In addition, descent flight envelops are provided as a data base for use by system specialists to determine the flight readiness for STS-1. The results of these dispersion analyses supersede results of the dispersion analysis previously documented.

1980-01-01

202

Cerebellar astrocytoma presenting as deterioration of handwriting in a child.  

PubMed

Deterioration of handwriting in an 11-year-old boy over a 2 month period was found to be caused by a cerebellar astrocytoma. The clinical picture was characterised by a lack of the classic symptoms of increased intracranial pressure. The only positive neurological findings pointed to an isolated right cerebellar symptomatology expressed by mild intention tremor and decreased tone of the right hand. Progressive deterioration of handwriting can be an ominous sign and it should be known to all professionals, as a lack of awareness can cause delay in expert referral and diagnosis. PMID:2985391

Harel, S; Holtzman, M; Jurgenson, U; Reider, I; Feinsod, M

1985-01-01

203

Sudden Onset of Oromandibular Dystonia after Cerebellar Stroke  

PubMed Central

Background We present the case of a 65-year-old female with sudden-onset involuntary mouth opening, deviation of the jaw, facial grimacing, and tongue movements that started 6 months prior to her admission. Case Report She was diagnosed with oromandibular dystonia. Differential diagnosis of oromandibular dystonia and various etiologies were investigated. Neuroimaging studies revealed a left cerebellar infarction. Discussion To our knowledge, this case is the first oromandibular dystonia presenting with cerebellar ischemic stroke. Possible roles of the cerebellum for the pathophysiology of oromandibular dystonia are discussed. PMID:25374766

Akin, Alper; Yilmaz, Rezzak; Selcuk, Ferda; Akbostanc?, M. Cenk

2014-01-01

204

Comparative study of cerebellar degeneration in canine neuroaxonal dystrophy, cerebellar cortical abiotrophy, and neuronal ceroid-lipofuscinosis.  

PubMed

The cerebellar lesions of three dogs with canine neuroaxonal dystrophy (NAD), one dog with cerebellar cortical abiotrophy (CCA), and 4 dogs with neuronal ceroid-lipofuscinosis (NCL) were examined to understand their pathogeneses. Purkinje cell loss was most severe in the vermis of a dog with CCA, and granule cell loss was most prominent in the cerebellar hemisphere of dogs with NCL. Immunohistochemically, CD3-and HLA-DR-positive cells were most frequent in the dogs with NCL, and moderate in dogs with NAD, but not in a dog with CCA. The number of cleaved caspase 3-positive cells was prominent in a dog with CCA, but no significant in the dogs with NAD. The results indicate different pathway of neuronal loss of these canine neuronal disorders. PMID:20585192

Nibe, Kazumi; Nakayama, Hiroyuki; Uchida, Kazuyuki

2010-11-01

205

Entry, Descent, and Landing for Human Mars Missions  

NASA Technical Reports Server (NTRS)

One of the most challenging aspects of a human mission to Mars is landing safely on the Martian surface. Mars has such low atmospheric density that decelerating large masses (tens of metric tons) requires methods that have not yet been demonstrated, and are not yet planned in future Mars missions. To identify the most promising options for Mars entry, descent, and landing, and to plan development of the needed technologies, NASA's Human Architecture Team (HAT) has refined candidate methods for emplacing needed elements of the human Mars exploration architecture (such as ascent vehicles and habitats) on the Mars surface. This paper explains the detailed, optimized simulations that have been developed to define the mass needed at Mars arrival to accomplish the entry, descent, and landing functions. Based on previous work, technology options for hypersonic deceleration include rigid, mid-L/D (lift-to-drag ratio) aeroshells, and inflatable aerodynamic decelerators (IADs). The hypersonic IADs, or HIADs, are about 20% less massive than the rigid vehicles, but both have their technology development challenges. For the supersonic regime, supersonic retropropulsion (SRP) is an attractive option, since a propulsive stage must be carried for terminal descent and can be ignited at higher speeds. The use of SRP eliminates the need for an additional deceleration system, but SRP is at a low Technology Readiness Level (TRL) in that the interacting plumes are not well-characterized, and their effect on vehicle stability has not been studied, to date. These architecture-level assessments have been used to define the key performance parameters and a technology development strategy for achieving the challenging mission of landing large payloads on Mars.

Munk, Michelle M.; DwyerCianciolo, Alicia M.

2012-01-01

206

Powered Descent Guidance with General Thrust-Pointing Constraints  

NASA Technical Reports Server (NTRS)

The Powered Descent Guidance (PDG) algorithm and software for generating Mars pinpoint or precision landing guidance profiles has been enhanced to incorporate thrust-pointing constraints. Pointing constraints would typically be needed for onboard sensor and navigation systems that have specific field-of-view requirements to generate valid ground proximity and terrain-relative state measurements. The original PDG algorithm was designed to enforce both control and state constraints, including maximum and minimum thrust bounds, avoidance of the ground or descent within a glide slope cone, and maximum speed limits. The thrust-bound and thrust-pointing constraints within PDG are non-convex, which in general requires nonlinear optimization methods to generate solutions. The short duration of Mars powered descent requires guaranteed PDG convergence to a solution within a finite time; however, nonlinear optimization methods have no guarantees of convergence to the global optimal or convergence within finite computation time. A lossless convexification developed for the original PDG algorithm relaxed the non-convex thrust bound constraints. This relaxation was theoretically proven to provide valid and optimal solutions for the original, non-convex problem within a convex framework. As with the thrust bound constraint, a relaxation of the thrust-pointing constraint also provides a lossless convexification that ensures the enhanced relaxed PDG algorithm remains convex and retains validity for the original nonconvex problem. The enhanced PDG algorithm provides guidance profiles for pinpoint and precision landing that minimize fuel usage, minimize landing error to the target, and ensure satisfaction of all position and control constraints, including thrust bounds and now thrust-pointing constraints.

Carson, John M., III; Acikmese, Behcet; Blackmore, Lars

2013-01-01

207

INSL3/RXFP2 signaling in testicular descent.  

PubMed

Mutations of the insulin-like peptide 3 (INSL3) hormone or its receptor, RXFP2, cause intraabdominal cryptorchidism in male mice. Specific RXFP2 expression in mouse gubernacula was detected at embryonic day 14.5 and markedly increased after birth in the developing cremaster muscle, as well as in the epididymis and testicular Leydig and germ cells. INSL3 treatment stimulated cell proliferation of embryonic gubernacular and Leydig cells, implicating active INSL3-mediated signaling. The transcription factor SOX9, a known male sex determination factor, upregulated the activity of the RXFP2 promoter. INSL3 is sufficient to direct the first transabdominal phase of testicular descent in the absence of hypothalamic-pituitary-gonadal axis signaling or Hoxa10, although these factors are important for inguinoscrotal testicular descent. Similarly, conditional ablation of the androgen receptor gene in gubernacular cells resulted in disruption of inguinoscrotal descent. We performed mutation screening of INSL3 and RXFP2 in human patients with cryptorchidism and control subjects from different populations in Europe and the USA. Several missense mutations were described in both the INSL3 and RXFP2 genes. A novel V39G INSL3 mutation in a patient with cryptorchidism was identified; however, the functional analysis of the mutant peptide did not reveal compromised function. In more than 2000 patients and controls analyzed to date, the T222P RXFP2 mutation is the only one strongly associated with the mutant phenotype. The T222P mutant receptor, when transfected into 293T cells, had severely decreased cell membrane expression, providing the basis for the functional deficiency of this mutation. PMID:19416188

Feng, Shu; Ferlin, Alberto; Truong, Anne; Bathgate, Ross; Wade, John D; Corbett, Sean; Han, Shuo; Tannour-Louet, Mounia; Lamb, Dolores J; Foresta, Carlo; Agoulnik, Alexander I

2009-04-01

208

Regularization Paths for Generalized Linear Models via Coordinate Descent  

PubMed Central

We develop fast algorithms for estimation of generalized linear models with convex penalties. The models include linear regression, two-class logistic regression, and multinomial regression problems while the penalties include ?1 (the lasso), ?2 (ridge regression) and mixtures of the two (the elastic net). The algorithms use cyclical coordinate descent, computed along a regularization path. The methods can handle large problems and can also deal efficiently with sparse features. In comparative timings we find that the new algorithms are considerably faster than competing methods. PMID:20808728

Friedman, Jerome; Hastie, Trevor; Tibshirani, Rob

2010-01-01

209

Finite descent obstructions and rational  points on curves  

Microsoft Academic Search

Let k be a number field and X a smooth projective k-variety. In this paper,\\u000awe study the information obtainable from descent via torsors under finite\\u000ak-group schemes on the location of the k-rational points on X within the adelic\\u000apoints.\\u000a Our main result is that if a curve C\\/k maps nontrivially into an abelian\\u000avariety A\\/k such that A(k)

Michael Stoll

2007-01-01

210

OFT ascent/descent ancillary data requirements document  

NASA Technical Reports Server (NTRS)

Requirements are presented for the ascent/descent (A/D) navigation and attitude-dependent ancillary data products to be generated for the space shuttle orbiter in support of orbital flight test requirements, MPAD guidance and navigation performance assessment, and the mission evaluation team. It was intended that this document serve as the sole requirements control instrument between MPB/MPAD and the A/D ancillary data users. The requirements are primarily functional in nature, but some detail level requirements are also included.

Bond, A. C., Jr.; Abramson, B.

1978-01-01

211

Gradient descent assimilation for the point-vortex model  

NASA Astrophysics Data System (ADS)

Data assimilation is concerned with incorporating (noisy) observations into (imperfect) models that describe the underlying dynamics of the system, in order to infer the properties of the current state, by ensuring that the assimilated trajectories are consistent with both the observations and model dynamics. For many physical systems, particularly in oceanography, observations are usually available in the form of Lagrangian (particle trajectory) data that are augmented into models describing the flow fields. The incorporation of Lagrangian data into models of flow presents several challenges concerning the potential complexity of the Lagrangian trajectories in relatively simple flow fields, for example the appearance of nonlinear effects that are triggered by the exponential rate of separation of tracer trajectories in the region of saddle points [1]. As such, standard linear-based data assimilation methods, such as the Kalman filter, can fail. A nonlinear approach known as gradient descent assimilation [2] is presented, in which analysis trajectories are found by minimising a cost function in an extended state space. The gradient descent approach is demonstrated in the context of assimilating Lagrangian tracer trajectories in two-dimensional flows of point-vortex systems. The point-vortex model plays an important role as a simplified version of many physical systems, including Bose-Einstein condensates, certain plasma configurations and inviscid turbulence, in which the model dynamics are described by a relatively simple system of nonlinear ODEs, which can exhibit regular or chaotic motion for the 2-point vortex or 3-point vortex system respectively. A set of tracer advection equations augment the point vortex model equations, allowing the observed tracer positions to update the state information about the unobserved vortex postions. The gradient descent approach to the two-point vortex system has been successfully demonstrated for the case of both full and partial observations in a wide variety of test cases. [1] K. Ide, L. Kuznetsov and C. K. R. T. Jones. Lagrangian data assimilation for point vortex systems, Journal of Turbulence, 3, 053 (2002). [2] K. Judd, L. A. Smith and A. Weisheimer. Gradient free descent: Shadowing and state estimation using limited derivative information, Physica D, 190, 153-166 (2004).

Suckling, E. B.; Smith, L. A.

2012-04-01

212

Cerebellar glucose consumption in normal and pathologic states using fluorine-FDG and PET  

SciTech Connect

We studied cerebellar metabolism in 118 subjects including young and elderly controls and patients suffering from stroke, supratentorial brain tumor and Alzheimer's disease using fluorine-18 fluorodeoxyglucose ((/sup 18/F)FDG) and position emission tomography (PET). Alzheimer's disease and normal aging did not alter mean cerebellar metabolism. In stroke and tumor mean cerebellar metabolism was lower in the hemisphere contralateral to the supratentorial lesion. In tumor bilaterally significant reductions in absolute cerebellar metabolism also were noted, unlike stroke. Primary sensory stimulation did not alter absolute or relative cerebellar metabolism. These results show that absolute and relative values for cerebellar metabolism vary depending on the process under study. Thus, analysis schemes employing normalization of regional metabolic data to cerebellar values may be subject to error.

Kushner, M.; Tobin, M.; Alavi, A.; Chawluk, J.; Rosen, M.; Fazekas, F.; Alavi, J.; Reivich, M.

1987-11-01

213

Posterior inferior cerebellar artery aneurysm in the fourth ventricle  

Microsoft Academic Search

We report a patient with a ruptured aneurysm of the choroidal branch of the right posterior inferior cerebellar artery (PICA), lying in and causing an isolated haemorrhage in the fourth ventricle. MRI on the first day after bleeding revealed an abnormal vessel in the fourth ventricle, which was surrounded by a mass of intermediate signal on T1- and T2-weighted images.

H. Urbach; B. Meyer; C. Cedzich; L. Solymosi

1995-01-01

214

Spectrum of the Posterior Inferior Cerebellar Artery Territory Infarcts  

Microsoft Academic Search

Background and Purpose: The clinical, etiological and stroke mechanisms are defined well before but the detailed clinical and etiologic mechanisms regarding to all clinical spectrum of posterior inferior cerebellar artery (PICA) infarcts were not systematically studied by diffusion-weighted imaging (DWI). Methods: Seventy-four patients with PICA territory ischemic lesion proved by DWI with decreased apparent diffusion coefficient and FLAIR (fluid attenuation

Emre Kumral; Ceyla Ataç; Nilgün Yünten

2005-01-01

215

Cell-Autonomous Death of Cerebellar Purkinje Neurons with Autophagy  

E-print Network

Cell-Autonomous Death of Cerebellar Purkinje Neurons with Autophagy in Niemann-Pick Type C Disease molecules such as sterols and steroids and a robust inflammatory response within the brain parenchyma the basis of neurodegeneration in chimeric mice that have functional npc1 in only some cells. Death

Quake, Stephen R.

216

Cerebellar Morphology in Tourette Syndrome and Obsessive-Compulsive Disorder  

PubMed Central

Objective Neuroanatomical and functional imaging studies have identified the cerebellum as an integral component of motor and language control. Few studies, however, have investigated the role of the cerebellum in Tourette syndrome (TS), a condition defined by the presence of semi-involuntary movements and sounds. Methods Magnetic resonance imaging was conducted in 163 persons with TS and 147 control participants. Multivariate linear regression models were used to explore effects on cerebellar surface morphology and underlying volumes for the main diagnosis effects of TS as well as comorbid obsessive-compulsive disorder (OCD) and attention-deficit/hyperactivity disorder. Additionally, the correlations of symptom severity with cerebellar morphology were also assessed. Results The TS group demonstrated reduced volumes of the cerebellar hemispheres bilaterally that derived primarily from reduced gray matter in crus I and lobules VI, VIIB, and VIIIA. These decreased regional volumes accompanied increasing tic symptom severity and motoric disinhibition as demonstrated by a finger tapping test. Males had reduced volumes of these same regions compared with females, irrespective of diagnosis. Comorbid OCD was associated with relative enlargement of these regions in proportion to the increasing severity of OCD symptoms. Interpretation The cerebellum is involved in the pathogenesis of TS and tic-related OCD. Baseline gender differences in cerebellar morphology may in part account for the more prevalent expression of TS in males. PMID:20437583

Tobe, Russell H.; Bansal, Ravi; Xu, Dongrong; Hao, Xuejun; Liu, Jun; Sanchez, Juan; Peterson, Bradley S.

2014-01-01

217

Cerebellar Morphology in Tourette Syndrome and Obsessive-Compulsive  

E-print Network

Cerebellar Morphology in Tourette Syndrome and Obsessive-Compulsive Disorder Russell H. Tobe, MD morphology and under- lying volumes for the main diagnosis effects of TS as well as comorbid obsessive and attenuates during adolescence. TS is 3­4 more com- mon in males.1,2 Obsessive-compulsive disorder (OCD

218

Cerebellar Zonal Patterning Relies on Purkinje Cell Neurotransmission  

PubMed Central

Cerebellar circuits are patterned into an array of topographic parasagittal domains called zones. The proper connectivity of zones is critical for motor coordination and motor learning, and in several neurological diseases cerebellar circuits degenerate in zonal patterns. Despite recent advances in understanding zone function, we still have a limited understanding of how zones are formed. Here, we focused our attention on Purkinje cells to gain a better understanding of their specific role in establishing zonal circuits. We used conditional mouse genetics to test the hypothesis that Purkinje cell neurotransmission is essential for refining prefunctional developmental zones into sharp functional zones. Our results show that inhibitory synaptic transmission in Purkinje cells is necessary for the precise patterning of Purkinje cell zones and the topographic targeting of mossy fiber afferents. As expected, blocking Purkinje cell neurotransmission caused ataxia. Using in vivo electrophysiology, we demonstrate that loss of Purkinje cell communication altered the firing rate and pattern of their target cerebellar nuclear neurons. Analysis of Purkinje cell complex spike firing revealed that feedback in the cerebellar nuclei to inferior olive to Purkinje cell loop is obstructed. Loss of Purkinje neurotransmission also caused ectopic zonal expression of tyrosine hydroxylase, which is only expressed in adult Purkinje cells when calcium is dysregulated and if excitability is altered. Our results suggest that Purkinje cell inhibitory neurotransmission establishes the functional circuitry of the cerebellum by patterning the molecular zones, fine-tuning afferent circuitry, and shaping neuronal activity. PMID:24920627

White, Joshua J.; Arancillo, Marife; Stay, Trace L.; George-Jones, Nicholas A.; Levy, Sabrina L.; Heck, Detlef H.

2014-01-01

219

Variable timing of synaptic transmission in cerebellar unipolar brush cells  

PubMed Central

The cerebellum ensures the smooth execution of movements, a task that requires accurate neural signaling on multiple time scales. Computational models of cerebellar timing mechanisms have suggested that temporal information in cerebellum-dependent behavioral tasks is in part computed locally in the cerebellar cortex. These models rely on the local generation of delayed signals spanning hundreds of milliseconds, yet the underlying neural mechanism remains elusive. Here we show that a granular layer interneuron, called the unipolar brush cell, is well suited to represent time intervals in a robust way in the cerebellar cortex. Unipolar brush cells exhibited delayed increases in excitatory synaptic input in response to presynaptic stimulation in mouse cerebellar slices. Depending on the frequency of stimulation, delays extended from zero up to hundreds of milliseconds. Such controllable protraction of delayed currents was the result of an unusual mode of synaptic integration, which was well described by a model of steady-state AMPA receptor activation. This functionality extends the capabilities of the cerebellum for adaptive control of behavior by facilitating appropriate output in a broad temporal window. PMID:24706875

van Dorp, Stijn; De Zeeuw, Chris I.

2014-01-01

220

Variation in Brain Organization and Cerebellar Foliation in Chondrichthyans: Batoids  

Microsoft Academic Search

Interspecific variation in relative brain size (encephalization), the relative size of the five major brain areas (the telencephalon, diencephalon, mesencephalon, cerebellum, and medulla) and the level of cerebellar foliation was assessed in over 20 representative species of batoid (skates and rays), from eight families. Using species as independent data points and phylogenetically independent contrasts, relationships among each of the neuroanatomical

Thomas J. Lisney; Kara E. Yopak; John C. Montgomery; Shaun P. Collin

2008-01-01

221

Concomitant tubercular and fungal cerebellar abscess in an immunocompromised girl.  

PubMed

Concomitant tubercular and fungal cerebellar abscess is rare and we report the first concomitant recurrent multi-lobulated tubercular and fungal cerebellar abscess in an immunocompromised girl with Histiocytosis-X. She presented with cerebellar abscess history diagnosed during the ongoing treatment for tuberculous meningitis. The abscess was drained. Upon the detection of cerebellar abscess recurrence and pulmonary infection, she was referred to our clinic five weeks after the first surgical intervention. Patient was conscious, co-operating but confused. She had severe cachexia, stiff neck and fever. Fundus examination showed bilateral papilledema. Cranial MR images revealed multiple lobulated lesions. Suboccipital craniectomy was performed and abscess was evacuated in toto. Lesion was multi-lobulated. Thick, yellow-gray purulent material was drained. Histopathological examinations yielded Langhans giant cells,budding and branching fungal structures. Fungal infection was identified. We emphasize that posterior decompression and total resection should be considered first in the management of lesions with mass effect in the posterior fossa. Also the presence of concomitant fatal fungal abscess highlights that although the clinic and former diagnoses of the patient may direct the clinician to a certain pathogen, unusual resistant organisms should not be. PMID:23344873

Simsek, Hakan; Kutlay, Murat; Colak, Ahmet; Haholu, Aptullah; Kaya, Hatice; Ozyurt, Mustafa; Demircan, Mehmet Nusret

2013-01-01

222

Cerebellar Substrates for Error Correction in Motor Conditioning  

Microsoft Academic Search

The authors evaluate a mapping of Rescorla and Wagner's (1972) behavioral model of classical conditioning onto the cerebellar substrates for motor reflex learning and illustrate how the limitations of the Rescorla-Wagner model are just as useful as its successes for guiding the development of new psychobiological theories of learning. They postulate that the inhibitory pathway that returns conditioned response information

Mark A. Gluck; M. Todd Allen; Catherine E. Myers; Richard F. Thompson

2001-01-01

223

From the Cover: Cerebellar role in fear-conditioning consolidation  

Microsoft Academic Search

Some cerebellar structures are known to be involved in the memorization of several conditioned responses. The role of the interpositus nucleus (IN) and the vermis (VE) in fear-conditioning consolidation was investigated by means of a combined behavioral and neurophysiological technique. The IN and VE were subjected to fully reversible tetrodotoxin (TTX) inactivation during consolidation in adult male Wistar rats that

Benedetto Sacchetti; Elisabetta Baldi; Carlo Ambrogi Lorenzini; Corrado Bucherelli

2002-01-01

224

Neurodevelopmental Outcomes in Children with Cerebellar Malformations: A Systematic Review  

ERIC Educational Resources Information Center

Cerebellar malformations are increasingly diagnosed in the fetal period. Consequently, their consideration requires stressful and often critical decisions from both clinicians and families. This has resulted in an emergent need to understand better the impact of these early life lesions on child development. We performed a comprehensive literature…

Bolduc, Marie-Eve; Limperopoulos, Catherine

2009-01-01

225

Translational Approach to Behavioral Learning: Lessons from Cerebellar Plasticity  

PubMed Central

The role of cerebellar plasticity has been increasingly recognized in learning. The privileged relationship between the cerebellum and the inferior olive offers an ideal circuit for attempting to integrate the numerous evidences of neuronal plasticity into a translational perspective. The high learning capacity of the Purkinje cells specifically controlled by the climbing fiber represents a major element within the feed-forward and feedback loops of the cerebellar cortex. Reciprocally connected with the basal ganglia and multimodal cerebral domains, this cerebellar network may realize fundamental functions in a wide range of behaviors. This review will outline the current understanding of three main experimental paradigms largely used for revealing cerebellar functions in behavioral learning: (1) the vestibuloocular reflex and smooth pursuit control, (2) the eyeblink conditioning, and (3) the sensory envelope plasticity. For each of these experimental conditions, we have critically revisited the chain of causalities linking together neural circuits, neural signals, and plasticity mechanisms, giving preference to behaving or alert animal physiology. Namely, recent experimental approaches mixing neural units and local field potentials recordings have demonstrated a spike timing dependent plasticity by which the cerebellum remains at a strategic crossroad for deciphering fundamental and translational mechanisms from cellular to network levels. PMID:24319600

Cheron, Guy; Dan, Bernard; Márquez-Ruiz, Javier

2013-01-01

226

Extrapyramidal and cerebellar syndrome with encephalopathy associated with cimetidine  

PubMed Central

A possible case of cimetidine induced extrapyramidal and cerebellar features is reported. Although confusion is a well recognized toxic effect of cimetidine, other neurotoxic features are less common, especially in patients without evidence of renal or hepatic disease. Cimetidine should be used with great care and possibly in a reduced dose in the elderly as neuropsychiatric side effects may occur. PMID:7134098

Handler, Clive E.; Besse, Christopher P.; Wilson, Adrian O.

1982-01-01

227

Speech and Language Findings Associated with Paraneoplastic Cerebellar Degeneration  

ERIC Educational Resources Information Center

Paraneoplastic cerebellar degeneration (PCD) is an autoimmune disease that can be associated with cancer of the breast, lung, and ovary. The clinical presentation of PCD commonly includes ataxia, visual disturbances, and dysarthria. The speech disturbances associated with PCD have not been well characterized, despite general acceptance that…

Paslawski, Teresa; Duffy, Joseph R.; Vernino, Steven

2005-01-01

228

Eyeblink Conditioning Deficits Indicate Timing and Cerebellar Abnormalities in Schizophrenia  

ERIC Educational Resources Information Center

Accumulating evidence indicates that individuals with schizophrenia manifest abnormalities in structures (cerebellum and basal ganglia) and neurotransmitter systems (dopamine) linked to internal-timing processes. A single-cue tone delay eyeblink conditioning paradigm comprised of 100 learning and 50 extinction trials was used to examine cerebellar

Brown, S.M.; Kieffaber, P.D.; Carroll, C.A.; Vohs, J.L.; Tracy, J.A.; Shekhar, A.; O'Donnell, B.F.; Steinmetz, J.E.; Hetrick, W.P.

2005-01-01

229

Is a Cerebellar Deficit the Underlying Cause of Reading Disabilities?  

ERIC Educational Resources Information Center

This study investigated whether children with dyslexia differed in their performance on reading, phonological, rapid naming, motor, and cerebellar-related tasks and automaticity measures compared to reading age (RA)-matched and chronological age (CA)-matched control groups. Participants were 51 children attending mainstream English elementary…

Irannejad, Shahrzad; Savage, Robert

2012-01-01

230

Late effects of radiotherapy on patients with cerebellar medulloblastoma  

Microsoft Academic Search

Nine long-term survivors of cerebellar medulloblastoma treated with surgery and irradiation were retrospectively examined with a complete battery of neuropsychological tests and the results compared with their nonirradiated siblings. Significant decreased scores were found in the full-scale intelligence quotients (IQ), performance IQ, and verbal IQ with all nine irradiated patients scoring below their siblings. Also, educational quotients (EQ) of the

C. L. Silverman; H. Palkes; B. Talent; E. Kovnar; J. W. Clouse; Prm Thomas

1984-01-01

231

Mars Exploration Rover Terminal Descent Mission Modeling and Simulation  

NASA Technical Reports Server (NTRS)

Because of NASA's added reliance on simulation for successful interplanetary missions, the MER mission has developed a detailed EDL trajectory modeling and simulation. This paper summarizes how the MER EDL sequence of events are modeled, verification of the methods used, and the inputs. This simulation is built upon a multibody parachute trajectory simulation tool that has been developed in POST I1 that accurately simulates the trajectory of multiple vehicles in flight with interacting forces. In this model the parachute and the suspended bodies are treated as 6 Degree-of-Freedom (6 DOF) bodies. The terminal descent phase of the mission consists of several Entry, Descent, Landing (EDL) events, such as parachute deployment, heatshield separation, deployment of the lander from the backshell, deployment of the airbags, RAD firings, TIRS firings, etc. For an accurate, reliable simulation these events need to be modeled seamlessly and robustly so that the simulations will remain numerically stable during Monte-Carlo simulations. This paper also summarizes how the events have been modeled, the numerical issues, and modeling challenges.

Raiszadeh, Behzad; Queen, Eric M.

2004-01-01

232

Controller evaluations of the descent advisor automation aid  

NASA Technical Reports Server (NTRS)

An automation aid to assist air traffic controllers in efficiently spacing traffic and meeting arrival times at a fix has been developed at NASA Ames Research Center. The automation aid, referred to as the descent advisor (DA), is based on accurate models of aircraft performance and weather conditions. The DA generates suggested clearances, including both top-of-descent point and speed profile data, for one or more aircraft in order to achieve specific time or distance separation objectives. The DA algorithm is interfaced with a mouse-based, menu-driven controller display that allows the air traffic controller to interactively use its accurate predictive capability to resolve conflicts and issue advisories to arrival aircraft. This paper focuses on operational issues concerning the utilization of the DA, specifically, how the DA can be used for prediction, intrail spacing, and metering. In order to evaluate the DA, a real time simulation was conducted using both current and retired controller subjects. Controllers operated in teams of two, as they do in the present environment; issues of training and team interaction will be discussed. Evaluations by controllers indicated considerable enthusiasm for the DA aid, and provided specific recommendations for using the tool effectively.

Tobias, Leonard; Volckers, Uwe; Erzberger, Heinz

1989-01-01

233

Accelerated Mini-batch Randomized Block Coordinate Descent Method  

PubMed Central

We consider regularized empirical risk minimization problems. In particular, we minimize the sum of a smooth empirical risk function and a nonsmooth regularization function. When the regularization function is block separable, we can solve the minimization problems in a randomized block coordinate descent (RBCD) manner. Existing RBCD methods usually decrease the objective value by exploiting the partial gradient of a randomly selected block of coordinates in each iteration. Thus they need all data to be accessible so that the partial gradient of the block gradient can be exactly obtained. However, such a “batch” setting may be computationally expensive in practice. In this paper, we propose a mini-batch randomized block coordinate descent (MRBCD) method, which estimates the partial gradient of the selected block based on a mini-batch of randomly sampled data in each iteration. We further accelerate the MRBCD method by exploiting the semi-stochastic optimization scheme, which effectively reduces the variance of the partial gradient estimators. Theoretically, we show that for strongly convex functions, the MRBCD method attains lower overall iteration complexity than existing RBCD methods. As an application, we further trim the MRBCD method to solve the regularized sparse learning problems. Our numerical experiments shows that the MRBCD method naturally exploits the sparsity structure and achieves better computational performance than existing methods. PMID:25620860

Zhao, Tuo; Yu, Mo; Wang, Yiming; Arora, Raman; Liu, Han

2014-01-01

234

Adaptive robotic control driven by a versatile spiking cerebellar network.  

PubMed

The cerebellum is involved in a large number of different neural processes, especially in associative learning and in fine motor control. To develop a comprehensive theory of sensorimotor learning and control, it is crucial to determine the neural basis of coding and plasticity embedded into the cerebellar neural circuit and how they are translated into behavioral outcomes in learning paradigms. Learning has to be inferred from the interaction of an embodied system with its real environment, and the same cerebellar principles derived from cell physiology have to be able to drive a variety of tasks of different nature, calling for complex timing and movement patterns. We have coupled a realistic cerebellar spiking neural network (SNN) with a real robot and challenged it in multiple diverse sensorimotor tasks. Encoding and decoding strategies based on neuronal firing rates were applied. Adaptive motor control protocols with acquisition and extinction phases have been designed and tested, including an associative Pavlovian task (Eye blinking classical conditioning), a vestibulo-ocular task and a perturbed arm reaching task operating in closed-loop. The SNN processed in real-time mossy fiber inputs as arbitrary contextual signals, irrespective of whether they conveyed a tone, a vestibular stimulus or the position of a limb. A bidirectional long-term plasticity rule implemented at parallel fibers-Purkinje cell synapses modulated the output activity in the deep cerebellar nuclei. In all tasks, the neurorobot learned to adjust timing and gain of the motor responses by tuning its output discharge. It succeeded in reproducing how human biological systems acquire, extinguish and express knowledge of a noisy and changing world. By varying stimuli and perturbations patterns, real-time control robustness and generalizability were validated. The implicit spiking dynamics of the cerebellar model fulfill timing, prediction and learning functions. PMID:25390365

Casellato, Claudia; Antonietti, Alberto; Garrido, Jesus A; Carrillo, Richard R; Luque, Niceto R; Ros, Eduardo; Pedrocchi, Alessandra; D'Angelo, Egidio

2014-01-01

235

Cerebellar damage diminishes long-latency responses to multijoint perturbations.  

PubMed

Damage to the cerebellum can cause significant problems in the coordination of voluntary arm movements. One prominent idea is that incoordination stems from an inability to predictively account for the complex mechanical interactions between the arm's several joints. Motivated by growing evidence that corrective feedback control shares important capabilities and neural substrates with feedforward control, we asked whether cerebellar damage impacts feedback stabilization of the multijoint arm appropriate for the arm's intersegmental dynamics. Specifically, we tested whether cerebellar dysfunction impacts the ability of posterior deltoid to incorporate elbow motion in its long-latency response (R2 = 45-75 ms and R3 = 75-100 ms after perturbation) to an unexpected torque perturbation. Healthy and cerebellar-damaged subjects were exposed to a selected pattern of shoulder-elbow displacements to probe the response pattern from this shoulder extensor muscle. The healthy elderly subjects expressed a long-latency response linked to both shoulder and elbow motion, including an increase/decrease in shoulder extensor activity with elbow flexion/extension. Critically, cerebellar-damaged subjects displayed the normal pattern of activity in the R3 period indicating an intact ability to rapidly integrate multijoint motion appropriate to the arm's intersegmental dynamics. However, cerebellar-damaged subjects had a lower magnitude of activity that was specific to the long-latency period (both R2 and R3) and a slightly delayed onset of multijoint sensitivity. Taken together, our results suggest that the basic motor pattern of the long-latency response is housed outside the cerebellum and is scaled by processes within the cerebellum. PMID:23390311

Kurtzer, Isaac; Trautman, Paxson; Rasquinha, Russell J; Bhanpuri, Nasir H; Scott, Stephen H; Bastian, Amy J

2013-04-01

236

Adaptive Robotic Control Driven by a Versatile Spiking Cerebellar Network  

PubMed Central

The cerebellum is involved in a large number of different neural processes, especially in associative learning and in fine motor control. To develop a comprehensive theory of sensorimotor learning and control, it is crucial to determine the neural basis of coding and plasticity embedded into the cerebellar neural circuit and how they are translated into behavioral outcomes in learning paradigms. Learning has to be inferred from the interaction of an embodied system with its real environment, and the same cerebellar principles derived from cell physiology have to be able to drive a variety of tasks of different nature, calling for complex timing and movement patterns. We have coupled a realistic cerebellar spiking neural network (SNN) with a real robot and challenged it in multiple diverse sensorimotor tasks. Encoding and decoding strategies based on neuronal firing rates were applied. Adaptive motor control protocols with acquisition and extinction phases have been designed and tested, including an associative Pavlovian task (Eye blinking classical conditioning), a vestibulo-ocular task and a perturbed arm reaching task operating in closed-loop. The SNN processed in real-time mossy fiber inputs as arbitrary contextual signals, irrespective of whether they conveyed a tone, a vestibular stimulus or the position of a limb. A bidirectional long-term plasticity rule implemented at parallel fibers-Purkinje cell synapses modulated the output activity in the deep cerebellar nuclei. In all tasks, the neurorobot learned to adjust timing and gain of the motor responses by tuning its output discharge. It succeeded in reproducing how human biological systems acquire, extinguish and express knowledge of a noisy and changing world. By varying stimuli and perturbations patterns, real-time control robustness and generalizability were validated. The implicit spiking dynamics of the cerebellar model fulfill timing, prediction and learning functions. PMID:25390365

Casellato, Claudia; Antonietti, Alberto; Garrido, Jesus A.; Carrillo, Richard R.; Luque, Niceto R.; Ros, Eduardo; Pedrocchi, Alessandra; D'Angelo, Egidio

2014-01-01

237

Functional Relations of Cerebellar Modules of the Cat  

PubMed Central

The cerebellum consists of parasagittal zones that define fundamental modules of neural processing. Each zone receives input from a distinct subdivision of the inferior olive (IO)—activity in one olivary subdivision will affect activity in one cerebellar module. To define functions of the cerebellar modules, we inactivated specific olivary subdivisions in six male cats with a glutamate receptor blocker. Olivary inactivation eliminates Purkinje cell complex spikes, which results in a high rate of Purkinje cell simple spike discharge. The increased simple spike discharge inhibits output from connected regions of the cerebellar nuclei. After inactivation, behavior was evaluated during a reach-to-grasp task and during locomotion. Inactivation of each subdivision produced unique behavioral deficits. Performance of the reach-to-grasp task was affected by inactivation of the rostral dorsal accessory olive (rDAO) and the rostral medial accessory olive (rMAO) and, possibly, the principal olive. rDAO inactivation produced paw drag during locomotion and a deficit in grasping the handle during the reach-to-grasp task. rMAO inactivation caused the cats to reach under the handle and produced severe limb drag during locomotion. Inactivation of the dorsal medial cell column, cell group ?, or caudal medial accessory olive produced little deficit in the reach-to-grasp task, but each produced a different deficit during locomotion. In all cases, the cats appeared to have intact sensation, good spatial awareness, and no change of affect. Normal cerebellar function requires low rates of IO discharge, and each cerebellar module has a specific and unique function in sensory–motor integration. PMID:20631170

Pong, Milton; Gibson, Alan R.

2010-01-01

238

Active lytic infection of human primary tonsillar B cells by KSHV and its noncytolytic control by activated CD4+ T cells.  

PubMed

Kaposi sarcoma-associated herpesvirus (KSHV) is a B-lymphotropic virus whose primary site of replication is the oropharynx. KSHV can infect both T and B cells from primary tonsillar explant cultures. However, T cells do not support lytic replication, while B cells spontaneously produce substantial amounts of infectious virus. Here, we provide evidence for a mechanism by which activated T cells may promote or stabilize latency of KSHV infection in B cells. When mixed cultures of B cells and activated T cells were exposed to KSHV, little spontaneous virus production was observed. Removing T cells from the mix or treating the mixed culture with immune suppressants enhanced virus production. Adding back activated T cells to purified infected B cells efficiently suppressed KSHV production, primarily due to CD4(+) T cells. This suppressive activity required T cell activation and direct cell-cell contact, but not prior exposure to KSHV antigen. Suppression was not MHC restricted and did not result in killing of the target cell. We therefore propose that oropharyngeal T cells activated by a variety of stimuli can recognize ligands on infected target B cells, leading to signaling events that prevent spontaneous lytic activation and promote latent infection in this compartment. PMID:21339648

Myoung, Jinjong; Ganem, Don

2011-03-01

239

Axial block coordinate descent (ABCD) algorithm for X-ray CT image reconstruction  

E-print Network

1 Axial block coordinate descent (ABCD) algorithm for X-ray CT image reconstruction Jeffrey A simultaneously by inverting a dense k2 �k2 matrix · Loop over z before proceeding to next transaxial block x y 2 y z #12;10 Axial block coordinate descent (ABCD) outline for k = 1,...,K: (K = # of x-y locations

Fessler, Jeffrey A.

240

Prostate Cancer in Men of African Descent: Opportunities for Global Research Collaborations  

Cancer.gov

Prostate cancer disproportionately affects men of African descent in terms of incidence, morbidity, and mortality worldwide. Significant knowledge gaps exist about the factors that predict disparities in prostate cancer incidence and outcomes between men of African descent and other ethnic or racial groups.

241

Analysis of AIRE Continuous Descent Arrival operations at Atlanta and Miami  

Microsoft Academic Search

A continuous descent arrival (CDA) is a cockpit based flight technique characterized by operations that descend continuously at or near idle power settings resulting in reduced noise and emissions compared to standard stair-step arrival techniques. The development of published optimized profile descent (OPD) procedures that permit use of the CDA technique is generally considered to be a key step in

Kevin R. Sprong; Kathryn A. Klein; C. Shiotsuki; J. Arrighi; S. Liu

2008-01-01

242

A block-based gradient descent search algorithm for block motion estimation in video coding  

Microsoft Academic Search

A block-based gradient descent search (BBGDS) algorithm is proposed in this paper to perform block motion estimation in video coding. The BBGDS evaluates the values of a given objective function starting from a small centralized checking block. The minimum within the checking block is found, and the gradient descent direction where the minimum is expected to lie is used to

Lurng-Kuo Liu; E. Feig

1996-01-01

243

Proving Mordell-Weil: A Descent in Three Parts A Senior Thesis Of  

E-print Network

3 #12;Introductions In 1659, Pierre de Fermat wrote to Christiaan Huygens claiming to have on elliptic curves. In this thesis, we examine three of these moments: (1) Pierre de Fermat's proof. Descent 1: Fermat's Infinite Descent 40 Conclusion 43 Appendix A. Cohomology of Groups 45 Bibliography 48

Stein, William

244

ccsd-00014292,version1-23Nov2005 The Shintani descents of Suzuki Groups  

E-print Network

ccsd-00014292,version1-23Nov2005 The Shintani descents of Suzuki Groups and consequences Olivier to every cuspidal unipotent character of the Suzuki group its root of unity and to give a possible. We compute to this end the Shintani descents of Suzuki groups and use results of Digne and Michel. 1

Boyer, Edmond

245

Miniature coherent velocimeter and altimeter (MCVA) for terminal descent control on lunar and planetary landers  

NASA Technical Reports Server (NTRS)

While the overall architecture of an Entry Descent and Landing (EDL) system may vary depending on specific mission requirementsw, measurements of the rate vector with respect to the surface is a primary requirement for the Terminal Descent Control (TDC) phase of any controlled lander.

Chang, Dan; Cardell, Greg; Szwaykowski, Piotr; Shaffat, Syed T.; Meras, Patrick

2005-01-01

246

Cerebellar Transcranial Direct Current Stimulation (ctDCS): A Novel Approach to Understanding Cerebellar Function in Health and Disease.  

PubMed

The cerebellum is critical for both motor and cognitive control. Dysfunction of the cerebellum is a component of multiple neurological disorders. In recent years, interventions have been developed that aim to excite or inhibit the activity and function of the human cerebellum. Transcranial direct current stimulation of the cerebellum (ctDCS) promises to be a powerful tool for the modulation of cerebellar excitability. This technique has gained popularity in recent years as it can be used to investigate human cerebellar function, is easily delivered, is well tolerated, and has not shown serious adverse effects. Importantly, the ability of ctDCS to modify behavior makes it an interesting approach with a potential therapeutic role for neurological patients. Through both electrical and non-electrical effects (vascular, metabolic) ctDCS is thought to modify the activity of the cerebellum and alter the output from cerebellar nuclei. Physiological studies have shown a polarity-specific effect on the modulation of cerebellar-motor cortex connectivity, likely via cerebellar-thalamocortical pathways. Modeling studies that have assessed commonly used electrode montages have shown that the ctDCS-generated electric field reaches the human cerebellum with little diffusion to neighboring structures. The posterior and inferior parts of the cerebellum (i.e., lobules VI-VIII) seem particularly susceptible to modulation by ctDCS. Numerous studies have shown to date that ctDCS can modulate motor learning, and affect cognitive and emotional processes. Importantly, this intervention has a good safety profile; similar to when applied over cerebral areas. Thus, investigations have begun exploring ctDCS as a viable intervention for patients with neurological conditions. PMID:25406224

Grimaldi, Giuliana; Argyropoulos, Georgios P; Bastian, Amy; Cortes, Mar; Davis, Nicholas J; Edwards, Dylan J; Ferrucci, Roberta; Fregni, Felipe; Galea, Joseph M; Hamada, Masahi; Manto, Mario; Miall, R Chris; Morales-Quezada, Leon; Pope, Paul A; Priori, Alberto; Rothwell, John; Tomlinson, S Paul; Celnik, Pablo

2014-11-18

247

Development of cerebellar neurons and glias revealed by in utero electroporation: Golgi-like labeling of cerebellar neurons and glias.  

PubMed

Cerebellar cortical functions rely on precisely arranged cytoarchitectures composed of several distinct types of neurons and glias. Studies have indicated that cerebellar excitatory and inhibitory neurons have distinct spatial origins, the upper rhombic lip (uRL) and ventricular zone (VZ), respectively, and that different types of neurons have different birthdates. However, the spatiotemporal relationship between uRL/VZ progenitors and their final phenotype remains poorly understood due to technical limitations. To address this issue, we performed in utero electroporation (IUE) of fluorescent protein plasmids using mouse embryos to label uRL/VZ progenitors at specific developmental stages, and observed labeled cells at maturity. To overcome any potential dilution of the plasmids caused by progenitor division, we also utilized constructs that enable permanent labeling of cells. Cerebellar neurons and glias were labeled in a Golgi-like manner enabling ready identification of labeled cells. Five types of cerebellar neurons, namely Purkinje, Golgi, Lugaro and unipolar brush cells, large-diameter deep nuclei (DN) neurons, and DN astrocytes were labeled by conventional plasmids, whereas plasmids that enable permanent labeling additionally labeled stellate, basket, and granule cells as well as three types of glias. IUE allows us to label uRL/VZ progenitors at different developmental stages. We found that the five types of neurons and DN astrocytes were labeled in an IUE stage-dependent manner, while stellate, basket, granule cells and three types of glias were labeled regardless of the IUE stage. Thus, the results indicate the IUE is an efficient method to track the development of cerebellar cells from uRL/VZ progenitors facing the ventricular lumen. They also indicate that while the generation of the five types of neurons by uRL/VZ progenitors is regulated in a time-dependent manner, the progenitor pool retains multipotency throughout embryonic development. PMID:23894597

Kita, Yoshiaki; Kawakami, Koichi; Takahashi, Yoshiko; Murakami, Fujio

2013-01-01

248

In and out of the loop: external and internal modulation of the olivo-cerebellar loop  

PubMed Central

Cerebellar anatomy is known for its crystal like structure, where neurons and connections are precisely and repeatedly organized with minor variations across the Cerebellar Cortex. The olivo-cerebellar loop, denoting the connections between the Cerebellar cortex, Inferior Olive and Cerebellar Nuclei (CN), is also modularly organized to form what is known as the cerebellar module. In contrast to the relatively organized and static anatomy, the cerebellum is innervated by a wide variety of neuromodulator carrying axons that are heterogeneously distributed along the olivo-cerebellar loop, providing heterogeneity to the static structure. In this manuscript we review modulatory processes in the olivo-cerebellar loop. We start by discussing the relationship between neuromodulators and the animal behavioral states. This is followed with an overview of the cerebellar neuromodulatory signals and a short discussion of why and when the cerebellar activity should be modulated. We then devote a section for three types of neurons where we briefly review its properties and propose possible neuromodulation scenarios. PMID:23626524

Libster, Avraham M.; Yarom, Yosef

2013-01-01

249

Evaluation of vertical profiles to design continuous descent approach procedure  

NASA Astrophysics Data System (ADS)

The current research focuses on predictability, variability and operational feasibility aspect of Continuous Descent Approach (CDA), which is among the key concepts of the Next Generation Air Transportation System (NextGen). The idle-thrust CDA is a fuel economical, noise and emission abatement procedure, but requires increased separation to accommodate for variability and uncertainties in vertical and speed profiles of arriving aircraft. Although a considerable amount of researches have been devoted to the estimation of potential benefits of the CDA, only few have attempted to explain the predictability, variability and operational feasibility aspect of CDA. The analytical equations derived using flight dynamics and Base of Aircraft and Data (BADA) Total Energy Model (TEM) in this research gives insight into dependency of vertical profile of CDA on various factors like wind speed and gradient, weight, aircraft type and configuration, thrust settings, atmospheric factors (deviation from ISA (DISA), pressure and density of the air) and descent speed profile. Application of the derived equations to idle-thrust CDA gives an insight into sensitivity of its vertical profile to multiple factors. This suggests fixed geometric flight path angle (FPA) CDA has higher degree of predictability and lesser variability at the cost of non-idle and low thrust engine settings. However, with optimized design this impact can be overall minimized. The CDA simulations were performed using Future ATM Concept Evaluation Tool (FACET) based on radar-track and aircraft type data (BADA) of the real air-traffic to some of the busiest airports in the USA (ATL, SFO and New York Metroplex (JFK, EWR and LGA)). The statistical analysis of the vertical profiles of CDA shows 1) mean geometric FPAs derived from various simulated vertical profiles are consistently shallower than 3° glideslope angle and 2) high level of variability in vertical profiles of idle-thrust CDA even in absence of uncertainties in external factors. Analysis from operational feasibility perspective suggests that two key features of the performance based Flight Management System (FMS) i.e. required time of arrival (RTA) and geometric descent path would help in reduction of unpredictability associated with arrival time and vertical profile of aircraft guided by the FMS coupled with auto-pilot (AP) and auto-throttle (AT). The statistical analysis of the vertical profiles of CDA also suggests that for procedure design window type, 'AT or above' and 'AT or below' altitude and FPA constraints are more realistic and useful compared to obsolete 'AT' type altitude constraint.

Pradeep, Priyank

250

Medial cerebellar nuclear projections and activity patterns link cerebellar output to orofacial and respiratory behavior  

PubMed Central

There is ample evidence that the cerebellum plays an important role in coordinating both respiratory and orofacial movements. However, the pathway by which the cerebellum engages brainstem substrates underlying these movements is not well understood. We used tract-tracing techniques in mice to show that neurons in the medial deep cerebellar nucleus (mDCN) project directly to these putative substrates. Injection of an anterograde tracer into the mDCN produced terminal labeling in the ventromedial medullary reticular formation, which was stronger on the contralateral side. Correspondingly, injection of retrograde tracers into these same areas resulted in robust neuronal cell labeling in the contralateral mDCN. Moreover, injection of two retrograde tracers at different rostral–caudal brainstem levels resulted in a subset of double-labeled cells, indicating that single mDCN neurons collateralize to multiple substrates. Using an awake and behaving recording preparation, we show that spiking activity in mDCN neurons is correlated with respiratory and orofacial behaviors, including whisking and fluid licking. Almost half of the recorded neurons showed activity correlated with more than one behavior, suggesting that these neurons may in fact modulate multiple brainstem substrates. Collectively, these results describe a potential pathway through which the cerebellum could modulate and coordinate respiratory and orofacial behaviors. PMID:23565078

Lu, Lianyi; Cao, Ying; Tokita, Kenichi; Heck, Detlef H.; Jr., John D. Boughter

2013-01-01

251

Mars Science Laboratory Entry, Descent, and Landing System Overview  

NASA Technical Reports Server (NTRS)

In 2010, the Mars Science Laboratory (MSL) mission will pioneer the next generation of robotic Entry, Descent, and Landing (EDL) systems by delivering the largest and most capable rover to date to the surface of Mars. In addition to landing more mass than prior missions to Mars, MSL will offer access to regions of Mars that have been previously unreachable. The MSL EDL sequence is a result of a more stringent requirement set than any of its predecessors. Notable among these requirements is landing a 900 kg rover in a landing ellipse much smaller than that of any previous Mars lander. In meeting these requirements, MSL is extending the limits of the EDL technologies qualified by the Mars Viking, Mars Pathfinder, and Mars Exploration Rover missions.

Prakash, Ravi; Burkhart, P. Dan; Chen, Allen; Comeaux, Keith A.; Guernsey, Carl S.; Devin, M. Kipp; Mendeck, Gavin F.; Powell, Richard W.; Rivellini, Tommaso P.; San Martin, A. Miguel; Sell, Steven W.; Steltzner, Adam D.; Way, David W.

2008-01-01

252

SparseNet: Coordinate Descent With Nonconvex Penalties  

PubMed Central

We address the problem of sparse selection in linear models. A number of nonconvex penalties have been proposed in the literature for this purpose, along with a variety of convex-relaxation algorithms for finding good solutions. In this article we pursue a coordinate-descent approach for optimization, and study its convergence properties. We characterize the properties of penalties suitable for this approach, study their corresponding threshold functions, and describe a df-standardizing reparametrization that assists our pathwise algorithm. The MC+ penalty is ideally suited to this task, and we use it to demonstrate the performance of our algorithm. Certain technical derivations and experiments related to this article are included in the Supplementary Materials section.

Mazumder, Rahul; Friedman, Jerome H.; Hastie, Trevor

2014-01-01

253

Transitions and transversions in evolutionary descent - An approach to understanding  

NASA Technical Reports Server (NTRS)

A quantitative theoretical groundwork is presented for determining the proportions of the possible types of base substitutions observed between 12 genes sharing a common ancestor and isolated from extant species. Three methods (direct count, regression, and informational entropy maximization) are described by which conditional base substitution probabilities that determine evolutionary descent can be estimated from experimental data. These methods are utilized to study the ratio of transversions to transitions during gene divergence. The limiting ratio is directly calculated from a knowledge of the 12 conditional probabilities for each type of base substitution and from a knowledge of the equilibrium base composition of the DNAs compared. An expression is developed for this calculation. It is concluded that multiple substitutions per se do not lead to a decrease in transition differences with increasing evolutionary divergence.

Holmquist, R.

1983-01-01

254

RITD - Adapting Mars Entry, Descent and Landing System for Earth  

NASA Astrophysics Data System (ADS)

Abstract A new generation of in?atable Entry, Descent and Landing System (EDLS) or Mars has been developed. It is used in both the initial atmospheric entry and atmospheric descent before the semi-hard impact of the penetrator into Martian surface. The EDLS applicability to Earth’s atmosphere is studied by the EU/RITD [1] project. Project focuses to the analysis and tests of the transonic behaviour of this compact and light weight payload entry system at the Earth re-entry 1. EDLS for Earth The dynamical stability of the craft is analysed, concentrating on the most critical part of the atmospheric re-entry, the transonic phase. In Martian atmosphere the MetNet vehicle stability during the transonic phase is understood. However, in the more dense Earth’s atmosphere, the transonic phase is shorter and turbulence more violent. Therefore, the EDLS has to be sufficiently dynamically stable to overcome the forces tending to deflect the craft from its nominal trajectory and attitude. The preliminary design of the inflatable EDLS for Earth will be commenced once the scaling of the re-entry system and the dynamical stability analysis have been performed. The RITD-project concentrates on mission and applications achievable with the current MetNet-type (i.e. “Mini-1” category) of lander, and on requirements posed by other type Earth re-entry concepts. 2. Entry Angle Determination for Mini-1 - lander For successful Earth landing, the suitable re-entry angle and velocity with specific descent vehicle (DV) mass and heat flux parameters need to be determined. These key parameters in determining the Earth re-entry for DV are: - qmax (kW/m2): maximal specific heat flux, - Q (MJ/m2): specific integral heat flux to DV front shield, - m (kg): descent vehicle (DV) mass, - V (m/s): re-entry velocity and - theta(deg.): flight-path angle at Earth re-entry For Earth re-entry, the calculation results in the optimal value of entry velocity for MetNet (“Mini-1” category) -type lander, with mass of 22kg, being VSOL = 5268 m/s. Using the basic pre-defined parameters for MetNet-type of lander in Earth atmosphere, we get the optimal angle of = -3.06 degrees for Earth re-entry. 3. Payload Mass for Earth Entry DV One of the key elements in Earth entry lander is the amount of available payload mass. The payload mass depends on, e.g., the lander size, landing type (soil or water), heat shield durability and additional landing gear. The payload mass will have an impact to the center of gravity of the lander. The payload with a “low” CoG (compared the the lander structure) has a larger tolerance than the payload with “high” CoG. In cases where payload CoG causes instability, the extra balance mass can be used to adjust CoG. This balance mass will reduce the available payload mass. A major limitation for payload mass is the heat shielding. Acknowledgements The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 263255. References [1] http://ritd.fmi.fi

Heilimo, Jyri; Aleksashkin, Sergey; Martynov, Maxim; Schmidt, Walter; Harri, Ari-Matti; Vsevolod Koryanov, D.; Kazakovtcev, Victor; Haukka, Harri; Arruego, Ignacio; Finchenko, Valery; Ostresko, Boris; Ponomarenko, Andrei; Martin, Susanna; Siili, Tero

255

RITD - Adapting Mars Entry, Descent and Landing System for Earth  

NASA Astrophysics Data System (ADS)

A new generation of inflatable Entry, Descent and Landing System (EDLS) for Mars has been developed. It is used in both the initial atmospheric entry and atmospheric descent before the semi-hard impact of the penetrator into Martian surface. The EDLS applicability to Earth's atmosphere is studied by the EU/RITD [1] project. Project focuses to the analysis and tests of the transonic behaviour of this compact and light weight payload entry system at the Earth re-entry. 1. EDLS for Earth The dynamical stability of the craft is analysed, concentrating on the most critical part of the atmospheric re-entry, the transonic phase. In Martian atmosphere the MetNet vehicle stability during the transonic phase is understood. However, in the more dense Earth's atmosphere, the transonic phase is shorter and turbulence more violent. Therefore, the EDLS has to be sufficiently dynamically stable to overcome the forces tending to deflect the craft from its nominal trajectory and attitude. The preliminary design of the inflatable EDLS for Earth will be commenced once the scaling of the re-entry system and the dynamical stability analysis have been performed. The RITD-project concentrates on mission and applications achievable with the current MetNet-type (i.e. 'Mini-1' category) of lander, and on requirements posed by other type Earth re-entry concepts. 2. Entry Angle Determination for Mini-1 - lander For successful Earth landing, the suitable re-entry angle and velocity with specific descent vehicle (DV) mass and heat flux parameters need to be determined. These key parameters in determining the Earth re-entry for DV are: qmax (kW/m2): maximal specific heat flux, Q (MJ/m2): specific integral heat flux to DV front shield, m (kg): descent vehicle (DV) mass, V (m/s): re-entry velocity and ? (deg.): flight-path angle at Earth re-entry For Earth re-entry, the calculation results in the optimal value of entry velocity for MetNet ('Mini-1' category) -type lander, with mass of 22kg, being VSOL = 5268 m/s. Using the basic pre-defined parameters for MetNet-type of lander in Earth atmosphere, we get the optimal angle of ? = -3.06 degrees for Earth re-entry. 3. Payload Mass for Earth Entry DV One of the key elements in Earth entry lander is the amount of available payload mass. The payload mass depends on, e.g., the lander size, landing type (soil or water), heat shield durability and additional landing gear. The payload mass will have an impact to the center of gravity of the lander. The payload with a 'low' CoG (compared the the lander structure) has a larger tolerance than the payload with 'high' CoG. In cases where payload CoG causes instability, the extra balance mass can be used to adjust CoG. This balance mass will reduce the available payload mass. A major limitation for payload mass is the heat shielding. Acknowledgements The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 263255. References [1] http://ritd.fmi.fi

Heilimo, Jyri; Harri, Ari-Matti; Aleksashkin, Sergey; Koryanov, Vsevolod; Arruego, Ignacio; Schmidt, Walter; Haukka, Harri; Finchenko, Valery; Martynov, Maxim; Ostresko, Boris; Ponomarenko, Andrey; Kazakovtsev, Viktor; Martin, Susanna; Siili, Tero

2014-05-01

256

CryoScout: A Descent Through the Mars Polar Cap  

NASA Technical Reports Server (NTRS)

CryoScout was proposed as a subsurface investigation of the stratigraphic climate record embedded in Mars North Polar cap. After landing on a gentle landscape in the midst of the mild summer season, CryoScout was to use the continuous polar sunlight to power the descent of a cryobot, a thermal probe, into the ice at a rate of about 1 m per day. CryoScout would probe deep enough into this time capsule to see the effects of planetary obliquity variations and discrete events such as dust storms or volcanic eruptions. By penetrating tens of meters of ice, the mission would explore at least one of the dominant "MOC layers" observed in exposed layered terrain.

Hecht, M. H.; Saunders, R. S.

2003-01-01

257

Assessment on EXPERT Descent and Landing System Aerodynamics  

NASA Astrophysics Data System (ADS)

EXPERT is a re-entry vehicle designed for validation of aero-thermodynamic models, numerical schemes in Computational Fluid Dynamics codes and test facilities for measuring flight data under an Earth re-entry environment. This paper addresses the design for the descent and landing sequence for EXPERT. It includes the descent sequence, the choice of drogue and main parachutes, and the parachute deployment condition, which can be supersonic or subsonic. The analysis is based mainly on an engineering tool, PASDA, together with some hand calculations for parachute sizing and design. The tool consists of a detailed 6-DoF simulation performed with the aerodynamics database of the vehicle, an empirical wakes model and the International Standard Atmosphere database. The aerodynamics database for the vehicle is generated by DNW experimental data and CFD codes within the framework of an ESA contract to CIRA. The analysis will be presented in terms of altitude, velocity, accelerations, angle-of- attack, pitch angle and angle of rigging line. Discussion on the advantages and disadvantages of each parachute deployment condition is included in addition to some comparison with the available data based on a Monte-Carlo method from a Russian company, FSUE NIIPS. Sensitivity on wind speed to the performance of EXPERT is shown to be strong. Supersonic deployment of drogue shows a better performance in stability at the expense of a larger G-load than those from the subsonic deployment of drogue. Further optimization on the parachute design is necessary in order to fulfill all the EXPERT specifications.

Wong, H.; Muylaert, J.; Northey, D.; Riley, D.

2009-01-01

258

Walking unsteadily: a case of acute cerebellar ataxia  

PubMed Central

Acute cerebellar ataxia is an infrequent neurological syndrome in adults especially if complicated by additional neurological deficits. We report the case of a 69-year-old woman who presented with sudden onset of left facial droop, dizziness, slurred speech and impaired balance. Her medical history included paroxysmal atrial fibrillation and a sigmoid diverticular abscess treated with ciprofloxacin and metronidazole. Cranial computed tomographic angiography and MRI showed no signs of acute ischaemia or haemorrhage but demonstrated symmetrically distributed lesions in the cerebellar dentate nuclei. A diagnosis of metronidazole-induced encephalopathy was suspected. Metronidazole was stopped and the patient completely recovered. Metronidazole is a commonly prescribed medication. Clinicians should be aware of the clinical and radiological presentation of metronidazole-induced encephalopathy so that this serious but completely reversible condition can be promptly diagnosed. PMID:23283615

Simonetta, Federico; Christou, Fotini; Vandoni, Riccardo E; Nierle, Thomas

2013-01-01

259

Cerebellar networks with the cerebral cortex and basal ganglia  

PubMed Central

The dominant view of cerebellar function has been that it is exclusively concerned with motor control and coordination. Recent results from neuroanatomical, behavioral and imaging studies have profoundly changed this view. Neuroanatomical studies using virus transneuronal tracers have demonstrated that the output from the cerebellum reaches vast areas of the neocortex, including regions of prefrontal and posterior parietal cortex. Furthermore, it has recently become clear that the cerebellum is reciprocally connected with the basal ganglia, indicating that the two subcortical structures are part of a densely interconnected network. Altogether, these results provide the neuroanatomical substrate for cerebellar involvement in non-motor functions mediated by the prefrontal and posterior parietal cortex, as well as in processes traditionally associated with the basal ganglia. PMID:23579055

Bostan, Andreea C.; Dum, Richard P.; Strick, Peter L.

2013-01-01

260

Cerebellar Cognitive Affective Syndrome Presented as Severe Borderline Personality Disorder  

PubMed Central

An increasing number of findings confirm the significance of cerebellum in affecting regulation and early learning. Most consistent findings refer to association of congenital vermis anomalies with deficits in nonmotor functions of cerebellum. In this paper we presented a young woman who was treated since sixteen years of age for polysubstance abuse, affective instability, and self-harming who was later diagnosed with borderline personality disorder. Since the neurological and neuropsychological reports pointed to signs of cerebellar dysfunction and dysexecutive syndrome, we performed magnetic resonance imaging of brain which demonstrated partially developed vermis and rhombencephalosynapsis. These findings match the description of cerebellar cognitive affective syndrome and show an overlap with clinical manifestations of borderline personality disorder. PMID:24715924

Pesic, Danilo; Peljto, Amir; Lukic, Biljana; Milovanovic, Maja; Svetozarevic, Snezana; Lecic Tosevski, Dusica

2014-01-01

261

Cerebellar and oculomotor dysfunction induced by rapid infusion of pethidine.  

PubMed

Pethidine is an opioid that gains its popularity for the effective pain control through acting on the opioid-receptors. However, rapid pain relief sometimes brings about unfavourable side effects that largely limit its clinical utility. Common side effects include nausea, vomiting and hypotension. In patients with impaired renal and liver function, and those who need long-term pain control, pethidine may cause excitatory central nervous system (CNS) effects through its neurotoxic metabolite, norpethidine, resulting in irritability and seizure attack. On the contrary, though not clinically apparent, pethidine potentially causes inhibitory impacts on the CNS and impairs normal cerebellar and oculomotor function in the short term. In this case report, we highlight opioid's inhibitory side effects on the cerebellar structure that causes dysmetria, dysarthria, reduced smooth pursuit gain and decreased saccadic velocity. PMID:24618873

Dai, Yang-Hong; Ou, Kuang-Ling; Chu, Po-Wei

2014-01-01

262

Cerebellar liponeurocytoma: a newly recognized clinico-pathological entity.  

PubMed

The term "cerebellar liponeurocytoma", recently adopted by the World Health Organization Working Group (WHO), replaced many other different terms used up to now to give name to this rare tumor. To our knowledge, less than 20 cases have been related up to now under different names like as "lipomatous medulloblastoma, lipidized medulloblastoma, neurolipocytoma, medullocytoma and lipomatous glioneurocytoma". The new nomenclature eliminates the word "medulloblastoma", reinforces its benign character, and includes it in the category of glioneuronal tumors. We describe an addictional case of this distinct clinico-pathological entity removed from the right cerebellar hemisphere of a 53-year-old woman. With the present case report, we hope to contribute to the knowledge on the diagnostic and prognostic implications derived from the finding of mature adipose-like tissue within a medulloblastomatous tumour. PMID:12364938

Montagna, Nádia; Moreira, Daniel; Vaz, Luiz Carlos; Reis, Marcelo

2002-09-01

263

Short latency cerebellar modulation of the basal ganglia.  

PubMed

The graceful, purposeful motion of our body is an engineering feat that remains unparalleled in robotic devices using advanced artificial intelligence. Much of the information required for complex movements is generated by the cerebellum and the basal ganglia in conjunction with the cortex. Cerebellum and basal ganglia have been thought to communicate with each other only through slow, multi-synaptic cortical loops, begging the question as to how they coordinate their outputs in real time. We found that the cerebellum rapidly modulates the activity of the striatum via a disynaptic pathway in mice. Under physiological conditions, this short latency pathway was capable of facilitating optimal motor control by allowing the basal ganglia to incorporate time-sensitive cerebellar information and by guiding the sign of cortico-striatal plasticity. Conversely, under pathological condition, this pathway relayed aberrant cerebellar activity to the basal ganglia to cause dystonia. PMID:25402853

Chen, Christopher H; Fremont, Rachel; Arteaga-Bracho, Eduardo E; Khodakhah, Kamran

2014-12-01

264

Ovarian cancer revealed by paraneoplastic cerebellar degeneration: a case report  

PubMed Central

The prevalence of paraneoplastic cerebellar degeneration (PCD) associated with gynecological cancer is rare. Here, we reported the first case of ovarian cancer revealed by PCD in our institute. we describe a 80- year –old Moroccan female presented with subacute vestibular and cerebellar syndromes, she had an inguinal lymphadenopathy,with high levels of Anti-YO. Rapid progression and absence of known etiologies point towards a probable paraneoplastic origin of the syndrome in this patient. The exact incidence of PNS among those diagnosed with cancer remains uncertain, it is important to report this cases in the literature to help early diagnosis and appropriate treatment, which are able to stabilize the neurological symptoms. PMID:25360186

Elomrani, Fadwa; Ouziane, Imane; Boutayeb, Saber; Bensouda, Youssef; Mrabti, Hind; Errihani, Hassan

2014-01-01

265

Cerebellar learning distinguishes inflammatory neuropathy with and without tremor  

PubMed Central

Objectives: This study aims to investigate if patients with inflammatory neuropathies and tremor have evidence of dysfunction in the cerebellum and interactions in sensorimotor cortex compared to nontremulous patients and healthy controls. Methods: A prospective data collection study investigating patients with inflammatory neuropathy and tremor, patients with inflammatory neuropathy without tremor, and healthy controls on a test of cerebellar associative learning (eyeblink classical conditioning), a test of sensorimotor integration (short afferent inhibition), and a test of associative plasticity (paired associative stimulation). We also recorded tremor in the arms using accelerometry and surface EMG. Results: We found impaired responses to eyeblink classical conditioning and paired associative stimulation in patients with neuropathy and tremor compared with neuropathy patients without tremor and healthy controls. Short afferent inhibition was normal in all groups. Conclusions: Our data strongly suggest impairment of cerebellar function is linked to the production of tremor in patients with inflammatory neuropathy. PMID:23596070

Schwingenschuh, Petra; Saifee, Tabish A.; Katschnig-Winter, Petra; Reilly, Mary M.; Lunn, Michael P.; Manji, Hadi; Aguirregomozcorta, Maria; Schmidt, Reinhold; Bhatia, Kailash P.; Rothwell, John C.

2013-01-01

266

Effects of Cerebellar Disease on Sequences of Rapid Eye Movements  

PubMed Central

Summary Studying saccades can illuminate the more complex decision-making processes required for everyday movements. The double-step task, in which a target jumps to two successive locations before the subject has time to react, has proven a powerful research tool to investigate the brain’s ability to program sequential responses. We asked how patients with a range of cerebellar disorders responded to the double-step task, specifically, whether the initial saccadic response made to a target is affected by the appearance of a second target jump. We also sought to determine whether cerebellar patients were able to make corrective saccades towards the remembered second target location, if it were turned off soon after presentation. We tested saccades to randomly interleaved single- and double-step target jumps to eight locations on a circle. Patient’s initial responses to double-step stimuli showed 50% more error than saccades to single target jumps, and often, they failed to make a saccade to the first target jump. The presence of a second target jump had similar, but smaller effects in control subjects (error increased by 18%). During memory-guided double-step trials, both patients and controls made corrective saccades in darkness to the remembered location of the second jump. We conclude that in cerebellar patients, the second target jump interferes with programming of the saccade to the first target jump of a double-step stimulus; this defect highlights patients’ impaired ability to respond appropriately to sudden, conflicting changes in their environment. Conversely, since cerebellar patients can make corrective memory-guided saccades in darkness, they retain the ability to remember spatial locations, possibly due to non-retinal neural signals (corollary discharge) from cerebral hemispheric areas concerned with spatial localization. PMID:21385592

King, Susan; Chen, Athena L.; Joshi, Anand; Serra, Alessandro; Leigh, R. John

2011-01-01

267

Neuroligin-2 accelerates GABAergic synapse maturation in cerebellar granule cells  

Microsoft Academic Search

Neuroligins (NLGs) are postsynaptic cell adhesion molecules that are thought to function in synaptogenesis. To investigate the role of NLGs on synaptic transmission once the synapse is formed, we transfected neuroligin-2 (NLG-2) in cultured mouse cerebellar granule cells (CGCs), and recorded GABAA (?-aminobutyric acid) receptor mediated miniature postsynaptic currents (mIPSCs). NLG-2 transfected cells had mIPSCs with faster decay than matching

Zhanyan Fu; Stefano Vicini

2009-01-01

268

Cerebellar syndrome with hydrocephalus due to Mycoplasma pneumoniae infection.  

PubMed Central

A 27 year old woman developed a cerebellar syndrome with serological evidence of recent Mycoplasma pneumoniae infection. The cranial computed tomographic scan showed effacement of the fourth ventricle, enhancement of the basal meninges and hydrocephalus affecting the lateral and third ventricles. Clinical and radiological recovery occurred over 5 weeks. We propose that this was a manifestation of immune-mediated encephalomyelitis induced by the infection rather than direct invasion of the central nervous system. Images Figure 1 PMID:2217014

Coleman, R. J.; Brown, J. S.; Butler, P.; Swash, M.

1990-01-01

269

Endogenous cerebellar neurogenesis in adult mice with progressive ataxia  

PubMed Central

Objective Transplanting exogenous neuronal progenitors to replace damaged neurons in the adult brain following injury or neurodegenerative disorders and achieve functional amelioration is a realistic goal. However, studies so far have rarely taken into consideration the preexisting inflammation triggered by the disease process that could hamper the effectiveness of transplanted cells. Here, we examined the fate and long-term consequences of human cerebellar granule neuron precursors (GNP) transplanted into the cerebellum of Harlequin mice, an adult model of progressive cerebellar degeneration with early-onset microgliosis. Methods Human embryonic stem cell-derived progenitors expressing Atoh1, a transcription factor key to GNP specification, were generated in vitro and stereotaxically transplanted into the cerebellum of preataxic Harlequin mice. The histological and functional impact of these transplants was followed using immunolabeling and Rotarod analysis. Results Although transplanted GNPs did not survive beyond a few weeks, they triggered the proliferation of endogenous nestin-positive precursors in the leptomeninges that crossed the molecular layer and differentiated into mature neurons. These phenomena were accompanied by the preservation of the granule and Purkinje cell layers and delayed ataxic changes. In vitro neurosphere generation confirmed the enhanced neurogenic potential of the cerebellar leptomeninges of Harlequin mice transplanted with exogenous GNPs. Interpretation The cerebellar leptomeninges of adult mice contain an endogenous neurogenic niche that can be stimulated to yield mature neurons from an as-yet unidentified population of progenitors. The transplantation of human GNPs not only stimulates this neurogenesis, but, despite the potentially hostile environment, leads to neuroprotection and functional amelioration. PMID:25574472

Kumar, Manoj; Csaba, Zsolt; Peineau, Stéphane; Srivastava, Rupali; Rasika, Sowmyalakshmi; Mani, Shyamala; Gressens, Pierre; El Ghouzzi, Vincent

2014-01-01

270

Missile guidance law design using adaptive cerebellar model articulation controller  

Microsoft Academic Search

An adaptive cerebellar model articulation controller (CMAC) is proposed for command to line-of-sight (CLOS) missile guidance law design. In this design, the three-dimensional (3-D) CLOS guidance problem is formulated as a tracking problem of a time-varying nonlinear system. The adaptive CMAC control system is comprised of a CMAC and a compensation controller. The CMAC control is used to imitate a

Chih-Min Lin; Ya-Fu Peng

2005-01-01

271

Isolated cerebellar tuberculoma mimicking posterior cranial fossa tumour.  

PubMed

Isolated central nervous system (CNS) tuberculoma is a rare disease. This disease is associated with high morbidity and mortality, despite modern methods of detection and treatment. CNS tuberculosis can present as meningitis, arachnoiditis, tuberculomas or the uncommon form of tuberculous subdural empyema and brain abscess. We present the clinical, radiological and pathological findings of cerebellar tuberculoma in an Iranian immunocompetent patient mimicking a malignant tumour. PMID:23966456

Binesh, Fariba; Zahir, Shokouh Taghipour; Bovanlu, Taghi Roshan

2013-01-01

272

Rebound Discharge in Deep Cerebellar Nuclear Neurons In Vitro  

Microsoft Academic Search

Neurons of the deep cerebellar nuclei (DCN) play a critical role in defining the output of cerebellum in the course of encoding\\u000a Purkinje cell inhibitory inputs. The earliest work performed with in vitro preparations established that DCN cells have the\\u000a capacity to translate membrane hyperpolarizations into a rebound increase in firing frequency. The primary means of distinguishing\\u000a between DCN neurons

Reza Tadayonnejad; Dustin Anderson; Michael L. Molineux; W. Hamish Mehaffey; Kusala Jayasuriya; Ray W. Turner

2010-01-01

273

Direct transcranial puncture for Onyx embolization of a cerebellar hemangioblastoma.  

PubMed

Intracranial hemangioblastomas are benign but hypervascular tumors, most commonly located in the cerebellum, which are difficult to resect without significant operative blood loss. While preoperative embolization may decrease the amount of operative bleeding, the vascular supply of cerebellar hemangioblastomas frequently precludes safe embolization by an endovascular route due to the risk of thromboembolic vertebrobasilar infarction. Direct puncture embolization overcomes many of the limitations of endovascular embolization but its safety and feasibility for intracranial tumors is unknown. We report a 48-year-old man who was diagnosed with a large cerebellar mass after presenting with headaches and gait ataxia. Based on diagnostic angiography, which demonstrated a highly vascular tumor supplied by the posterior inferior cerebellar and posterior meningeal arteries, we decided to embolize the tumor by a direct transcranial puncture approach. After trephinating the skull in a standard fashion, a catheter-needle construct, composed of an Echelon 10 microcatheter (ev3 Endovascular, Plymouth, MN, USA) placed into a 21-gauge spinal needle, was inserted into the tumor under biplanar angiographic guidance. Using continuous angiographic monitoring, 9cc of Onyx 34 (ev3 Endovascular) was injected through the catheter, resulting in 75% tumor devascularization without evidence of complications. The patient was taken directly to surgery where a gross total resection of the hemangioblastoma was achieved with an acceptable operative blood loss. At his 2 year follow-up, the patient was neurologically intact without neuroimaging evidence of residual tumor. We describe, to our knowledge, the first case of direct transcranial puncture for preoperative embolization of a cerebellar hemangioblastoma. PMID:24370504

Ding, Dale; Starke, Robert M; Evans, Avery J; Liu, Kenneth C

2014-06-01

274

Electrophysiological monitoring of injury progression in the rat cerebellar cortex  

PubMed Central

The changes of excitability in affected neural networks can be used as a marker to study the temporal course of traumatic brain injury (TBI). The cerebellum is an ideal platform to study brain injury mechanisms at the network level using the electrophysiological methods. Within its crystalline morphology, the cerebellar cortex contains highly organized topographical subunits that are defined by two main inputs, the climbing (CFs) and mossy fibers (MFs). Here we demonstrate the use of cerebellar evoked potentials (EPs) mediated through these afferent systems for monitoring the injury progression in a rat model of fluid percussion injury (FPI). A mechanical tap on the dorsal hand was used as a stimulus, and EPs were recorded from the paramedian lobule (PML) of the posterior cerebellum via multi-electrode arrays (MEAs). Post-injury evoked response amplitudes (EPAs) were analyzed on a daily basis for 1 week and compared with pre-injury values. We found a trend of consistently decreasing EPAs in all nine animals, losing as much as 72 ± 4% of baseline amplitudes measured before the injury. Notably, our results highlighted two particular time windows; the first 24 h of injury in the acute period and day-3 to day-7 in the delayed period where the largest drops (~50% and 24%) were observed in the EPAs. In addition, cross-correlations of spontaneous signals between electrode pairs declined (from 0.47 ± 0.1 to 0.35 ± 0.04, p < 0.001) along with the EPAs throughout the week of injury. In support of the electrophysiological findings, immunohistochemical analysis at day-7 post-injury showed detectable Purkinje cell loss at low FPI pressures and more with the largest pressures used. Our results suggest that sensory evoked potentials (SEPs) recorded from the cerebellar surface can be a useful technique to monitor the course of cerebellar injury and identify the phases of injury progression even at mild levels. PMID:25346664

Ordek, Gokhan; Proddutur, Archana; Santhakumar, Vijayalakshmi; Pfister, Bryan J.; Sahin, Mesut

2014-01-01

275

Recurrent Cerebellar Hemorrhage: Case Report and Review of the Literature  

Microsoft Academic Search

We report a case of cerebellar hemorrhage (CH) that recurred in other hemisphere after 4 months of the first attack. A 58-year-old\\u000a man presented with general weakness and computerized tomography (CT) of the brain showed a 41 mm hematoma in the right cerebellum\\u000a with intraventricular extension. The satisfactory outcome was obtained after emergency surgical intervention and intensive\\u000a rehabilitation. However, the patient irregularly

Yung-Tsan Wu; Ming-Fu Hsieh; Heng-Yi Chu; Shao-Chi Lu; Shin-Tsu Chang; Tsung-Ying Li

2010-01-01

276

Adams Oliver syndrome: Description of a new phenotype with cerebellar abnormalities in a family  

PubMed Central

Summary Background To describe cerebellar abnormalities in a family composed by a father and two affected sibs with Adams Oliver syndrome (AOS) (OMIM 100300). Material/Methods Brain MRI and MR angiography were performed at 1.5T. Results The siblings presented cerebellar cortex dysplasia characterized by the presence of cysts. Conclusions Abnormalities of CNS are an unusual manifestation of AOS. To our knowledge, this is the first report of cerebellar cortical dysplasia in a family with AOS. PMID:24505229

D’Amico, Alessandra; Melis, Daniela; D’Arco, Felice; Di Paolo, Nilde; Carotenuto, Barbara; D’Anna, Gennaro; Russo, Carmela; Boemio, Pasquale; Brunetti, Arturo

2013-01-01

277

Correlation of LMP10 Expression and Clinical Outcome in Human Papillomavirus (HPV) Positive and HPV-Negative Tonsillar and Base of Tongue Cancer  

PubMed Central

Aim To examine LMP10 expression and its possible impact on clinical outcome in human papillomavirus (HPV) positive and HPV-negative tonsillar and base of tongue squamous cell carcinoma (TSCC and BOTSCC). Background Outcome is better in HPV-positive TSCC and BOTSCC compared to matching HPV-negative tumours, with roughly 80% vs. 40% 5-year disease free survival (DFS) with less aggressive treatment than today’s chemoradiotherapy. Since current treatment often results in harmful side effects, less intensive therapy, with sustained patient survival would be an attractive alternative. However, other markers together with HPV status are necessary to select patients and for this purpose LMP10 expression is investigated here in parallel to HPV status and clinical outcome. Materials and Methods From 385 patients diagnosed between 2000 and 2007 at the Karolinska University Hospital, 278 formalin fixed paraffin embedded TSCC and BOTSCC biopsies, with known HPV DNA status, were tested for LMP10 nuclear and cytoplasmic expression (fraction of positive cells and staining intensity). The data was then correlated to clinical outcome. Results An absent/low compared to a moderate/high LMP10 nuclear fraction of positive cells was correlated to a better 3-year DFS in the HPV-positive group of patients (log-rank p?=?0.005), but not in the HPV-negative group. In the HPV-negative group of patients, in contrast to the HPV-positive group, moderate/high LMP10 cytoplasmic fraction and weak/moderate/high LMP10 cytoplasmic intensity correlated to a better 3-year DFS (p?=?0.003 and p?=?0.001) and 3-year overall survival (p?=?0.001 and 0.009). Conclusion LMP10 nuclear expression in the HPV-positive group and LMP10 cytoplasmic expression in the HPV-negative group of patients correlated to better clinical outcome. PMID:24752327

Tertipis, Nikolaos; Haeggblom, Linnea; Nordfors, Cecilia; Grün, Nathalie; Näsman, Anders; Vlastos, Andrea

2014-01-01

278

Cerebellar ataxia impairs modulation of arm stiffness during postural maintenance.  

PubMed

Impedance control enables humans to effectively interact with their environment during postural and movement tasks, adjusting the mechanical behavior of their limbs to account for instability. Previous work has shown that people are able to selectively modulate the end-point stiffness of their arms, adjusting for varying directions of environmental disturbances. Behavioral studies also suggest that separate controllers are used for impedance modulation versus joint torque coordination. Here we tested whether people with cerebellar damage have deficits in impedance control. It is known that these individuals have poor motor coordination, which has typically been attributed to deficits in joint torque control. Subjects performed a static postural maintenance task with two different types of directional force perturbations. On average, patients with cerebellar ataxia modified stiffness differentially for the two perturbation conditions, although significantly less than age-matched control subjects. Thus cerebellar damage may impair the ability to modulate arm impedance. Surprisingly, the patients' intact ability to generally alter their limb stiffness during the postural task (albeit less than age-matched control subjects) improved their movement performance in a subsequent tracing task. The transfer of stiffness control from the static to the movement task may be a strategy that can be used by patients to compensate for their motor deficits. PMID:23843434

Gibo, Tricia L; Bastian, Amy J; Okamura, Allison M

2013-10-01

279

Cerebellar ataxia impairs modulation of arm stiffness during postural maintenance  

PubMed Central

Impedance control enables humans to effectively interact with their environment during postural and movement tasks, adjusting the mechanical behavior of their limbs to account for instability. Previous work has shown that people are able to selectively modulate the end-point stiffness of their arms, adjusting for varying directions of environmental disturbances. Behavioral studies also suggest that separate controllers are used for impedance modulation versus joint torque coordination. Here we tested whether people with cerebellar damage have deficits in impedance control. It is known that these individuals have poor motor coordination, which has typically been attributed to deficits in joint torque control. Subjects performed a static postural maintenance task with two different types of directional force perturbations. On average, patients with cerebellar ataxia modified stiffness differentially for the two perturbation conditions, although significantly less than age-matched control subjects. Thus cerebellar damage may impair the ability to modulate arm impedance. Surprisingly, the patients' intact ability to generally alter their limb stiffness during the postural task (albeit less than age-matched control subjects) improved their movement performance in a subsequent tracing task. The transfer of stiffness control from the static to the movement task may be a strategy that can be used by patients to compensate for their motor deficits. PMID:23843434

Gibo, Tricia L.; Bastian, Amy J.

2013-01-01

280

Ondansetron, a 5-HT3 antagonist, improves cerebellar tremor.  

PubMed Central

It has been previously shown that ondansetron, a 5-HT3 antagonist, can ameliorate vertigo in patients with acute brainstem disorders. A coincidental benefit was the improvement of cerebellar tremor in some patients with both vertigo and tremor. To further evaluate this effect, a placebo controlled, double blind, crossover study was conducted of a single dose of intravenous ondansetron in 20 patients with cerebellar tremor caused by multiple sclerosis, cerebellar degeneration, or drug toxicity. The principal outcome measures were the change in blind assessment of a writing task (spiral copying) and the timed completion of a nine hole peg test. Thirteen of 19 patients were deemed to have improved spiral copying after treatment with ondansetron when compared with baseline performance. One patient had a better response to the placebo compared with baseline performance (P = 0.00024). Patients completed the nine hole peg test in less time after ondansetron than after placebo (P = 0.08). Twelve patients thought that their tremor was functionally improved with the ondansetron treatment. None thought that the placebo gave improvement (P = 0.00098). The efficacy of orally administered ondansetron in tremor control is currently under study. PMID:9069487

Rice, G P; Lesaux, J; Vandervoort, P; Macewan, L; Ebers, G C

1997-01-01

281

FABP4 is a candidate marker of cerebellar liponeurocytomas.  

PubMed

Cerebellar liponeurocytoma (cLPN) is a very rare central nervous system (CNS) tumour recently recognized as a clinical and pathological entity distinct from medulloblastoma (MB), and included in the WHO classification of CNS tumours under the heading "glioneuronal tumours". cLPN typically develop in adult age and have a favourable prognosis compared with MB. In this work, we reviewed the clinical and neuroradiological data of two novel cases of adult cLPN diagnosed at our institution; one patient developed distant metastases. We tried to identify novel molecular markers for this malignancy. We found that the transcription factor NEUROG1 (but not ATOH1) is expressed in cLPN, unlike normal adult cerebellum, and that fatty acid binding protein 4 (FABP4), typically found in adipocytes, is significantly overexpressed compared with both normal adult cerebellum and human MB. These findings suggest cLPN occur as a result of transformation of cerebellar progenitors, which are distinct from cerebellar granule progenitors, and aberrantly differentiate into adipocyte-like tumour cells. They also suggest that analysis of FABP4 expression is of help to differentiate cLPN from MB. PMID:22476608

Anghileri, Elena; Eoli, Marica; Paterra, Rosina; Ferroli, Paolo; Pollo, Bianca; Cuccarini, Valeria; Maderna, Emanuela; Tringali, Giovanni; Saini, Marco; Salsano, Ettore; Finocchiaro, Gaetano

2012-07-01

282

Comparing cerebellar and motor cortical activity in reaching and grasping.  

PubMed

The activity of single cells in the cerebellar and motor cortex of awake monkeys was recorded during separate studies of whole-arm reaching movements and during the application of force-pulse perturbations to hand-held objects. Two general observations about the contribution of the cerebellum to the control of movement emerge from the data. The first, derived from the study of whole arm reaching, suggests that although both the motor cortex and cerebellum generate a signal related to movement direction, the cerebellar signal is less precise and varies from trial to trial even when the movement kinematics remain unchanged. The second observation, derived from the study of predictable perturbations of a hand-held object, indicates that cerebellar cortical neurons better reflect preparatory motor strategies formed from the anticipation of cutaneous and proprioceptive stimuli acquired by previous experience. In spite of strong relations to grip force and receptive fields stimulated by preparatory grip forces increase, the neurons of the percentral motor cortex showed very little anticipatory activity compared with either the premotor areas or the cerebellum. PMID:8334592

Smith, A M; Dugas, C; Fortier, P; Kalaska, J; Picard, N

1993-05-01

283

Congenital Cerebellar Mixed Germ Cell Tumor Presenting with Hemorrhage in a Newborn  

PubMed Central

We report here on a neonate with congenital cerebellar mixed germ cell tumor, and this initially presented as cerebellar hemorrhage. Postnatal cranial ultrasonography revealed an echogenic cerebellar mass that exhibited the signal characteristics of hemorrhage rather than tumor on MR images. The short-term follow-up images also suggested a resolving cerebellar hemorrhage. One month later, the neonate developed vomiting. A second set of MR images demonstrated an enlarged mass that exhibited changed signal intensity at the same site, which suggested a neoplasm. Histological examination after the surgical resection revealed a mixed germ cell tumor. PMID:18607121

Kim, Sung Mok; Yoo, So-Young; Park, Won Soon; Jang, Yun-Sil; Shin, Hyung-Jin; Suh, Yeon-Lim

2008-01-01

284

Cerebellar Output in Zebrafish: An Analysis of Spatial Patterns and Topography in Eurydendroid Cell Projections  

PubMed Central

The cerebellum is a brain region responsible for motor coordination and for refining motor programs. While a great deal is known about the structure and connectivity of the mammalian cerebellum, fundamental questions regarding its function in behavior remain unanswered. Recently, the zebrafish has emerged as a useful model organism for cerebellar studies, owing in part to the similarity in cerebellar circuits between zebrafish and mammals. While the cell types composing their cerebellar cortical circuits are generally conserved with mammals, zebrafish lack deep cerebellar nuclei, and instead a majority of cerebellar output comes from a single type of neuron: the eurydendroid cell. To describe spatial patterns of cerebellar output in zebrafish, we have used genetic techniques to label and trace eurydendroid cells individually and en masse. We have found that cerebellar output targets the thalamus and optic tectum, and have confirmed the presence of pre-synaptic terminals from eurydendroid cells in these structures using a synaptically targeted GFP. By observing individual eurydendroid cells, we have shown that different medial-lateral regions of the cerebellum have eurydendroid cells projecting to different targets. Finally, we found topographic organization in the connectivity between the cerebellum and the optic tectum, where more medial eurydendroid cells project to the rostral tectum while lateral cells project to the caudal tectum. These findings indicate that there is spatial logic underpinning cerebellar output in zebrafish with likely implications for cerebellar function. PMID:23554587

Heap, Lucy A.; Goh, Chi Ching; Kassahn, Karin S.; Scott, Ethan K.

2013-01-01

285

The Clinical Impact of Cerebellar Grey Matter Pathology in Multiple Sclerosis  

PubMed Central

Background The cerebellum is an important site for cortical demyelination in multiple sclerosis, but the functional significance of this finding is not fully understood. Objective To evaluate the clinical and cognitive impact of cerebellar grey-matter pathology in multiple sclerosis patients. Methods Forty-two relapsing-remitting multiple sclerosis patients and 30 controls underwent clinical assessment including the Multiple Sclerosis Functional Composite, Expanded Disability Status Scale (EDSS) and cerebellar functional system (FS) score, and cognitive evaluation, including the Paced Auditory Serial Addition Test (PASAT) and the Symbol-Digit Modalities Test (SDMT). Magnetic resonance imaging was performed with a 3T scanner and variables of interest were: brain white-matter and cortical lesion load, cerebellar intracortical and leukocortical lesion volumes, and brain cortical and cerebellar white-matter and grey-matter volumes. Results After multivariate analysis high burden of cerebellar intracortical lesions was the only predictor for the EDSS (p<0.001), cerebellar FS (p?=?0.002), arm function (p?=?0.049), and for leg function (p<0.001). Patients with high burden of cerebellar leukocortical lesions had lower PASAT scores (p?=?0.013), while patients with greater volumes of cerebellar intracortical lesions had worse SDMT scores (p?=?0.015). Conclusions Cerebellar grey-matter pathology is widely present and contributes to clinical dysfunction in relapsing-remitting multiple sclerosis patients, independently of brain grey-matter damage. PMID:24789257

Damasceno, Alfredo; Damasceno, Benito Pereira; Cendes, Fernando

2014-01-01

286

Description of the computations and pilot procedures for planning fuel-conservative descents with a small programmable calculator  

NASA Technical Reports Server (NTRS)

A simplified flight management descent algorithm was developed and programmed on a small programmable calculator. It was designed to aid the pilot in planning and executing a fuel conservative descent to arrive at a metering fix at a time designated by the air traffic control system. The algorithm may also be used for planning fuel conservative descents when time is not a consideration. The descent path was calculated for a constant Mach/airspeed schedule from linear approximations of airplane performance with considerations given for gross weight, wind, and nonstandard temperature effects. The flight management descent algorithm and the vertical performance modeling required for the DC-10 airplane is described.

Vicroy, D. D.; Knox, C. E.

1983-01-01

287

Experimental constraints on the Skaergaard liquid line of descent  

NASA Astrophysics Data System (ADS)

New experimental information permits a forward approach to modeling the liquid line of descent of the Skaergaard intrusion. A series of melting experiments on chilled margins of evolved tholeiitic and ferrobasaltic dikes associated with the intrusion is, in combination with existing data, used to develop quantitative crystallization models that allow liquid and solid compositions to be predicted for initial magma compositions and crystallization conditions open or closed with respect to oxygen. The new experimental results comprise 6 experiments with melts coexisting with plagioclase and olivine, 29 experiments in addition containing augite, 14 experiments in addition containing ilmenite and/or magnetite, and 6 experiments in addition containing pigeonite and sometimes lacking olivine. All melting experiments were done at atmospheric pressure and with a furnace gas mostly controlled to the fayalite-magnetite-quartz oxygen buffer (FMQ). Using these experimental results, the melt evolution can be constrained for the layered series of the Skaergaard intrusion. Fractionation of a LZa troctolitic assemblage drives the residual liquid toward increasing iron with slight increase in silica. The appearance of augite as an abundant mineral phase in the LZb and the fractionation of a gabbroic assemblage adjust the liquid trend to one of slightly decreasing silica with continued strong increase in iron. Silica decline is principally dependent on the crystallization of augite and restricted to LZb. The appearance of Fe-Ti oxide minerals and the fractionation of Fe-Ti oxide gabbroic assemblages in LZc deflect the evolution trends of iron and silica. The modeling based on the experimental results suggests marked LZc-MZ silica enrichment concurrently with increasing iron content until upper MZ and thereafter relatively constant or slightly decreasing iron. The iron concentration level at which the deflection in iron and silica contents occurs is dependent on several factors of which the oxygen fugacity ( fO 2) has the strongest effect. Because of the restricted variation in fO 2 modeled in LZ (˜ 0.1 log unit above FMQ), the saturation of oxide minerals and the liquid line of descent are unlikely to deviate strongly from the predicted variation based on open system experimental conditions. For the same reason, there is no support for the suggestion that widely different LZc oxide mineral modes will result from crystallization conditions closed with respect to oxygen as opposed to the experimental conditions. Modeling based on the new experimental result suggests that iron can continue to increase through LZc, past the appearance of Fe-Ti oxides, and supports the possibility that iron may have continued to increase well into MZ. However, the forward modeling supports only a modest MZ and UZ decrease in fO 2 (< 1 log unit below FMQ). This result is supported by a good correspondence between the experimental modes and the actual observed gabbro modes. A marked UZ drop in fO 2 (˜ 2-3 log units below FMQ), as has been suggested, requires relatively high total modal content of Fe-Ti oxides (> 20 wt.%) and dominating magnetite over ilmenite not permitted based on the experimental observations. Such high oxide modes will always result in liquid lines of descent that are characterized by strong enrichment in silica with strong depletion in iron. The forward modeling illustrates that only for unrealistic small amounts of Fe-Ti oxide minerals will iron enrichment accompany silica depletion into UZ.

Thy, P.; Lesher, C. E.; Nielsen, T. F. D.; Brooks, C. K.

2006-11-01

288

A conflict analysis of 4D descent strategies in a metered, multiple-arrival route environment  

NASA Technical Reports Server (NTRS)

A conflict analysis was performed on multiple arrival traffic at a typical metered airport. The Flow Management Evaluation Model (FMEM) was used to simulate arrival operations using Denver Stapleton's arrival route structure. Sensitivities of conflict performance to three different 4-D descent strategies (clear-idle Mach/Constant AirSpeed (CAS), constant descent angle Mach/CAS and energy optimal) were examined for three traffic mixes represented by those found at Denver Stapleton, John F. Kennedy and typical en route metering (ERM) airports. The Monte Carlo technique was used to generate simulation entry point times. Analysis results indicate that the clean-idle descent strategy offers the best compromise in overall performance. Performance measures primarily include susceptibility to conflict and conflict severity. Fuel usage performance is extrapolated from previous descent strategy studies.

Izumi, K. H.; Harris, C. S.

1990-01-01

289

A taxonomy of descent algorithms for nonlinear programs and variational inequalities  

E-print Network

A taxonomy of descent algorithms for nonlinear programs and the choices of cost approximating mappings and merit functions. The* * taxonomy is illustrated on classical algorithms and is utilized to interrelate known alg* *orithm frameworks. Keywords. Taxonomy

Patriksson, Michael

290

Antarctic Polar Descent and Planetary Wave Activity Observed in ISAMS CO from April to July 1992  

NASA Technical Reports Server (NTRS)

Antarctic polar descent and planetary wave activity in the upper stratosphere and lower mesosphere are observed in ISAMS CO data from April to July 1992. CO-derived mean April-to-May upper stratosphere descent rates of 15 K/day (0.25 km/day) at 60 S and 20 K/day (0.33 km/day) at 80 S are compared with descent rates from diabatic trajectory analyses. At 60 S there is excellent agreement, while at 80 S the trajectory-derived descent is significantly larger in early April. Zonal wavenumber 1 enhancement of CO is observed on 9 and 28 May, coincident with enhanced wave 1 in UKMO geopotential height. The 9 May event extends from 40 to 70 km and shows westward phase tilt with height, while the 28 May event extends from 40 to 50 km and shows virtually no phase tilt with height.

Allen, D. R.; Stanford, J. L.; Nakamura, N.; Lopez-Valverde, M. A.; Lopez-Puertas, M.; Taylor, F. W.; Remedios, J. J.

2000-01-01

291

User's manual for a fuel-conservative descent planning algorithm implemented on a small programmable calculator  

NASA Technical Reports Server (NTRS)

A simplified flight management descent algorithm was developed and programmed on a small programmable calculator. It was designed to aid the pilot in planning and executing a fuel conservative descent to arrive at a metering fix at a time designated by the air traffic control system. The algorithm may also be used for planning fuel conservative descents when time is not a consideration. The descent path was calculated for a constant Mach/airspeed schedule from linear approximations of airplane performance with considerations given for gross weight, wind, and nonstandard temperature effects. An explanation and examples of how the algorithm is used, as well as a detailed flow chart and listing of the algorithm are contained.

Vicroy, D. D.

1984-01-01

292

Distributed Algorithms for Multicommodity Flow Problems via Approximate Steepest Descent Framework  

E-print Network

Distributed Algorithms for Multicommodity Flow Problems via Approximate Steepest Descent Framework Baruch Awerbuch Rohit Khandekar Satish Rao Abstract We consider solutions for distributed multicommodity dimensionality. One classical ex- ample is multicommodity flow: there is an exponential number of paths, yet

Amir, Yair

293

Development of a Mars Airplane Entry, Descent, and Flight Trajectory  

NASA Technical Reports Server (NTRS)

An entry, descent, and flight (EDF) trajectory profile for a Mars airplane mission is defined as consisting of the following elements: ballistic entry of an aeroshell; supersonic deployment of a decelerator parachute; subsonic release of a heat shield; release, unfolding, and orientation of an airplane to flight attitude; and execution of a pull up maneuver to achieve trimmed, horizontal flight. Using the Program to Optimize Simulated Trajectories (POST) a trajectory optimization problem was formulated. Model data representative of a specific Mars airplane configuration, current models of the Mars surface topography and atmosphere, and current estimates of the interplanetary trajectory, were incorporated into the analysis. The goal is to develop an EDF trajectory to maximize the surface-relative altitude of the airplane at the end of a pull up maneuver, while subject to the mission design constraints. The trajectory performance was evaluated for three potential mission sites and was found to be site-sensitive. The trajectory performance, examined for sensitivity to a number of design and constraint variables, was found to be most sensitive to airplane mass, aerodynamic performance characteristics, and the pull up Mach constraint. Based on the results of this sensitivity study, an airplane-drag optimized trajectory was developed that showed a significant performance improvement.

Murray, James E.; Tartabini, Paul V.

2001-01-01

294

HLA Type Inference via Haplotypes Identical by Descent  

NASA Astrophysics Data System (ADS)

The Human Leukocyte Antigen (HLA) genes play a major role in adaptive immune response and are used to differentiate self antigens from non self ones. HLA genes are hyper variable with nearly every locus harboring over a dozen alleles. This variation plays an important role in susceptibility to multiple autoimmune diseases and needs to be matched on for organ transplantation. Unfortunately, HLA typing by serological methods is time consuming and expensive compared to high throughput Single Nucleotide Polymorphism (SNP) data. We present a new computational method to infer per-locus HLA types using shared segments Identical By Descent (IBD), inferred from SNP genotype data. IBD information is modeled as graph where shared haplotypes are explored among clusters of individuals with known and unknown HLA types to identify the latter. We analyze performance of the method in a previously typed subset of the HapMap population, achieving accuracy of 96% in HLA-A, 94% in HLA-B, 95% in HLA-C, 77% in HLA-DR1, 93% in HLA-DQA1 and 90% in HLA-DQB1 genes. We compare our method to a tag SNP based approach and demonstrate higher sensitivity and specificity. Our method demonstrates the power of using shared haplotype segments for large-scale imputation at the HLA locus.

Setty, Manu N.; Gusev, Alexander; Pe'Er, Itsik

295

Race, language, and mental evolution in Darwin's descent of man.  

PubMed

Charles Darwin was notoriously ambiguous in his remarks about the relationship between human evolution and biological race. He stressed the original unity of the races, yet he also helped to popularize the notion of a racial hierarchy filling the gaps between the highest anthropoids and civilized Europeans. A focus on Darwin's explanation of how humans initially evolved, however, shows that he mainly stressed not hierarchy but a version of humanity's original mental unity. In his book The Descent of Man, Darwin emphasized a substantial degree of mental development (including the incipient use of language) in the early, monogenetic phase of human evolution. This development, he argued, necessarily came before primeval man's numerical increase, geographic dispersion, and racial diversification, because only thus could one explain how that group was able to spread at the expense of rival ape-like populations. This scenario stood opposed to a new evolutionary polygenism formulated in the wake of Darwin's Origin of Species by his ostensible supporters Alfred Russel Wallace and Ernst Haeckel. Darwin judged this outlook inadequate to the task of explaining humanity's emergence. PMID:17623873

Alter, Stephen G

2007-01-01

296

Evolution and ecology of directed aerial descent in arboreal ants.  

PubMed

Directed aerial descent (DAD) is used by a variety of arboreal animals to escape predators, to remain in the canopy, and to access resources. Here, we build upon the discovery of DAD in ants of tropical canopies by summarizing its known phylogenetic distribution among ant genera, and within both the subfamily Pseudomyrmecinae and the genus Cephalotes. DAD has multiple evolutionary origins in ants, occurring independently in numerous genera in the subfamilies Myrmicinae, Formicinae, and Pseudomyrmecinae. Ablation experiments and video recordings of ants in a vertical wind tunnel showed that DAD in Cephalotes atratus is achieved via postural changes, specifically orientation of the legs and gaster. The occurrence of DAD in Formicinae indicates that the presence of a postpetiole is not essential for the behavior. Evidence to date indicates that gliding behavior is accomplished by visual targeting mediated by the compound eyes, and is restricted to diurnally active ants that nest in trees. Occlusion of ocelli in Pseudomyrmex gracilis workers had no effect on their success or performance in gliding. Experimental assessment of the fate of ants that fall to the understory showed that ants landing in water are 15 times more likely to suffer lethal attacks than are ants landing in leaf litter. Variation in both the aerodynamic mechanisms and selective advantages of DAD merits further study given the broad taxonomic diversity of arboreal ants that engage in this intriguing form of flight. PMID:21562023

Yanoviak, Stephen P; Munk, Yonatan; Dudley, Robert

2011-12-01

297

Minimum Landing Error Powered-Descent Guidance for Planetary Missions  

NASA Technical Reports Server (NTRS)

An algorithm improves the accuracy with which a lander can be delivered to the surface of Mars. The main idea behind this innovation is the use of a lossless convexification, which converts an otherwise non-convex constraint related to thruster throttling to a convex constraint, enabling convex optimization to be used. The convexification leads directly to an algorithm that guarantees finding the global optimum of the original nonconvex optimization problem with a deterministic upper bound on the number of iterations required for convergence. In this innovation, previous work in powered-descent guidance using convex optimization is extended to handle the case where the lander must get as close as possible to the target given the available fuel, but is not required to arrive exactly at the target. The new algorithm calculates the minimum-fuel trajectory to the target, if one exists, and calculates the trajectory that minimizes the distance to the target if no solution to the target exists. This approach poses the problem as two Second-Order Cone Programs, which can be solved to global optimality with deterministic bounds on the number of iterations required.

Blackmore, Lars; Acikmese, Behcet

2011-01-01

298

Estimating Controller Intervention Probabilities for Optimized Profile Descent Arrivals  

NASA Technical Reports Server (NTRS)

Simulations of arrival traffic at Dallas/Fort-Worth and Denver airports were conducted to evaluate incorporating scheduling and separation constraints into advisories that define continuous descent approaches. The goal was to reduce the number of controller interventions required to ensure flights maintain minimum separation distances of 5 nmi horizontally and 1000 ft vertically. It was shown that simply incorporating arrival meter fix crossing-time constraints into the advisory generation could eliminate over half of the all predicted separation violations and more than 80% of the predicted violations between two arrival flights. Predicted separation violations between arrivals and non-arrivals were 32% of all predicted separation violations at Denver and 41% at Dallas/Fort-Worth. A probabilistic analysis of meter fix crossing-time errors is included which shows that some controller interventions will still be required even when the predicted crossing-times of the advisories are set to add a 1 or 2 nmi buffer above the minimum in-trail separation of 5 nmi. The 2 nmi buffer was shown to increase average flight delays by up to 30 sec when compared to the 1 nmi buffer, but it only resulted in a maximum decrease in average arrival throughput of one flight per hour.

Meyn, Larry A.; Erzberger, Heinz; Huynh, Phu V.

2011-01-01

299

Vision-Aided Inertial Navigation for Spacecraft Entry, Descent, and Landing  

Microsoft Academic Search

In this paper, we present the vision-aided inertial navigation (VISINAV) algorithm that enables precision planetary landing. The vision front-end of the VISINAV system extracts 2-D-to-3-D correspondences between descent images and a surface map (mapped landmarks), as well as 2-D-to-2-D feature tracks through a sequence of descent images (opportunistic features). An extended Kalman filter (EKF) tightly integrates both types of visual

Anastasios I. Mourikis; Nikolas Trawny; Stergios I. Roumeliotis; Andrew Edie Johnson; Adnan Ansar; Larry Matthies

2009-01-01

300

Development/Plasticity/Repair BDNF-Mediated Cerebellar Granule Cell Development Is  

E-print Network

Development/Plasticity/Repair BDNF-Mediated Cerebellar Granule Cell Development Is Impaired in Mice (CREB) correlates with Bdnf transcription, which is required for normal development of cerebellar in decreased CREB phosphorylation (pCREB), Bdnf exon I and IV-containing mRNAs, and brain-derived neurotrophic

West, Anne

301

Media composition modulates excitatory amino acid - induced death of rat cerebellar granule cells  

Microsoft Academic Search

This study examined the effects of maintaining cells in different media and the role of serum in glutamate and NMDA - induced neurotoxicity in rat cerebellar granule cells. Glutamate stimulated a concentration - dependent cell death with similar potency in cerebellar granule cells grown in BME and Neurobasal media without serum. However, the maximal cell death to glutamate and N-

Anita M Wood; Priyanka Tiwari; David R Bristow

1997-01-01

302

Peripheral stimuli excite coronal beams of Golgi cells in rat cerebellar cortex  

Microsoft Academic Search

Cerebellar granule cells constitute the largest neurone population of the brain. Their axons run as parallel fibres along the coronal axis, and the one-dimensional spread of excitation that is expected to result from this arrangement is a key assumption of theories of cerebellar function. In many studies using various techniques, however, it was not possible to evoke such a beam-like

A. VOLNY-LURAGHI; R. MAEX; E. DE SCHUTTER

2002-01-01

303

Cerebellar granuloprival degeneration in an Australian kelpie and a Labrador retriever dog  

PubMed Central

A 7-month-old Australian kelpie dog and a 14-month-old Labrador retriever dog were diagnosed with an uncommon form of cerebellar abiotrophy called cerebellar granuloprival degeneration. This was characterized by a loss of the granular neurons with relative sparing of the Purkinje neurons. PMID:23814302

Huska, Jonathan; Gaitero, Luis; Snyman, Heindrich N.; Foster, Robert A.; Pumarola, Marti; Rodenas, Sergio

2013-01-01

304

Differences in behavioural test battery performance between mice with hippocampal and cerebellar lesions  

Microsoft Academic Search

Effects of hippocampal or cerebellar lesions have been described extensively, but the ability of behavioural tests for laboratory mice to distinguish between such lesions has not been studied in detail. We compared the behavioural consequences of large bilateral hippocampal and hemispheric cerebellar lesions with eight commonly used tests that included elements of neuromotor performance, exploratory behaviour, and learning and memory

Hannelore Goddyn; Sandra Leo; Theo Meert; Rudi D’Hooge

2006-01-01

305

Ataxia associated with Hashimoto's disease: progressive non-familial adult onset cerebellar degeneration with autoimmune thyroiditis  

Microsoft Academic Search

Acquired cerebellar ataxia has been described with hypothyroidism, and is typically reversible by thyroid hormone replacement therapy. The cerebellar dysfunction has been attributed to metabolic and physiological effects of the endocrine disorder. In a few patients, however, ataxia has persisted despite thyroid replacement therapy. Other mechanisms may be involved in ataxia associated with thyroid disorders.OBJECTIVETo document progressive non-familial adult onset

M Selim; D A Drachman

2001-01-01

306

Purkinje Cell Activity in the Cerebellar Anterior Lobe after Rabbit Eyeblink Conditioning  

ERIC Educational Resources Information Center

The cerebellar anterior lobe may play a critical role in the execution and proper timing of learned responses. The current study was designed to monitor Purkinje cell activity in the rabbit cerebellar anterior lobe after eyeblink conditioning, and to assess whether Purkinje cells in recording locations may project to the interpositus nucleus.…

Green, John T.; Steinmetz, Joseph E.

2005-01-01

307

THIAMINE DEFICIENCY IN THE PATHOGENESIS OF CHRONIC ETHANOL-ASSOCIATED CEREBELLAR DAMAGE IN VITRO  

E-print Network

THIAMINE DEFICIENCY IN THE PATHOGENESIS OF CHRONIC ETHANOL-ASSOCIATED CEREBELLAR DAMAGE IN VITRO P-dependent individuals. Thiamine deficiency, in particular, is thought to contribute to ethanol-associated cerebellar de the ef- fects of thiamine depletion and ethanol exposure on cytotox- icity in rat cerebellum. Organotypic

Cooper, Robin L.

308

Hochreiter, Sepp Copy Number Aberrations Affecting the Developing Cerebellar Vermis are Associated  

E-print Network

Cerebellar Vermis are Associated with Autism Spectrum Disorders Sepp Hochreiter, Djork-Arné Clevert Motivation: We investigated neurodevelopmental dysfunctions in autism spectrum disorders (ASD% of the examined ASD brains, well-defined cerebellar abnormalities were found. Also studies on children with vermal

Hochreiter, Sepp

309

The Cerebellar Deficit Hypothesis and Dyslexic Tendencies in a Non-Clinical Sample  

ERIC Educational Resources Information Center

In order to assess the relationship between cerebellar deficits and dyslexic tendencies in a non-clinical sample, 27 primary school children aged 8-9 completed a cerebellar soft signs battery and were additionally assessed for reading age, sequential memory, picture arrangement and knowledge of common sequences. An average measure of the soft…

Brookes, Rebecca L.; Stirling, John

2005-01-01

310

Differential Effects of Age and Sex on the Cerebellar Hemispheres and the Vermis: A Prospective MR Study  

Microsoft Academic Search

PURPOSE: The purpose of this study was to determine the effects of age and sex on the size of the cerebellar hemispheres, the cerebellar vermis, and the pons in healthy adults. METHODS: We estimated the volumes of the cerebellar hemispheres (excluding the vermis and the peduncles), the cross-sectional area of the vermis, and the cross-sectional area of the ventral pons

Naftali Raz; James H. Dupuis; Susan D. Briggs; Catherine McGavran; James D. Acker

1998-01-01

311

Cerebellar Integrity in the Amyotrophic Lateral Sclerosis - Frontotemporal Dementia Continuum  

PubMed Central

Amyotrophic lateral sclerosis (ALS) and behavioural variant frontotemporal dementia (bvFTD) are multisystem neurodegenerative disorders that manifest overlapping cognitive, neuropsychiatric and motor features. The cerebellum has long been known to be crucial for intact motor function although emerging evidence over the past decade has attributed cognitive and neuropsychiatric processes to this structure. The current study set out i) to establish the integrity of cerebellar subregions in the amyotrophic lateral sclerosis-behavioural variant frontotemporal dementia spectrum (ALS-bvFTD) and ii) determine whether specific cerebellar atrophy regions are associated with cognitive, neuropsychiatric and motor symptoms in the patients. Seventy-eight patients diagnosed with ALS, ALS-bvFTD, behavioural variant frontotemporal dementia (bvFTD), most without C9ORF72 gene abnormalities, and healthy controls were investigated. Participants underwent cognitive, neuropsychiatric and functional evaluation as well as structural imaging using voxel-based morphometry (VBM) to examine the grey matter subregions of the cerebellar lobules, vermis and crus. VBM analyses revealed: i) significant grey matter atrophy in the cerebellum across the whole ALS-bvFTD continuum; ii) atrophy predominantly of the superior cerebellum and crus in bvFTD patients, atrophy of the inferior cerebellum and vermis in ALS patients, while ALS-bvFTD patients had both patterns of atrophy. Post-hoc covariance analyses revealed that cognitive and neuropsychiatric symptoms were particularly associated with atrophy of the crus and superior lobule, while motor symptoms were more associated with atrophy of the inferior lobules. Taken together, these findings indicate an important role of the cerebellum in the ALS-bvFTD disease spectrum, with all three clinical phenotypes demonstrating specific patterns of subregional atrophy that associated with different symptomology. PMID:25144223

Tan, Rachel H.; Devenney, Emma; Dobson-Stone, Carol; Kwok, John B.; Hodges, John R.; Kiernan, Matthew C.; Halliday, Glenda M.; Hornberger, Michael

2014-01-01

312

Optogenetic Manipulation of Cerebellar Purkinje Cell Activity In Vivo  

E-print Network

Purkinje cells (PCs) are the sole output neurons of the cerebellar cortex. Although their anatomical connections and physiological response properties have been extensively studied, the causal role of their activity in behavioral, cognitive and autonomic functions is still unclear because PC activity cannot be selectively controlled. Here we developed a novel technique using optogenetics for selective and rapidly reversible manipulation of PC activity in vivo. We injected into rat cerebellar cortex lentiviruses expressing either the light-activated cationic channel channelrhodopsin-2 (ChR2) or lightdriven chloride pump halorhodopsin (eNpHR) under the control of the PC-specific L7 promoter. Transgene expression was observed in most PCs (ChR2, 92.6%; eNpHR, 95.3%), as determined by immunohistochemical analysis. In vivo electrophysiological recordings showed that all light-responsive PCs in ChR2-transduced rats increased frequency of simple spike in response to blue laser illumination. Similarly, most light-responsive PCs (93.8%) in eNpHR-transduced rats decreased frequency of simple spike in response to orange laser illumination. We then applied these techniques to characterize the roles of rat cerebellar uvula, one of the cardiovascular regulatory regions in the cerebellum, in resting blood pressure (BP) regulation in anesthetized rats. ChR2-mediated photostimulation and eNpHR-mediated photoinhibition of the uvula had opposite effects on resting BP, inducing depressor and pressor responses, respectively. In contrast, manipulation of PC activity within the neighboring lobule VIII had no effect on BP. Blue and orange laser illumination onto PBS-injected

Tadashi Tsubota; Yohei Ohashi; Keita Tamura; Ayana Sato; Yasushi Miyashita

313

Probabilistic Identification of Cerebellar Cortical Neurones across Species  

PubMed Central

Despite our fine-grain anatomical knowledge of the cerebellar cortex, electrophysiological studies of circuit information processing over the last fifty years have been hampered by the difficulty of reliably assigning signals to identified cell types. We approached this problem by assessing the spontaneous activity signatures of identified cerebellar cortical neurones. A range of statistics describing firing frequency and irregularity were then used, individually and in combination, to build Gaussian Process Classifiers (GPC) leading to a probabilistic classification of each neurone type and the computation of equi-probable decision boundaries between cell classes. Firing frequency statistics were useful for separating Purkinje cells from granular layer units, whilst firing irregularity measures proved most useful for distinguishing cells within granular layer cell classes. Considered as single statistics, we achieved classification accuracies of 72.5% and 92.7% for granular layer and molecular layer units respectively. Combining statistics to form twin-variate GPC models substantially improved classification accuracies with the combination of mean spike frequency and log-interval entropy offering classification accuracies of 92.7% and 99.2% for our molecular and granular layer models, respectively. A cross-species comparison was performed, using data drawn from anaesthetised mice and decerebrate cats, where our models offered 80% and 100% classification accuracy. We then used our models to assess non-identified data from awake monkeys and rabbits in order to highlight subsets of neurones with the greatest degree of similarity to identified cell classes. In this way, our GPC-based approach for tentatively identifying neurones from their spontaneous activity signatures, in the absence of an established ground-truth, nonetheless affords the experimenter a statistically robust means of grouping cells with properties matching known cell classes. Our approach therefore may have broad application to a variety of future cerebellar cortical investigations, particularly in awake animals where opportunities for definitive cell identification are limited. PMID:23469215

Van Dijck, Gert; Van Hulle, Marc M.; Heiney, Shane A.; Blazquez, Pablo M.; Meng, Hui; Angelaki, Dora E.; Arenz, Alexander; Margrie, Troy W.; Mostofi, Abteen; Edgley, Steve; Bengtsson, Fredrik; Ekerot, Carl-Fredrik; Jörntell, Henrik; Dalley, Jeffrey W.; Holtzman, Tahl

2013-01-01

314

Diagnostic Approach to Childhood-onset Cerebellar Atrophy: A 10-Year Retrospective Study of 300 Patients  

PubMed Central

Hereditary ataxias associated with cerebellar atrophy are a heterogeneous group of disorders. Selection of appropriate clinical and genetic tests for patients with cerebellar atrophy poses a diagnostic challenge. Neuroimaging is a crucial initial investigation in the diagnostic evaluation of ataxia in childhood, and the presence of cerebellar atrophy helps guide further investigations. We performed a detailed review of 300 patients with confirmed cerebellar atrophy on magnetic resonance imaging over a 10-year period. A diagnosis was established in 47% of patients: Mitochondrial disorders were most common, followed by the neuronal ceroid lipofuscinoses, ataxia telangectasia, and late GM2-gangliosidosis. We review the common causes of cerebellar atrophy in childhood and propose a diagnostic approach based on correlating specific neuroimaging patterns with clinical and genetic diagnoses. PMID:22764178

Al-Maawali, Almundher; Blaser, Susan; Yoon, Grace

2013-01-01

315

Cerebellar Ataxia from Multiple Potential Causes: Hypothyroidism, Hashimoto's Thyroiditis, Thalamic Stimulation, and Essential Tremor  

PubMed Central

Background Both hypothyroidism and Hashimoto's thyroiditis (HT) can rarely be associated with cerebellar ataxia. Severe essential tremor (ET) as well as bilateral thalamic deep brain stimulation (DBS) may lead to subtle cerebellar signs. Case Report We report a 74-year-old male with hypothyroidism and a 20-year history of ET who developed cerebellar ataxia after bilateral thalamic DBS. Extensive workup revealed elevated thyroid stimulating hormone and thyroperoxidase antibody titers confirming the diagnosis of HT. Discussion Our case demonstrates multiple possible causes of cerebellar ataxia in a patient, including hypothyroidism, HT, chronic ET, and bilateral thalamic DBS. Counseling of patients may be appropriate when multiple risk factors for cerebellar ataxia coexist in one individual. PMID:23439792

Shneyder, Natalya; Lyons, Mark K.; Driver-dunckley, Erika; Evidente, Virgilio Gerald H.

2012-01-01

316

Neuroimaging of white matter injury, intraventricular and cerebellar hemorrhage.  

PubMed

White matter injury and hemorrhage are common findings in extremely preterm infants. Large hemorrhages and extensive cystic lesions are identified with cranial ultrasound. MRI, which is more sensitive, is especially useful in the identification of small intraventricular hemorrhage; cerebellar hemorrhage; punctate lesion in the white matter and cerebellum; and diffuse, noncystic white matter injury. Imaging sequences such as diffusion-weighted, diffusion tensor, and susceptibility weighted imaging may improve recognition and prediction of outcome. These techniques improve understanding of the underlying pathophysiology of white matter injury and its effects on brain development and neurodevelopmental outcome. PMID:24524447

Benders, Manon J N L; Kersbergen, Karina J; de Vries, Linda S

2014-03-01

317

Understanding Cerebellar Liponeurocytomas: Case Report and Literature Review  

PubMed Central

Cerebellar liponeurocytomas were recognized in the 2000 WHO 3rd edition of CNS tumors as a distinct grade I pathological entity, a tumor with a more favorable prognosis than medulloblastoma. But reports of long-term recurrences and some possible aggressive behavior led to an upgrade on the latest WHO 4th edition of CNS tumors. The case of a 64-year-old female patient is reported in this paper. More than 30 cases of this lately recognized pathological entity have been reported to date. The diagnostic, radiological, and pathological features associated with this tumor are discussed through a literature review. PMID:24716015

Oudrhiri, M. Y.; Raouzi, N.; El Kacemi, I.; El Fatemi, N.; Gana, R.; Maaqili, M. R.; Bellakhdar, F.

2014-01-01

318

Application of a simple cerebellar model to geologic surface mapping  

USGS Publications Warehouse

Neurophysiological research into the structure and function of the cerebellum has inspired computational models that simulate information processing associated with coordination and motor movement. The cerebellar model arithmetic computer (CMAC) has a design structure which makes it readily applicable as an automated mapping device that "senses" a surface, based on a sample of discrete observations of surface elevation. The model operates as an iterative learning process, where cell weights are continuously modified by feedback to improve surface representation. The storage requirements are substantially less than those of a conventional memory allocation, and the model is extended easily to mapping in multidimensional space, where the memory savings are even greater. ?? 1991.

Hagens, A.; Doveton, J.H.

1991-01-01

319

Hereditary lissencephaly and cerebellar hypoplasia in Churra lambs  

PubMed Central

Background Lissencephaly is a rare developmental brain disorder in veterinary and human medicine associated with defects in neuronal migration leading to a characteristic marked reduction or absence of the convolutional pattern of the cerebral hemispheres. In many human cases the disease has a genetic basis. In sheep, brain malformations, mainly cerebellar hypoplasia and forms of hydrocephalus, are frequently due to in utero viral infections. Although breed-related malformations of the brain have been described in sheep, breed-related lissencephaly has not been previously recorded in a peer reviewed publication. Results Here we report neuropathological findings in 42 newborn lambs from a pure Churra breed flock, with clinical signs of weakness, inability to walk, difficulty in sucking and muscular rigidity observed immediately after birth. All the lambs showed near-total agyria with only a rudimentary formation of few sulci and gyri, and a severe cerebellar hypoplasia. On coronal section, the cerebral grey matter was markedly thicker than that of age-matched unaffected lambs and the ventricular system was moderately dilated. Histologically, the normal layers of the cerebral cortex were disorganized and, using an immunohistochemical technique against neurofilaments, three layers were identified instead of the six present in normal brains. The hippocampus was also markedly disorganised and the number and size of lobules were reduced in the cerebellum. Heterotopic neurons were present in different areas of the white matter. The remainder of the brain structures appeared normal. The pathological features reported are consistent with the type LCH-b (lissencephaly with cerebellar hypoplasia group b) defined in human medicine. No involvement of pestivirus or bluetongue virus was detected by immunohistochemistry. An analysis of pedigree data was consistent with a monogenic autosomal recessive pattern inheritance. Conclusions The study describes the clinical and pathological findings of lissencephaly with cerebellar hypoplasia in Churra lambs for which an autosomal recessive inheritance was the most likely cause. Histopathological features observed in the cerebral cortex and hippocampus are consistent with a possible failure in neuronal migration during brain development. This report suggests that lissencephaly should be considered in the differential diagnosis of congenital neurological disease in newborn lambs showing weakness, inability to walk and difficulty sucking. PMID:23938146

2013-01-01

320

Cerebellar abnormalities in Huntington's disease: a role in motor and psychiatric impairment?  

PubMed

The cerebellum has received limited attention in Huntington's disease (HD), despite signs of possible cerebellar dysfunction, including motor incoordination and impaired gait, which are currently attributed to basal ganglia atrophy and disrupted fronto-striatal circuits. This study is the first to investigate a potential contribution of macro- and microstructural cerebellar damage to clinical manifestations of HD. T1- and diffusion-weighted 3T magnetic resonance imaging (MRI) scans were obtained from 12 controls and 22 early-stage HD participants. Manual delineation and voxel-based morphometry were used to assess between-group differences in cerebellar volume, and diffusion metrics were compared between groups within the cerebellar gray and white matter. Associations between these imaging measures and clinical scores were examined within the HD group. Reduced paravermal volume was detected in HD compared with controls using voxel-based morphometry (P?cerebellar gray matter and white matter. Smaller cerebellar volumes, although not significantly reduced, were significantly associated with impaired gait and psychiatric morbidity and of borderline significance with pronate/supinate-hand task performance. Abnormal cerebellar diffusion was associated with increased total motor score, impaired saccade initiation, tandem walking, and timed finger tapping. In conclusion, atrophy of the paravermis, possibly encompassing the cerebellar nuclei, and microstructural abnormalities within the cerebellum may contribute to HD neuropathology. Aberrant cerebellar diffusion and reduced cerebellar volume together associate with impaired motor function and increased psychiatric symptoms in stage I HD, potentially implicating the cerebellum more centrally in HD presentation than previously recognized. PMID:25123926

Rees, Elin M; Farmer, Ruth; Cole, James H; Haider, Salman; Durr, Alexandra; Landwehrmeyer, Bernhard; Scahill, Rachael I; Tabrizi, Sarah J; Hobbs, Nicola Z

2014-11-01

321

Atmospheric Environments for Entry, Descent and Landing (EDL)  

NASA Technical Reports Server (NTRS)

Scientific measurements of atmospheric properties have been made by a wide variety of planetary flyby missions, orbiters, and landers. Although landers can make in-situ observations of near-surface atmospheric conditions (and can collect atmospheric data during their entry phase), the vast majority of data on planetary atmospheres has been collected by remote sensing techniques from flyby and orbiter spacecraft (and to some extent by Earth-based remote sensing). Many of these remote sensing observations (made over a variety of spectral ranges), consist of vertical profiles of atmospheric temperature as a function of atmospheric pressure level. While these measurements are of great interest to atmospheric scientists and modelers of planetary atmospheres, the primary interest for engineers designing entry descent and landing (EDL) systems is information about atmospheric density as a function of geometric altitude. Fortunately, as described in in this paper, it is possible to use a combination of the gas-law relation and the hydrostatic balance relation to convert temperature-versus-pressure, scientific observations into density-versus-altitude data for use in engineering applications. The following section provides a brief introduction to atmospheric thermodynamics, as well as constituents, and winds for EDL. It also gives methodology for using atmospheric information to do "back-of-the-envelope" calculations of various EDL aeroheating parameters, including peak deceleration rate ("g-load"), peak convective heat rate. and total heat load on EDL spacecraft thermal protection systems. Brief information is also provided about atmospheric variations and perturbations for EDL guidance and control issues, and atmospheric issues for EDL parachute systems. Subsequent sections give details of the atmospheric environments for five destinations for possible EDL missions: Venus. Earth. Mars, Saturn, and Titan. Specific atmospheric information is provided for these destinations, and example results are presented for the "back-of-the-envelope" calculations mentioned above.

Justus, Carl G.; Braun, Robert D.

2007-01-01

322

Pharmacogenomics of warfarin in populations of African descent  

PubMed Central

Warfarin is the most commonly prescribed oral anticoagulant worldwide despite its narrow therapeutic index and the notorious inter- and intra-individual variability in dose required for the target clinical effect. Pharmacogenetic polymorphisms are major determinants of warfarin pharmacokinetic and dynamics and included in several warfarin dosing algorithms. This review focuses on warfarin pharmacogenomics in sub-Saharan peoples, African Americans and admixed Brazilians. These ‘Black’ populations differ in several aspects, notably their extent of recent admixture with Europeans, a factor which impacts on the frequency distribution of pharmacogenomic polymorphisms relevant to warfarin dose requirement for the target clinical effect. Whereas a small number of polymorphisms in VKORC1 (3673G > A, rs9923231), CYP2C9 (alleles *2 and *3, rs1799853 and rs1057910, respectively) and arguably CYP4F2 (rs2108622), may capture most of the pharmacogenomic influence on warfarin dose variance in White populations, additional polymorphisms in these, and in other, genes (e.g. CALU rs339097) increase the predictive power of pharmacogenetic warfarin dosing algorithms in the Black populations examined. A personalized strategy for initiation of warfarin therapy, allowing for improved safety and cost-effectiveness for populations of African descent must take into account their pharmacogenomic diversity, as well as socio-economical, cultural and medical factors. Accounting for this heterogeneity in algorithms that are ‘friendly’ enough to be adopted by warfarin prescribers worldwide requires gathering information from trials at different population levels, but demands also a critical appraisal of racial/ethnic labels that are commonly used in the clinical pharmacology literature but do not accurately reflect genetic ancestry and population diversity. PMID:22676711

Suarez-Kurtz, Guilherme; Botton, Mariana R

2013-01-01

323

Mars Exploration Rover Entry, Descent, and Landing: A Thermal Perspective  

NASA Technical Reports Server (NTRS)

Perhaps the most challenging mission phase for the Mars Exploration Rovers was the Entry, Descent, and Landing (EDL). During this phase, the entry vehicle attached to its cruise stage was transformed into a stowed tetrahedral Lander that was surrounded by inflated airbags through a series of complex events. There was only one opportunity to successfully execute an automated command sequence without any possible ground intervention. The success of EDL was reliant upon the system thermal design: 1) to thermally condition EDL hardware from cruise storage temperatures to operating temperature ranges; 2) to maintain the Rover electronics within operating temperature ranges without the benefit of the cruise single phase cooling loop, which had been evacuated in preparation for EDL; and 3) to maintain the cruise stage propulsion components for the critical turn to entry attitude. Since the EDL architecture was inherited from Mars Pathfinder (MPF), the initial EDL thermal design would be inherited from MPF. However, hardware and implementation differences from MPF ultimately changed the MPF inheritance approach for the EDL thermal design. With the lack of full inheritance, the verification and validation of the EDL thermal design took on increased significance. This paper will summarize the verification and validation approach for the EDL thermal design along with applicable system level thermal testing results as well as appropriate thermal analyses. In addition, the lessons learned during the system-level testing will be discussed. Finally, the in-flight EDL experiences of both MER-A and -B missions (Spirit and Opportunity, respectively) will be presented, demonstrated how lessons learned from Spirit were applied to Opportunity.

Tsuyuki, Glenn T.; Sunada, Eric T.; Novak, Keith S.; Kinsella, Gary M.; Phillip, Charles J.

2005-01-01

324

Cyclic coordinate descent: A robotics algorithm for protein loop closure  

PubMed Central

In protein structure prediction, it is often the case that a protein segment must be adjusted to connect two fixed segments. This occurs during loop structure prediction in homology modeling as well as in ab initio structure prediction. Several algorithms for this purpose are based on the inverse Jacobian of the distance constraints with respect to dihedral angle degrees of freedom. These algorithms are sometimes unstable and fail to converge. We present an algorithm developed originally for inverse kinematics applications in robotics. In robotics, an end effector in the form of a robot hand must reach for an object in space by altering adjustable joint angles and arm lengths. In loop prediction, dihedral angles must be adjusted to move the C-terminal residue of a segment to superimpose on a fixed anchor residue in the protein structure. The algorithm, referred to as cyclic coordinate descent or CCD, involves adjusting one dihedral angle at a time to minimize the sum of the squared distances between three backbone atoms of the moving C-terminal anchor and the corresponding atoms in the fixed C-terminal anchor. The result is an equation in one variable for the proposed change in each dihedral. The algorithm proceeds iteratively through all of the adjustable dihedral angles from the N-terminal to the C-terminal end of the loop. CCD is suitable as a component of loop prediction methods that generate large numbers of trial structures. It succeeds in closing loops in a large test set 99.79% of the time, and fails occasionally only for short, highly extended loops. It is very fast, closing loops of length 8 in 0.037 sec on average. PMID:12717019

Canutescu, Adrian A.; Dunbrack, Roland L.

2003-01-01

325

Cerebellar TMS in Treatment of a Patient with Cerebellar Ataxia: Evidence from Clinical, Biomechanics and Neurophysiological Assessments  

PubMed Central

We describe a patient with a probable diagnosis of idiopathic late-onset cerebellar atrophy who shows improvement of limb coordination, speech and gait following 21 days of transcranial magnetic stimulation (TMS) applied to scalp regions presumably corresponding to the cerebellum. This case study provides, for the first time, a quantitative assessment of gait improvement in response to TMS therapy in ataxia, as well as neurophysiological evidence in support of modification of cerebello-cortical interaction that may underlie some of the improvements. PMID:23625327

Farzan, Faranak; Wu, Yunfen; Manor, Brad; Anastasio, Elana M.; Lough, Matthew; Novak, Vera; Greenstein, Patricia E.; Pascual-Leone, Alvaro

2013-01-01

326

Planning fuel-conservative descents in an airline environmental using a small programmable calculator: Algorithm development and flight test results  

NASA Technical Reports Server (NTRS)

A simple, airborne, flight-management descent algorithm was developed and programmed into a small programmable calculator. The algorithm may be operated in either a time mode or speed mode. The time mode was designed to aid the pilot in planning and executing a fuel-conservative descent to arrive at a metering fix at a time designated by the air traffic control system. The speed model was designed for planning fuel-conservative descents when time is not a consideration. The descent path for both modes was calculated for a constant with considerations given for the descent Mach/airspeed schedule, gross weight, wind, wind gradient, and nonstandard temperature effects. Flight tests, using the algorithm on the programmable calculator, showed that the open-loop guidance could be useful to airline flight crews for planning and executing fuel-conservative descents.

Knox, C. E.; Vicroy, D. D.; Simmon, D. A.

1985-01-01

327

Shake rattle and roll: the bony labyrinth and aerial descent in squamates.  

PubMed

Controlled aerial descent has evolved many times independently in vertebrates. Squamates (lizards and snakes) are unusual in that respect due to the large number of independent origins of the evolution of this behavior. Although some squamates such as flying geckos of the genus Ptychozoon and the flying dragons of the genus Draco show obvious adaptations including skin flaps or enlarged ribs allowing them to increase their surface area and slow down their descent, many others appear unspecialized. Yet, specializations can be expected at the level of the sensory and neural systems allowing animals to maintain stability during controlled aerial descent. The vestibular system is a likely candidate given that it is an acceleration detector and is well-suited to detect changes in pitch, roll and yaw. Here we use conventional and synchrotron ?CT scans to quantify the morphology of the vestibular system in squamates able to perform controlled aerial descent compared to species characterized by a terrestrial or climbing life style. Our results show the presence of a strong phylogenetic signal in the data with the vestibular system in species from the same family being morphologically similar. However, both our shape analysis and an analysis of the dimensions of the vestibular system showed clear differences among animals with different life-styles. Species able to perform a controlled aerial descent differed in the position and shape of the inner ear, especially of the posterior ampulla. Given the limited stability of squamates against roll and the fact that the posterior ampulla is tuned to changes in roll this suggests an adaptive evolution of the vestibular system in squamates using controlled aerial descent. Future studies testing for similar differences in other groups of vertebrates known to use controlled aerial descent are needed to test the generality of this observation. PMID:21700578

Boistel, Renaud; Herrel, Anthony; Lebrun, Renaud; Daghfous, Gheylen; Tafforeau, Paul; Losos, Jonathan B; Vanhooydonck, Bieke

2011-12-01

328

Cerebellar fastigial nucleus influence on ipsilateral abducens activity during saccades.  

PubMed

To characterize the cerebellar influence on neurons in the abducens (ABD) nucleus, we recorded ABD neurons before and after we inactivated the caudal part of the ipsilateral cerebellar fastigial nucleus (cFN) with muscimol injection. cFN activity influences the horizontal component of saccades. cFN inactivation increased the activity of most ipsilateral ABD neurons (19/22 in 2 monkeys) during ipsiversive (hypermetric) saccades, primarily by increasing burst duration. During contraversive (hypometric) saccades, the off-direction pause of most (10/15) ABD neurons was shorter than normal because of the early resumption of ABD activity. Early ABD firing caused the early contraction of antagonist muscles that reduced eye rotation and made contraversive saccades hypometric. Thus the cerebellum controls ipsilateral ABD activity by truncating on-direction bursts during ipsiversive saccades and extending off-direction pauses during contraversive saccades. We conclude that cFN output keeps saccades accurate by controlling when ABD on-direction bursts and off-direction pauses end. PMID:24478158

Kojima, Yoshiko; Robinson, Farrel R; Soetedjo, Robijanto

2014-04-01

329

Evidence for nicotinic acetylcholine receptor activation in rat cerebellar slices.  

PubMed

Neuronal nicotinic ACh receptor (nAChR) activation is known to enhance glutamate and GABA release in different brain areas. Moreover, nAChRs play an important role in neuronal differentiation. By using the patch-clamp technique, we have investigated the presence of nAChRs in cerebellar granule cells in slices from P5-P14 rats. Application of ACh (1 mM) could elicit a variety of effects. Some cells did not respond at all. In other cells, a somatic current was activated. In a proportion of cells, postsynaptic currents (PSCs), with or without somatic current, were elicited. Somatic nAChRs are likely to be of the alpha(4)beta(2) subtype, but the presence of other subunit combinations (alpha(7)- or beta(4)-containing receptors) cannot be ruled out. The ACh-induced PSCs were glutamatergic in nature. Thus, in a reasonable proportion of cells, nicotinic receptors are present presynaptically. They are likely to be alpha(7) receptors whose activation elicits Glu release via a TTX-sensitive mechanism. Our experiments are the first electrophysiological evidence showing, in a native cerebellar preparation, the presence of nicotinic receptors at the mossy fibre-granule cell synapse at early developmental stages. PMID:11796144

De Filippi, G; Baldwinson, T; Sher, E

2001-12-01

330

Deep Learning for Cerebellar Ataxia Classification and Functional Score Regression  

PubMed Central

Cerebellar ataxia is a progressive neuro-degenerative disease that has multiple genetic versions, each with a characteristic pattern of anatomical degeneration that yields distinctive motor and cognitive problems. Studying this pattern of degeneration can help with the diagnosis of disease subtypes, evaluation of disease stage, and treatment planning. In this work, we propose a learning framework using MR image data for discriminating a set of cerebellar ataxia types and predicting a disease related functional score. We address the difficulty in analyzing high-dimensional image data with limited training subjects by: 1) training weak classifiers/regressors on a set of image subdomains separately, and combining the weak classifier/regressor outputs to make the decision; 2) perturbing the image subdomain to increase the training samples; 3) using a deep learning technique called the stacked auto-encoder to develop highly representative feature vectors of the input data. Experiments show that our approach can reliably classify between one of four categories (healthy control and three types of ataxia), and predict the functional staging score for ataxia. PMID:25553339

Yang, Zhen; Zhong, Shenghua; Carass, Aaron; Ying, Sarah H.; Prince, Jerry L.

2014-01-01

331

Behavioural aspects of cerebellar function in adults with Asperger syndrome.  

PubMed

Aside from social deficits, Asperger and autistic individuals also exhibit motor control abnormalities such as impaired gait, balance, manual dexterity and grip. One brain area that has consistently been reported on autopsy and imaging studies to be abnormal in such individuals is the cerebellum. As the cerebellum controls sensorimotor coordination and lesions here typically cause hypotonia, dysmetria and dyscoordination, we performed a series of quantitative tests aimed at investigating cerebellar function in Asperger individuals. Tests examining visually guided movement (rapid pointing), speeded complex movement (finger tapping, rapid hand turning), muscle tone (catching dropped weight), prediction, coordination and timing (balance, grip force and interval timing) were conducted on 12 Asperger subjects and 12 age and IQ matched controls. In comparison to control subjects, Asperger subject's demonstrated: (i) decreased pointing accuracy and rate, (ii) increased postural instability, and (iii) decreased timing accuracy. IQ was found to co-vary with some parameters of each of these tasks and no further impairments were found on the remaining tests. We suggest that these specific deficits reflect impairment in the ability to integrate sensory input with appropriate motor commands and are consistent with cerebellar dysfunction in Asperger syndrome. PMID:16321884

Gowen, Emma; Miall, R Chris

2005-01-01

332

Coordinated Scaling of Cortical and Cerebellar Numbers of Neurons  

PubMed Central

While larger brains possess concertedly larger cerebral cortices and cerebella, the relative size of the cerebral cortex increases with brain size, but relative cerebellar size does not. In the absence of data on numbers of neurons in these structures, this discrepancy has been used to dispute the hypothesis that the cerebral cortex and cerebellum function and have evolved in concert and to support a trend towards neocorticalization in evolution. However, the rationale for interpreting changes in absolute and relative size of the cerebral cortex and cerebellum relies on the assumption that they reflect absolute and relative numbers of neurons in these structures across all species – an assumption that our recent studies have shown to be flawed. Here I show for the first time that the numbers of neurons in the cerebral cortex and cerebellum are directly correlated across 19 mammalian species of four different orders, including humans, and increase concertedly in a similar fashion both within and across the orders Eulipotyphla (Insectivora), Rodentia, Scandentia and Primata, such that on average a ratio of 3.6 neurons in the cerebellum to every neuron in the cerebral cortex is maintained across species. This coordinated scaling of cortical and cerebellar numbers of neurons provides direct evidence in favor of concerted function, scaling and evolution of these brain structures, and suggests that the common notion that equates cognitive advancement with neocortical expansion should be revisited to consider in its stead the coordinated scaling of neocortex and cerebellum as a functional ensemble. PMID:20300467

Herculano-Houzel, Suzana

2010-01-01

333

Is cerebellar granule cell migration regulated by an internal clock?  

PubMed

We have studied the time course of migratory behavior of cerebellar granule cells in the microwell tissue culture system. [3H]Thymidine served as a marker for particular granule cell generations. When cultured 4 hr after [3H]thymidine injection for 6 days in microwell cultures, labeled granule cells were seen to migrate along fiber bundles expanding between reaggregates called "cables" for 3 to 4 days. After 5 and 6 days in vitro the percentage of labeled non-migrating cells found in clusters in reaggregates and on cables increased considerably. Whereas unlabeled cells continued to migrate. Comparable results were obtained when granule cells developed in vivo for various times after label and their developmental state was determined in vitro. Cells from cerebellar populations labeled 1 to 4 days before culture maintained their ability to migrate in vitro, even after granule cells had entered the internal granule cell layer. In contrast, the percentage of migrating cells labeled 5 and 6 days before culture was reduced significantly. The results suggest that the time span of granule cell migration is predetermined intrinsically rather than by external signals. PMID:6502207

Trenkner, E; Smith, D; Segil, N

1984-11-01

334

Influence of thyroid hormones on maturation of rat cerebellar astrocytes.  

PubMed

Thyroid hormone influences brain maturation through interaction with nuclear receptors and regulation of gene expression. Their role on astrocyte maturation remains unclear. We have analyzed the role of thyroid hormone in rat cerebellar astrocyte maturation by comparing the sequential patterns of intermediate filament expression in normal and hypothyroid animals. During normal development astroglial cells sequentially express nestin, vimentin, and glial fibrillary acidic protein. Differentiated astrocytes appeared in the superior medullary vellum by postnatal day 2 and reached the white mater and internal granular layer by postnatal day 4. Intermediate filament marker expression was transiently lost from postnatal days 6 to 8 in anterior lobes, without an increased apoptosis. Vimentin expression was replaced by glial fibrillary acidic protein between postnatal days 10 and 32. The differentiated astrocytes were evenly distributed throughout the cerebellar slices, including the internal granular layer. Differences between normal and hypothyroid rats were observed starting from postnatal day 4, with lack of differentiated astrocytes in the internal granular layer. The transient decrease of astrocyte markers immunoreactivity in the anterior lobe did not take place in hypothyroid rats. The vimentin-glial fibrillary acidic protein transition was delayed and most differentiated astrocytes remained confined to the white matter. The results indicate that thyroid hormone deficiency induces a delay and a partial arrest of astrocyte differentiation. Astrocytes express thyroid hormone receptor alpha and beta subtypes suggesting that astrocytes are direct target cells of thyroid hormones. PMID:17408906

Manzano, Jimena; Bernal, Juan; Morte, Beatriz

2007-05-01

335

Congenital disorders of glycosylation with emphasis on cerebellar involvement.  

PubMed

Congenital disorders of glycosylation (CDG) are genetic diseases due to defective glycosylation of proteins and lipids. The authors present an update on these disorders affecting the central nervous system with a focus on cerebellar involvement. The rate of identification of novel CDG shows an exponential increase. Some 76 CDG are actually known, not taking into account the defects in glycan-modifying proteins. Neurologic involvement is present in the large majority of CDG. Screening methods are limited to serum transferrin isoelectrofocusing (for N-glycosylation disorders with sialic acid deficiency), and serum apolipoprotein C-III isoelectrofocusing (for core 1 mucin-type O-glycosylation disorders). Whole exome/genome sequencing is increasingly used in the diagnostic workup of patients with CDG-X. Treatment is greatly lagging behind because only one CDG is efficiently treatable (MPI-CDG). Cerebellar involvement is an important feature of PMM2-CDG, the congenital muscular dystrophies due to dystroglycanopathy, and SRD5A3-CDG. It has also been reported in some patients with ALG1-CDG, ALG3-CDG, ALG9-CDG, ALG6-CDG, ALG8-CDG, PIGA-CDG, DPM1-CDG, DPM2-CDG, B4GALT1-CDG, SLC35A2-CDG, COG1-CDG, COG5-CDG, COG7-CDG, and COG8-CDG. PMID:25192513

Barone, Rita; Fiumara, Agata; Jaeken, Jaak

2014-07-01

336

Cerebellar morphology and the effects of stimulant medications in youths with attention deficit-hyperactivity disorder.  

PubMed

The cerebellum is emerging as a key anatomical structure underlying normal attentional and cognitive control mechanisms. Dysregulation within cerebellar circuits may contribute to the core symptoms of Attention Deficit/Hyperactivity Disorder (ADHD). In the present study we aimed to characterize surface morphological features of the cerebellum in ADHD and healthy comparison youths. Further, we studied the association of cerebellar morphology with the severity of ADHD symptoms and the effects of stimulant treatment. We examined 46 youths with ADHD and 59 comparison youths 8-18 years of age in a cross-sectional, case-control study using magnetic resonance imaging. Measures of cerebellar surface morphology were the primary outcome. Relative to comparison participants, youths with ADHD exhibited smaller regional volumes corresponding to the lateral surface of the left anterior and the right posterior cerebellar hemispheres. Stimulant medication was associated with larger regional volumes over the left cerebellar surface, whereas more severe ADHD symptoms were associated with smaller regional volumes in the vermis. We used optimized measures of morphology to detect alterations in cerebellar anatomy specific to ADHD, dimensions of symptomology, and stimulant treatment. Duration of treatment correlated positively with volumes of specific cerebellar subregions, supporting a model whereby compensatory morphological changes support the effects of stimulant treatment. PMID:24077064

Ivanov, Iliyan; Murrough, James W; Bansal, Ravi; Hao, Xuejun; Peterson, Bradley S

2014-02-01

337

Cerebellar language mapping and cerebral language dominance in pediatric epilepsy surgery patients  

PubMed Central

Objective Children with epilepsy often have reorganization of language networks and abnormal brain anatomy, making determination of language lateralization difficult. We characterized the proportion and distribution of language task activation in the cerebellum to determine the relationship to cerebral language lateralization. Methods Forty-six pediatric epilepsy surgery candidates (aged 7–19 years) completed an fMRI auditory semantic decision language task. Distribution of activated voxels and language laterality indices were computed using: (a) Broca's and Wernicke's areas and their right cerebral homologues; and (b) left and right cerebellar hemispheres. Language task activation was anatomically localized in the cerebellum. Results Lateralized language task activation in either cerebral hemisphere was highly correlated with lateralized language task activation in the contralateral cerebellar hemisphere (Broca vs. cerebellar: ? = ?0.54, p < 0.01). Cerebellar language activation was located within Crus I/II, areas previously implicated in non-motor functional networks. Conclusions Cerebellar language activation occurs in homologous regions of Crus I/II contralateral to cerebral language activation in patients with both right and left cerebral language dominance. Cerebellar language laterality could contribute to comprehensive pre-operative evaluation of language lateralization in pediatric epilepsy surgery patients. Our data suggest that patients with atypical cerebellar language activation are at risk for having atypical cerebral language organization. PMID:25379442

Gelinas, Jennifer N.; Fitzpatrick, Kevin P.V.; Kim, Hong Cheol; Bjornson, Bruce H.

2014-01-01

338

Glutamate dysfunction associated with developmental cerebellar damage: relevance to autism spectrum disorders.  

PubMed

Neural abnormalities commonly associated with autism spectrum disorders include prefrontal cortex (PFC) dysfunction and cerebellar pathology in the form of Purkinje cell loss and cerebellar hypoplasia. It has been reported that loss of cerebellar Purkinje cells results in aberrant dopamine neurotransmission in the PFC which occurs via dysregulation of multisynaptic efferents from the cerebellum to the PFC. Using a mouse model, we investigated the possibility that developmental cerebellar Purkinje cell loss could disrupt glutamatergic cerebellar projections to the PFC that ultimately modulate DA release. We measured glutamate release evoked by local electrical stimulation using fixed-potential amperometry in combination with glutamate selective enzyme-based recording probes in urethane-anesthetized Lurcher mutant and wildtype mice. Target sites included the mediodorsal and ventrolateral thalamic nuclei, reticulotegmental nuclei, pedunculopontine nuclei, and ventral tegmental area. With the exception of the ventral tegmental area, the results indicated that in comparison to wildtype mice, evoked glutamate release was reduced in Lurcher mutants by between 9 and 72% at all stimulated sites. These results are consistent with the notion that developmental loss of cerebellar Purkinje cells drives reductions in evoked glutamate release in cerebellar efferent pathways that ultimately influence PFC dopamine release. Possible mechanisms whereby reductions in glutamate release could occur are discussed. PMID:24307139

McKimm, Eric; Corkill, Beau; Goldowitz, Dan; Albritton, Lorraine M; Homayouni, Ramin; Blaha, Charles D; Mittleman, Guy

2014-06-01

339

Mechanisms of human cerebellar dysmetria: experimental evidence and current conceptual bases  

PubMed Central

The human cerebellum contains more neurons than any other region in the brain and is a major actor in motor control. Cerebellar circuitry is unique by its stereotyped architecture and its modular organization. Understanding the motor codes underlying the organization of limb movement and the rules of signal processing applied by the cerebellar circuits remains a major challenge for the forthcoming decades. One of the cardinal deficits observed in cerebellar patients is dysmetria, designating the inability to perform accurate movements. Patients overshoot (hypermetria) or undershoot (hypometria) the aimed target during voluntary goal-directed tasks. The mechanisms of cerebellar dysmetria are reviewed, with an emphasis on the roles of cerebellar pathways in controlling fundamental aspects of movement control such as anticipation, timing of motor commands, sensorimotor synchronization, maintenance of sensorimotor associations and tuning of the magnitudes of muscle activities. An overview of recent advances in our understanding of the contribution of cerebellar circuitry in the elaboration and shaping of motor commands is provided, with a discussion on the relevant anatomy, the results of the neurophysiological studies, and the computational models which have been proposed to approach cerebellar function. PMID:19364396

Manto, Mario

2009-01-01

340

Tracer-Based Determination of Vortex Descent in the 1999-2000 Arctic Winter  

NASA Technical Reports Server (NTRS)

A detailed analysis of available in situ and remotely sensed N2O and CH4 data measured in the 1999-2000 winter Arctic vortex has been performed in order to quantify the temporal evolution of vortex descent. Differences in potential temperature (theta) among balloon and aircraft vertical profiles (an average of 19-23 K on a given N2O or CH4 isopleth) indicated significant vortex inhomogeneity in late fall as compared with late winter profiles. A composite fall vortex profile was constructed for November 26, 1999, whose error bars encompassed the observed variability. High-latitude, extravortex profiles measured in different years and seasons revealed substantial variability in N2O and CH4 on theta surfaces, but all were clearly distinguishable from the first vortex profiles measured in late fall 1999. From these extravortex-vortex differences, we inferred descent prior to November 26: 397+/-15 K (1sigma) at 30 ppbv N2O and 640 ppbv CH4, and 28+/-13 K above 200 ppbv N2O and 1280 ppbv CH4. Changes in theta were determined on five N2O and CH4 isopleths from November 26 through March 12, and descent rates were calculated on each N2O isopleth for several time intervals. The maximum descent rates were seen between November 26 and January 27: 0.82+/-0.20 K/day averaged over 50-250 ppbv N2O. By late winter (February 26-March 12), the average rate had decreased to 0.10+/-0.25 K/day. Descent rates also decreased with increasing N2O; the winter average (November 26-March 5) descent rate varied from 0.75+/-0.10 K/day at 50 ppbv to 0.40+/-0.11 K/day at 250 ppbv. Comparison of these results with observations and models of descent in prior years showed very good overall agreement. Two models of the 1999-2000 vortex descent, SLIMCAT and REPROBUS, despite theta offsets with respect to observed profiles of up to 20 K on most tracer isopleths, produced descent rates that agreed very favorably with the inferred rates from observation.

Greenblatt, Jeffery B.; Jost, Hans-Juerg; Loewenstein, Max; Podolske, James R.; Hurst, Dale F.; Elkins, James W.; Schauffler, Sue M.; Atlas, Elliot L.; Herman, Robert L.; Webster, Christopher R.

2001-01-01

341

Cerebellar Transcranial Magnetic Stimulation: The Role of Coil Geometry and Tissue Depth?  

PubMed Central

Background While transcranial magnetic stimulation (TMS) coil geometry has important effects on the evoked magnetic field, no study has systematically examined how different coil designs affect the effectiveness of cerebellar stimulation. Hypothesis The depth of the cerebellar targets will limit efficiency. Angled coils designed to stimulate deeper tissue are more effective in eliciting cerebellar stimulation. Methods Experiment 1 examined basic input–output properties of the figure-of-eight, batwing and double-cone coils, assessed with stimulation of motor cortex. Experiment 2 assessed the ability of each coil to activate cerebellum, using cerebellar-brain inhibition (CBI). Experiment 3 mapped distances from the scalp to cerebellar and motor cortical targets in a sample of 100 subjects' structural magnetic resonance images. Results Experiment 1 showed batwing and double-cone coils have significantly lower resting motor thresholds, and recruitment curves with steeper slopes than the figure-of-eight coil. Experiment 2 showed the double-cone coil was the most efficient for eliciting CBI. The batwing coil induced CBI only at higher stimulus intensities. The figure-of-eight coil did not elicit reliable CBI. Experiment 3 confirmed that cerebellar tissue is significantly deeper than primary motor cortex tissue, and we provide a map of scalp-to-target distances. Conclusions The double-cone and batwing coils designed to stimulate deeper tissue can effectively stimulate cerebellar targets. The double-cone coil was found to be most effective. The depth map provides a guide to the accessible regions of the cerebellar volume. These results can guide coil selection and stimulation parameters when designing cerebellar TMS studies. PMID:24924734

Hardwick, Robert M.; Lesage, Elise; Miall, R. Chris

2014-01-01

342

Qualitative and quantitative aspects of the microanatomy of the African elephant cerebellar cortex.  

PubMed

The current study provides a number of novel observations on the organization and structure of the cerebellar cortex of the African elephant by using a combination of basic neuroanatomical and immunohistochemical stains with Golgi and stereologic analysis. While the majority of our observations indicate that the cerebellar cortex of the African elephant is comparable to other mammalian species, several features were unique to the elephant. The three-layered organization of the cerebellar cortex, the neuronal types and some aspects of the expression of calcium-binding proteins were common to a broad range of mammalian species. The Lugaro neurons observed in the elephant were greatly enlarged in comparison to those of other large-brained mammals, suggesting a possible alteration in the processing of neural information in the elephant cerebellar cortex. Analysis of Golgi impregnations indicated that the dendritic complexity of the different interneuron types was higher in elephants than other mammals. Expression of parvalbumin in the parallel fibers and calbindin expressed in the stellate and basket cells also suggested changes in the elephant cerebellar neuronal circuitry. The stereologic analysis confirmed and extended previous observations by demonstrating that neuronal density is low in the elephant cerebellar cortex, providing for a larger volume fraction of the neuropil. With previous results indicating that the elephants have the largest relative cerebellar size amongst mammals, and one of the absolutely largest mammalian cerebella, the current observations suggest that the elephants have a greater volume of a potentially more complexly organized cerebellar cortex compared to other mammals. This quantitatively larger and more complex cerebellar cortex likely represents part of the neural machinery required to control the complex motor patterns involved in movement of the trunk and the production of infrasonic vocalizations. PMID:23296570

Maseko, Busisiwe C; Jacobs, Bob; Spocter, Muhammad A; Sherwood, Chet C; Hof, Patrick R; Manger, Paul R

2013-01-01

343

Cerebellar Abnormalities Contribute to Disability Including Cognitive Impairment in Multiple Sclerosis  

PubMed Central

The cerebellum is known to be involved not only in motor but also cognitive and affective processes. Structural changes in the cerebellum in relation to cognitive dysfunction are an emerging topic in the field of neuro-psychiatric disorders. In Multiple Sclerosis (MS) cerebellar motor and cognitive dysfunction occur in parallel, early in the onset of the disease, and the cerebellum is one of the predilection sites of atrophy. This study is aimed at determining the relationship between cerebellar volumes, clinical cerebellar signs, cognitive functioning and fatigue in MS. Cerebellar volumetry was conducted using T1-weighted MPRAGE magnetic resonance imaging of 172 MS patients. All patients underwent a clinical and brief neuropsychological assessment (information processing speed, working memory), including fatigue testing. Patients with and without cerebellar signs differed significantly regarding normalized cerebellar total volume (nTCV), normalized brain volume (nBV) and whole brain T2 lesion volume (LV). Patients with cerebellar dysfunction likewise performed worse in cognitive tests. A regression analysis indicated that age and nTCV explained 26.3% of the variance in SDMT (symbol digit modalities test) performance. However, only age, T2 LV and nBV remained predictors in the full model (r2?=?0.36). The full model for the prediction of PASAT (Paced Auditory Serial Addition Test) scores (r2?=?0.23) included age, cerebellar and T2 LV. In the case of fatigue, only age and nBV (r2?=?0.17) emerged as significant predictors. These data support the view that cerebellar abnormalities contribute to disability, including cognitive impairment in MS. However, this contribution does not seem to be independent of, and may even be dominated by wider spread MS pathology as reflected by nBV and T2 LV. PMID:24466290

Weier, Katrin; Penner, Iris K.; Magon, Stefano; Amann, Michael; Naegelin, Yvonne; Andelova, Michaela; Derfuss, Tobias; Stippich, Christoph; Radue, Ernst-Wilhelm; Kappos, Ludwig; Sprenger, Till

2014-01-01

344

Cerebellar abnormalities contribute to disability including cognitive impairment in multiple sclerosis.  

PubMed

The cerebellum is known to be involved not only in motor but also cognitive and affective processes. Structural changes in the cerebellum in relation to cognitive dysfunction are an emerging topic in the field of neuro-psychiatric disorders. In Multiple Sclerosis (MS) cerebellar motor and cognitive dysfunction occur in parallel, early in the onset of the disease, and the cerebellum is one of the predilection sites of atrophy. This study is aimed at determining the relationship between cerebellar volumes, clinical cerebellar signs, cognitive functioning and fatigue in MS. Cerebellar volumetry was conducted using T1-weighted MPRAGE magnetic resonance imaging of 172 MS patients. All patients underwent a clinical and brief neuropsychological assessment (information processing speed, working memory), including fatigue testing. Patients with and without cerebellar signs differed significantly regarding normalized cerebellar total volume (nTCV), normalized brain volume (nBV) and whole brain T2 lesion volume (LV). Patients with cerebellar dysfunction likewise performed worse in cognitive tests. A regression analysis indicated that age and nTCV explained 26.3% of the variance in SDMT (symbol digit modalities test) performance. However, only age, T2 LV and nBV remained predictors in the full model (r(2)?=?0.36). The full model for the prediction of PASAT (Paced Auditory Serial Addition Test) scores (r(2)?=?0.23) included age, cerebellar and T2 LV. In the case of fatigue, only age and nBV (r(2)?=?0.17) emerged as significant predictors. These data support the view that cerebellar abnormalities contribute to disability, including cognitive impairment in MS. However, this contribution does not seem to be independent of, and may even be dominated by wider spread MS pathology as reflected by nBV and T2 LV. PMID:24466290

Weier, Katrin; Penner, Iris K; Magon, Stefano; Amann, Michael; Naegelin, Yvonne; Andelova, Michaela; Derfuss, Tobias; Stippich, Christoph; Radue, Ernst-Wilhelm; Kappos, Ludwig; Sprenger, Till

2014-01-01

345

Quadratic steepest descent on potential energy surfaces. I. Basic formalism and quantitative assessment  

NASA Astrophysics Data System (ADS)

A novel second-order algorithm is formulated for determining steepest-descent lines on potential energy surfaces. The reaction path is deduced from successive exact steepest-descent lines of local quadratic approximations to the surface. At each step, a distinction is made between three points: the center for the local quadratic Taylor expansion of the surface, the junction of the two adjacent local steepest-descent line approximations, and the predicted approximation to the true steepest-descent line. This flexibility returns a more efficient yield from the calculated information and increases the accuracy of the local quadratic approximations by almost an order of magnitude. In addition, the step size is varied with the curvature and, if desired, can be readjusted by a trust region assessment. Applications to the Gonzalez-Schlegel and the Müller-Brown surfaces show the method to compare favorably with existing methods. Several measures are given for assessing the accuracy achieved without knowledge of the exact steepest-descent line. The optimal evaluation of the predicted gradient and curvature for dynamical applications is discussed.

Sun, Jun-Qiang; Ruedenberg, Klaus

1993-10-01

346

Aerodynamics of Reentry Vehicle Clipper at Descent Phase  

NASA Astrophysics Data System (ADS)

From Gagarin spacecraft to reusable orbiter Buran, RSC Energia has traveled a long way in the search for the most optimal and, which is no less important, the most reliable spacecraft for manned space flight. During the forty years of space exploration, in cooperation with a broad base of subcontractors, a number of problems have been solved which assure a safe long stay in space. Vostok and Voskhod spacecraft were replaced with Soyuz supporting a crew of three. During missions to a space station, it provides crew rescue capability in case of a space station emergency at all times (the spacecraft life is 200 days).The latest modification of Soyuz spacecraft -Soyuz TMA -in contrast to its predecessors, allows to become a space flight participant to a person of virtually any anthropometric parameters with a mass of 50 to 95 kg capable of withstanding up to 6 g load during descent. At present, Soyuz TMA spacecraft are the state-of-the-art, reliable and only means of the ISS crew delivery, in-flight support and return. Introduced on the basis of many years of experience in operation of manned spacecraft were not only the principles of deep redundancy of on-board systems and equipment, but, to assure the main task of the spacecraft -the crew return to Earth -the principles of functional redundancy. That is, vital operations can be performed by different systems based on different physical principles. The emergency escape system that was developed is the only one in the world that provides crew rescue in case of LV failure at any phase in its flight. Several generations of space stations that have been developed have broadened, virtually beyond all limits, capabilities of man in space. The docking system developed at RSC Energia allowed not only to dock spacecraft in space, but also to construct in orbit various complex space systems. These include large space stations, and may include in the future the in-orbit construction of systems for the exploration of the Moon and Mars.. Logistics spacecraft Progress have been flying regularly since 1978. The tasks of these unmanned spacecraft include supplying the space station with all the necessities for long-duration missions, such as propellant for the space station propulsion system, crew life support consumables, scientific equipment for conducting experiments. Various modifications of the spacecraft have expanded the space station capabilities. 1988 saw the first, and, much to our regret, the last flight of the reusable orbiter Buran.. Buran could deliver to orbit up to 30 tons of cargo, return 20 tons to Earth and have a crew of up to 10. However, due to our country's economic situation the project was suspended.

Semenov, Yu. P.; Reshetin, A. G.; Dyadkin, A. A.; Petrov, N. K.; Simakova, T. V.; Tokarev, V. A.

2005-02-01

347

Up-down asymmetry of cerebellar activation during vertical pursuit eye movements.  

PubMed

Animal experiments have demonstrated that the vast majority of vertical gaze-velocity Purkinje cells in the cerebellar floccular lobe, whose firing rate is modulated during vertical smooth pursuit eye movements, show a preference for downward pursuit. Here we validate the functional vertical asymmetry of the cerebellar flocculus in humans using functional magnetic resonance imaging by demonstrating a significantly higher activation of the floccular lobe for downward than for upward pursuit. The findings corroborate our recent hypothesis on the pathogenesis of cerebellar downbeat nystagmus. PMID:19415407

Glasauer, Stefan; Stephan, Thomas; Kalla, Roger; Marti, Sarah; Straumann, Dominik

2009-09-01

348

Cerebellar ataxia in a young patient: A rare path to lupus  

PubMed Central

Cerebellar ataxia is a rare manifestation of neuropsychiatric systemic lupus erythematosus (SLE). Development of vasculitic infarcts in the cerebellum is the most plausible reason of this manifestation. We report the case of a patient who presented with characteristic skin rashes of lupus along with cerebellar signs. Imaging of brain in this patient revealed prominent cerebellar atrophy. She was treated with mycophenolate mofetil and oral corticosteroid, and there was no further progression of her neurological signs after the initiation of therapy. In the clinical context of varied presentations of neurolupus, this is one of the rare sightings and our treatment protocol holds promise as first-line therapy in future. PMID:25540550

Ghosh, Kaushik; Chatterjee, Atri; Ghosh, Susmita; Chakraborty, Sisir

2014-01-01

349

Advances in POST2 End-to-End Descent and Landing Simulation for the ALHAT Project  

NASA Technical Reports Server (NTRS)

Program to Optimize Simulated Trajectories II (POST2) is used as a basis for an end-to-end descent and landing trajectory simulation that is essential in determining design and integration capability and system performance of the lunar descent and landing system and environment models for the Autonomous Landing and Hazard Avoidance Technology (ALHAT) project. The POST2 simulation provides a six degree-of-freedom capability necessary to test, design and operate a descent and landing system for successful lunar landing. This paper presents advances in the development and model-implementation of the POST2 simulation, as well as preliminary system performance analysis, used for the testing and evaluation of ALHAT project system models.

Davis, Jody L.; Striepe, Scott A.; Maddock, Robert W.; Hines, Glenn D.; Paschall, Stephen, II; Cohanim, Babak E.; Fill, Thomas; Johnson, Michael C.; Bishop, Robert H.; DeMars, Kyle J.; Sostaric, Ronald r.; Johnson, Andrew E.

2008-01-01

350

Coordinate great circle descent algorithm with application to single-index models  

PubMed Central

Coordinate descent algorithm has been widely used to solve high dimensional optimization problems with a non-differentiable objective function recently. To provide theoretical justification, Tseng (2001) showed that it leads to a stationary point when the non-differentiable part of the objective function is separable. Motivated by the single index model, we consider optimization problems with a unit-norm constraint in this article. Because of this unit-norm constraint, the coordinate descent algorithm cannot be applied. In addition, non-separability of the non-differentiable part of the objective function makes the result of Tseng (2001) not directly applicable. In this paper, we propose a novel coordinate great circle descent algorithm to solve this family of optimization problems. The validity of the algorithm is justified both theoretically and via simulation studies. We also use the Boston housing data to illustrate this algorithm by applying it to fit single-index models.

Zeng, Peng

2014-01-01

351

Descent and Landing Triggers for the Orion Multi-Purpose Crew Vehicle Exploration Flight Test-1  

NASA Technical Reports Server (NTRS)

The Orion Multi-Purpose Crew Vehicle (MPCV) will perform a flight test known as Exploration Flight Test-1 (EFT-1) currently scheduled for 2014. One of the primary functions of this test is to exercise all of the important Guidance, Navigation, Control (GN&C), and Propulsion systems, along with the flight software for future flights. The Descent and Landing segment of the flight is governed by the requirements levied on the GN&C system by the Landing and Recovery System (LRS). The LRS is a complex system of parachutes and flight control modes that ensure that the Orion MPCV safely lands at its designated target in the Pacific Ocean. The Descent and Landing segment begins with the jettisoning of the Forward Bay Cover and concludes with sensing touchdown. This paper discusses the requirements, design, testing, analysis and performance of the current EFT-1 Descent and Landing Triggers flight software.

Bihari, Brian D.; Semrau, Jeffrey D.; Duke, Charity J.

2013-01-01

352

Evolutionary analyses of non-genealogical bonds produced by introgressive descent  

PubMed Central

All evolutionary biologists are familiar with evolutionary units that evolve by vertical descent in a tree-like fashion in single lineages. However, many other kinds of processes contribute to evolutionary diversity. In vertical descent, the genetic material of a particular evolutionary unit is propagated by replication inside its own lineage. In what we call introgressive descent, the genetic material of a particular evolutionary unit propagates into different host structures and is replicated within these host structures. Thus, introgressive descent generates a variety of evolutionary units and leaves recognizable patterns in resemblance networks. We characterize six kinds of evolutionary units, of which five involve mosaic lineages generated by introgressive descent. To facilitate detection of these units in resemblance networks, we introduce terminology based on two notions, P3s (subgraphs of three nodes: A, B, and C) and mosaic P3s, and suggest an apparatus for systematic detection of introgressive descent. Mosaic P3s correspond to a distinct type of evolutionary bond that is orthogonal to the bonds of kinship and genealogy usually examined by evolutionary biologists. We argue that recognition of these evolutionary bonds stimulates radical rethinking of key questions in evolutionary biology (e.g., the relations among evolutionary players in very early phases of evolutionary history, the origin and emergence of novelties, and the production of new lineages). This line of research will expand the study of biological complexity beyond the usual genealogical bonds, revealing additional sources of biodiversity. It provides an important step to a more realistic pluralist treatment of evolutionary complexity. PMID:23090996

Bapteste, Eric; Lopez, Philippe; Bouchard, Frédéric; Baquero, Fernando; McInerney, James O.; Burian, Richard M.

2012-01-01

353

Hippocampal-cerebellar interaction during spatio-temporal prediction.  

PubMed

The hippocampus and cerebellum play a role in the process of temporal memory formation. The interaction between these brain regions during the prediction of motor executions nevertheless remains unclear. Using fMRI, we show here that the hippocampus and cerebellum are co-activated during a timing-dependent task that requires accurate prediction timing of finger movements following preceding visual cues, but not during 2 control tasks: a reaction task requiring identical coordination of individual and combined fingers without predicting the motor timing, or an imagery task. In addition, functional connectivity analyses reveal that the hippocampus showed increased functional connectivity with the bilateral hemispheres of the cerebellum. These results suggest that hippocampal-cerebellar interplay occurs during spatio-temporal prediction of movements on the basis of visuomotor integration. PMID:23968839

Onuki, Yoshiyuki; Van Someren, Eus J W; De Zeeuw, Chris I; Van der Werf, Ysbrand D

2015-02-01

354

Large cerebellar mass lesion: A rare intracranial manifestation of blastomycosis  

PubMed Central

Background: Blastomyces dermatitidis is a dimorphic fungus found endemically in the Mississippi and Ohio River basins and in the Midwestern and Canadian provinces that border the Great Lakes. Unlike other fungal infections, it most commonly affects immunocompetent hosts. Blastomycosis typically manifests as pulmonary infection, but may affect nearly any organ, including the skin, bone, and genitourinary system. Central nervous system (CNS) blastomycosis is rare, but potentially fatal manifestation of this disease. When it does occur, it most commonly presents as acute or chronic meningitis. Case Description: We present a case of a patient who suffered intractable nausea and vomiting for several months before discovery of a large cerebellar blastomycoma causing mass effect and obstructive hydrocephalus. The enhancing lesion with unusual peripheral cystic structures is a unique radiographic appearance of CNS blastomycosis. Conclusion: We review this patient's purely intraparenchymal manifestation of CNS blastomycosis and describe the unique imaging characteristics encountered. PMID:24231945

Munich, Stephan A.; Johnson, Andrew K.; Ahuja, Sumeet K.; Venizelos, Alexander; Byrne, Richard W.

2013-01-01

355

[Cerebellar gangliocytoma in an 11-year-old child].  

PubMed

Cerebellar gangliocytoma can correspond to Lhermitte-Duclos disease, a benign hamartomatous malformation encountered in young adults. It can also be a part of gangliogliomas/gangliocytomas family, which usually encompasses temporal pediatric neoplasms associated with longstanding seizures. We report a case of a young 11-year-old patient who presented with a gangliocytoma of the cerebellum revealed by neurologic manifestations (headache, dyspraxia, equilibrium and gait disturbances). Diagnosis was made on surgical material. Tumour was characterized by dysplastic mature ganglion cells, perivascular lymphocytic infiltrates and no glial neoplastic component. By immunohistochemistry, ganglion cells expressed neurofilaments, MAP2 protein, synaptophysin, chromogranin A and S100 protein. BRAF V600E mutation was absent. Clinical characteristics, radiology, histopathology of the two main diagnoses are discussed. PMID:25499864

Joly, Marie; Valmary-Degano, Séverine; Cattin, Françoise; Vasiljevic, Alexandre; Jouvet, Anne; Viennet, Gabriel

2014-12-01

356

Genetic aspects of autosomal dominant late onset cerebellar ataxia.  

PubMed Central

The genetic features of eight families with autosomal dominant late onset cerebellar ataxia with randomly distributed associated clinical features are described. The ratio of affected to unaffected offspring of affected subjects was not significantly different from 1:1. The mutant gene was fully penetrant when cases who died before the period of risk of developing the disease were excluded. The proportion of new mutants with this disorder appears to be low. Biological fitness was not impaired. Affected females tended to have large families than affected males. The ages of onset of females and males were not significantly different, but the offspring of affected males had earlier ages of onset and death than those of affected females. A cumulative age of onset curve is presented which should aid genetic counselling of subjects at risk and their children. PMID:7334501

Harding, A E

1981-01-01

357

Cerebellar cavernous malformations with and without associated developmental venous anomalies  

PubMed Central

Background The clinical profiles of cerebellar cavernous malformations (CCMs) with and without associated developmental venous anomalies (DVAs) are not well known. The aims of this study were to analyze the clinical and radiological characteristics of CCMs and to assess the various therapeutic strategies. Methods A consecutive series of 41 patients with identified CCMs were retrospectively reviewed. Of these, 11 patients (26.8%) were found to have associated DVAs. We compared the clinical profile of the two groups of patients (CCMs with and without DVAs). The CCMs with DVAs cases underwent radical resection of the CCMs, and the distal radicles of the DVAs that directly drain from the CCMs were coagulated and dissected at the length of the CCMs. Results There were no statistically significant differences between the two groups with regard to age, sex, location and size of lesions, multiplicity, and surgical prognosis. The patients with CCMs with DVAs did not experience any brain swelling or hemorrhagic tendency intraoperatively. The postoperative course was uneventful for all of the 36 surgical patients with the exception of two of the patients with CCMs with associated DVAs, who suffered from serious cerebellar edema, and one of these two patients underwent an emergency suboccipital decompression craniotomy. With the exception of three patients who were lost to follow-up (mean, 22.3 months), all of the CCMs patients exhibited good long-term prognosis (modified Rankin scale values of 0–2) and no reoccurrence. Conclusions It is not rare that associated DVAs occur in CCMs. The total removal of the CCM combined with the coagulation and dissection of the distal radicles of DVA at the length of the associated CCM may result in good long-term prognosis in patients. PMID:24088363

2013-01-01

358

The Genetic or Mythical Ancestry of Descent Groups: Lessons from the Y Chromosome  

PubMed Central

Traditional societies are often organized into descent groups called “lineages,” “clans,” and “tribes.” Each of these descent groups claims to have a common ancestor, and this ancestry distinguishes the group's members from the rest of the population. To test the hypothesis of common ancestry within these groups, we compared ethnological and genetic data from five Central Asian populations. We show that, although people from the same lineage and clan share generally a recent common ancestor, no such common ancestry is observed at the tribal level. Thus, a tribe might be a conglomerate of clans who subsequently invented a mythical ancestor to strengthen group unity. PMID:15467979

Chaix, Raphaëlle; Austerlitz, Frédéric; Khegay, Tatyana; Jacquesson, Svetlana; Hammer, Michael F.; Heyer, Evelyne; Quintana-Murci, Lluís

2004-01-01

359

Aerothermodynamics calculation of thermal destruction of "Fregat" upper stage at descent in the Earth's atmosphere  

NASA Astrophysics Data System (ADS)

The engineering calculation method has been developed for investigation of the process of thermal destruction of "Fregat" upper stage at deorbiting and descent into the Earth's atmosphere. The results of calculation of its descent trajectory and characteristics of aerodynamic heating are presented. Within the framework of the thermodynamic approach, the authors investigated the process of pressure increase in the tanks due to heating and evaporation of the liquid phase of fuel. Stresses in the shells, the height and the energy equivalent of explosive destruction of tanks were calculated depending on the degree of their filling with remains of the components of liquid fuel.

Glazunov, A. A.; Goldin, V. D.; Zverev, V. G.; Ustinov, S. N.; Finchenko, V. S.

2013-06-01

360

Initial Field Evaluation of Pilot Procedures for Flying CTAS Descent Clearances  

NASA Technical Reports Server (NTRS)

The Center TRACON Automation System (CTAS) is a new support system that is designed to assist air traffic controllers in the management of arrival traffic. CTAS will provide controllers with more information about current air traffic, enabling them to provide clearances for efficient, conflict-free descents that help achieve an orderly stream of aircraft at the final approach fix. CTAS is a computer-based system that functions as a "ground-based FMS" that can predict flight trajectories and arrival times for all incoming aircraft. CTAS uses an aircraft's cruise airspeed; current air traffic, winds and temperature; performance characteristics of the aircraft type; and individual airline preferences to create a flight profile from cruise altitude to the final approach fix. Controllers can use this flight profile to provide a descent clearance that will allow an aircraft to fly an efficient descent and merge more smoothly with other arriving aircraft. A field test of the CTAS Descent Advisor software was conducted at the Denver Center for aircraft arriving at the Stapleton International Airport from September 12-29. CTAS Descent clearances were given to a NASA flight test aircraft and to 77 airline flights that arrived during low traffic periods. For the airline portion of the field test, cockpit procedures and pilot briefing packages for both FMS equipped and unequipped aircraft were developed in cooperation with an airline. The procedures developed for the FMS equipped aircraft were to fly a VNAV descent at a controller specified speed to cross a metering fix at a specified altitude and speed. For nonFMS aircraft, the clearance also specified a CTAS calculated top-of-descent point. Some CTAS related flight deck issues included how much time was available to the pilots' for compliance, the amount of information that needed to be interpreted in the clearance and possible repercussions of misunderstandings. Data collected during the study ranged from subjective data (including the airline pilots' opinions and comments about the new descent clearances and procedures) to objective data (including observations of aircraft performance from the flight deck). This paper will present data and the resulting changes in the design of the procedures and clearance phraseology.

Palmer, Everett; Goka, Tsuyoshi; Cashion, Patricia; Feary, Michael; Graham, Holly; Smith, Nancy; Shafto, Michael (Technical Monitor)

1994-01-01

361

Overview of the NASA Entry, Descent and Landing Systems Analysis Study  

NASA Technical Reports Server (NTRS)

NASA senior management commissioned the Entry, Descent and Landing Systems Analysis (EDL-SA) Study in 2008 to identify and roadmap the Entry, Descent and Landing (EDL) technology investments that the agency needed to make in order to successfully land large payloads at Mars for both robotic and human-scale missions. This paper summarizes the approach and top-level results from Year 1 of the Study, which focused on landing 10-50 mt on Mars, but also included a trade study of the best advanced parachute design for increasing the landed payloads within the EDL architecture of the Mars Science Laboratory (MSL) mission.

Zang, Thomas A.; Dwyer-Cianciolo, Alicia M.; Kinney, David J.; Howard, Austin R.; Chen, George T.; Ivanov, Mark C.; Sostaric, Ronald R.; Westhelle, Carlos H.

2010-01-01

362

Entry, Descent and Landing Systems Analysis: Exploration Class Simulation Overview and Results  

NASA Technical Reports Server (NTRS)

NASA senior management commissioned the Entry, Descent and Landing Systems Analysis (EDL-SA) Study in 2008 to identify and roadmap the Entry, Descent and Landing (EDL) technology investments that the agency needed to make in order to successfully land large payloads at Mars for both robotic and exploration or human-scale missions. The year one exploration class mission activity considered technologies capable of delivering a 40-mt payload. This paper provides an overview of the exploration class mission study, including technologies considered, models developed and initial simulation results from the EDL-SA year one effort.

DwyerCianciolo, Alicia M.; Davis, Jody L.; Shidner, Jeremy D.; Powell, Richard W.

2010-01-01

363

Case report of subacute cerebellar ataxia of adolescence with long-term sequelae.  

PubMed

Acute ataxia is not an uncommon childhood complaint. It most commonly occurs in young patients secondary to a postinfectious cerebellitis, which is typically associated with a very good prognosis and recovery. In adolescence, acute cerebellar ataxia is more often the product of an etiology likely to progress into a chronic disorder without recovery to preillness baseline. In the present case, the authors describe a 15-year-old girl with subacute cerebellar ataxia of presumed immune-mediated etiology that advanced into a chronic cerebellar ataxia. Due to a family history, celiac disease was suspected as the origin of the ataxia; biopsy ruled out enteropathy, and the severe, abrupt radiological changes to the patient's cerebellum are inconsistent with the reported sequelae of gluten ataxia. This case serves as a discussion for diagnostic challenges in adolescent patients with acute cerebellar ataxia with long-term sequelae as well as providing an adjunct discussion on the neurological complications of celiac disease. PMID:23034974

Stowe, Robert C; Karkare, Shefali; Puri, Vinay

2013-12-01

364

Behavioural aspects of cerebellar function in adults with Asperger EMMA GOWEN & R. CHRIS MIALL  

E-print Network

Behavioural aspects of cerebellar function in adults with Asperger syndrome EMMA GOWEN & R. CHRIS from social deficits, Asperger and autistic individuals also exhibit motor control abnormalities in Asperger individuals. Tests examining visually guided movement (rapid pointing), speeded complex movement

Miall, Chris

365

Juvenile nephronophthisis associated with retinal pigmentary dystrophy, cerebellar ataxia, and skeletal abnormalities  

Microsoft Academic Search

A boy aged 9 3\\/4 years with interstitial nephritis, retinal pigmentary dystrophy, cerebellar ataxia, and skeletal abnormalities is described. The association may be due to a new genetic disorder, since 2 similar cases have been reported.

M Popovi?-Rolovi?; N Cali?-Perisíc; G Bunjevacki; D Negovanovi?

1976-01-01

366

Cell assembly patterns of embryonic mouse cerebellar cells on carbohydrate-derivatized polylysine culture substrata  

PubMed Central

Four carbohydrate derivatives of poly-D-lysine have been synthesized and assayed as substrates for the tissue culture of embryonic mouse cerebellar cells. On poly-beta-(D-glucopyranosyl)-poly-D-lysine and on poly-beta-(N-acetyl-D-glucosaminyl)-poly-D-lysine, dissociated cerebellar cells formed a monolayer. On poly-beta-(D-galactopyranosyl)- poly-D-lysine, cellular aggregates were formed and cables of processes were extended between the aggregates. On poly-beta-(L-fucosyl)-poly-D- lysine, cerebellar cells failed to attach and died within 24 h. On poly- (N-acetyl)-poly-D-lysine, cell attachment was identical to that on poly- D-lysine. At low concentrations of underivatized poly-D-lysine (0.5-2.0 microgram/ml) dissociated embryonic cerebellar cells formed cellular aggregates, whereas at higher concentrations of poly-D-lysine monolayering was extensive. PMID:7228900

1981-01-01

367

Comparison of cerebellar and motor cortex activity during reaching: directional tuning and response variability.  

PubMed

1. The responses of 262 motor cortex cells and 223 cerebellar neurons were recorded during whole-arm reaching movements toward targets lights in eight evenly distributed directions radiating from a common central starting position. The reaching movements were followed by a 2-s target hold period where a fixed arm posture was actively maintained to stabilize the hand over the target light. 2. Cerebellar neurons had a higher mean tonic discharge rate while holding over the starting position (22.9 imp/s) than did motor cortex cells (12.5 imp/s). The mean population response curve describing the changes in activities with movement direction was likewise shifted toward higher frequencies in the cerebellum compared with the motor cortex, but the amplitude of the two curves was about equal. Therefore, the baseline discharges of cerebellar neurons were higher, but their changes in activity during movement were similar to those of motor cortical cells. 3. Motor cortex neurons were more strongly related to active maintenance of different arm postures than were cerebellar units. This was shown by a larger posture-related population response curve in the motor cortex (half-wave amplitude of cosine function was 11.2 imp/s, compared with 7.0 imp/s for cerebellar neurons), which represented the average response curve calculated from all the cells of the population. Furthermore, the motor cortex population had a higher percentage of single cells with tonic responses while the hand was held over different targets (tonic and phasic-tonic cells composed 57% of motor cortex population, compared with 38% of cerebellar population). Proportionately more cerebellar cells were phasically related to the movements. 4. The majority of motor cortex cells (58%) showed reciprocal changes relative to the center-hold time activity where the activity increased for movements in the preferred direction and decreased for movements in the opposite direction. Most of the remaining cells (40%) showed graded changes where the activity increased gradually as reaching was directed closer to the preferred direction. In contrast, the most common cerebellar response pattern was graded (38%). Only 26% were reciprocal and 18% were non-directional. The remaining 2% of motor cortical cells and 18% of cerebellar neurons could not be readily assigned to any of these three response classes. 5. Sector widths were calculated to measure the dispersion of individual cerebellar and motor cortical cell activities about the eight movement directions. Sector widths calculated from the absolute activities were always broader for cerebellar neurons (i.e., the cells were more broadly tuned).(ABSTRACT TRUNCATED AT 400 WORDS) PMID:8492153

Fortier, P A; Smith, A M; Kalaska, J F

1993-04-01

368

Expression of Cerebellar Long-Term Depression Requires Postsynaptic Clathrin-Mediated Endocytosis  

Microsoft Academic Search

Cerebellar long-term depression (LTD) is a cellular model system of information storage that may underlie certain forms of motor learning. While cerebellar LTD is expressed as a selective modification of postsynaptic AMPA receptors, this might involve changes in receptor number\\/distribution, unitary conductance, kinetics, or glutamate affinity. The observation that GluR2-containing synaptic AMPA receptors could be internalized by regulated clathrin-mediated endocytosis

Yu Tian Wang; David J. Linden

2000-01-01

369

Structural and Functional Magnetic Resonance Imaging of the Human Cerebellar Nuclei  

Microsoft Academic Search

The present review focuses on recent developments in structural and functional magnetic resonance imaging (MRI) of the deep\\u000a cerebellar nuclei (DCN), the main output structure of the cerebellum. The high iron content in the DCN allows for their visibility\\u000a in T2*-weighted images. Spatial resolution has improved allowing the identification of DCN in individual cerebellar patients\\u000a and healthy subjects. Based on

Michael Küper; Markus Thürling; Stefan Maderwald; Mark E. Ladd; Dagmar Timmann

370

VGCC antibody-positive paraneoplastic cerebellar degeneration presenting with positioning vertigo.  

PubMed

A 70-year-old woman developed paraneoplastic cerebellar degeneration (PCD) due to P/Q-type and N-type voltage-gated calcium channel antibodies and small cell lung cancer, the main clinical manifestations of which were severe positioning vertigo and vomiting. Loss of the visual suppression of caloric nystagmus, spontaneous downbeat nystagmus, periodic alternating nystagmus, and positioning vertigo in our patient most probably corresponds to the cerebellar flocculus/paraflocculus lesion caused by PCD. PMID:21678073

Ogawa, Emina; Sakakibara, Ryuji; Kawashima, Kengo; Yoshida, Tomoe; Kishi, Masahiko; Tateno, Fuyuki; Kataoka, Manabu; Kawashima, Tatsuo; Yamamoto, Masahiko

2011-12-01

371

Glucose6-phosphate dehydrogenase supports the functioning of the synapses in rat cerebellar cortex  

Microsoft Academic Search

This study investigates heterogeneous glucose-6-phosphate dehydrogenase (G6PD) expression in the rat cerebellar cortex. G6PD activity and its electrophoretic pattern, evaluated on the cerebellar homogenate, were found to be similar to those of other brain areas. However, histochemical and immunohistochemical analyses revealed that the highest expression of G6PD activity and protein was in Purkinje’s cells, followed by the molecular and granular

Enrica Biagiotti; Loretta Guidi; Samuela Capellacci; Patrizia Ambrogini; Stefano Papa; Paolo Del Grande; Paolino Ninfali

2001-01-01

372

Cerebellar Transcranial Direct Current Stimulation Impairs the Practice-dependent Proficiency Increase in Working Memory  

Microsoft Academic Search

How the cerebellum is involved in the practice and proficiency of non-motor functions is still unclear. We tested whether transcranial direct current stimulation (tDCS) over the cerebellum (cerebellar tDCS) induces after-effects on the practice-dependent increase in the proficiency of a working memory (WM) task (Sternberg test) in 13 healthy subjects. We also assessed the effects of cerebellar tDCS on visual

R. Ferrucci; S. Marceglia; M. Vergari; F. Cogiamanian; S. Mrakic-sposta; F. Mameli; S. Zago; S. Barbieri; A. Priori

2008-01-01

373

Cerebellar infarction originating from vertebral artery stenosis caused by a hypertrophied uncovertebral joint.  

PubMed

We report a case of cerebellar infarction originating from vertebral artery stenosis caused by a hypertrophied uncovertebral joint. A 38-year-old man presented with sudden onset of headache, dizziness, and dysarthria. The magnetic resonance imaging scan of the brain revealed acute infarction in the right cerebellar hemisphere in the territory of the posterior inferior cerebellar artery (PICA) and superior cerebellar artery (SCA). Magnetic resonance, 3-dimensional computed tomographic, and conventional angiography revealed severe right vertebral artery stenosis by extrinsic compression of the hypertrophied right C5-C6 uncovertebral joint. The diagnosis was acute cerebellar infarction, which was probably caused by embolism from the right vertebral artery stenosis that was caused by the hypertrophied C5-C6 uncovertebral joint. C5-C6 anterior discectomy and fusion were performed together with direct uncovertebral joint decompression. Postoperative 3-dimensional computed tomographic angiography revealed improvement in antegrade filling in the right vertebral artery. The imaging findings for this patient and the pathogenesis of cerebellar infarction for our patient are discussed. PMID:22365284

Choi, Jong Mun; Hong, Hyeok Jin; Chang, Suk Ki; Oh, Sung Han

2012-11-01

374

Depolarization or glutamate receptor activation blocks apoptotic cell death of cultured cerebellar granule neurons.  

PubMed

Cerebellar granule neurons can be readily maintained in culture if depolarized with high concentrations of K+ or subtoxic concentrations of various excitatory amino acids. We now report that these depolarizing stimuli promote cerebellar granule neuron survival by blocking their programmed death via apoptosis. Cerebellar granule neurons maintained in depolarizing conditions and then changed to non-depolarizing conditions, exhibit the morphological and biochemical features of apoptosis, including cytoplasmic blebbing, condensation and aggregation of nuclear chromatin and internucleosomal DNA fragmentation. Inhibitors of RNA or protein synthesis greatly attenuate cell death induced by non-depolarizing culture conditions. In contrast, cerebellar granule neurons, when exposed to fresh serum-containing medium or to high concentrations of glutamate, exhibit a delayed-type of neurotoxicity which is non-apoptotic in nature. Given the actions of excitatory amino acid receptor agonists in preventing apoptosis of cultured cerebellar granule neurons, we hypothesize that the functional innervation of postmigratory granule neurons during cerebellar development may prevent further elimination of these neurons by blocking their programmed death. PMID:7804844

Yan, G M; Ni, B; Weller, M; Wood, K A; Paul, S M

1994-09-01

375

Diphenylhydantoin induces apoptotic cell death of cultured rat cerebellar granule neurons.  

PubMed

Apoptosis is one form of physiological or programmed cell death responsible for the selective elimination of various cell types during development. We have observed and characterized a delayed-type of neurotoxicity induced in cultured cerebellar granule neurons by diphenylhydantoin. Diphenylhydantoin toxicity of cerebellar granule neurons is time and concentration dependent. Morphological studies using Nomarski optics and staining with the fluorescent dye Hoechst 33258 demonstrate that diphenylhydantoin-induced neurotoxicity of cerebellar granule neurons is associated with cytoplasmic blebbing, heterochromatic clumping and condensation of chromatin that precede cell death. Unlike glutamate toxicity (excitotoxicity) diphenylhydantoin-induced neurotoxicity of cerebellar granule neurons is attenuated by actinomycin D and cycloheximide, and is associated with nucleosomal size DNA fragmentation. Since we have previously reported that depolarization of cultured cerebellar granule neurons with high concentrations of K+ promotes the survival of these neurons by blocking apoptosis, we examined the effects of diphenylhydantoin on the K(+)-evoked increase in intracellular calcium. Using microfluorimetry and fura-2 to measure intracellular calcium we found that neurotoxic concentrations of diphenylhydantoin markedly reduce the increase in intracellular calcium associated with elevated extracellular potassium. Taken together, these data demonstrate that exposure of cultured cerebellar granule neurons to pharmacologically relevant concentrations of diphenylhydantoin results in a delayed type of neurotoxicity characterized by the biochemical and morphological features of apoptosis. PMID:7636763

Yan, G M; Irwin, R P; Lin, S Z; Weller, M; Wood, K A; Paul, S M

1995-08-01

376

DOI 10.1007/s12311-010-0209-2 Behavioural Significance of Cerebellar Modules  

E-print Network

# The Author(s) 2010. This article is published with open access at Springerlink.com Abstract A key organisational feature of the cerebellum is its division into a series of cerebellar modules. Each module is defined by its climbing input originating from a well-defined region of the inferior olive, which targets one or more longitudinal zones of Purkinje cells within the cerebellar cortex. In turn, Purkinje cells within each zone project to specific regions of the cerebellar and vestibular nuclei. While much is known about the neuronal wiring of individual cerebellar modules, their behavioural significance remains poorly understood. Here, we briefly review some recent data on the functional role of three different cerebellar modules: the vermal A module, the paravermal C2 module and the lateral D2 module. The available evidence suggests that these modules have some differences in function: the A module is concerned with balance and the postural base for voluntary movements, the C2 module is concerned more with limb control and the D2 module is involved in predicting target motion in visually guided movements. However, these are not likely to be the only functions of these modules and the A and C2 modules are also both concerned with eye and head movements, suggesting that individual cerebellar modules do not necessarily have distinct functions in motor control.

Nadia L. Cerminara

2010-01-01

377

A Wind Tunnel Study on the Mars Pathfinder (MPF) Lander Descent Pressure Sensor  

NASA Technical Reports Server (NTRS)

The primary focus of this study was to determine the accuracy of the Mars Pathfinder lander local pressure readings in accordance with the actual ambient atmospheric pressures of Mars during parachute descent. In order to obtain good measurements, the plane of the lander pressure sensor opening should ideally be situated so that it is parallel to the freestream. However, due to two unfavorable conditions, the sensor was positioned in locations where correction factors are required. One of these disadvantages is due to the fact that the parachute attachment point rotated the lander's center of gravity forcing the location of the pressure sensor opening to be off tangent to the freestream. The second and most troublesome factor was that the lander descends with slight oscillations that could vary the amplitude of the sensor readings. In order to accurately map the correction factors required at each sensor position, an experiment simulating the lander descent was conducted in the Martian Surface Wind Tunnel at NASA Ames Research Center. Using a 115 scale model at Earth ambient pressures, the test settings provided the necessary Reynolds number conditions in which the actual lander was possibly subjected to during the descent. In the analysis and results of this experiment, the readings from the lander sensor were converted to the form of pressure coefficients. With a contour map of pressure coefficients at each lander oscillatory position, this report will provide a guideline to determine the correction factors required for the Mars Pathfinder lander descent pressure sensor readings.

Soriano, J. Francisco; Coquilla, Rachael V.; Wilson, Gregory R.; Seiff, Alvin; Rivell, Tomas

2001-01-01

378

The Role of Educational Background, Activity, and Past Experiences in Mexican-Descent Families' Science Conversations.  

ERIC Educational Resources Information Center

Two studies investigated science conversations between Mexican-descent parents and children during a visit to a children's museum and at home after a family science workshop. Although more-educated parents gave more explanations about science in the museum, all families engaged in causal conversations, especially at home. (Contains 42 references.)…

Tenenbaum, Harriet R.; Callanan, Maureen A.; Alba-Speyer, Consuelo; Sandoval, Leticia

2002-01-01

379

PARTIAL DESCENT ON HYPERELLIPTIC CURVES AND THE GENERALIZED FERMAT EQUATION x3  

E-print Network

PARTIAL DESCENT ON HYPERELLIPTIC CURVES AND THE GENERALIZED FERMAT EQUATION x3 + y4 + z5 = 0 SAMIR then C(Q) = . We shall demonstrate the effectiveness of our new method by solving the generalized Fermat new method by solving the generalized Fermat equation with signature (3, 4, 5). Let p, q, r Z2

Stoll, Michael

380

A Terminal Descent Sensor Trade Study Overview for the Orion Landing and Recovery System  

NASA Technical Reports Server (NTRS)

This trade study was conducted as a part of the Orion Landing System Advanced Development Project to determine possible Terminal Descent Sensor (TDS) architectures that could be used for a rocket assisted landing system. Several technologies were considered for the Orion TDS including radar, lidar, GPS applications, mechanical sensors, and gamma ray altimetry.

Dunn, Catherine; Prakash, Ravi

2008-01-01

381

Tracking control of trim trajectories of a blimp for ascent and descent flight manoeuvres  

Microsoft Academic Search

A blimp is a small airship that has no metal framework and collapses when deflated. It belongs to family of unmanned aerial vehicles (UAVs). In this paper we address the problem of designing tracking feedback control of an underactuated autonomous UAV. The ascent and descent flight conditions as one in which the rate of change (of magnitude) of the airship's

L. Beji; A. Abichou

2005-01-01

382

Model reference adaptive control of a maglev system with stable maximum descent criterion  

Microsoft Academic Search

This paper develops a model-reference adaptive controller (MRC) design framework for magnetically suspended vehicles (maglev) using the criterion of stable maximum descent. The adaptation algorithm is constrained to reduce the airgap error between the reference model and the actual system. The explicit relationship between the parameters of the performance criterion (function of the airgap error and its derivative) and the

P. K. Sinha; Alexandre N. Pechev

1999-01-01

383

Sexual Health Discussions between African-American Mothers and Mothers of Latino Descent and Their Children  

ERIC Educational Resources Information Center

We examined approaches used by African-American mothers and mothers of Latino descent for informal sex-related discussions with their children to inform sexually transmitted infection (STI)/HIV intervention development efforts. We recruited mothers (of children aged 12-15) from youth service agencies and a university in southern California.…

Murray, Ashley; Ellis, Monica U.; Castellanos, Ted; Gaul, Zaneta; Sutton, Madeline Y.; Sneed, Carl D.

2014-01-01

384

Space-Based Nonlinear Dynamic Inversion Control for Aircraft Continuous Descent Approach  

E-print Network

and safety in flight operations. This communi- cation proposes a new representation of aircraft flightSpace-Based Nonlinear Dynamic Inversion Control for Aircraft Continuous Descent Approach Hakim aircraft. The main novelty is that the adopted independent variable is the distance to land. This new

Paris-Sud XI, Université de

385

A Critical Analysis of Western Perspectives on Families of Arab Descent  

ERIC Educational Resources Information Center

Western research on families of Arab descent has increased in the current decade, compared to the previous 30 years. In this review of 256 empirical articles, through a critical postcolonial lens, domestic violence and family planning were the two most established areas of study. Generally, samples have come from a small group of countries such as…

Beitin, Ben K.; Allen, Katherine R.; Bekheet, Maureen

2010-01-01

386

THE MARS SCIENCE LABORATORY (MSL) MARS DESCENT IMAGER (MARDI) FLIGHT INSTRUMENT. M. C. Malin1  

E-print Network

algorithms for future autonomous landing and hazard avoidance systems. Although not an original requirementTHE MARS SCIENCE LABORATORY (MSL) MARS DESCENT IMAGER (MARDI) FLIGHT INSTRUMENT. M. C. Malin1 , M , and R. A. Yingst17 , 1 Malin Space Science Systems, PO Box 910148, San Diego CA 92191-0148, 2 Jet

Willson, Reg

387

Entry, Descent, and Landing System Design for the Mars Gravity Biosatellite  

Microsoft Academic Search

Execution of a full entry, descent, and landing (EDL) from low Earth orbit is a rare requirement among university- class spacecraft. Successful completion of the Mars Gravity Biosatellite mission requires the recovery of a mammalian payload for post-flight analysis of the effects of partial gravity. The EDL design for the Mars Gravity Biosatellite is driven by requirements on the allowable

Ashley M. Korzun; Brandon P. Smith; Christine M. Hartzell; Scott K. Martinelli; Kyle B. Hott; Chi-Yau Yu; Robert D. Braun

388

Showing Up, Remaining Engaged, and Partaking as Students: Resilience Among Students of Mexican Descent  

Microsoft Academic Search

This paper examines the ways in which 12 high school students of Mexican descent remain resilient amid difficult and stressful realities. Through an examination of students' interview responses, a case is made that students' ability to engage in school and figure out everyday ways to partake as students are signs of resilience. This work suggests the need to shift from

Teresa Sosa

2012-01-01

389

Irish descent, religion and food consumption in the west of Scotland  

Microsoft Academic Search

Mortality and morbidity of people of Irish descent in Britain is high, including from cardiovascular causes potentially linked with diet. The west of Scotland has long had a pattern of Irish migration, where migrants were poorer than the host population, and their different religious background gave rise to prolonged discrimination. This paper uses data collected in 1987\\/88 from the west

K. Mullen; R. Williams; K. Hunt

2000-01-01

390

The proof of sufficient descent condition for a new type of conjugate gradient methods  

NASA Astrophysics Data System (ADS)

Conjugate gradient methods are effective in solving linear equations and solving non-linear optimization. In this work we compare our new conjugate gradient coefficient ?k with classical formula under strong Wolfe line search; our method contains sufficient descent condition. Numerical results have shown that the new ?k performs better than classical formula.

Abashar, Abdelrhaman; Mamat, Mustafa; Rivaie, Mohd; Mohd, Ismail; Omer, Osman

2014-06-01

391

A simple and rapid method for calculating identity-by-descent matrices using multiple markers  

Microsoft Academic Search

A fast, partly recursive deterministic method for calculating Identity-by-Descent (IBD) probabilities was developed with the objective of using IBD in Quantitative Trait Locus (QTL) mapping. The method combined a recursive method for a single marker locus with a method to estimate IBD between sibs using multiple markers. Simulated data was used to compare the deterministic method developed in the present

Ricardo Pong-Wong; Andrew Winston George; John Arthur Woolliams; Chris Simon Haley

2001-01-01

392

Diversity of vestibular nuclei neurons targeted by cerebellar nodulus inhibition  

PubMed Central

Key points Electrical stimulation of the cerebellar nodulus and ventral uvula decreases the time constant of the horizontal vestibulo-ocular reflex during yaw rotation. Unlike the flocculus and ventral paraflocculus which target a particular cell group, nodulus/ventral uvula inhibition targets a large diversity of cell types in the vestibular nuclei. Twenty per cent of nodulus/ventral uvula-target neurons were sensitive to both vestibular stimuli and eye movements, whereas the majority was only sensitive to vestibular stimuli. Most nodulus/ventral uvula-target cells responded to both rotation and translation and only approximately half discriminated translational and gravitational accelerations. Projections of the nodulus/ventral uvula to both eye movement-and non-eye movement-sensitive vestibular nuclei neurons suggest a role in both eye movement generation and vestibulo-spinal or thalamo-cortical systems. Abstract?A functional role of the cerebellar nodulus and ventral uvula (lobules X and IXc,d of the vermis) for vestibular processing has been strongly suggested by direct reciprocal connections with the vestibular nuclei, as well as direct vestibular afferent inputs as mossy fibres. Here we have explored the types of neurons in the macaque vestibular nuclei targeted by nodulus/ventral uvula inhibition using orthodromic identification from the caudal vermis. We found that all nodulus-target neurons are tuned to vestibular stimuli, and most are insensitive to eye movements. Such non-eye-movement neurons are thought to project to vestibulo-spinal and/or thalamo-cortical pathways. Less than 20% of nodulus-target neurons were sensitive to eye movements, suggesting that the caudal vermis can also directly influence vestibulo-ocular pathways. In general, response properties of nodulus-target neurons were diverse, spanning the whole continuum previously described in the vestibular nuclei. Most nodulus-target cells responded to both rotation and translation stimuli and only a few were selectively tuned to translation motion only. Other neurons were sensitive to net linear acceleration, similar to otolith afferents. These results demonstrate that, unlike the flocculus and ventral paraflocculus which target a particular cell group, nodulus/ventral uvula inhibition targets a large diversity of cell types in the vestibular nuclei, consistent with a broad functional significance contributing to vestibulo-ocular, vestibulo-thalamic and vestibulo-spinal pathways. PMID:24127616

Meng, Hui; Blázquez, Pablo M; Dickman, J David; Angelaki, Dora E

2014-01-01

393

Development of cerebellar connectivity in human fetal brains revealed by high angular resolution diffusion tractography.  

PubMed

High angular resolution diffusion imaging (HARDI) tractography has provided insights into major white matter pathways and cortical development in the human fetal cerebrum. Our objective in this study was to further apply HARDI tracography to the developing human cerebellum ranging from fetal to adult stages, to outline in broad strokes the 3-dimensional development of white matter and local gray matter organization in the cerebellum. We imaged intact fixed fetal cerebellum specimens at 17 gestational weeks (W), 21W, 31W, 36W, and 38W along with an adult cerebellum for comparison. At the earliest gestational age studied (17W), coherent pathways that formed the superior, middle, and inferior cerebellar peduncles were already detected, but pathways between deep cerebellar nuclei and the cortex were not observed until after 38W. At 36-38W, we identified emerging regional specification of the middle cerebellar peduncle. In the cerebellar cortex, we observed disappearance of radial organization in the sagittal orientation during the studied developmental stages similar to our previous observations in developing cerebral cortex. In contrast, in the axial orientation, cerebellar cortical pathways emerged first sparsely (31W) and then with increased prominence at 36-38W with pathways detected both in the radial and tangential directions to the cortical surface. The cerebellar vermis first contained only pathways tangential to the long axes of folia (17-21W), but pathways parallel to the long axes of folia emerged between 21 and 31W. Our results show the potential for HARDI tractography to image developing human cerebellar connectivity. PMID:24650603

Takahashi, Emi; Hayashi, Emiko; Schmahmann, Jeremy D; Grant, P Ellen

2014-08-01

394

Cerebellar contributions to visuomotor adaptation and motor sequence learning: an ALE meta-analysis.  

PubMed

Cerebellar contributions to motor learning are well-documented. For example, under some conditions, patients with cerebellar damage are impaired at visuomotor adaptation and at acquiring new action sequences. Moreover, cerebellar activation has been observed in functional MRI (fMRI) investigations of various motor learning tasks. The early phases of motor learning are cognitively demanding, relying on processes such as working memory, which have been linked to the cerebellum as well. Here, we investigated cerebellar contributions to motor learning using activation likelihood estimation (ALE) meta-analysis. This allowed us to determine, across studies and tasks, whether or not the location of cerebellar activation is constant across differing motor learning tasks, and whether or not cerebellar activation in early learning overlaps with that observed for working memory. We found that different regions of the anterior cerebellum are engaged for implicit and explicit sequence learning and visuomotor adaptation, providing additional evidence for the modularity of cerebellar function. Furthermore, we found that lobule VI of the cerebellum, which has been implicated in working memory, is activated during the early stages of explicit motor sequence learning. This provides evidence for a potential role for the cerebellum in the cognitive processing associated with motor learning. However, though lobule VI was activated across both early explicit sequence learning and working memory studies, there was no spatial overlap between these two regions. Together, our results support the idea of modularity in the formation of internal representations of new motor tasks in the cerebellum, and highlight the cognitive processing relied upon during the early phases of motor skill learning. PMID:23403800

Bernard, Jessica A; Seidler, Rachael D

2013-01-01

395

Regional cerebellar volume and cognitive function from adolescence to late middle age.  

PubMed

Cerebellar morphology and function have been implicated in a variety of developmental disorders, and in healthy aging. Although recent work has sought to characterize the relationships between volume and age in this structure during adolescence, young, and older adulthood, there have been no investigations of regional cerebellar volume from adolescence through late middle age. Middle age in particular has been largely understudied, and investigating this period of the lifespan may be especially important for our understanding of senescence. Understanding regional patterns of cerebellar volume with respect to age during this portion of the lifespan may provide important insight into healthy aging and cognitive function as well as pathology from adolescence into later life. We investigated regional cerebellar volume using a highly novel lobular segmentation approach in conjunction with a battery of cognitive tasks in a cross-sectional sample of 123 individuals from 12 to 65 years old. Our results indicated that regional cerebellar volumes show different patterns with respect to age. In particular, the more posterior aspect of the neocerebellum follows a quadratic "inverse-U" pattern while the vermis and anterior cerebellum follow logarithmic patterns. In addition, we quantified the relationships between age and a variety of cognitive assessments and found relationships between regional cerebellar volumes and performance. Finally, exploratory analyses of sex differences in the relationships between regional cerebellar volume, age, and cognition were investigated. Taken together, these results provide key insights into the development and aging of the human cerebellum, and its role in cognitive function across the lifespan. Hum Brain Mapp 36:1102-1120, 2015. © 2014 Wiley Periodicals, Inc. PMID:25395058

Bernard, Jessica A; Leopold, Daniel R; Calhoun, Vince D; Mittal, Vijay A

2015-03-01

396

Comparative neuronal morphology of the cerebellar cortex in afrotherians, carnivores, cetartiodactyls, and primates  

PubMed Central

Although the basic morphological characteristics of neurons in the cerebellar cortex have been documented in several species, virtually nothing is known about the quantitative morphological characteristics of these neurons across different taxa. To that end, the present study investigated cerebellar neuronal morphology among eight different, large-brained mammalian species comprising a broad phylogenetic range: afrotherians (African elephant, Florida manatee), carnivores (Siberian tiger, clouded leopard), cetartiodactyls (humpback whale, giraffe) and primates (human, common chimpanzee). Specifically, several neuron types (e.g., stellate, basket, Lugaro, Golgi, and granule neurons; N = 317) of the cerebellar cortex were stained with a modified rapid Golgi technique and quantified on a computer-assisted microscopy system. There was a 64-fold variation in brain mass across species in our sample (from clouded leopard to the elephant) and a 103-fold variation in cerebellar volume. Most dendritic measures tended to increase with cerebellar volume. The cerebellar cortex in these species exhibited the trilaminate pattern common to all mammals. Morphologically, neuron types in the cerebellar cortex were generally consistent with those described in primates (Fox et al., 1967) and rodents (Palay and Chan-Palay, 1974), although there was substantial quantitative variation across species. In particular, Lugaro neurons in the elephant appeared to be disproportionately larger than those in other species. To explore potential quantitative differences in dendritic measures across species, MARSplines analyses were used to evaluate whether species could be differentiated from each other based on dendritic characteristics alone. Results of these analyses indicated that there were significant differences among all species in dendritic measures. PMID:24795574

Jacobs, Bob; Johnson, Nicholas L.; Wahl, Devin; Schall, Matthew; Maseko, Busisiwe C.; Lewandowski, Albert; Raghanti, Mary A.; Wicinski, Bridget; Butti, Camilla; Hopkins, William D.; Bertelsen, Mads F.; Walsh, Timothy; Roberts, John R.; Reep, Roger L.; Hof, Patrick R.; Sherwood, Chet C.; Manger, Paul R.

2014-01-01

397

Motor dysfunction in cerebellar Purkinje cell-specific vesicular GABA transporter knockout mice  

PubMed Central

?-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the adult mammalian central nervous system and plays modulatory roles in neural development. The vesicular GABA transporter (VGAT) is an essential molecule for GABAergic neurotransmission due to its role in vesicular GABA release. Cerebellar Purkinje cells (PCs) are GABAergic projection neurons that are indispensable for cerebellar function. To elucidate the significance of VGAT in cerebellar PCs, we generated and characterized PC-specific VGAT knockout (L7-VGAT) mice. VGAT mRNAs and proteins were specifically absent in the 40-week-old L7-VGAT PCs. The morphological characteristics, such as lamination and foliation of the cerebellar cortex, of the L7-VGAT mice were similar to those of the control littermate mice. Moreover, the protein expression levels and patterns of pre- (calbindin and parvalbumin) and postsynaptic (GABA-A receptor ?1 subunit and gephyrin) molecules between the L7-VGAT and control mice were similar in the deep cerebellar nuclei that receive PC projections. However, the L7-VGAT mice performed poorly in the accelerating rotarod test and displayed ataxic gait in the footprint test. The L7-VGAT mice also exhibited severer ataxia as VGAT deficits progressed. These results suggest that VGAT in cerebellar PCs is not essential for the rough maintenance of cerebellar structure, but does play an important role in motor coordination. The L7-VGAT mice are a novel model of ataxia without PC degeneration, and would also be useful for studying the role of PCs in cognition and emotion. PMID:24474904

Kayakabe, Mikiko; Kakizaki, Toshikazu; Kaneko, Ryosuke; Sasaki, Atsushi; Nakazato, Yoichi; Shibasaki, Koji; Ishizaki, Yasuki; Saito, Hiromitsu; Suzuki, Noboru; Furuya, Nobuhiko; Yanagawa, Yuchio

2014-01-01

398

Remote cerebellar hemorrhage due to ventriculoperitoneal shunt in an infant: a case report  

PubMed Central

Introduction Cerebellar hemorrhage remote from the operative site is an unpredictable and rare complication in neurosurgery, with reported rates of morbidity and mortality in the literature of 8.4% and 7.8%, respectively. The range of procedures associated with remote cerebellar hemorrhage is diverse and includes both supratentorial and spinal procedures that entail significant cerebral spinal fluid loss or resection of supratentorial content. We present here the first documented case of remote cerebellar hemorrhage after controlled supratentorial cerebral spinal fluid drainage by ventriculoperitoneal shunt, and discuss the proposed pathophysiology and treatment. Case presentation We present the case of a four-month-old Saudi Arabian male baby who presented with progressive symptoms and signs of congenital hydrocephalus. An uneventful ventriculoperitoneal shunting was performed with our patient recovering smoothly in the immediate postoperative period. On the next day, he had frequent episodes of vomiting and became lethargic. An urgent computed tomography scan of his brain revealed mild ventricular decompression and unexpected cerebellar hemorrhage. The infant was put under close observation, with marked spontaneous improvement over 48?hours and complete resolution of the hemorrhage on a follow-up computed tomography brain scan two weeks later. On regular outpatient visits at one, three and twelve months, he had no neurological deficit. Conclusion Remote cerebellar hemorrhage is a complication that remains enigmatic in terms of both the underlying mechanism and clinical behavior. Our case revealed that the risk factors identified in the literature are not sufficient in predicting patients at risk of developing remote cerebellar hemorrhage. Our report also adds to the growing body of evidence challenging the currently accepted hypothesis explaining the pathomechanism of remote cerebellar hemorrhage. It thereby remains an unpredictable hazard that requires further study and increased awareness, as many cases in the literature are incidental findings. PMID:22846583

2012-01-01

399

Comparative neuronal morphology of the cerebellar cortex in afrotherians, carnivores, cetartiodactyls, and primates.  

PubMed

Although the basic morphological characteristics of neurons in the cerebellar cortex have been documented in several species, virtually nothing is known about the quantitative morphological characteristics of these neurons across different taxa. To that end, the present study investigated cerebellar neuronal morphology among eight different, large-brained mammalian species comprising a broad phylogenetic range: afrotherians (African elephant, Florida manatee), carnivores (Siberian tiger, clouded leopard), cetartiodactyls (humpback whale, giraffe) and primates (human, common chimpanzee). Specifically, several neuron types (e.g., stellate, basket, Lugaro, Golgi, and granule neurons; N = 317) of the cerebellar cortex were stained with a modified rapid Golgi technique and quantified on a computer-assisted microscopy system. There was a 64-fold variation in brain mass across species in our sample (from clouded leopard to the elephant) and a 103-fold variation in cerebellar volume. Most dendritic measures tended to increase with cerebellar volume. The cerebellar cortex in these species exhibited the trilaminate pattern common to all mammals. Morphologically, neuron types in the cerebellar cortex were generally consistent with those described in primates (Fox et al., 1967) and rodents (Palay and Chan-Palay, 1974), although there was substantial quantitative variation across species. In particular, Lugaro neurons in the elephant appeared to be disproportionately larger than those in other species. To explore potential quantitative differences in dendritic measures across species, MARSplines analyses were used to evaluate whether species could be differentiated from each other based on dendritic characteristics alone. Results of these analyses indicated that there were significant differences among all species in dendritic measures. PMID:24795574

Jacobs, Bob; Johnson, Nicholas L; Wahl, Devin; Schall, Matthew; Maseko, Busisiwe C; Lewandowski, Albert; Raghanti, Mary A; Wicinski, Bridget; Butti, Camilla; Hopkins, William D; Bertelsen, Mads F; Walsh, Timothy; Roberts, John R; Reep, Roger L; Hof, Patrick R; Sherwood, Chet C; Manger, Paul R

2014-01-01

400

Human chorionic gonadotropin but not the calcitonin gene-related peptide induces postnatal testicular descent in mice.  

PubMed

The androgen-regulated paracrine factor, calcitonin gene-related peptide (CGRP), has been proposed as a possible mediator of testicular descent. This peptide has been found to increase rhythmic contractions of gubernaculae and is known to be released by the genitofemoral nerve. We have investigated the ability of CGRP to induce premature testicular descent. CGRP was administered alone, or in combination with human chorionic gonadotropin (hCG) to C57BL/6 male mice postnatally. The extent of testicular descent at 18 days postpartum was then ascertained. The potential relationship between testicular weight and descent was also examined. Our results show that testes of mice treated with either hCG alone, or in combination with 500 ng CGRP, were at a significantly lower position than those of controls by 16% and 17%, respectively. In contrast, mice treated with 500 ng of CGRP alone had testes at a higher position when compared to those of controls, by 19%. In mice treated with 50 ng of CGRP alone or in combination with hCG, testes were at a position similar to those in controls. Furthermore, testicular descent was analyzed in relation to testicular weight, and we found that significantly smaller testes per gram of body weight than those of controls were at a significantly lower position compared to those of controls. Our data demonstrate that CGRP had no effect on postnatal testicular descent and that there is no relationship between postnatal descent and testicular weight. PMID:7559144

Houle, A M; Gagné, D

1995-01-01

401

Cerebro-cerebellar connectivity is increased in primary lateral sclerosis  

PubMed Central

Increased functional connectivity in resting state networks was found in several studies of patients with motor neuron disorders, although diffusion tensor imaging studies consistently show loss of white matter integrity. To understand the relationship between structural connectivity and functional connectivity, we examined the structural connections between regions with altered functional connectivity in patients with primary lateral sclerosis (PLS), a long-lived motor neuron disease. Connectivity matrices were constructed from resting state fMRI in 16 PLS patients to identify areas of differing connectivity between patients and healthy controls. Probabilistic fiber tracking was used to examine structural connections between regions of differing connectivity. PLS patients had 12 regions with increased functional connectivity compared to controls, with a predominance of cerebro-cerebellar connections. Increased functional connectivity was strongest between the cerebellum and cortical motor areas and between the cerebellum and frontal and temporal cortex. Fiber tracking detected no difference in connections between regions with increased functional connectivity. We conclude that functional connectivity changes are not strongly based in structural connectivity. Increased functional connectivity may be caused by common inputs, or by reduced selectivity of cortical activation, which could result from loss of intracortical inhibition when cortical afferents are intact. PMID:25610792

Meoded, Avner; Morrissette, Arthur E.; Katipally, Rohan; Schanz, Olivia; Gotts, Stephen J.; Floeter, Mary Kay

2014-01-01

402

Components of action potential repolarization in cerebellar parallel fibres.  

PubMed

Repolarization of the presynaptic action potential is essential for transmitter release, excitability and energy expenditure. Little is known about repolarization in thin, unmyelinated axons forming en passant synapses, which represent the most common type of axons in the mammalian brain's grey matter.We used rat cerebellar parallel fibres, an example of typical grey matter axons, to investigate the effects of K(+) channel blockers on repolarization. We show that repolarization is composed of a fast tetraethylammonium (TEA)-sensitive component, determining the width and amplitude of the spike, and a slow margatoxin (MgTX)-sensitive depolarized after-potential (DAP). These two components could be recorded at the granule cell soma as antidromic action potentials and from the axons with a newly developed miniaturized grease-gap method. A considerable proportion of fast repolarization remained in the presence of TEA, MgTX, or both. This residual was abolished by the addition of quinine. The importance of proper control of fast repolarization was demonstrated by somatic recordings of antidromic action potentials. In these experiments, the relatively broad K(+) channel blocker 4-aminopyridine reduced the fast repolarization, resulting in bursts of action potentials forming on top of the DAP. We conclude that repolarization of the action potential in parallel fibres is supported by at least three groups of K(+) channels. Differences in their temporal profiles allow relatively independent control of the spike and the DAP, whereas overlap of their temporal profiles provides robust control of axonal bursting properties. PMID:25239461

Pekala, Dobromila; Baginskas, Armantas; Szkudlarek, Hanna J; Raastad, Morten

2014-11-15

403

Spontaneous activity does not predict morphological type in cerebellar interneurons.  

PubMed

The effort to determine morphological and anatomically defined neuronal characteristics from extracellularly recorded physiological signatures has been attempted with varying success in different brain areas. Recent studies have attempted such classification of cerebellar interneurons (CINs) based on statistical measures of spontaneous activity. Previously, such efforts in different brain areas have used supervised clustering methods based on standard parameterizations of spontaneous interspike interval (ISI) histograms. We worried that this might bias researchers toward positive identification results and decided to take a different approach. We recorded CINs from anesthetized cats. We used unsupervised clustering methods applied to a nonparametric representation of the ISI histograms to identify groups of CINs with similar spontaneous activity and then asked how these groups map onto different cell types. Our approach was a fuzzy C-means clustering algorithm applied to the Kullbach-Leibler distances between ISI histograms. We found that there is, in fact, a natural clustering of the spontaneous activity of CINs into six groups but that there was no relationship between this clustering and the standard morphologically defined cell types. These results proved robust when generalization was tested to completely new datasets, including datasets recorded under different anesthesia conditions and in different laboratories and different species (rats). Our results suggest the importance of an unsupervised approach in categorizing neurons according to their extracellular activity. Indeed, a reexamination of such categorization efforts throughout the brain may be necessary. One important open question is that of functional differences of our six spontaneously defined clusters during actual behavior. PMID:25632121

Haar, Shlomi; Givon-Mayo, Ronit; Barmack, Neal H; Yakhnitsa, Vadim; Donchin, Opher

2015-01-28

404

Cerebellar contribution to spatial navigation: new insights into potential mechanisms.  

PubMed

The contribution of the cerebellum to the non-motor aspects of spatial navigation is now established, but the mechanisms of its participation remain unclear. The L7-PKCI mouse model, in which inhibited PKC activity suppresses parallel fiber-Purkinje cell long-term depression (LTD), provides the opportunity to study their spatial abilities in the absence of any motor impairment. L7-PKCI mice are deficient in the spatial but not the cued version of the watermaze task. Their performances are preserved when alleys guide their trajectories in the starmaze task, suggesting that cerebellar PKC-dependent mechanisms are required for the production of an optimal trajectory toward a goal. Furthermore, electrophysiological recordings in freely moving L7-PKCI mice revealed that their hippocampal place cell properties are affected when they have to rely on self motion information: in the absence of external information as well as in a conflicting situation between self-motion and external information. This suggests that the cerebellum is involved in the processing of self-motion information and is required for the construction of the spatial representation in the hippocampus. PMID:25630873

Lefort, Julie M; Rochefort, Christelle; Rondi-Reig, Laure

2015-02-01

405

Missile guidance law design using adaptive cerebellar model articulation controller.  

PubMed

An adaptive cerebellar model articulation controller (CMAC) is proposed for command to line-of-sight (CLOS) missile guidance law design. In this design, the three-dimensional (3-D) CLOS guidance problem is formulated as a tracking problem of a time-varying nonlinear system. The adaptive CMAC control system is comprised of a CMAC and a compensation controller. The CMAC control is used to imitate a feedback linearization control law and the compensation controller is utilized to compensate the difference between the feedback linearization control law and the CMAC control. The online adaptive law is derived based on the Lyapunov stability theorem to learn the weights of receptive-field basis functions in CMAC control. In addition, in order to relax the requirement of approximation error bound, an estimation law is derived to estimate the error bound. Then the adaptive CMAC control system is designed to achieve satisfactory tracking performance. Simulation results for different engagement scenarios illustrate the validity of the proposed adaptive CMAC-based guidance law. PMID:15940993

Lin, Chih-Min; Peng, Ya-Fu

2005-05-01

406

Endovascular Treatment for Ruptured Distal Anterior Inferior Cerebellar Artery Aneurysm  

PubMed Central

A 42-year-old woman presented with Hunt and Hess grade (HHG) III subarachnoid hemorrhage (SAH) caused by a ruptured left distal anterior inferior cerebellar artery (AICA) aneurysm. Computed tomography showed a thin SAH on the cerebellopontine angle cistern, and small vermian intracerebral hemorrhage and intraventricular hemorrhage in the fourth ventricle. Digital subtraction angiography revealed the aneurysm on the postmeatal segment of left distal AICA, a branching point of rostrolateral and caudomedial branch of the left distal AICA. Despite thin caliber, tortuous running course and far distal location, the AICA aneurysm was obliterated successfully with endovascular coils without compromising AICA flow. However, the patient developed left side sensorineural hearing loss postoperatively, in spite of definite patency of distal AICA on the final angiogram. She was discharged home without neurologic sequela except hearing loss and tinnitus. Endovascular treatment of distal AICA aneurysm, beyond the meatal loop, is feasible while preserving the AICA flow. However, because the cochlear hair cell is vulnerable to ischemia, unilateral hearing loss can occur, possibly caused by the temporary occlusion of AICA flow by microcatheter during endovascular treatment. PMID:24765609

Oh, Jae-Sang; Shim, Jai-Joon; Bae, Hack-Gun; Yoon, Il-Gyu

2014-01-01

407

Continuous network of endoplasmic reticulum in cerebellar Purkinje neurons.  

PubMed Central

Purkinje neurons in rat cerebellar slices injected with an oil drop saturated with 1,1'-dihexadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate [DiIC16(3) or DiI] to label the endoplasmic reticulum were observed by confocal microscopy. DiI spread throughout the cell body and dendrites and into the axon. DiI spreading is due to diffusion in a continuous bilayer and is not due to membrane trafficking because it also spreads in fixed neurons. DiI stained such features of the endoplasmic reticulum as densities at branch points, reticular networks in the cell body and dendrites, nuclear envelope, spines, and aggregates formed during anoxia nuclear envelope, spines, and aggregates formed during anoxia in low extracellular Ca2+. In cultured rat hippocampal neurons, where optical conditions provide more detail, DiI labeled a clearly delineated network of endoplasmic reticulum in the cell body. We conclude that there is a continuous compartment of endoplasmic reticulum extending from the cell body throughout the dendrites. This compartment may coordinate and integrate neuronal functions. Images PMID:7519781

Terasaki, M; Slater, N T; Fein, A; Schmidek, A; Reese, T S

1994-01-01

408

False-Positive Head-Impulse Test in Cerebellar Ataxia  

PubMed Central

The objective of this study was to compare the findings of the bedside head-impulse test (HIT), passive head rotation gain, and caloric irrigation in patients with cerebellar ataxia (CA). In 16 patients with CA and bilaterally pathological bedside HIT, vestibuloocular reflex (VOR) gains were measured during HIT and passive head rotation by scleral search coil technique. Eight of the patients had pathologically reduced caloric responsiveness, while the other eight had normal caloric responses. Those with normal calorics showed a slightly reduced HIT gain (mean?±?SD: 0.73?±?0.15). In those with pathological calorics, gains 80 and 100?ms after the HIT as well as the passive rotation VOR gains were significantly lower. The corrective saccade after head turn occurred earlier in patients with pathological calorics (111?±?62?ms after onset of the HIT) than in those with normal calorics (191?±?17?ms, p?=?0.0064). We identified two groups of patients with CA: those with an isolated moderate HIT deficit only, probably due to floccular dysfunction, and those with combined HIT, passive rotation, and caloric deficit, probably due to a peripheral vestibular deficit. From a clinical point of view, these results show that the bedside HIT alone can be false-positive for establishing a diagnosis of a bilateral peripheral vestibular deficit in patients with CA. PMID:23162531

Kremmyda, Olympia; Kirchner, Hanni; Glasauer, Stefan; Brandt, Thomas; Jahn, Klaus; Strupp, Michael

2012-01-01

409

Local flow management/profile descent algorithm. Fuel-efficient, time-controlled profiles for the NASA TSRV airplane  

NASA Technical Reports Server (NTRS)

The Local Flow Management/Profile Descent (LFM/PD) algorithm designed for the NASA Transport System Research Vehicle program is described. The algorithm provides fuel-efficient altitude and airspeed profiles consistent with ATC restrictions in a time-based metering environment over a fixed ground track. The model design constraints include accommodation of both published profile descent procedures and unpublished profile descents, incorporation of fuel efficiency as a flight profile criterion, operation within the performance capabilities of the Boeing 737-100 airplane with JT8D-7 engines, and conformity to standard air traffic navigation and control procedures. Holding and path stretching capabilities are included for long delay situations.

Groce, J. L.; Izumi, K. H.; Markham, C. H.; Schwab, R. W.; Thompson, J. L.

1986-01-01

410

Structural and functional magnetic resonance imaging of the human cerebellar nuclei.  

PubMed

The present review focuses on recent developments in structural and functional magnetic resonance imaging (MRI) of the deep cerebellar nuclei (DCN), the main output structure of the cerebellum. The high iron content in the DCN allows for their visibility in T2*-weighted images. Spatial resolution has improved allowing the identification of DCN in individual cerebellar patients and healthy subjects. Based on findings in larger groups of healthy subjects, probabilistic MRI-based atlases of the deep cerebellar nuclei have been developed, which are important tools in human lesion and functional imaging studies. High iron content in the DCN, on the other hand, decreases the blood oxygenation level dependent-signal making functional imaging a difficult challenge. Compared to the vast amount of studies reporting activation of the cerebellar cortex, the number of studies demonstrating activation of the DCN is much less. Most studies report activation of the dentate nucleus. Dentate activations appear to be more reliable in more complex tasks for reasons currently unknown. As yet, few studies tried to show activations of functional subunits of the dentate nucleus. Increased signal-to-noise ratio and better spatial resolution using higher MR field strength together with recent progress in dentate normalization methods will allow identification of functional subunits and their interactions with the cerebellar cortex in future studies. PMID:20665253

Küper, Michael; Thürling, Markus; Maderwald, Stefan; Ladd, Mark E; Timmann, Dagmar

2012-06-01

411

Role of Cdc42 in neurite outgrowth of PC12 cells and cerebellar granule neurons.  

PubMed

Inactivation of Rho GTPases inhibited the neurite outgrowth of PC12 cells. The role of Cdc42 in neurite outgrowth was then studied by selective inhibition of Cdc42 signals. Overexpression of ACK42, Cdc42 binding domain of ACK-1, inhibited NGF-induced neurite outgrowth in PC12 cells. ACK42 also inhibited the neurite outgrowth of PC12 cells induced by constitutively activated mutant of Cdc42, but not Rac. These results suggest that Cdc42 plays an important role in mediating NGF-induced neurite outgrowth of PC12 cells. Inhibition of neurite outgrowth was also demonstrated using a cell permeable chimeric protein, penetratin-ACK42. A dominant negative mutant of Rac, RacN17 inhibited Cdc42-induced neurite outgrowth of PC12 cells suggesting that Rac acts downstream of Cdc42. Further studies, using primary-cultures of rat cerebellar granule neurons, showed that Cdc42 is also involved in the neurite outgrowth of cerebellar granule neurons. Both penetratin-ACK42 and Clostridium difficile toxin B, which inactivates all members of Rho GTPases strongly inhibited the neurite outgrowth of cerebellar granule neurons. These results show that Cdc42 plays a similar and essential role in the development of neurite outgrowth of PC12 cells and cerebellar granule neurons. These results provide evidence that Cdc42 produces signals that are essential for the neurite outgrowth of PC12 cells and cerebellar granule neurons. PMID:16328953

Ahmed, Ijaz; Calle, Yolanda; Iwashita, Shintaro; Nur-E-Kamal, Alam

2006-01-01

412

Activation of Wnt/?-Catenin Signalling Affects Differentiation of Cells Arising from the Cerebellar Ventricular Zone  

PubMed Central

Development of the cerebellum proceeds under the precise spatio-temporal control of several key developmental signalling pathways, including the Wnt/?-catenin pathway. We recently reported the activity of Wnt/?-catenin signalling in the perinatal cerebellar ventricular zone (VZ), a germinal centre in the developing cerebellum that gives rise to GABAergic and glial cells. In order to investigate the normal function of Wnt/?-catenin signalling in the VZ and the cell lineages it gives rise to, we used a combination of ex vivo cerebellar slice culture and in vivo genetic manipulation to dysregulate its activity during late embryonic development. Activation of the pathway at the cerebellar ventricular zone led to a reduction in the number of cells expressing the glial lineage markers Sox9 and GFAP and the interneuron marker Pax2, but had no consistent effect on either proliferation or apoptosis. Our findings suggest that activation of the Wnt/?-catenin pathway in the cerebellar ventricular zone causes a shift in the cell types produced, most likely due to disruption of normal differentiation. Thus, we propose that regulation of Wnt/?-catenin signalling levels are required for normal development of cells arising from the cerebellar ventricular zone during late embryogenesis. PMID:22880037

Selvadurai, Hayden J.; Mason, John O.

2012-01-01

413

Recovery of motor and cognitive function after cerebellar lesions in a songbird – role of estrogens  

PubMed Central

In addition to its key role in complex motor function, the cerebellum is increasingly recognized to have a role in cognition. Songbirds are particularly good models for the investigation of motor and cognitive processes but little is known about the role of the songbird cerebellum in these processes. To explore cerebellar function in a songbird, we lesioned the cerebellum of adult female zebra finches and examined the effects on a spatial working memory task and on motor function during this task. There is evidence for steroid synthesis in the songbird brain and neurosteroids may have an impact on some forms of neural plasticity in adult songbirds. We therefore hypothesized that neurosteroids would affect motor and cognitive function after a cerebellar injury. We found that cerebellar lesions produced deficits in motor and cognitive aspects of a spatial task. In line with our prediction, birds in which estrogen synthesis was blocked had impaired performance in our spatial task compared with those that had estrogen synthesis blocked but estrogen replaced. There was no clear effect of estrogen replacement on motor function. We also found that lesions induced expression of the estrogen synthetic enzyme aromatase in reactive astrocytes and Bergmann glia around a cerebellar lesion. These data suggest that the cerebellum of songbirds mediates both motor and cognitive function and that estrogens may improve the recovery of cognitive aspects of cerebellar function after injury. PMID:19302157

Spence, Rory D.; Zhen, Yin; White, Stephanie; Schlinger, Barney A.; Day, Lainy B.

2010-01-01

414

Effects of Human Cerebellar Thalamus Disruption on Adaptive Control of Reaching  

PubMed Central

Lesion or degeneration of the cerebellum can profoundly impair adaptive control of reaching in humans. Computational models have proposed that internal models that help control movements form in the cerebellum and influence planned motor output through the cerebello-thalamo-cortical pathway. However, lesion studies of the cerebellar thalamus have not consistently found impairment in reaching or adaptation of reaching. To elucidate the role of the cerebellar thalamus in humans, we studied a group of essential tremor (ET) patients with deep brain stimulation (DBS) electrodes placed in the cerebellar thalamus. The stimulation can be turned on or off remotely and is thought to reduce tremor by blocking the spread of the pathological output from the cerebellum. We studied the effect of thalamic DBS on the ability to adapt arm movements to novel force fields. Although thalamic DBS resulted in a dramatic and significant reduction of tremor in ET, it also impaired motor adaptation: the larger the stimulation voltage, the greater the reduction in rates of adaptation. We next examined ET patients that had undergone unilateral thalamotomy in the cerebellar thalamus and found that adaptation with the contralateral arm was impaired compared with the ipsilateral arm. Therefore, although both lesion and electrical stimulation of the cerebellar thalamus are highly effective in reducing tremor, they significantly impair the ability of the brain to form internal models of action. Adaptive control of reaching appears to depend on the integrity of the cerebello-thalamo-cortical pathway. PMID:16357337

Chen, Haiyin; Hua, Sherwin E.; Smith, Maurice A.; Lenz, Frederick A.; Shadmehr, Reza

2006-01-01

415

Impaired Cerebellar Functional Connectivity in Schizophrenia Patients and Their Healthy Siblings  

PubMed Central

The long-standing notion of schizophrenia as a disorder of connectivity is supported by emerging evidence from recent neuroimaging studies, suggesting impairments of both structural and functional connectivity in schizophrenia. However, investigations are generally restricted to supratentorial brain regions, thereby excluding the cerebellum. As increasing evidence suggests that the cerebellum contributes to cognitive and affective processing, aberrant connectivity in schizophrenia may include cerebellar dysconnectivity. Moreover, as schizophrenia is highly heritable, unaffected family members of schizophrenia patients may exhibit similar connectivity profiles. The present study applies resting-state functional magnetic resonance imaging to determine cerebellar functional connectivity profiles, and the familial component of cerebellar connectivity profiles, in 62 schizophrenia patients and 67 siblings of schizophrenia patients. Compared to healthy control subjects, schizophrenia patients showed impaired functional connectivity between the cerebellum and several left-sided cerebral regions, including the hippocampus, thalamus, middle cingulate gyrus, triangular part of the inferior frontal gyrus, supplementary motor area, and lingual gyrus (all p?cerebellar functional connectivity, suggesting that cerebellar dysconnectivity in schizophrenia might be related to familial factors. In conclusion, our findings suggest that dysconnectivity in schizophrenia involves the cerebellum and that this defect may be related to the risk to develop the illness. PMID:22203807

Collin, Guusje; Hulshoff Pol, Hilleke E.; Haijma, Sander V.; Cahn, Wiepke; Kahn, René S.; van den Heuvel, Martijn P.

2011-01-01

416

Dynamic modulation of cerebellar excitability for abrupt, but not gradual, visuomotor adaptation.  

PubMed

The cerebellum is critically important for error-driven adaptive motor learning, as evidenced by the fact that cerebellar patients do not adapt well to sudden predictable perturbations. However, recent work has shown that cerebellar patients adapt much better if the perturbation is gradually introduced. Here we explore physiological mechanisms that underlie this distinction between abrupt and gradual motor adaptation in humans. We used transcranial magnetic stimulation to evaluate whether neural mechanisms within the cerebellum contribute to either process during a visuomotor reach adaptation. When a visuomotor rotation was introduced abruptly, cerebellar excitability changed early in learning and approached baseline levels near the end of the adaptation block. However, we observed no modulation of cerebellar excitability when we presented the visuomotor rotation gradually during learning. Similarly, we did not observe cerebellar modulation during trial-by-trial adaptation to random visuomotor displacements or during reaches without perturbations. This suggests that the cerebellum is most active during the early phases of adaptation when large perturbations are successfully compensated. PMID:22915105

Schlerf, John E; Galea, Joseph M; Bastian, Amy J; Celnik, Pablo A

2012-08-22

417

Abnormal Cerebellar Cytoarchitecture and Impaired Inhibitory Signaling in Adult Mice Lacking Testicular Orphan Nuclear Receptor 4  

PubMed Central

Since Testicular orphan nuclear receptor 4 (TR4) was cloned, its physiological functions remain largely unknown. In this study, the TR4 knockout (TR4?/?) mouse model was used to investigate the role of TR4 in the adult cerebellum. Behaviorally, these null mice exhibit unsteady gait, as well as involuntary postural and kinetic movements, indicating a disturbance of cerebellar function. In the TR4?/? brain, cerebellar restricted hypoplasia is severe and cerebellar vermal lobules VI and VII are underdeveloped, while no structural alterations in the cerebral cortex are observed. Histological analysis of the TR4?/? cerebellar cortex reveals reductions in granule cell density, as well as a decreased number of parallel fiber boutons that are enlarged in size. Further analyses reveal that the levels of GABA and GAD are decreased in both Purkinje cells and interneurons of the TR4?/? cerebellum, suggesting that the inhibitory circuits signaling within and from the cerebellum may be perturbed. In addition, in the TR4?/? cerebellum, immunoreactivity of GluR2/3 was reduced in Purkinje cells, but increased in the deep cerebellar nuclei. Together, these results suggest that the behavioral phenotype of TR4?/? mice may result from disrupted inhibitory pathways in the cerebellum. No progressive atrophy was observed at various adult stages in the TR4?/? brain, therefore the disturbances most likely originate from a failure to establish proper connections between principal neurons in the cerebellum during development. PMID:17706948

Chen, Yei-Tsung; Collins, Loretta L.; Uno, Hideo; Chou, Samuel M.; Meshul, Charles K.; Chang, Shu-Shi; Chang, Chawnshang

2007-01-01

418

Integration of purkinje cell inhibition by cerebellar nucleo-olivary neurons.  

PubMed

Neurons in the cerebellar cortex, cerebellar nuclei, and inferior olive (IO) form a trisynaptic loop critical for motor learning. IO neurons excite Purkinje cells via climbing fibers and depress their parallel fiber inputs. Purkinje cells inhibit diverse cells in the cerebellar nuclei, including small GABAergic nucleo-olivary neurons that project to the IO. To investigate how these neurons integrate synaptic signals from Purkinje cells, we retrogradely labeled nucleo-olivary cells in the contralateral interpositus and lateral nuclei with cholera toxin subunit B-Alexa Fluor 488 and recorded their electrophysiological properties in cerebellar slices from weanling mice. Nucleo-olivary cells fired action potentials over a relatively narrow dynamic range (maximal rate, ?70 spikes/s), unlike large cells that project to premotor areas (maximal rate, ?400 spikes/s). GABAA receptor-mediated IPSCs evoked by electrical or optogenetic stimulation of Purkinje cells were more than 10-fold slower in nucleo-olivary cells (decay time, ?25 ms) than in large cells (?2 ms), and repetitive stimulation at 20-150 Hz evoked greatly summating IPSCs. Nucleo-olivary firing rates varied inversely with IPSP frequency, and the timing of Purkinje IPSPs and nucleo-olivary spikes was uncorrelated. These attributes contrast with large cells, whose brief IPSCs and rapid firing rates can permit well timed postinhibitory spiking. Thus, the intrinsic and synaptic properties of these two projection neurons from the cerebellar nuclei tailor them for differential integration and transmission of their Purkinje cell input. PMID:25589749

Najac, Marion; Raman, Indira M

2015-01-14

419

A test of the cerebellar hypothesis of dyslexia in adequate and inadequate responders to reading intervention  

PubMed Central

The cerebellar hypothesis of dyslexia posits that cerebellar deficits are associated with reading disabilities and may explain why some individuals with reading disabilities fail to respond to reading interventions. We tested these hypotheses in a sample of children who participated in a grade 1 reading intervention study (n = 174) and a group of typically achieving children (n = 62). At posttest, children were classified as adequately responding to the intervention (n = 82), inadequately responding with decoding and fluency deficits (n = 36), or inadequately responding with only fluency deficits (n = 56). Based on the Bead Threading and Postural Stability subtests from the Dyslexia Screening Test-Junior, we found little evidence that assessments of cerebellar functions were associated with academic performance or responder status. In addition, we did not find evidence supporting the hypothesis that cerebellar deficits are more prominent for poor readers with “specific” reading disabilities (i.e., with discrepancies relative to IQ) than for poor readers with reading scores consistent with IQ. In contrast, measures of phonological awareness, rapid naming, and vocabulary were strongly associated with responder status and academic outcomes. These results add to accumulating evidence that fails to associate cerebellar functions with reading difficulties. PMID:20298639

Barth, Amy E.; Denton, Carolyn A.; Stuebing, Karla K.; Fletcher, Jack M.; Cirino, Paul T.; Francis, David J.; Vaughn, Sharon

2013-01-01

420

Sequence Learning is Preserved in Individuals with Cerebellar Degeneration when the Movements are Directly Cued  

PubMed Central

Cerebellar pathology is associated with impairments on a range of motor learning tasks including sequence learning. However, various lines of evidence are at odds with the idea that the cerebellum plays a central role in the associative processes underlying sequence learning. Behavioral studies indicate that sequence learning, at least with short periods of practice, involves the establishment of effector-independent, abstract spatial associations, a form of representation not associated with cerebellar function. Moreover, neuroimaging studies have failed to identify learning-related changes within the cerebellum. We hypothesize that the cerebellar contribution to sequence learning may be indirect, related to the maintenance of stimulus–response associations in working memory, rather than through processes directly involved in the formation of sequential predictions. Consistent with this hypothesis, individuals with cerebellar pathology were impaired in learning movement sequences when the task involved a demanding stimulus–response translation. When this translation process was eliminated by having the stimuli directly indicate the response location, the cerebellar ataxia group demonstrated normal sequence learning. This dissociation provides an important constraint on the functional domain of the cerebellum in motor learning. PMID:18752399

Spencer, Rebecca M. C.; Ivry, Richard B.

2015-01-01

421

Effects of Inactivating Individual Cerebellar Nuclei on the Performance and Retention of an Operantly Conditioned Forelimb Movement  

E-print Network

of the major cerebellar nuclear regions in cats on the execu- The cerebellum is known to play a significant located in any one of the cerebellar nuclei. All cats were trained to perform a task in which they were changes in the organization of the reaching com- ies was the fact that the deficits were described over

Bracha, Vlastislav

422

Agenesis of the vermis with fusion of the cerebellar hemispheres, septo-optic dysplasia and associated anomalies  

Microsoft Academic Search

Agenesis of the cerebellar vermis with fusion of the dentate nuclei and cerebellar hemispheres (rhombencephalosynapsis) is a rare cerebral malformation. We report the case of a 7-h-old girl whose mother had taken the drug phencyclidine during the first 6 weeks of pregnancy. Absence of the septum pellucidum, hypoplasia of the commissural system, optic nerves, chiasm and tracts, moderate hydrocephalus, and

J. Michaud; E. M. Mizrahi; H. Urich

1982-01-01

423

Barhl1 regulates migration and survival of cerebellar granule cells by controlling expression of the neurotrophin-3 gene.  

PubMed

The neurons generated at the germinal rhombic lip undergo long distance migration along divergent pathways to settle in widely dispersed locations within the hindbrain, giving rise to cerebellar granule cells and precerebellar nuclei. Neurotrophin-3 (NT-3) signaling has been shown to be required for proper migration and survival of cerebellar granule cells. The molecular bases that govern NT-3 expression within the cerebellum, however, remain unknown at present. Here we report that, during early mouse neurogenesis, the Barhl1 homeobox gene is highly expressed by the rhombic lip and rhombic lip-derived migratory neurons. Its expression is later restricted to cerebellar granule cells and precerebellar neurons extending mossy fibers, two groups of neurons that synaptically connect in the adult cerebellar system. Loss of Barhl1 function causes cerebellar phenotypes with a striking similarity to those of NT-3 conditional null mice, which include attenuated cerebellar foliation as well as defective radial migration and increased apoptotic death of granule cells. Correlating with these defects, we find that NT-3 expression is dramatically downregulated in granule cells of the posterior lobe of Barhl1(-)/- cerebella. Moreover, in the precerebellar system of Barhl1(-/-) mice, all five nuclei that project mossy fibers fail to form correctly because of aberrant neuronal migration and elevated apoptosis. These results suggest that Barhl1 plays an essential role in the migration and survival of cerebellar granule cells and precerebellar neurons and functionally link Barhl1 to the NT-3 signaling pathway during cerebellar development. PMID:15044550

Li, Shengguo; Qiu, Feng; Xu, Anlong; Price, Sandy M; Xiang, Mengqing

2004-03-24

424

Location and restoration of function after cerebellar tumor removal-a longitudinal study of children and adolescents.  

PubMed

Sequelae in children following cerebellar tumor removal surgery are well defined, and predictors for poor recovery include lesions of the cerebellar nuclei and the inferior vermis. Dynamic reorganization is thought to promote functional recovery in particular within the first year after surgery. Yet, the time course and mechanisms of recovery within this critical time frame are elusive and longitudinal studies are missing. Thus, a group of children and adolescents (n = 12, range 6-17 years) were followed longitudinally after cerebellar surgery and compared to age- and gender-matched controls (n = 11). Patients were examined (1) within the first days, (2) 3 months, and (3) 1 year after surgery. Each time behavioral tests of balance and upper limb motor function, ataxia rating, and a MRI scan were performed. Data were used for subsequent lesion-symptom mapping of cerebellar function. Behavioral improvements continued beyond 3 months, but were not complete in all patients after 1 year. At that time, remaining deficits were mild. Within the first 3 months, cerebellar lesion volumes were notably reduced by vanishing edema. Reduction in edema affecting the deep cerebellar nuclei but not reduction of total cerebellar lesion volume was a major predictor of early functional recovery. Persistent impairment in balance and upper limb function was linked to permanent lesions of the inferior vermis and the deep cerebellar nuclei. PMID:22562748

Küper, M; Döring, K; Spangenberg, C; Konczak, J; Gizewski, E R; Schoch, B; Timmann, D

2013-02-01

425

Entry, Descent and Landing Systems Analysis Study: Phase 2 Report on Exploration Feed-Forward Systems  

NASA Technical Reports Server (NTRS)

NASA senior management commissioned the Entry, Descent and Landing Systems Analysis (EDL-SA) Study in 2008 to identify and roadmap the Entry, Descent and Landing (EDL) technology investments that the agency needed to successfully land large payloads at Mars for both robotic and human-scale missions. Year 1 of the study focused on technologies required for Exploration-class missions to land payloads of 10 to 50 t. Inflatable decelerators, rigid aeroshell and supersonic retro-propulsion emerged as the top candidate technologies. In Year 2 of the study, low TRL technologies identified in Year 1, inflatables aeroshells and supersonic retropropulsion, were combined to create a demonstration precursor robotic mission. This part of the EDL-SA Year 2 effort, called Exploration Feed Forward (EFF), took much of the systems analysis simulation and component model development from Year 1 to the next level of detail.

Dwyer Ciancolo, Alicia M.; Davis, Jody L.; Engelund, Walter C.; Komar, D. R.; Queen, Eric M.; Samareh, Jamshid A.; Way, David W.; Zang, Thomas A.; Murch, Jeff G.; Krizan, Shawn A.; Olds, Aaron D.; Powell, Richard W.; Shidner, Jeremy D.; Kinney, Daivd J.; McGuire, M. Kathleen; Arnold, James O.; Covington, M. Alan; Sostaric, Ronald R.; Zumwalt, Carlie H.; Llama, Eduardo G.

2011-01-01

426

A multi tracer analysis of thermosphere to stratosphere descent triggered by the 2013 Stratospheric Sudden Warming  

NASA Astrophysics Data System (ADS)

winter observations in 2013 by the Solar Occultation for Ice Experiment (SOFIE) show significant transport from the lower-thermosphere to the stratosphere of air enriched in nitric oxide, but depleted in water and methane. The transport is triggered by the Stratospheric Sudden Warming (SSW) on 11 January and is continuously tracked for over 3 months. Ultimately, evidence for lower thermospheric air is seen at 40 km in mid-April. Area integrated nitric oxide (NO) fluxes are compared with previous events in 2004, 2006, and 2009, to show that this event is the second largest in the past 10 years. The SOFIE data are combined with a meteorological analysis to infer descent rates from 40 to 90 km. The descent profile initially peaks near 75 km, shifting downward by approximately 5 km per 10 days. Our work demonstrates the utility of SOFIE tracer measurements in diagnosing vertical transport from the stratosphere to the edge of space.

Bailey, S. M.; Thurairajah, B.; Randall, C. E.; Holt, L.; Siskind, D. E.; Harvey, V. L.; Venkataramani, K.; Hervig, M. E.; Rong, P.; Russell, J. M.

2014-07-01

427

Post2 End-to-End Descent and Landing Simulation for ALHAT Design Analysis Cycle 2  

NASA Technical Reports Server (NTRS)

The ALHAT project is an agency-level program involving NASA centers, academia, and industry, with a primary goal to develop a safe, autonomous, precision-landing system for robotic and crew-piloted lunar and planetary descent vehicles. POST2 is used as the 6DOF descent and landing trajectory simulation for determining integrated system performance of ALHAT landing-system models and lunar environment models. This paper presents updates in the development of the ALHAT POST2 simulation, as well as preliminary system performance analysis for ALDAC-2 used for the testing and assessment of ALHAT system models. The ALDAC-2 POST2 Monte Carlo simulation results have been generated and focus on HRN model performance with the fully integrated system, as well performance improvements of AGNC and TSAR model since the previous design analysis cycle

Davis, Jody L.; Striepe, Scott A.; Maddock, Robert W.; Johnson, Andrew E.; Paschall, Stephen C., II

2010-01-01

428

Entry, Descent and Landing Systems Analysis: Exploration Feed Forward Internal Peer Review Slide Package  

NASA Technical Reports Server (NTRS)

NASA senior management commissioned the Entry, Descent and Landing Systems Analysis (EDL-SA) Study in 2008 to identify and roadmap the Entry, Descent and Landing (EDL) technology investments that the agency needed to successfully land large payloads at Mars for both robotic and human-scale missions. Year 1 of the study focused on technologies required for Exploration-class missions to land payloads of 10 to 50 mt. Inflatable decelerators, rigid aeroshell and supersonic retro-propulsion emerged as the top candidate technologies. In Year 2 of the study, low TRL technologies identified in Year 1, inflatables aeroshells and supersonic retropropulsion, were combined to create a demonstration precursor robotic mission. This part of the EDL-SA Year 2 effort, called Exploration Feed Forward (EFF), took much of the systems analysis simulation and component model development from Year 1 to the next level of detail.

Dwyer Cianciolo, Alicia M. (Editor)

2011-01-01

429

Capture Conditions for Merging Trajectory Segments to Model Realistic Aircraft Descents  

NASA Technical Reports Server (NTRS)

A typical commercial aircraft trajectory consists of a series of flight segments. An aircraft switches from one segment to another when certain specified variables reach their desired values. Trajectory synthesis for air traffic control automation must be consistent with practical pilot procedures. We examine capture conditions for merging trajectory segments to model commercial aircraft descent in trajectory synthesis. These conditions translate into bounds on measurements of atmospheric wind, pressure, and temperature. They also define ranges of thrust and drag feasible for a descent trajectory. Capture conditions are derived for the Center-TRACON Automation System developed at NASA Ames Research Center for automated air traffic control. Various uses of capture conditions are discussed. A Boeing 727-200 aircraft is used to provide numerical examples of capture conditions.

Zhao, Yiyuan; Slattery, Rhonda A.

1996-01-01

430

Aerosol and Cloud Properties at the Huygens Entry Site as Derived from the Descent Imager/Spectral  

NASA Technical Reports Server (NTRS)

The Huygens Probe descended through Titan s atmosphere on January 14, 2005. The Descent Imager/Spectral Radiometer (DISR) instrument made optical measurements which constrain the nature and vertical distribution and of the aerosols in the atmosphere.

Doose, L. R.; Engel, S.; Tomasko, M. G.; Dafoe, L. E.; West, R.; Lemmon, M.

2005-01-01

431

25 CFR 18.104 - May a tribe include provisions in its tribal probate code regarding the distribution and descent...  

Code of Federal Regulations, 2010 CFR

...a tribe include provisions in its tribal probate code regarding the distribution and descent of trust...DEPARTMENT OF THE INTERIOR PROBATE TRIBAL PROBATE CODES Approval of Tribal Probate Codes § 18.104 May a tribe include provisions...

2010-04-01

432

A Tribute to Italian Physiologists of Jewish Descent Evicted During the Persecution Ordered by the Fascist Regime in 1938  

NSDL National Science Digital Library

The present report commemorates the persecution of five renown Italian physiologists of Jewish descent that lost their chairs in medical schools because of the anti-semitic policies of the fascist regime.

Ermanno Manni (Catholic University Institute of Human Physiology, School of Medicine)

2007-06-01

433

The uncertain significance of low vitamin D levels in African descent populations: a review of the bone and cardiometabolic literature.  

PubMed

Vitamin D levels in people of African descent are often described as inadequate or deficient. Whether low vitamin D levels in people of African descent lead to compromised bone or cardiometabolic health is unknown. Clarity on this issue is essential because if clinically significant vitamin D deficiency is present, vitamin D supplementation is necessary. However, if vitamin D is metabolically sufficient, vitamin D supplementation could be wasteful of scarce resources and even harmful. In this review vitamin D physiology is described with a focus on issues specific to populations of African descent such as the influence of melanin on endogenous vitamin D production and lactose intolerance on the willingness of people to ingest vitamin D fortified foods. Then data on the relationship of vitamin D to bone and cardiometabolic health in people of African descent are evaluated. PMID:24267433

O'Connor, Michelle Y; Thoreson, Caroline K; Ramsey, Natalie L M; Ricks, Madia; Sumner, Anne E

2013-01-01

434

The role of regularity and synchrony of cerebellar Purkinje cells for pathological nystagmus.  

PubMed

Previous theories assumed that the beneficial effect of the potassium channel blocker 4-aminopyridine (4-AP) for patients suffering from downbeat nystagmus (DBN) or episodic ataxia type 2 (EA2) is due to an increase of excitability of cerebellar Purkinje cells (PC). Recent experimental results using therapeutic doses of 4-AP with a mouse model of EA2 challenged the theory showing that 4-AP does not change the firing rate of PC but their regularity. Based on a mathematical model of the ocular motor and cerebellar circuitry, we show that changes in regularity have no effect without synchrony in PC firing. Together with synchronous firing, an increase in regularity may lead to a decrease in overall inhibition and may invert the inhibitory to an excitatory response due to imprinting, a novel effect of synchronized neural inhibition. Both effects are unlikely to be the causative mechanism for the success of 4-AP in treating cerebellar disorders. PMID:21950989

Glasauer, Stefan; Rössert, Christian; Strupp, Michael

2011-09-01

435

Exophytic Cerebellar Glioblastoma in the Cerebellopontine Angle: Case Report and Review of the Literature  

PubMed Central

We report the unique case of a 69-year-old man with a cerebellar glioblastoma showing an exophytic growth pattern. Magnetic resonance imaging revealed a heterogeneously gadolinium-enhancing tumor in the right cerebellopontine angle. The preoperative differential diagnoses included an intraaxial tumor, such as high-grade glioma, and an extraaxial tumor, such as a meningioma or neurinoma. The tumor with a clear boundary was subtotally removed, except for the adhesion site to the petrosal vein, and the histologic diagnosis was glioblastoma. Immunohistochemical analyses demonstrated that the tumor cells were immunopositive for epidermal growth factor receptor and immunonegative for p53 mutation and IDH1 R132H, indicating that it had different genetic features from a typical cerebellar glioblastoma. Conventional radiotherapy with 60?Gy concurrent with temozolomide was performed, and the condition of the patient has remained stable for 24 months since the operation. Exophytic cerebellar glioblastoma should be considered in the differential diagnosis of cerebellopontine angle tumor. PMID:25083393

Matsuda, Masahide; Onuma, Kuniyuki; Satomi, Kaishi; Nakai, Kei; Yamamoto, Tetsuya; Matsumura, Akira

2014-01-01

436