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1

Posterior fossa arachnoid cysts and cerebellar tonsillar descent: short review.  

PubMed

The objective of this study was to analyze the association of cerebellar tonsillar descent and syringomyelia in patients with posterior fossa arachnoid cysts. We reviewed the medical records of ten patients (mean, age 33; range, 24-49 years) diagnosed with posterior fossa arachnoid cyst and tonsillar descent. Symptoms evolved over a mean of 12 months (range, 6 months to 3 years). Syringomyelia was present in six cases. Six patients underwent a suboccipital craniectomy, three cases underwent an additional C1 laminectomy, and a further case had a limited craniectomy and tonsillar reduction. Three patients were also treated for hydrocephalus: one with a ventriculoperitoneal shunt and two with endoscopic third ventriculostomy. Two patients had conservative treatment. The posterior fossa arachnoid cysts were located at the vermis-cisterna magna (n = 4), the cerebellar hemispheres (n = 2), the cerebellopontine angle (n = 3), and the quadrigeminal cistern (n = 1). A patient with achondroplasia showed features of platybasia. Associated malformations included craniofacial dysmorphism in a patient diagnosed of trichorhinophalangeal syndrome and a case with a primary temporal arachnoid cyst. After a mean follow-up of 2 years (range, 3 months to 5 years), four patients showed resolution of their neurological symptoms, and two exhibited persisting ocular findings. Headaches and nuchalgia improved in four cases and persisted in four. Syringomyelia was resolved in four patients and improved in two. Patients harboring a posterior fossa arachnoid cyst may evolve with acquired Chiari malformation and syringomyelia. Initial management should be directed to decompressing the foramen magnum and should include the resection of the arachnoid cyst's walls. A wait-and-see attitude can be implemented in selected cases. In our experience, hydrocephalus should be properly addressed before treating the arachnoid cyst. PMID:20480382

Galarza, Marcelo; López-Guerrero, Antonio López; Martínez-Lage, Juan F

2010-07-01

2

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.

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

2013-01-01

3

Dimensions of the posterior fossa in patients symptomatic for Chiari I malformation but without cerebellar tonsillar descent  

PubMed Central

Background Chiari I malformation (CMI) is diagnosed by rigid radiographic criteria along with appropriate clinical symptomatology. The aim of this study was to investigate the dimensions of the posterior cranial fossa in patients without significant tonsillar descent but with symptoms comparable to CMI. Methods Twenty-two patients with signs and symptoms comparable to CMI but without accepted radiographic criteria of tonsillar descent > 3–5 mm were referred to our clinic for evaluation. A history and physical examination were performed on all patients. In reviewing their MRI scans, nine morphometric measurements were recorded. The measurements were compared to measurements from a cohort of twenty-five individuals with cranial neuralgias from our practice. Results For patients with Chiari-like symptomatology, the following statistically significant abnormalities were identified: reduced length of the clivus, reduced length of basisphenoid, reduced length of basiocciput, and increased angle of the tentorium. Multiple morphometric studies have demonstrated similar findings in CMI. Conclusion The current classification of CMI is likely too restrictive. Preliminary morphologic data suggests that a subgroup of patients exists with tonsillar descent less than 3 mm below the foramen magnum but with congenitally hypoplastic posterior fossa causing symptomatology consistent with CMI.

Sekula, Raymond F; Jannetta, Peter J; Casey, Kenneth F; Marchan, Edward M; Sekula, L Kathleen; McCrady, Christine S

2005-01-01

4

Surgical management of cerebellar tonsillar herniation in three patients with macrocephaly-cutis marmorata telangiectatica congenita. Report of three cases.  

PubMed

The authors report on three patients with a congenital brain overgrowth syndrome, macrocephaly-cutis marmorata telangiectatica congenita (M-CMTC), who experienced neurological sequelae associated with herniation of the cerebellar tonsils through the foramen magnum. In two of these patients, the authors document postnatal brain overgrowth that contributed to recurrent descent of the cerebellar tonsils and complicated the surgical treatment in one of the patients. The authors address the neurosurgical concerns related to this syndrome with special attention to acquired tonsillar ectopia and postulate that some patients may be at risk for progressive tonsillar herniation and consequent neurological symptoms due to cerebellar overgrowth. Ectopic cerebellar tonsils have been reported previously in cases of M-CMTC, and this phenomenon may be a secondary event associated with brain overgrowth rather than due to a congenitally small posterior fossa. PMID:17465364

Conway, Robert L; Danielpour, Moise; Graham, John M

2007-04-01

5

Progressive cerebellar tonsillar herniation with recurrent divergence insufficiency esotropia.  

PubMed

The Chiari malformations are characterized by herniation of posterior fossa contents through the foramen magnum. Chiari I malformation is currently defined as ectopia of the cerebellar tonsils more than 5 mm below the foramen magnum. Extension of the cerebellar tonsils up to 3 mm may be found in the normal population. Although Chiari malformations are congenital, symptoms often do not manifest until the third and fourth decades of life, or even later. Patients usually present with headache, lower cranial nerve palsies, downbeat nystagmus, ataxia, or dissociated anesthesia of the trunk and extremities. Definitive diagnosis is made by magnetic resonance imaging (MRI), which shows the compressed tonsils extending through the foramen magnum into the cervical subarachnoid space. One of the rare presenting signs of Chiari I malformations is acquired esotropia with a divergence insufficiency pattern. We report such a case in which the initial neuroimaging showed tonsillar herniation, but of insufficient magnitude to meet diagnostic criteria for Chiari I malformation. When the strabismus recurred after initially successful eye muscle surgery, follow-up scan showed progressive tonsillar herniation. PMID:15226735

Pokharel, Dipesh; Siatkowski, R Michael

2004-06-01

6

Bilateral retrocerebellar arachnoid cysts exerting mass effect and associated with cerebellar tonsillar ectopia in an otherwise healthy adult.  

PubMed

Rarely, midline or unilateral posterior fossa arachnoid cysts (ACs) exert local mass effect resulting in the symptoms and signs of cerebellar and brainstem dysfunction. These cysts are sometimes seen in conjunction with cerebellar tonsillar ectopia (TE), although the relationship between these two entities is unclear. Bilateral ACs in the posterior fossa are virtually unprecedented. We describe the case of a 33-year-old man with a history of multiple minor head injuries observed to harbour asymptomatic, bilateral cerebrospinal fluid-density collections over the cerebellar hemispheres. Six years later, he presented with headaches, limb paraesthesias, and drop attacks. Computed tomography, magnetic resonance imaging, and operative findings during burrhole drainage of the lesions showed bilateral posterior fossa ACs, with associated cerebellar TE of 11 mm. The cysts partially recurred, necessitating reopening of the burrholes, after which the patient's symptoms resolved entirely. We then discuss the challenges in diagnosing this unusual case, the relationship between AC and TE, and the role of minor head injury in the symptomatic progression of AC. PMID:23615422

Killeen, Tim; Tromop-VAN-Dalen, Chani; Alexander, Hamish; Wickremesekera, Agadha

2013-01-01

7

Cerebellar Herniation in Syringomyelia: Relation between Tonsillar Herniation and the Dimensions of the Syrinx and the Remaining Spinal Cord  

Microsoft Academic Search

The dimensions of the syrinx, the remaining spinal cord and the degree of cerebellar herniation were analyzed by one- and two-dimensional MRI studies in 22 patients with syringomyelia. A deep and\\/or broad cyst tends to be a long one. The dimensions of the syrinx and the spinal cord have an inverse relationship. The degree of cerebellar herniation is not related

Harald Masur; Christoph Oberwittler; Georg Reuther; Petra Heyen

1995-01-01

8

Diplopia and visual impairment as presenting symptoms of shunt failure in association with tonsillar herniation in idiopathic intracranial hypertension.  

PubMed

Two cases of cerebellar tonsilar herniation due to shunt complications in idiopathic intracranial hypertension are reported in which both patients presented with visual symptoms. One patient had horizontal diplopia due to an acute sixth nerve palsy along with severe constriction of visual fields while the second patient had symptoms of blurred vision. Both patients required neurosurgery, one patient requiring surgery for tonsillar descent and revision of an over-draining lumbar peritoneal shunt and the second patient only requiring revision of his over-draining lumbar peritoneal shunt. Following surgery the visual signs of reduced vision, cranial nerve palsy, and visual field loss gradually resolved. Both patients had normal ocular movements and visual fields at final follow-up. PMID:23211144

Rowe, Fiona J

2012-12-01

9

Giant posterior fossa arachnoid cyst causing tonsillar herniation and cervical syringomyelia.  

PubMed

Acquired cerebellar tonsillar herniation and syringomyelia associated with posterior fossa mass lesions is an exception rather than the rule. In the present article, we describe the neuroimaging findings in a case of 28-year-old female patient presented with a history of paraesthesia involving right upper limb of 8-month duration. Magnetic resonance imaging showed a giant retrocerebellar arachnoid causing tonsillar herniation with cervical syringomyelia. The findings in the present case supports that the one of the primary mechanism for the development of syringomyelia may be the obstruction to the flow of cerebrospinal fluid causing alterations in the passage of extracellular fluid in the spinal cord and leading to syringomyelia. PMID:24381458

Joshi, Vijay P; Valsangkar, Ashwin; Nivargi, Satish; Vora, Nitant; Dekhne, Anish; Agrawal, Amit

2013-01-01

10

Adeno-tonsillar surgery in Italy.  

PubMed

Indications to surgery for adeno-tonsillar inflammatory disorders and analysis of the effectiveness of surgical treatment, compared with watchful waiting strategy, continue to be the subject of scientific debate. The present investigation focuses on the surgical activity of 14 Italian Otorhinolaryngological Units between 1999 and 2004. Surgical interventions (adeno-tonsillectomy, adenoidectomy, tonsillectomy) on 26915 children (age range: 2-11 years) were considered. Data on adeno-tonsillar interventions were analysed in relation to other interventions of ENT interest, performed in the same units and in the same period. Adeno-tonsillar interventions accounted for 35.4% of all operations of ENT interest. Adeno-tonsillectomy accounted for 56.6% of overall adeno-tonsillar operations, adenoidectomy 31.6%, tonsillectomy 11.8%. The percentage for the three interventions was homogeneous in the period of the study and in the recruited units. The percentage of children who underwent adeno-tonsillar surgery in paediatric units was higher as compared to general units, as far as concerns the overall number of operations performed. In southern Italy, the number of adeno-tonsillar interventions, in general, and of adeno-tonsillectomy, in particular, was higher compared to that in northern Italy. Results of the present study suggest that environmental factors, cultural issues and local health demands, may influence indications and, therefore, the different incidence of the operations under consideration in the units taking part in the investigation. PMID:18533547

Motta, G; Casolino, D; Cassiano, B; Conticello, S; Esposito, E; Galletti, F; Galli, V; Larotonda, G; Laudadio, P; Mansi, N; Mevio, E; Mira, E; Motta, G; Ceroni, A Rinaldi; Tarantino, V; Tavormina, P; Vicini, C; Motta, S; Aversa, S; Canani, F Berni; Cappello, V; Carra, P; Cifarelli, D; Cinquegrana, G; Consolo, E; Ondolo, C; Ripa, G; Romano, G

2008-02-01

11

Adeno-tonsillar surgery in Italy  

PubMed Central

Summary Indications to surgery for adeno-tonsillar inflammatory disorders and analysis of the effectiveness of surgical treatment, compared with watchful waiting strategy, continue to be the subject of scientific debate. The present investigation focuses on the surgical activity of 14 Italian Otorhinolaryngological Units between 1999 and 2004. Surgical interventions (adeno-tonsillectomy, adenoidectomy, tonsillectomy) on 26915 children (age range: 2-11 years) were considered. Data on adeno-tonsillar interventions were analysed in relation to other interventions of ENT interest, performed in the same units and in the same period. Adeno-tonsillar interventions accounted for 35.4% of all operations of ENT interest. Adeno-tonsillectomy accounted for 56.6% of overall adeno-tonsillar operations, adenoidectomy 31.6%, tonsillectomy 11.8%. The percentage for the three interventions was homogeneous in the period of the study and in the recruited units. The percentage of children who underwent adeno-tonsillar surgery in paediatric units was higher as compared to general units, as far as concerns the overall number of operations performed. In southern Italy, the number of adeno-tonsillar interventions, in general, and of adeno-tonsillectomy, in particular, was higher compared to that in northern Italy. Results of the present study suggest that environmental factors, cultural issues and local health demands, may influence indications and, therefore, the different incidence of the operations under consideration in the units taking part in the investigation.

G. Motta; Casolino, D; Cassiano, B; Conticello, S; Esposito, E; Galletti, F; Galli, V; Larotonda, G; Laudadio, P; Mansi, N; Mevio, E; Mira, E; Motta Jr, G; Rinaldi Ceroni, A; Tarantino, V; Tavormina, P; Vicini, C; Motta, S

2008-01-01

12

Management of Tonsillar Lipoma: Is Tonsillectomy Essential?  

PubMed Central

Tonsillar lipomas are rare benign tumors, with only a limited number of cases reported in the literature. Excision of the lipoma along with tonsillectomy has been proposed as the usual treatment option. We report a case of tonsillar lipoma which was managed by excision of the lesion without the need for a tonsillectomy. No recurrence was reported at a 2-year followup. A worldwide literature review was done to better define the clinical and histopathological features of these lesions. The authors propose that routine tonsillectomy is not required for these benign lesions and that simple excision of the stalk of the lipoma is sufficient.

Kanotra, Sohit P.; Davies, Joel

2014-01-01

13

Management of tonsillar lipoma: is tonsillectomy essential?  

PubMed

Tonsillar lipomas are rare benign tumors, with only a limited number of cases reported in the literature. Excision of the lipoma along with tonsillectomy has been proposed as the usual treatment option. We report a case of tonsillar lipoma which was managed by excision of the lesion without the need for a tonsillectomy. No recurrence was reported at a 2-year followup. A worldwide literature review was done to better define the clinical and histopathological features of these lesions. The authors propose that routine tonsillectomy is not required for these benign lesions and that simple excision of the stalk of the lipoma is sufficient. PMID:24649389

Kanotra, Sohit P; Davies, Joel

2014-01-01

14

Bacteriological evaluation of tonsillar microbial flora according to age and tonsillar size in recurrent tonsillitis.  

PubMed

Although numerous studies based on the bacteriology of the tonsil have been carried out, none of them analyzed the variation of tonsillar flora with respect to both age and tonsillar size. The purpose of this study was to isolate the facultative and obligate anaerobes both from the surface and the core of tonsils in recurrent tonsillitis as well as to analyze the variation of isolated bacterial strains according to age and tonsillar size. A prospective study was performed on 111 patients who underwent tonsillectomy. We analyzed the differences between the bacterial pathogens in recurrent tonsillitis and semi-growth estimates with regard to age and tonsillar grade. Among 111 cases, 604 bacterial strains of 21 different from the tonsil superficial and core were isolated. The most common facultative anaerobic species isolated from the surface and core were Coagulase-negative staphylococci, Alpha-hemolytic streptococci and Diphtheroid bacilli in all subgroups except patients below 8 years old. The most commonly obligate anaerobic species isolated from the core were Propionibacterium acnes, Prevotella melaninogenica and Peptostreptococcus anaerobius. We found no significant difference in the cultured bacteria with respect to age and tonsillar size. The study subgroups did not differ in the occurrence of semiquantitative growth estimates of 3-4+. Our study demonstrates that there is polymicrobial aerobic and anaerobic flora in tonsils with regardless of patient's age and tonsillar size. This polymicrobial spectrum of bacteria may contribute to recurrence and to the failure of conservative treatment of these cases and therefore leads to surgical therapy. PMID:24487459

Develioglu, Omer Necati; Ipek, Havva Duru; Bahar, Hrisi; Can, Gunay; Kulekci, Mehmet; Aygun, Gokhan

2014-06-01

15

Progression of pre-existing Chiari type I malformation secondary to cerebellar hemorrhage: case report.  

PubMed

A previously healthy 32-year-old man was surgically treated under a diagnosis of right subcortical hematoma. Magnetic resonance imaging incidentally demonstrated tonsillar herniation. Thirty-two months later, he was readmitted with complaints of occipital, neck, and shoulder pain as well as cerebellar ataxia. Subsequent magnetic resonance imaging demonstrated cerebellar hemorrhage and progression in the downward herniation of the tonsils. Conservative treatment resulted in spontaneous disappearance of the cerebellar hematoma, and the clinical signs and radiological findings improved. Patients with Chiari type I malformation require neuroimaging follow up because the downward herniation of the tonsils can progress in association with subsequent pathophysiological disorders. PMID:19246872

Kojima, Atsuhiro; Mayanagi, Keita; Okui, Shunichi

2009-02-01

16

Posterior fossa arachnoid cyst, tonsillar herniation, and syringomyelia in trichorhinophalangeal syndrome Type I.  

PubMed

The authors report the case of a patient with Chiari malformation Type I (CM-I) and syringomyelia probably caused by a retrocerebellar arachnoid cyst. The patient's phenotype corresponded to trichorhinophalangeal syndrome Type I. The authors attributed the origin of both the retrocerebellar cyst and the abnormal posterior fossa to endochondral ossification anomalies that occur in this syndrome. The patient's spinal pain was most likely a result of the combination of CM-I and syringomyelia. To the best of the authors' knowledge, this is the first report on the association of CM-I and syringomyelia with a retrocerebellar arachnoid cyst occurring in a patient with trichorhinophalangeal syndrome Type I. The authors discuss the pathogenetic mechanisms involved in the production of tonsillar descent and syringomyelia in this patient, and review the current literature on related conditions that can result in this association. PMID:18826365

Martínez-Lage, Juan F; Ruiz-Espejo, Antonio; Guillén-Navarro, Encarna; Almagro, María-José

2008-10-01

17

[Laser tonsillectomy in tonsillar hyperplasia of early childhood].  

PubMed

Tonsillotomy, the partial resection of hyperplastic tonsils, is generally rejected in Germany as a treatment option for obstructions of the isthmus faucium in early childhood. We think this approach merits consideration. The favorable results obtained with tonsillotomy in the University Hospital Benjamin Franklin (n = 637), a private clinic, and an ENT practice with surgical facilities (n = 189) showed that there is no justification for adhering to literature reports of severe late complications with scarred tonsillar crypts and peritonsillar abscesses. No patient has developed any of these complications thus far. Following tonsillotomy, preoperative complaints (snoring, respiratory obstruction, dysphagia, and failure to grow) decreased considerably. Thus, tonsillotomy proved to be a suitable modality for treating tonsillar hyperplasia in early childhood. The prerequisite for long-term success is strict limitation of this intervention to the diagnosis of tonsillar hyperplasia. PMID:12089813

Helling, K; Abrams, J; Bertram, W K; Hohner, S; Scherer, H

2002-05-01

18

Autosomal Recessive Cerebellar Hypoplasia  

Microsoft Academic Search

Cerebellar hypoplasia is found in association with a variety of neurologic and systemic disorders. It is the primary finding in the uncommonly reported condition of autosomal recessive cerebellar hypoplasia. We describe two siblings with cerebellar hypoplasia documented in both by magnetic resonance imaging (MRI) and review the clinical features of previously reported cases of autosomal recessive cerebellar hypoplasia. The most

Katherine D. Mathews; Adel K. Afifi; James W. Hanson

1989-01-01

19

Lingual tonsillar metastasis from rectal carcinoma: a rare occurrence.  

PubMed

A 66-year-old man presenting with sacral pain 18 months after radical transabdominal resection of rectal mucinous adenocarcinoma underwent F-FDG PET/CT cancer surveillance. Detection of multiple nodules in lingual tonsil and left neck by imaging initially suggested tonsillar squamous carcinoma (as a second primary) with spread to cervical nodes, given the rarity with which rectal carcinoma metastasizes to the head and neck. Ultimately, the tonsillar neoplasm proved to be adenocarcinoma of colorectal origin based on its shared histologic features and compatible immunostaining profile. PMID:24686212

Su, Minggang; Jiang, Chong; Li, Lin; Li, Fanglan; Tian, Rong

2014-06-01

20

Chronic Tonsillar Herniation and Crouzon’s Syndrome  

Microsoft Academic Search

Patients born with craniofacial syndromes such as Crouzon’s syndrome will often develop hydrocephalus after their initial craniofacial reconstructive procedures. We have treated 10 patients with Crouzon’s syndrome; 5 patients required a shunting procedure after cranial remodeling. Each of these 5 shunted patients later demonstrated chronic tonsillar herniation on magnetic resonance imaging studies. One of these patients exhibited signs of pseudotumor

Paul M. Francis; Stephen Beals; Harold L. Rekate; Hal W. Pittman; Kim Manwaring; Jacque Reiff

1992-01-01

21

Spontaneous cerebellar hematoma associated with chronic cerebellar stimulation. Case report.  

PubMed

A 24-year-old man developed a spontaneous cerebellar hematoma 5 years after the implantation of cerebellar electrodes. No vascular malformations were found either intraoperatively or radiographically. The histopathological findings of the cerebellar tissue obtained at biopsy from the region surrounding the electrodes support the hypothesis of a causal relationship between the spontaneous cerebellar hemorrhage and chronic cerebellar stimulation. PMID:3490550

Zuccarello, M; Sawaya, R; Lukin, R; deCourten-Myers, G

1986-12-01

22

Terminal Descent Sensor Simulation  

NASA Technical Reports Server (NTRS)

Sulcata software simulates the operation of the Mars Science Laboratory (MSL) radar terminal descent sensor (TDS). The program models TDS radar antennas, RF hardware, and digital processing, as well as the physics of scattering from a coherent ground surface. This application is specific to this sensor and is flexible enough to handle end-to-end design validation. Sulcata is a high-fidelity simulation and is used for performance evaluation, anomaly resolution, and design validation. Within the trajectory frame, almost all internal vectors are represented in whatever coordinate system is used to represent platform position. The trajectory frame must be planet-fixed. The platform body frame is specified relative to arbitrary reference points relative to the platform (spacecraft or test vehicle). Its rotation is a function of time from the trajectory coordinate system specified via dynamics input (file for open loop, callback for closed loop). Orientation of the frame relative to the body is arbitrary, but constant over time. The TDS frame must have a constant rotation and translation from the platform body frame specified at run time. The DEM frame has an arbitrary, but time-constant, rotation and translation with respect to the simulation frame specified at run time. It has the same orientation as sigma0 frame, but is possibly translated. Surface sigma0 has the same arbitrary rotation and translation as DEM frame.

Chen, Curtis W.

2009-01-01

23

Isodense cerebellar hematoma.  

PubMed

One week after chiropractic manipulations, a 60-year-old normotensive man suffered acute onset of vertigo, ataxia, and dysarthria. CT disclosed an isodense mass of the posterior fossa. Vertebral arteriography showed that the avascular mass arose from the right cerebellar hemisphere. Hydrocephalus developed, and suboccipital craniotomy revealed a large cerebellar hematoma due to a small arteriovenous malformation. A similar episode occurred 2 months later. CT isodense cerebellar hematomas should be considered before giving anticoagulant therapy. PMID:6684255

Jacome, D E

1983-09-01

24

A characterization of human tonsillar lymphocytes after separation from other tonsillar cells in an isokinetic gradient of ficoll in tissue culture medium.  

PubMed Central

Purified human tonsillar lymphocytes responded less to mitogentic stimulation than did unseparated tonsillar cells. Their response to mitogens was restored when they were combined with cells from all other gradient fractions. We interpret our data as evidence that the majority of tonsillar lymphocytes require the presence of more rapidly sedimenting cells for a maximum response to the tested mitogens. The purified tonsillar lymphoyctes were 47.0% lymphocytes that have detectable surface immunoglobulin and 29.9% lumphocytes that form rosettes with sheep red blood cells. The predominant cell surface immunoglobulin was IgM. Digestion of the tonsil with trypsin yielded tenfold more plasma cells, more vialbe cells, and a larger proportion of blasts, histiocytes, and binucleated cells than were obtained by mechanical dissociation of the tissue. Images Figure 2 Figure 1

Willson, J. K.; Zaremba, J. L.; Pitts, A. M.; Pretlow, T. G.

1976-01-01

25

Epidemiology and survival of HPV-related tonsillar carcinoma  

PubMed Central

The aim of this study was to determine the proportion of human papilloma virus (HPV)-positive cases in tonsillar carcinomas and investigate its development over the last decade. Further aim was to show the oncologic results in accord to HPV status and various treatment modalities. A retrospective study was conducted between 2000 and 2012 and included 275 patients treated for tonsillar carcinoma. P16 immunohistochemistry was used as a surrogate marker for HPV-associated carcinogenesis. A total of 101 (36.7%) patients proved to be p16 positive and 174 p16 negative. 80.2% of the p16-positive cases presented with T1-2 tumor. Of the early-stage patients, 79% of the p16-positive and 52.3% of the p16-negative presented with lymph node metastases. The percentage of p16-positive patients increased from 23.2% in the period 2005–2007 to 58.6% in the period 2010–2012 in the whole population and from 30.9% to 76.9% in T1-2 carcinomas. Early T-category p16-positive carcinomas had significantly better disease-specific survival (92.4% vs. 75.5%, P = 0.007) and overall survival (OS, 79.6% vs. 54.3%, P < 0.001) compared to p16-negative tumors. This study showed an increase in the percentage of p16-positive patients in tonsillar carcinoma from 23.2% in the years between 2005 and 2007 to 58.6% between 2010 and 2012. The majority (80.2%) of p16-positive patients presented with early T-category tumor but most of these (79.0%) had also lymph node metastases. Nevertheless, p16-positive patients had excellent oncologic results after surgery and adjuvant radiotherapy and could be considered for de-escalation of treatment.

Psychogios, Georgios; Alexiou, Christoph; Agaimy, Abba; Brunner, Kathrin; Koch, Michael; Mantsopoulos, Konstantinos; Tomppert, Andrea; Iro, Heinrich

2014-01-01

26

The cerebellar cognitive profile.  

PubMed

The cerebellar role in non-motor functions is supported by the clinical finding that lesions confined to cerebellum produce the cerebellar cognitive affective syndrome. Nevertheless, there is no consensus regarding the overall cerebellar contribution to cognition. Among other reasons, this deficiency might be attributed to the small sample sizes and narrow breadths of existing studies on lesions in cerebellar patients, which have focused primarily on a single cognitive domain. The aim of this study was to examine the expression of cerebellar cognitive affective syndrome with regard to lesion topography in a large group of subjects with cerebellar damage. We retrospectively analysed charts from patients in the Ataxia Lab of Santa Lucia Foundation between 1997 and 2007. Of 223 charts, 156 were included in the study, focusing on the importance of the cerebellum in cognition and the relevance of lesion topography in defining the cognitive domains that have been affected. Vascular topography and the involvement of deep cerebellar nuclei were the chief factors that determined the cognitive profile. Of the various cognitive domains, the ability to sequence was the most adversely affected in nearly all subjects, supporting the hypothesis that sequencing is a basic cerebellar operation. PMID:22036960

Tedesco, Anna M; Chiricozzi, Francesca R; Clausi, Silvia; Lupo, Michela; Molinari, Marco; Leggio, Maria G

2011-12-01

27

Posttraumatic cerebellar hematoma.  

PubMed

A posttraumatic cerebellar hematoma in a 12-year-old boy is reported. It was observed by CT scan that the hematoma is discharged incompletely into the subdural space. The surgical treatment was successful with complete recovery. It is suggested that CT scan should be performed as soon as possible in cranial trauma with cerebellar signs. PMID:7128249

Fernández-Alvarez, E; Fábregues, I; Pineda, M; Costa, J; Lafuente, J

1982-01-01

28

Mars Science Laboratory's Descent Stage  

NASA Technical Reports Server (NTRS)

This portion of NASA's Mars Science Laboratory, called the descent stage, does its main work during the final few minutes before touchdown on Mars.

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 Mars Science Laboratory spacecraft is being assembled and tested for launch in 2011.

This image was taken at NASA's Jet Propulsion Laboratory, Pasadena, Calif., which manages the Mars Science Laboratory Mission for NASA's Science Mission Directorate, Washington. JPL is a division of the California Institute of Technology.

2008-01-01

29

EXOMARS Descent Module GNC Performance  

NASA Astrophysics Data System (ADS)

The ExoMars mission is the first ESA led robotic mission of the Aurora Programme and combines technology development with investigations of major scientific interest. Italy is by far the major contributor to the mission through the strong support of the Italian Space Agency (ASI). ExoMars will search for traces of past and present life, characterize the Mars geochemistry and water distribution, improve the knowledge of the Mars environment and geophysics, and identify possible surface hazards to future human exploration missions. ExoMars will also validate the technology for safe Entry, Descent and Landing (EDL) of a large size Descent Module (DM) carrying a Rover with medium range surface mobility and the access to subsurface. The ExoMars project is presently undergoing its Phase B1 with Thales Alenia Space-Italia as Industrial Prime Contractor. Additionally, as Descent Module responsible, a dedicated simulation tool is under development in Thales Alenia Space-Italia, Turin site, for the end-to-end design and validation / verification of the DM Entry Descent and Landing.

Portigliotti, S.; Capuano, M.; Montagna, M.; Martella, P.; Venditto, P.

2007-08-01

30

Acute Spontaneous Cerebellar Hemorrhage  

PubMed Central

Acute spontaneous cerebellar hemorrhage presenting with ataxia, dysarthria, vomiting, dizziness, and coma is commonly the result of hypertension. Early diagnosis is possible, and appropriate treatment, if timely executed, may be lifesaving. ImagesFigure 1Figure 2Figure 3

Dayes, Lloyd A.; Purtzer, Thomas J.; Shahhal, Imad; Cojocaru, Traian; Knierim, David; Soloniuk, Donald

1986-01-01

31

The descent of testis and reason for failed descent.  

PubMed

Although an enormous number of theories have been proposed to explain the descent of testis, none has provided a satisfactory explanation that covers the whole spectrum. Recent evidence suggests a hitherto unrecognized mechanism. This novel explanation precisely defihes all of the factors proven to be involved in the process, and links the features associated with normal or failed descent. The gubernaculum gives rise to both smooth and striated muscles. The testis is descended through the processus vaginalis via the propulsive force generated by the muscles. Propulsion describes the risk of torsion. Failure in descent in associated with a diminution in smooth muscle content, and a decrease in sympathetic tonus that depends on androgens. Alterations in G-protein linked signaling due to differences in primary messengers resulting from changes in sympathetic and parasympathetic tonuses provide the basis for blunting of testosterone response to human chorionic gonadotropin (hCG) and the decrease in fertility, but also for the increase in the risk of malignancy. PMID:15499793

Tanyel, F Cahit

2004-01-01

32

HPV positive tonsillar cancer in two laser surgeons: case reports  

PubMed Central

A 53 year-old male gynecologist presented with human papillomavirus (HPV) 16 positive tonsillar squamous cell carcinoma. He had no identifiable risk factors with the exception of long term occupational exposure to laser plumes, having performed laser ablations and loop electrosurgical excision procedures (LEEP) on greater than 3000 dysplastic cervical and vulvar lesions over 20 years of practice. The second patient is a 62 year old male gynecologist with a 30 year history of laser ablation and LEEP who subsequently developed HPV 16 positive base of tongue cancer. He also had very few other risk factors for oropharyngeal cancer or HPV infection. HPV is a probable causative agent for oropharyngeal squamous cell carcinoma and has been reported as being transmittable through laser plume. This paper suggests that HPV transmitted through laser plume can result in subsequent squamous cell carcinoma.

2013-01-01

33

Principal components: A descent algorithm  

NASA Astrophysics Data System (ADS)

A descent procedure is proposed for the search of low-dimensional subspaces of a high-dimensional space that satisfy an optimality criterion. Specifically, the procedure is applied to finding the subspace spanned by the first m singular components of an n-dimensional dataset. The procedure minimizes the associated cost function through a series of orthogonal transformations, each represented economically as the exponential of a skew-symmetric matrix drawn from a low-dimensional space.

Salas-Boni, Rebeca; Tabak, Esteban G.

2014-06-01

34

[Neuropsychological dysfunction after cerebellar stroke].  

PubMed

Secondary to an ischemic cerebellar lesion in the territory of the right posterior inferior cerebellar artery (PICA), a 62-year-old man suffered relevant neuropsychological dysfunction. This included disturbances of executive functions, impaired visuospatial memory, blunting of affect, inappropriate behaviour, and linguistic difficulties. In this case report, we discuss the clinical presentation of so-called cerebellar cognitive affective syndrome. PMID:15682343

Willert, C; Schaumann-Kuchling, C; Adamaszek, M; Spitzer, C

2005-08-01

35

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

36

Cerebellar liponeurocytoma: case report.  

PubMed

Liponeurocytoma (lipomatous medulloblastoma) is a rarely and recently described tumor. We report an additional case of this uncommon lesion in an adult and we describe its clinical, radiological and histological features. A 45-year-old woman presented with symptoms and signs of increased intracranial pressure and cerebellar dysfunction. Computed tomography (CT) and magnetic resonance imaging (MRI) scans showed a heterogenous poorly circumscribed mass situated within the cerebellar vermis. After complete tumour resection, pathologic examination with immunohistochemical study confirmed the diagnosis. The postoperative course after 18 months was favorable with no evidence of tumor recurrence. PMID:23158671

Beizig, N; Ziadi, S; Ladib, M; Mokni, M

2013-02-01

37

Benign cerebellar hematomas in children.  

PubMed

Cerebellar hematoma is generally regarded as a rapidly progressive condition which necessitates prompt evacuation in most cases. Unlike adults, where hypertension is the most common etiological factor, children generally have underlying structural lesions (angiomas, tumors) that per se demand surgical intervention. While several reports describe nonsurgical management of cerebellar hematomas in adults, the spontaneous resolution of juvenile cerebellar hematomas is almost unknown. This paper describes a 16-year-old boy with a cerebellar hematoma of obscure etiology that was managed conservatively. This report indicates that nonsurgical treatment of cerebellar hematomas, once structural lesions have been excluded, may be attempted in neurologically stable children. PMID:3731170

Pozzati, E; Nasi, M T; Galassi, E; Fabrizi, A

1986-01-01

38

Grade 4 tonsillar hypertrophy associated with decreased retronasal olfactory function: a pilot study.  

PubMed

Tonsillar hypertrophy is common in children, but it can also be present in adults. Enlarged tonsils, a significant anatomical barrier, may affect the flow of odor molecules from the oral cavity to the nasal passages, which has not yet been studied. Thus, we aimed to investigate the mass effect of palatine tonsillar hypertrophy on retronasal olfaction. This study was carried out in 146 subjects, with a mean age of 22.1 ± 2.2 years, ranging 20-29 years. An oropharyngeal examination of the participants was completed, and tonsillar hypertrophy was graded according to the subjective tonsil size scale. The participants were divided into four groups according to their tonsil size grading; then, each subject's orthonasal olfactory and retronasal olfactory functions were assessed using "Sniffin' Sticks" and retronasal olfactory testing. There were no differences observed between the groups in terms of age, gender, cigarette smoking, or alcohol consumption. In addition, there was no difference between the groups in terms of "Sniffin' Sticks" subtests and TDI scores. It was determined that the retronasal olfactory scores of the participants with grade 4 tonsil size were significantly lower than the retronasal olfactory scores of the participants with grade 1 tonsil size. The current investigation demonstrates that grade 4 tonsillar hypertrophy has significant negative effects on the retronasal route of olfactory sensing, when compared with grade 1 tonsillar hypertrophy. PMID:24609735

Cayonu, Melih; Salihoglu, Murat; Altundag, Aytug; Tekeli, Hakan; Kayabasoglu, Gürkan

2014-08-01

39

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

40

[Chronic traumatic cerebellar hematoma].  

PubMed

Traumatic hematomas of the posterior cranial fossa are a rarity. The paper is concerned with clinical cases of chronic intracerebellar hematoma characterized by general cerebral and cerebellar symptoms. Early diagnosis and surgical intervention made it possible to attain a favourable outcome in the immediate postoperative period. PMID:2171260

Okladnikov, G I; Nesterenko, L Kh; Kurov, O M

1990-01-01

41

Metronidazole induced cerebellar ataxia  

PubMed Central

Metronidazole is a widely used antimicrobial usually prescribed by many specialist doctors for a short duration of 10-15 days. Prolonged use of metronidazole is rare. The present case is of a patient who used the drug for 4 months and developed peripheral neuropathy, convulsions, and cerebellar ataxia. He was treated with diazepam and levetiracetam. The patient recovered completely following discontinuation of metronidazole.

Hari, Aditya; Srikanth, B. Akshaya; Lakshmi, G. Sriranga

2013-01-01

42

Paraneoplastic cerebellar degeneration  

Microsoft Academic Search

Six patients developed a pancerebellar syndrome with symptoms preceding the diagnosis of neoplasia in five (median - 4 months) and following in one (2 years). In all patients, the initial cranial computed tomographic (CT) scans were normal. Five patients had repeat CTs and of these three were abnormal; cerebellar atrophy appearing 7 to 25 months following the initial CT. Median

Harry S Greenberg

1984-01-01

43

Cerebellar cleft: a form of prenatal cerebellar disruption.  

PubMed

In contrast to malformations, cerebellar disruptions have attracted little interest in the literature. We draw attention for the first time to the hypothesis that cerebellar clefts are residual changes following a prenatal cerebellar insult, and represent disruptions. We reviewed the clinical records and MR findings of six patients with a cerebellar cleft, two of whom also had prenatal MRI at 24 weeks of gestation. The clefts were located in the left cerebellar hemisphere in five cases, in the right in one patient. Other typical findings included disorderly alignment of the cerebellar folia and fissures, irregular gray/white matter junction, and abnormal arborization of the white matter in all patients. The cerebellar cleft extended into the fourth ventricle in three cases, and in two children cystic cortical lesions were seen. Supratentorial schizencephaly was found in two patients. In two patients there was a documented fetal cerebellar hemorrhage at 24 weeks of gestation. We conclude that cerebellar clefts are residual changes resulting from a prenatal cerebellar insult and consequently represent disruptions rather than primary malformations. The supratentorial findings are also in agreement with an acquired lesion. The outcome in these children was variable, mainly depending of the presence of supratentorial lesions. PMID:18671186

Poretti, A; Leventer, R J; Cowan, F M; Rutherford, M A; Steinlin, M; Klein, A; Scheer, I; Huisman, T A G M; Boltshauser, E

2008-04-01

44

Around Solomon’s Descent Algebras  

Microsoft Academic Search

We study different problems related to the Solomon’s descent algebra ?(W) of a finite Coxeter group (W,S): positive elements, morphisms between descent algebras, Loewy length... One of the main result is that, if W is irreducible and if the longest element is central, then the Loewy length of ?(W) is equal to .

C. Bonnafé; Götz Pfeiffer

2008-01-01

45

Correlation as Probability of Common Descent.  

ERIC Educational Resources Information Center

One interpretation of the Pearson product-moment correlation ("r"), correlation as the probability of originating from common descent, important to the genetic measurement of inbreeding, is examined. The conditions under which "r" can be interpreted as the probability of "identity by descent" are specified, and the possibility of generalizing this…

Falk, Ruma; Well, Arnold D.

1996-01-01

46

Tonsillar Kaposi sarcoma in a patient with membranous glomerulonephritis on immunosuppressive therapy.  

PubMed

Kaposi sarcoma is a malignant vascular neoplasm uncommonly seen in immunosuppressed patients. Herein we report an unusual case of tonsillar Kaposi sarcoma in a patient with membranous glomerulonephritis treated with prednisolone and cyclosporine. The patient presented after 10 months of starting the treatment with a tonsillar mass. Histological examination was typical of monomorphic spindle cell proliferation with slit-like vascular channels. The tumor cells expressed CD34, D2-40 and positive nuclear stain for HHV-8. Kaposi sarcoma is associated with immunosuppression and rarely occurs in the tonsil. Clinicians should be aware of this rare presentation of Kaposi sarcoma. PMID:23904308

Al-Brahim, Nabeel; Zaki, Ashraf H; El-Merhi, Khaled; Ahmad, Mahmoud S

2013-07-01

47

Low Morning Serum Cortisol Levels in Children with Tonsillar Hypertrophy and Moderate-to-Severe OSA  

PubMed Central

Background: Hypertrophic tonsillar tissue in children with obstructive sleep apnea (OSA) has enhanced expression of glucocorticoid receptors, which may reflect low endogenous cortisol levels. We have evaluated the effect of the interaction between tonsillar hypertrophy and OSA severity on morning serum cortisol levels. Methods: Children with and without snoring underwent polysomnography, tonsillar size grading, and measurement of morning serum cortisol. Results: Seventy children (2-13 years old) were recruited: 30 with moderate-to-severe OSA (apnea-hypopnea index [AHI] > 5 episodes/h), 26 with mild OSA (AHI > 1 and ? 5), and 14 controls (no snoring; AHI ? 1). Tonsillar hypertrophy was present in 56.7%, 53.8%, and 42.9% of participants in each group, respectively. Application of a general linear model demonstrated a significant effect of the interaction between severity of OSA and tonsillar hypertrophy on cortisol levels (P = 0.04), after adjustment for obesity, gender, and age. Among children with tonsillar hypertrophy, subjects with moderate-to-severe OSA (n = 17; AHI 14.7 ± 10.6), mild OSA (n = 14; AHI 2.3 ± 1.2), and control participants (n = 6; AHI 0.7 ± 0.2) were significantly different regarding cortisol levels (P = 0.02). Subjects with moderate-to-severe OSA had lower cortisol (16.9 ± 8.7 mcg/dL) than those with mild OSA (23.3 ± 4.2; P = 0.01) and those without OSA (controls) (23.6 ± 5.3 mcg/dL; P = 0.04). In contrast, children with normal-size tonsils and moderate-to-severe OSA, mild OSA, and controls did not differ in cortisol levels. Conclusions: Children with moderate-to-severe obstructive sleep apnea and the phenotype of hypertrophic tonsils have reduced morning serum cortisol levels and potentially decreased glucocorticoid inhibitory effects on tonsillar growth. Citation: Malakasioti G; Alexopoulos EI; Varlami V; Chaidas K; Liakos N; Gourgoulianis K; Kaditis AG. Low morning serum cortisol levels in children with tonsillar hypertrophy and moderate-to-severe OSA. SLEEP 2013;36(9):1349-1354.

Malakasioti, Georgia; Alexopoulos, Emmanouel I.; Varlami, Vasiliki; Chaidas, Konstantinos; Liakos, Nikolaos; Gourgoulianis, Konstantinos; Kaditis, Athanasios G.

2013-01-01

48

Childhood Cerebellar Ataxia  

PubMed Central

Childhood presentations of ataxia, an impairment of balance and coordination caused by damage to or dysfunction of the cerebellum, can often be challenging to diagnose. Presentations tend to be clinically heterogeneous but key considerations may vary based on the child's age at onset, the course of illness, and subtle differences in phenotype. Systematic investigation is recommended for efficient diagnosis. In this review, we outline common etiologies and describe a comprehensive approach to the evaluation of both acquired and genetic cerebellar ataxia in children.

Fogel, Brent L.

2012-01-01

49

Aging of cerebellar Purkinje cells  

Microsoft Academic Search

Cerebellar Purkinje cells (PCs), the sole output neurons in the cerebellar cortex, play an important role in the cerebellar\\u000a circuit. PCs appear to be rather sensitive to aging, exhibiting significant changes in both morphology and function during\\u000a senescence. This article reviews such changes during the normal aging process, including a decrease in the quantity of cells,\\u000a atrophy in the soma,

Changzheng Zhang; Qingfeng Zhu; Tianmiao Hua

2010-01-01

50

Descent advisor preliminary field test  

NASA Technical Reports Server (NTRS)

A field test of the Descent Advisor (DA) automation tool was conducted at the Denver Air Route Traffic Control Center in September 1994. DA is being developed to assist Center controllers in the efficient management and control of arrival traffic. DA generates advisories, based on trajectory predictions, to achieve accurate meter-fix arrival times in a fuel efficient manner while assisting the controller with the prediction and resolution of potential conflicts. The test objectives were to evaluate the accuracy of DA trajectory predictions for conventional- and flight-management-system-equipped jet transports, to identify significant sources of trajectory prediction error, and to investigate procedural and training issues (both air and ground) associated with DA operations. Various commercial aircraft (97 flights total) and a Boeing 737-100 research aircraft participated in the test. Preliminary results from the primary test set of 24 commercial flights indicate a mean DA arrival time prediction error of 2.4 sec late with a standard deviation of 13.1 sec. This paper describes the field test and presents preliminary results for the commercial flights.

Green, Steven M.; Vivona, Robert A.; Sanford, Beverly

1995-01-01

51

Transoral, retromolar, para-tonsillar approach to the styloid process in 6 patients with Eagle's syndrome  

PubMed Central

Objectives: Eagle’s syndrome is caused by an elongated or mineralised styloid process and characterised by facial and pharyngeal pain, odynophagia and dysphagia. Diagnosis is based on clinical findings. However radiologic imaging, like panoramic radiograph, helps to confirm the diagnosis. There are different treatments of the Eagle’s syndrome. Anti-inflammatory medication (carbamazepime, corticosteroids) and/or surgical interventions are established. The aim of the different surgical techniques is to resect the elongated styloid process near the skull base. Study Design: A transoral, retromolar, para-tonsillar approach was performed to expose and resect the elongated calcified styloid process in a consecutive series of six patients. The use of different angled ring curettes, generally used in hypophysis surgery, facilitated the preparation of the styloid process through the surrounding tissue to the skull base, without a compromise to the surrounding tissue. Clinical examinations were performed pre- and postoperatively (3 month and after 1 year after surgery) in all patients. Results: No intra- or postoperative complications were observed. The hypophysis ring curettes facilitated the preparation of the styloid process to the skull base. Conclusions: The transoral, retromolar, para-tonsillar approach is a secure and fast method to resect an elongated symptomatic styloid process. Side effects of the classical transoral trans-tonsillar approach did not occur. Key words:Retromolar, para-tonsillar approach, Eagle syndrome, clinical features.

Eckert, Alexander W.; Scheller, Christian

2014-01-01

52

Artist's rendering of Descent to Lunar Surface  

NASA Technical Reports Server (NTRS)

Descent to Lunar Surface: The Commander and Lunar Module Pilot transfer to the IM, separate it from the Command and Service Module, and fire the IM descent engine to land on the Moon. After checking out the spacecraft and eating and resting, the Commander climbs down the ladder and places his left foot on the Moon while his right foot is inside the Lunar Module landing pad.

1969-01-01

53

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

54

Cerebellar cognitive affective syndrome.  

PubMed

There has been persistent uncertainty as to whether lesions of the cerebellum are associated with clinically significant disturbances of behavior and cognition. To address this question, 20 patients with diseases confined to the cerebellum were studied prospectively over a 7-year period and the nature and severity of the changes in neurological and mental function were evaluated. Neurological examination, bedside mental state testing, neuropsychological studies, and anatomic neuroimaging were administered at the time of presentation and during follow-up assessments. Behavioral changes were clinically prominent in patients with lesions involving the posterior lobe of the cerebellum and the vermis and, in some cases, overwhelmed other aspects of the presentation. These changes were characterized by an impairment of working memory, planning, set shifting, verbal fluency, abstract reasoning, and perseveration; visual-spatial disorganization, visual memory deficits, and logical sequencing; and a bland or frankly inappropriate affect. Lesions of the anterior lobe of the cerebellum produced only minor changes in executive and visual-spatial functions. This newly defined clinical entity is called the cerebellar cognitive affective syndrome. The constellation of deficits is suggestive of disruption of the cerebellar modulation of neural circuits than link frontal, parietal, temporal, and limbic cortices with the cerebellum. PMID:9378601

Schmahmann, J D; Sherman, J C

1997-01-01

55

Cerebellar involvement in executive control.  

PubMed

The cerebellum has long been considered to be mainly involved in motor function. In the last 20 years, evidence from neuroimaging studies and from investigations of patients with cerebellar lesions has shown that the cerebellum plays a role in a range of cognitive functions. While cerebellar contributions have been shown for learning and memory, the cerebellum has also been linked to higher order cognitive control processes frequently referred to as executive functions. Although it is widely accepted that the cerebellum contributes to cognitive processing, the nature of cerebellar involvement is not well understood. The present paper focuses on the role of the cerebellum in executive processing, reviewing findings derived from neuroimaging studies or from studies investigating deficits related to cerebellar dysfunction. As executive functions cannot be considered as a unitary concept, special emphasis is put on cerebellar contributions to different aspects of executive control such as working memory, multitasking or inhibition. Referring to models derived from motor control, possible mechanisms of cerebellar involvement in executive processing are discussed. Finally, methodological problems in assessing executive deficits in general and in assessing the cerebellar contribution to executive processing in particular are addressed. PMID:17786814

Bellebaum, Christian; Daum, Irene

2007-01-01

56

Visuospatial abilities in cerebellar disorders  

PubMed Central

Background: Cerebellar involvement in spatial data management has been suggested on experimental and clinical grounds. Objective: To attempt a specific analysis of visuospatial abilities in a group of subjects with focal or atrophic cerebellar damage. Methods: Visuospatial performance was tested using the spatial subtests of the WAIS, the Benton line orientation test, and two tests of mental rotation of objects—the Minnesota paper form board test (MIN) and the differential aptitude test (DAT). Results: In the Benton line orientation test, a test of sensory analysis and elementary perception, no deficits were present in subjects with cerebellar damage. In MIN, which analyses the capacity to process bidimensional complex figures mentally, and in the DAT, which is based on mental folding and manipulation of tridimensional stimuli, subjects with cerebellar damage were impaired. Conclusions: The results indicate that lesions of the cerebellar circuits affect visuospatial ability. The ability to rotate objects mentally is a possible functional substrate of the observed deficits. A comparison between visuospatial performance of subjects with focal right and left cerebellar lesions shows side differences in the characteristics of the visuospatial syndrome. Thus cerebellar influences on spatial cognition appear to act on multiple cognitive modules.

Molinari, M; Petrosini, L; Misciagna, S; Leggio, M

2004-01-01

57

Reference energy-altitude descent guidance: Simulator evaluation. [aircraft descent and fuel conservation  

NASA Technical Reports Server (NTRS)

Descent guidance was developed to provide a pilot with information to ake a fuel-conservative descent and cross a designated geographical waypoint at a preselected altitude and airspeed. The guidance was designed to reduce fuel usage during the descent and reduce the mental work load associated with planning a fuel-conservative descent. A piloted simulation was conducted to evaluate the operational use of this guidance concept. The results of the simulation tests show that the use of the guidance reduced fuel consumption and mental work load during the descent. Use of the guidance also decreased the airspeed error, but had no effect on the altitude error when the designated waypoint was crossed. Physical work load increased with the use of the guidance, but remained well within acceptable levels. The pilots found the guidance easy to use as presented and reported that it would be useful in an operational environment.

Abbot, K. H.; Knox, C. E.

1985-01-01

58

[Cerebellar syndrome in Gaucher's disease].  

PubMed

This is a report on a 37-year-old female patient with enzymatically verified Gaucher's disease. The clinical symptoms corresponded to the neuronopathic form of the disease (type 3). A progressive cerebellar syndrome had been developing for 1 year. So far, there have been no records of complex cerebellar symptoms in connection with Gaucher's disease in the literature. After ruling out other differential diagnoses Gaucher's disease was considered to be the cause of such cerebellar symptoms, which could be attributed to toxic glucocerebroside deposits in the cerebellum. PMID:19590844

Ukley, B; Bachhuber, A; Hermann, W

2009-10-01

59

Mars Science Laboratory Rover and Descent Stage  

NASA Technical Reports Server (NTRS)

In this February 17, 2009, image, NASA's Mars Science Laboratory rover is attached to the spacecraft's descent stage. The image was taken inside the Spacecraft Assembly Facility at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

This is the way the spacecraft will look after it comes out of its protective aeroshell and is descending to the Martian surface in 2012. Here, the descent stage sits on top of the rover, with its eight main engines straddling the rover structure. The rover is the big white box below the descent stage. At this point, the rover lacks its appendages (robotic arm, mast and most wheels), as these elements are still being assembled and were not needed for space-simulation testing of the spacecraft in late 2008.

2009-01-01

60

In vitro antimicrobial activity in comparison with tonsillar tissue penetration of mezlocillin.  

PubMed

The aim of this study was to determine the role of mezlocillin, a new acylureidopenicillin, in otorhinolaryngology. One hundred and forty-four bacterial strains were isolated from 100 patients suffering from infections of the oropharyngeal tract. Among the isolates only 10 (6.9%) resulted in being mezlocillin-resistant by the agar diffusion method. Minimum inhibitory and minimum bactericidal concentrations were also determined. Pharmacokinetic parameters e.g., diffusion in tonsillar tissue and serum concentrations, were studied. Mean mezlocillin tonsillar levels of 3.5 micrograms/g and 1.8 micrograms/g and serum concentrations of 60.2 micrograms/ml and 10.6 micrograms/ml, 1 h and 4 h respectively after administration, were found. PMID:3802299

Martinetto, P; Gariglio, M; Cavallo, G P; Malcangi, A; Vitale, M

1986-12-01

61

Assessment of GPS radiosonde descent data  

NASA Astrophysics Data System (ADS)

Radiosondes are widely used to obtain basic meteorological parameters such as pressure (P), temperature (T), relative humidity (RH) and horizontal winds during the balloon ascent up to the altitude of balloon burst, usually ~ 32-35 km. Data from the radiosondes released from Gadanki (13.5° N, 79.2° E), a tropical station in India, have been collected during the ascent and during the descent as well without attaching any parachute or its equivalent since the year 2008. In the present study an attempt has been made to characterize the radiosonde descent data with the main objective of exploring its usefulness and reliability for scientific purposes. We compared the data obtained during ascent and descent phases of the same sounding. The mean differences in T, RH and horizontal winds between ascent and descent data are found to be small and are sometimes even within the uncertainty of the measurements and/or expected diurnal variation itself. The very good consistency observed between the ascent and the descent data shows that one more profile of the meteorological parameters can be constructed within 3 h of time of balloon launch practically at no additional cost. Further checks are done by utilizing the 3-hourly radiosonde observations collected during the Tropical Tropopause Dynamics campaigns conducted at Gadanki. In the process of checking the consistency between the radiosonde ascent and descent data, several new findings are arrived at and are reported in this study. In general, it has taken more than half an hour for the balloon to reach the ground from the burst altitude. It is also observed that the fall velocity is close to 10 m s-1 near the surface. Finally, it is suggested to record the observations also when the balloon is descending as this information is useful for scientific purposes.

Venkat Ratnam, M.; Pravallika, N.; Babu, S. Ravindra; Basha, G.; Pramitha, M.; Krishna Murthy, B. V.

2014-04-01

62

Stent recanalization of carotid tonsillar loop dissection using the Enterprise vascular reconstruction device.  

PubMed

Although advances in endovascular techniques have permitted reconstruction of intimal dissections and related pseudoaneurysms of the extracranial cervical internal carotid artery, highly tortuous tonsillar loop anatomic variants still pose an obstacle to conventional extracranial self-expanding carotid stents. During a 12year period, nine of 48 cases with cervical carotid dissections were associated with a tonsillar loop. Five patients required endovascular treatment, which was performed using a microcatheter-based technique with the low-profile Enterprise vascular reconstruction device (Codman Neurovascular, Raynham, MA, USA). Technical, radiographic, and clinical outcomes were analyzed for each patient. Dissection etiology was spontaneous in three patients, iatrogenic in one, and traumatic in one. Four near-occlusive tonsillar loop dissections were successfully recanalized during the acute phase. Dissection-related stenosis improved from 90±22% to 31±13%, with tandem stents needed in three instances to seal the inflow zone. There were no procedure-related transient ischemic attacks (TIA), minor/major strokes, or deaths. Angiographic follow-up for a mean of 28.0±21.6months showed all stents were patent, with average stenosis of 25.2±12.2%. Focal ovalization and kinking of the closed-cell design was noted at the sharpest curve in one patient. Clinical outcome (follow-up of 28.1±21.5months) demonstrated overall improvement with no clinical worsening, new TIA, or stroke. Tonsillar loop-associated carotid dissections can be successfully and durably recanalized using the low-profile Enterprise stent with an excellent long-term patency rate and low procedural risk. The possibility of stent kinking and low radial force should be considered when planning reconstruction with this device. PMID:24642024

Rahal, Jason P; Gao, Bulang; Safain, Mina G; Malek, Adel M

2014-07-01

63

Speech prosody in cerebellar ataxia  

NASA Astrophysics Data System (ADS)

The present study sought an acoustic signature for the speech disturbance recognized in cerebellar degeneration. Magnetic resonance imaging was used for a radiological rating of cerebellar involvement in six cerebellar ataxic dysarthric speakers. Acoustic measures of the [pap] syllables in contrastive prosodic conditions and of normal vs. brain-damaged patients were used to further our understanding both of the speech degeneration that accompanies cerebellar pathology and of speech motor control and movement in general. Pair-wise comparisons of the prosodic conditions within the normal group showed statistically significant differences for four prosodic contrasts. For three of the four contrasts analyzed, the normal speakers showed both longer durations and higher formant and fundamental frequency values in the more prominent first condition of the contrast. The acoustic measures of the normal prosodic contrast values were then used as a model to measure the degree of speech deterioration for individual cerebellar subjects. This estimate of speech deterioration as determined by individual differences between cerebellar and normal subjects' acoustic values of the four prosodic contrasts was used in correlation analyses with MRI ratings. Moderate correlations between speech deterioration and cerebellar atrophy were found in the measures of syllable duration and f0. A strong negative correlation was found for F1. Moreover, the normal model presented by these acoustic data allows for a description of the flexibility of task- oriented behavior in normal speech motor control. These data challenge spatio-temporal theory which explains movement as an artifact of time wherein longer durations predict more extreme movements and give further evidence for gestural internal dynamics of movement in which time emerges from articulatory events rather than dictating those events. This model provides a sensitive index of cerebellar pathology with quantitative acoustic analyses.

Casper, Maureen

64

Cerebellar hematoma following transsphenoidal surgery.  

PubMed

Cerebellar hemorrhage after supratentorial surgery is a very infrequent complication. Most cases occur following aneurysm or brain tumor surgery, or evacuation of extracerebral collections. The underlying mechanism of formation of these hematomas is unclear. We present an example of cerebellar hemorrhage following transsphenoidal resection of a pituitary adenoma. To our knowledge, this is the first case reported of hemorrhage in the posterior fossa after a transsphenoidal approach. PMID:15902894

Miranda, P; Alén, J F; Rivas, J; Pérez, A; Ramos, A

2005-04-01

65

Cerebellar involvement in executive control  

Microsoft Academic Search

The cerebellum has long been considered to be mainly involved in motor function. In the last 20 years, evidence from neuroimaging\\u000a studies and from investigations of patients with cerebellar lesions has shown that the cerebellum plays a role in a range\\u000a of cognitive functions. While cerebellar contributions have been shown for learning and memory, the cerebellum has also been\\u000a linked

Christian Bellebaum; Irene Daum

2007-01-01

66

Morphological spectrum of prenatal cerebellar disruptions.  

PubMed

There is increasing evidence that the cerebellum is susceptible to both prenatal infections and haemorrhages as well as being vulnerable in extremely preterm babies, but not to perinatal and postnatal hypoxic-ischaemic injuries. Starting with the imaging appearance we describe and illustrate a spectrum of prenatal cerebellar disruptions: cerebellar agenesis; unilateral cerebellar hypoplasia; unilateral cerebellar cleft; global cerebellar hypoplasia; vanishing cerebellum in myelomeningocele; and disruption of cerebellar development in preterm infants. We discuss neuroradiological characteristics, possible disruptive events, and clinical findings in the different morphological patterns. Remarkably, the same disruptive agent can cause different neuroradiological patterns, which appear likely to represent a morphological spectrum. The analysis of imaging patterns is crucial in recognising cerebellar disruptions. Recognition of cerebellar disruptions and their differentiation from cerebellar malformations is important in terms of diagnosis, prognosis, and genetic counselling. PMID:18945628

Poretti, Andrea; Prayer, Daniela; Boltshauser, Eugen

2009-09-01

67

[An adult case of cerebellar mutism after removal of cerebellar hematoma].  

PubMed

Cerebellar mutism is a well documented complication of posterior fossa tumor surgery in children. But only one case presenting with cerebellar mutism after removal of a cerebellar hematoma in adults was reported previously. We present 64-year-old male developing cerebellar mustism after surgery for hypertensive cerebellar hemorrhage. A cerebellar hematoma was located in the right side dentate nucleus and cerebellar peduncle dominantly not extending to the cerebellar vermis. During the period of cerebellar mutism, single photon emission computed tomography revealed a decrease in the contralateral temporo-parietal cerebral blood flow. Cerebellar mutism in this case may be associated with the low blood flow in the contralateral supplementary motor cortex owing to injury to the dentate-thalamo-cortical pathway at the dentate nucleus and cerebellar peduncle. The relevant literature is reviewed. PMID:11424360

Kawai, H; Ohta, F; Matsumoto, Y; Yamamoto, Y

2001-05-01

68

Convergence Properties of Gradient Descent Noise Reduction  

Microsoft Academic Search

Gradient descent noise reduction is a technique that attempts to recover the true signal, or trajectory, from noisy observations of a non-lin ear dynamical system for which the dynamics are known. This paper provides the first ri gorous proof that the algorithm will recover the original trajectory for a broad c lass of dynamical sys- tems under certain conditions. The

David Ridout; Kevin Judd

69

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

70

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

71

An extended descent framework for variational inequalities  

Microsoft Academic Search

In this paper, we develop a very general descent framework for solving asymmetric, monotone variational inequalities. We introduce two classes of differentiable merit functions and the associated global convergence frameworks which include, as special instances, the projection, Newton, quasi-Newton, linear Jacobi, and nonlinear methods. The generic algorithm is very flexible and consequently well suited for exploiting any particular structure of

D. L. Zhu; P. Marcotte

1994-01-01

72

Automation for Accommodating Fuel-Efficient Descents in Constrained Airspace.  

National Technical Information Service (NTIS)

Continuous descents at low engine power are desired to reduce fuel consumption, emissions and noise during arrival operations. The challenge is to allow airplanes to fly these types of efficient descents without interruption during busy traffic conditions...

R. A. Coopenbarger

2010-01-01

73

The Mars Exploration Rovers Descent Image Motion Estimation System  

Microsoft Academic Search

Descent image motion estimation system is the first machine-vision system for estimating lander velocity during planetary descent. Composed of sensors and software, DIMES features a descent imager, a radar altimeter, an inertial-measurement unit, and an algorithm for combining sensor measurements to estimate horizontal velocity - the speed across the planet's surface the lander travels as it descends. Although the sensors

Yang Cheng; Jay Goguen; Andrew Edie Johnson; Chris Leger; Larry Matthies; A. Miguel San Martin; Reg G. Willson

2004-01-01

74

Surgical treatment of cerebellar metastases  

PubMed Central

Background: Cerebral metastases are a common neurosurgical finding. Surgery confers several advantages to other therapies, including immediate symptomatic improvement, diagnosis, and relief from corticosteroid dependence. Here we evaluate patients with cerebellar metastases who underwent surgery and compare their findings to those in the literature, and address the benefit of avoiding ventriculo-peritoneal shunting in patients undergoing surgery. Methods: We performed a retrospective analysis involving 50 patients with cerebellar metastases who underwent surgical resection. Ventriculo-peritoneal shunts were placed in patients necessitating permanent CSF drainage. We evaluated presentation, diagnosis, complications, and outcome. Results: Our review included 21 males and 29 females, 29 to 82 years of age. Primary tumors included lung (48%), breast (14%), GI (14%), endometrial/ovarian (6%), melanoma (6%), sarcoma (4%), lymphoma (4%), laryngeal (2%), and other (2%). Clinical symptoms at presentation commonly were those secondary to elevated intracranial pressure and were the initial complaint in 34% of patients. Preoperatively, 29 patients were noted to have hydrocephalus. Importantly, 76% of these patients were able to avoid placement of a ventriculo-peritoneal shunt following surgery. Only two complications were noted in our series of 50 patients, including a symptomatic pseudomeningocele and a wound infection. No symptomatic postoperative hematoma developed in any surgical case. Conclusion: A review of the literature has shown a high complication rate in patients undergoing surgical resection of cerebellar metastases. We have shown that surgical resection of cerebellar metastases is a safe procedure and is effective in the treatment of hydrocephalus in the majority of patients harboring cerebellar lesions.

Ghods, Ali J.; Munoz, Lorenzo; Byrne, Richard

2011-01-01

75

Review of Tonsillar Lymphoma in Pediatric Patients from the Pediatric Oncology Group: What Can Be Learned about Some Indications for Microscopic Examination?  

Microsoft Academic Search

Financial considerations have led to suggestions that routine microscopic evaluation of tonsils and adenoids is neither cost effective nor clinically indicated. However, the possibility of tonsillar lymphoma must be carefully weighed when making institutional policy decisions. One way to find an appropriate algorithm for pathologic examination is to examine the characteristics of biopsy-proved tonsillar lymphomas. To investigate the clinicopathologic characteristics

Kadria Sayed; H. SAVELL JR; Robert E. Hutchison; James Kepner; Michael P. Link; Molly Schwenn; Hazem Mahmoud; David M. Parham

2005-01-01

76

Paraneoplastic cerebellar degeneration associated with Hodgkin's disease  

Microsoft Academic Search

A case of paraneoplastic cerebellar degeneration (PCD) associated with Hodgkin's disease is presented. The features that make this case particularly interesting are the simultaneous occurrence of PCD with a relapse of Hodgkin's disease, which has been present for 17 years, and the arrested progression of cerebellar dysfunction after a subacute onset. Cerebellar atrophy was revealed by computed tomography and magnetic

K. Wessel; H. C. Diener; G. Schroth; J. Dichgans

1987-01-01

77

[Diaschisis phenomenon. Crossed cerebellar diaschisis].  

PubMed

The authors describe the diaschisis phenomenon-its history, the present state of art and its types, in particular crossed cerebellar diaschisis. We report its diagnosis, occurrence, accompanying signs and symptoms. The report is based on two cases. Cerebral blood flow imaging was performed by SPECT using 99m Tc-HMPAO complex. The images obtained showed crossed cerebellar diaschisis in both cases. Remote and opposite blood flow disturbances could be the reason for dysfunction, possible symptoms and clinical signs no matter whether CT imaging does or does not display lesions. Diaschisis may be a defense mechanism of the damage brain. PMID:9678994

Pietrzykowski, J; Chmielowski, K; Skrzy?ski, S; Krzysztof Podgórski, J

1997-01-01

78

A Quiver Presentation for Solomon's Descent Algebra  

Microsoft Academic Search

The descent algebra $\\\\Sigma(W)$ is a subalgebra of the group algebra $\\\\Q W$\\u000aof a finite Coxeter group $W$, which supports a homomorphism with nilpotent\\u000akernel and commutative image in the character ring of $W$. Thus $\\\\Sigma(W)$ is\\u000aa basic algebra, and as such it has a presentation as a quiver with relations.\\u000aHere we construct $\\\\Sigma(W)$ as a quotient

OTZ PFEIFFER

2007-01-01

79

BALLUTE ENTRY, DESCENT AND LANDING ON TRITON  

Microsoft Academic Search

A ballute for entry and descent has been evaluated for the moon Triton of the planet Neptune. A spherical ballute was evaluated, with a surface density of 10 g\\/m 2 of Kapton that is capable of peak temperatures up to 500°C, radiating on both sides with emissivity of 0.8. An acceptably wide entry corridor was found for deceleration at moderate

Angus McRonald

2006-01-01

80

A gentle Hessian for efficient gradient descent  

Microsoft Academic Search

Several second-order optimization methods for gradient descent algorithms have been proposed over the years, but they usually need to compute the inverse of the Hessian of the cost function (or an approximation of this inverse) during training. In most cases, this leads to an O(n2) cost in time and space per iteration, where n is the number of parameters, which

Ronan Collobert; Samy Bengio

2004-01-01

81

Hereditary cerebellar degenerative disease (cerebellar cortical abiotrophy) in rabbits.  

PubMed

A pair of rabbits gave birth to a set of littermates (F1) with symptoms of early-onset ataxia. Microscopic examination revealed cerebellar degenerative disease in 5 of 6 littermates. Light microscopy was used to compare the thickness of each cerebellar layer in affected animals in contrast to a normal control. Affected animals showed narrowing of the molecular layer of the vermis, reduced density of Purkinje cell dendrites and irregular thickness in their branchlets, and reduced density of granular cells and scattered pyknotic cells in the granular layer. Pyknotic cells were apoptotic granular cells, confirmed by positive staining using the TUNEL method. Electron microscopy confirmed the thinning of the molecular layer seen by light microscopy and also showed a reduced number of parallel fibers, which indicate granular cells axons, and a reduced number of synaptic junctions between Purkinje and granular cells. Purkinje cells had electron-dense, irregularly shaped cytoplasm with irregularly shaped nuclei, and some of these cells had a central chromatolysis-like region. These findings support a diagnosis of cerebellar cortical abiotrophy, a hereditary condition that causes nerve function impairment leading to early-onset progressive degeneration of the cerebellar cortex. PMID:21646443

Sato, J; Sasaki, S; Yamada, N; Tsuchitani, M

2012-07-01

82

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

83

1 alpha,25-Dihydroxyvitamin D3 receptors in human thymic and tonsillar lymphocytes.  

PubMed

In vitro activated human peripheral blood lymphocytes possess the receptor protein for 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3). In the present study we have examined whether activated lymphocytes that occur in vivo in human thymuses and tonsils also possess receptors for 1,25(OH)2D3. Freshly isolated lymphocyte preparations, from five separate surgical specimens of thymus and tonsil, were depleted of monocytes and examined, before and after fractionation on a density gradient of Percoll, for [3H] 1,25(OH)2D3 binding by means of sucrose density gradient sedimentation, by saturation analysis of the binding, and by DNA-cellulose chromatography. The state of activation of the lymphocyte preparations was determined using [3H] thymidine incorporation, DNA and RNA quantitation (using acridine orange), and by determining the presence or absence of markers of activation (interleukin-2 receptor, transferrin receptor, and HLA-DR molecules). In both the thymic and the tonsillar lymphocyte preparations we detected a 1,25(OH)2D3-binding molecule possessing sedimentation coefficient of 3.3 S and dissociation constant of 10(-10) M as well as DNA binding capability. In thymic lymphocytes, the 1,25(OH)2D3 receptor concentration correlated positively with the number of lymphocytes expressing the transferrin receptor (r = 0.84; p less than 0.05). In addition, in both thymic and tonsillar lymphocytes the concentration of 1,25(OH)2D3 receptors correlated positively with the number of cells in the G1a phase of the cell cycle (r = 0.79, p less than 0.01, and r = 0.88, p less than 0.001 for thymic and tonsillar lymphocytes, respectively). In contrast, the 1,25(OH)2D3 receptor concentration in these preparations did not correlate with the rate of cell proliferation.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2843004

Provvedini, D M; Rulot, C M; Sobol, R E; Tsoukas, C D; Manolagas, S C

1987-06-01

84

CD44 and hyaluronan-dependent rolling interactions of lymphocytes on tonsillar stroma  

PubMed Central

Little is known about how lymphocytes migrate within secondary lymphoid organs. Stromal cells and their associated reticular fibers form a network of fibers that radiate from high endothelial venules to all areas of the lymph node and may provide a scaffold for lymphocyte migration. We studied interactions of lymphocytes with cultured human tonsillar stromal cells and their extracellular matrix using shear stress to distinguish transient interactions from firm adhesion. Tonsillar lymphocytes and SKW3 T lymphoma cells tethered and rolled on monolayers of cultured tonsillar stromal cells and their matrix. A significant proportion of these rolling interactions were independent of divalent cations and were mediated by CD44 binding to hyaluronan, as shown by inhibition with mAb to CD44, soluble hyaluronan, as hyaluronidase treatment of the substrate, and O-glycoprotease treatment of the rolling cells. O-glycoprotease treatment of the substrate also blocked binding completely to stromal matrix and partially to stromal monolayers. SKW3 cells tethered and rolled on plastic-immobilized hyaluronan, confirming the specificity of this interaction. By contrast, monolayers of resting or stimulated human umbilical vein endothelial cells failed to support CD44- and hyaluronan-dependent rolling. SKW3 cells added under flow conditions to frozen sections of human tonsil bound and rolled along reticular fibers in the presence of EDTA. Rolling was blocked by either CD44 mAb or hyaluronan. We propose that lymphocytes migrating through secondary lymphoid organs may use CD44 to bind to hyaluronan immobilized on stromal cells and reticular fibers.

1996-01-01

85

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

86

Palatine tonsillar metastasis of rectal adenocarcinoma: a case report and literature review.  

PubMed

Cases of primary colorectal adenocarcinoma metastasized to the palatine tonsil are extremely rare. To the best of our knowledge, only 10 cases have thus far been previously documented in the English literature. A 37-year-old Chinese woman presented with a right palatine tonsil swelling and odynophagia 5 months after a surgical resection of rectal adenocarcinoma was performed. The patient underwent a tonsillectomy, and a metastatic poorly differentiated adenocarcinoma from a colorectal origin was revealed by immunohistochemical analysis. The manner in which tonsillar metastases are involved remains unknown and should be further studied. Here, we report a new case, briefly summarize these 10 cases and review the literature. PMID:23705669

Wang, Hao; Chen, Ping

2013-01-01

87

Effects of guidelines on adeno-tonsillar surgery on the clinical behaviour of otorhinolaryngologists in Italy  

PubMed Central

Background Several guidelines on adeno-tonsillar disease have been proposed in recent years and some discrepancies in relation both to clinical manifestations and indications for surgical treatment have emerged. The aim of the study was to verify what influence (adeno)-tonsillectomy guidelines have had on the clinical behaviour of ENT specialists in Italy. Our study is a retrospective and multi-centre case series with chart review. Methods The survey involved 14,770 children, aged between the ages of 2 and 11, who had undergone adeno-tonsillar surgery between 2002 and 2008 in fourteen Italian tertiary and secondary referral centres. Anova test was used for the statistical analysis, assuming p < 0.05 as the minimum statistical significance value. Results The frequency of adeno-tonsillar surgeries did not change significantly (p>0.05) during the study period and following the Italian policy document publication. Overall, adeno-tonsillectomy was the most frequent intervention (64.1%), followed by adenoidectomy (31.1%) and tonsillectomy (4.8%). The indications for surgery did not change significantly for each of the operations (p>0.05), with the exception of adeno-tonsillectomy in case of feverish episodes due to acute recurrent tonsillitis ? 5 without nasal obstruction (decreased p= 0.010) , even when the feverish episodes due to acute recurrent tonsillitis were < 5 over the last year. Nasal obstruction was associated with feverish episodes due to acute recurrent tonsillitis in 65.2% of operated cases, while otitis media had been diagnosed in 43.3% of the patients studied. Conclusions The recommendations first developed in Italy in a 2003 policy document and then resumed in guidelines in 2008, were not implemented by ENT units involved in the survey. The study highlights the fact that the indications for adeno-tonsillar operations are based on the overall clinical presentation (comorbidity) rather than on a single symptom. Guidelines are necessary to give coherent recommendations based on both the findings obtained through randomized controlled trials and the data collected from observational studies.

2013-01-01

88

Cerebellar cleft: confirmation of the neuroimaging pattern.  

PubMed

We recently described the neuroimaging and clinical findings in 6 children with cerebellar clefts and proposed that they result from disruptive changes following prenatal cerebellar hemorrhage. We now report an additional series of 9 patients analyzing the clinical and neuroimaging findings. The clefts were located in the left cerebellar hemisphere in 5 cases, in the right in 3, and bilaterally in one child who had bilateral cerebellar hemorrhages as a preterm infant at 30 weeks gestation. In one patient born at 24 weeks of gestation a unilateral cerebellar hemorrhage has been found at the age of 4 months. Other findings included disordered alignment of the folia and fissures, an irregular gray/white matter junction, and abnormal arborization of the white matter in all cases. Supratentorial abnormalities were found in 4 cases. All but 2 patients were born at term. We confirm the distinct neuroimaging pattern of cerebellar clefts. Considering the documented fetal cerebellar hemorrhage in our first series, we postulate that cerebellar clefts usually represent residual disruptive changes after a prenatal cerebellar hemorrhage. Exceptionally, as now documented in 2 patients, cerebellar clefts can be found after neonatal cerebellar hemorrhages in preterm infants. The short-term outcome in these children was variable. PMID:20221959

Poretti, A; Huisman, T A G M; Cowan, F M; Del Giudice, E; Jeannet, P Y; Prayer, D; Rutherford, M A; du Plessis, A J; Limperopoulos, C; Boltshauser, E

2009-10-01

89

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.

Consalez, G. Giacomo; Hawkes, Richard

2013-01-01

90

Cerebellar ataxia following snake bite.  

PubMed

Neurotoxic snake envenomations are frequently encountered in medicine emergencies. Here we report a case of snakebite who presented with neuromuscular paralysis and respiratory failure, showed full recovery after effective treatment. Patient however developed cerebellar ataxia possibly due to delayed neurotoxicity of venom. PMID:21125785

Awasthi, R; Narang, Shiva; Chowdhury, Partho P

2010-06-01

91

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

92

Arachnoid cyst resulting in tonsillar herniation and syringomyelia in a patient with achondroplasia. Case report.  

PubMed

Achondroplasia has been associated with varying degrees of cervicomedullary and spinal compression, although usually in the pediatric population. Large arachnoid cysts have also been found to result in tonsillar herniation and syringomyelia. The authors present the case of a patient with achondroplasia who presented with symptoms of foramen magnum compression and syringomyelia, and who was subsequently found to have a large posterior fossa arachnoid cyst. This 38-year-old woman with achondroplasia presented with an 8-month history of headache and numbness of the hands and fingers. Admission magnetic resonance (MR) imaging of the head and spine revealed a large arachnoid cyst in the posterior cranial fossa, a 6-mm tonsillar herniation consistent with an acquired Chiari malformation, and a large cervicothoracic syrinx. The patient was treated using suboccipital craniectomy, C-1 laminectomy, fenestration of the arachnoid cyst, and decompression of the acquired Chiari malformation with duraplasty. Surgical decompression resulted in improvement of the presenting symptoms, adequate decompression of crowding at the foramen magnum, and resolution of the syrinx. Although there was only partial reduction in the retrocerebellar cisternal space on follow-up MR imaging, no residual symptoms were related to this. PMID:16398464

Bauer, Andrew M; Mueller, Diane M; Oró, John J

2005-11-01

93

System for Estimating Horizontal Velocity During Descent  

NASA Technical Reports Server (NTRS)

The descent image motion estimation system (DIMES) is a system of hardware and software, designed for original use in estimating the horizontal velocity of a spacecraft descending toward a landing on Mars. The estimated horizontal velocity is used in generating rocket-firing commands to reduce the horizontal velocity as part of an overall control scheme to minimize the landing impact. DIMES can also be used for estimating the horizontal velocity of a remotely controlled or autonomous aircraft for purposes of navigation and control.

Johnson, Andrew; Cheng, Yang; Wilson, Reg; Goguen, Jay; Martin, Alejandro San; Leger, Chris; Matthies, Larry

2007-01-01

94

Algorithm 851: CG_DESCENT, a conjugate gradient method with guaranteed descent  

Microsoft Academic Search

Recently, a new nonlinear conjugate gradient scheme was developed which satisfies the descent condition gTkdk ? ?7\\/8 ‖gk‖2 and which is globally convergent whenever the line search fulfills the Wolfe conditions. This article studies the convergence behavior of the algorithm; extensive numerical tests and comparisons with other methods for large-scale unconstrained optimization are given.

William W. Hager; Hongchao Zhang

2006-01-01

95

Ultrastructure of cerebellar capillary hemangioblastoma  

Microsoft Academic Search

Large pinocytic vacuolar bodies (megalopinocytic vesicles) containing electron-dense granulo-fibrillary material, not previously described in micro-vascular endothelium of brain tumors, were observed in endothelial cells of all five cases of cerebellar hemangioblastoma studied ultrastructurally. They were present in 23% of a total of 132 capillary profiles studied. Some were prominent and aggregated to occupy a large portion of the endothelial cytoplasm.

K.-L. Ho

1986-01-01

96

Reversible cerebellar ataxia due to ovarian teratoma.  

PubMed

Cerebellar dysfunction is a classic paraneoplastic syndrome associated with various types of cancer, including gynecological and breast tumors, small-cell lung cancer, thymoma, and Hodgkin's lymphoma. We present a 22-year-old woman with acute cerebellar ataxia that subsided upon removal of an ovarian teratoma. This patient may represent a new category of immune-mediated cerebellar ataxia that is reversible with removal of an underlying tumor. PMID:24726236

Park, Jung E; Liang, Tsao-Wei

2014-08-01

97

Palatine Tonsillar Metastasis of Small-Cell Neuroendocrine Carcinoma from the Lung Detected by FDG-PET/CT After Tonsillectomy: A Case Report  

PubMed Central

Metastasis from a malignant tumor to the palatine tonsils is rare, accounting for only 0.8% of all tonsillar tumors, with only 100 cases reported in the English-language literature. Various malignant lung carcinomas may metastasize to the tonsils. A few cases of tonsillar metastasis from neuroendocrine lung carcinoma have been reported. A 67-year-old female underwent a right tonsillectomy because of a sore throat and an enlarged right tonsil. The postoperative pathology showed right tonsillar small cell neuroendocrine carcinoma (SCNC). Fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) demonstrated metabolic activity in the lower lobe of the right lung. In addition, hypermetabolic foci were noted in the lymph nodes of the right neck and mediastinum. A needle biopsy of the pulmonary mass showed SCNC. The patient received chemotherapy and died of multiple distant metastases after 6 months. This is the first report using PET/CT to evaluate tonsillar metastasis from lung SCNC.

Chen, Xiao-Hong; Bao, Yang-Yang; Zhou, Shui-Hong; Wang, Qin-Ying; Zhao, Kui

2013-01-01

98

25 CFR 11.711 - Descent and distribution.  

Code of Federal Regulations, 2011 CFR

...1 2011-04-01 2011-04-01 false Descent and distribution. 11.711 Section 11.711 Indians BUREAU OF INDIAN...ORDER CODE Probate Proceedings § 11.711 Descent and distribution. (a) The court shall distribute the estate...

2011-04-01

99

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

100

Planetary entry, descent, and landing technologies  

NASA Astrophysics Data System (ADS)

Martian meteorological lander (MML) is intended for landing on the Martian surface in order to monitor the atmosphere at landing point for one Martian year. MMLs shall become the basic elements of a global network of meteorological mini-landers, observing the dynamics of changes of the atmospheric parameters on the Red Planet. The MML main scientific tasks are as follows: (1) Study of vertical structure of the Martian atmosphere throughout the MML descent; (2) On-surface meteorological observations for one Martian year. One of the essential factors influencing the lander's design is its entry, descent, and landing (EDL) sequence. During Phase A of the MML development, five different options for the lander's design were carefully analyzed. All of these options ensure the accomplishment of the above-mentioned scientific tasks with high effectiveness. CONCEPT A (conventional approach): Two lander options (with a parachute system + airbag and an inflatable airbrake + airbag) were analyzed. They are similar in terms of fulfilling braking phases and completely analogous in landing by means of airbags. CONCEPT B (innovative approach): Three lander options were analyzed. The distinguishing feature is the presence of inflatable braking units (IBU) in their configurations. SELECTED OPTION (innovative approach): Incorporating a unique design approach and modern technologies, the selected option of the lander represents a combination of the options analyzed in the framework of Concept B study. Currently, the selected lander option undergoes systems testing (Phase D1). Several MMLs can be delivered to Mars in frameworks of various missions as primary or piggybacking payload: (1) USA-led "Mars Scout" (2007); (2) France-led "NetLander" (2007/2009); (3) Russia-led "Mars-Deimos-Phobos sample return" (2007); (4) Independent mission (currently under preliminary study); etc.

Pichkhadze, K.; Vorontsov, V.; Polyakov, A.; Ivankov, A.; Taalas, P.; Pellinen, R.; Harri, A.-M.; Linkin, V.

2003-04-01

101

Bridle Device in Mars Science Laboratory Descent Stage  

NASA Technical Reports Server (NTRS)

This view of a portion of the descent stage of NASA's Mars Science Laboratory shows two of the stage's three spherical fuel tanks flanking the bridle device assembly. The photograph was taken in early October 2008 from the center of the descent stage looking outward. The top of the descent stage is toward the top of the image.

The bridle device assembly is about two-thirds of a meter, or 2 feet, from top to bottom, and has two main parts. The cylinder on the top is the descent brake. The conical-shaped mechanism below that is the bridle assembly, including a spool of nylon and Vectran cords that will be attached to the rover.

When pyrotechnic bolts fire to sever the rigid connection between the rover and the descent stage, gravity will pull the tethered rover away from the descent stage. The bridle or tether, attached to three points on the rover, will unspool from the bridle assembly, beginning from the larger-diameter portion. The rotation rate of the assembly, hence the descent rate of the rover, will be governed by the descent brake. Inside the housing of that brake are gear boxes and banks of mechanical resistors engineered to prevent the bridle from spooling out too quickly or too slowly. The length of the bridle will allow the rover to be lowered about 7.5 meters (25 feet) while still tethered to the descent stage.

The Starsys division of SpaceDev Inc., Poway, Calif., provided the descent brake. NASA's Jet Propulsion Laboratory, Pasadena, Calif., built the bridle assembly. Vectran is a product of Kuraray Co. Ltd., Tokyo. 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

102

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

103

Cerebellar synaptic protein expression in schizophrenia  

Microsoft Academic Search

A cortico-subcortico-cerebellar neural circuit has been postulated to be important in the pathophysiology of schizophrenia. This study investigated whether there are synaptic changes in the cerebellum to accompany its putative involvement in the disorder. We measured the expression of three synaptic proteins (synaptophysin, complexin I and complexin II) in the cerebellar cortex of 16 subjects with schizophrenia and 16 controls

S. L Eastwood; D Cotter; P. J Harrison

2001-01-01

104

[Spontaneous cerebellar hematoma with a favorable course].  

PubMed

Echo-eg, EEG, dopplerography and computer-aided tomography of the brain were employed to examine 8 patients with spontaneous cerebellar hematomas. Clinically, minor intracerebellar hematomas are characterized by acutely occurring intensive systemic dizziness, nausea, moderate coordination disorders without consciousness derangement or pyramidal and sensible disturbances. It is demonstrated that cerebellar hemorrhages may run a favourable course without any surgical treatment. PMID:1647098

Mironov, N V; Arkhipov, S L; Gavrilov, E S; Iakhno, N N

1991-01-01

105

Posterior Fossa Dermoid Cysts Causing Cerebellar Abscesses  

Microsoft Academic Search

Dermoid cysts are uncommon tumors, and posterior fossa dermoid cysts may rarely cause abscess formation or formation of daughter abscesses within the cerebellum. At present, there are only 16 cases with posterior fossa dermoid cysts causing cerebellar abscesses reported in the literature. Two cases, 22 and 14 months old, with posterior fossa dermoid cysts and dermal sinus causing multiple cerebellar

Feyza Karagöz Güzey; N. Serdar Bas; Altay Sencer; Erhan Emel; M. Kemal Hamamcioglu; Nezih Özkan; Kemal Hepgul; Abdurrahman Aycan

2007-01-01

106

Learning of Sensory Sequences in Cerebellar Patients  

ERIC Educational Resources Information Center

A possible role of the cerebellum in detecting and recognizing event sequences has been proposed. The present study sought to determine whether patients with cerebellar lesions are impaired in the acquisition and discrimination of sequences of sensory stimuli of different modalities. A group of 26 cerebellar patients and 26 controls matched for…

Frings, Markus; Boenisch, Raoul; Gerwig, Marcus; Diener, Hans-Christoph; Timmann, Dagmar

2004-01-01

107

Altered cerebellar feedback projections in Asperger syndrome.  

PubMed

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 magnetic resonance imaging. For each subject, tract-specific measurements of mean diffusivity and fractional anisotropy were made within the inferior, middle, superior cerebellar peduncles and short intracerebellar fibres. No group differences were observed in mean diffusivity. However, people with Asperger syndrome had significantly lower fractional anisotropy in the short intracerebellar fibres (p<0.001) and right superior cerebellar (output) peduncle (p<0.001) compared to controls; but no difference in the input tracts. Severity of social impairment, as measured by the Autistic Diagnostic Interview, was negatively correlated with diffusion anisotropy in the fibres of the left superior cerebellar peduncle. These findings suggest a vulnerability of specific cerebellar neural pathways in people with Asperger syndrome. The localised abnormalities in the main cerebellar outflow pathway may prevent the cerebral cortex from receiving those cerebellar feedback inputs necessary for a successful adaptive social behaviour. PMID:18495494

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

2008-07-15

108

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

109

The bihemispheric posterior inferior cerebellar artery  

Microsoft Academic Search

Rarely, a solitary posterior inferior cerebellar artery (PICA) will supply both cerebellar hemispheres. We report four cases of this variant. We present a retrospective review of clinical information and imaging of patients undergoing angiography at our institution to identify patients with a bihemispheric PICA. There were four patients: three males and one female. One patient presented with a ruptured arteriovenous

Sean P. Cullen; Augustin Ozanne; Hortensia Alvarez; Pierre Lasjaunias

2005-01-01

110

Cerebellar hemangioblastoma manifesting as hearing disturbance.  

PubMed

A 49-year-old man presented with a rare case of cerebellar hemangioblastoma manifesting as only hearing disturbance. He had suffered from hearing difficulty in the right ear for a few months. Magnetic resonance imaging revealed a cystic mass lesion with an internal fluid level and surrounding flow voids in the right cerebellopontine (CP) angle. Cerebral angiography disclosed a vascular-rich tumor fed by both the superior cerebellar and anterior inferior cerebellar arteries. En bloc resection of the tumor was planned under a preoperative diagnosis of cerebellar hemangioblastoma. The tumor protruded into the CP cistern and compressed cranial nerve VIII. The feeding arteries were meticulously coagulated and the tumor was successfully removed. The histological diagnosis was hemangioblastoma. After the operation, the patient's hearing acuity improved dramatically. Cerebellar hemangioblastoma should be considered in the differential diagnosis of CP angle tumors associated with hearing disturbance. PMID:19779288

Amano, Toshiyuki; Tokunaga, So; Shono, Tadahisa; Mizoguchi, Masahiro; Matsumoto, Kenichi; Yoshida, Fumiaki; Sasaki, Tomio

2009-09-01

111

Cerebellar Stroke-manifesting as Mania  

PubMed Central

Secondary mania resulting from cerebral Cortex are described commonly. But secondary mania produced by cerebellar lesions are relatively uncommon. This case report describes a patient who developed cerebellar stoke and manic features simultaneously. 28 years old male developed giddiness and projectile vomiting. Then he would lie down for about an hour only to find that he could not walk. He became quarrelsome. His Psycho motor activities and speech were increased. He was euphoric and was expressing grandiose ideas. Bender Gestalt Test showed signs of organicity. Score in Young mania relating scale was 32; productivity was low in Rorschach. Neurological examination revealed left cerebellar signs like ataxia and slurring of speech. Computed tomography of brain showed left cerebellar infarct. Relationship between Psychiatric manifestations and cerebellar lesion are discussed.

Jagadesan, Venkatesan; Thiruvengadam, Kannapiran R.; Muralidharan, Rengarajalu

2014-01-01

112

Local Search for Multiobjective Function Optimization: Pareto Descent Method  

NASA Astrophysics Data System (ADS)

Many real-world problems entail multiple conflicting objectives, which makes multiobjective optimization an important subject. Much attention has been paid to Genetic Algorithm (GA) as a potent multiobjective optimization method, and the effectiveness of its hybridization with local search (LS) has recently been reported in the literature. However, there have been a relatively small number of studies on LS methods for multiobjective function optimization. Although each of the existing LS methods has some strong points, they have respective drawbacks such as high computational cost and inefficiency of improving objective functions. Hence, a more effective and efficient LS method is being sought, which can be used to enhance the performance of the hybridization. Pareto descent directions are defined in this paper as descent directions to which no other descent directions are superior in improving all objective functions. Moving solutions in such directions is expected to maximally improve all objective functions simultaneously. This paper proposes a new LS method, Pareto Descent Method (PDM), which finds Pareto descent directions and moves solutions in such directions. In the case part or all of them are infeasible, it finds feasible Pareto descent directions or descent directions as necessary and moves solutions in these directions. PDM finds these directions by solving linear programming problems. Thus, it is computationally inexpensive. Experiments have shown that PDM is superior to existing methods.

Harada, Ken; Sakuma, Jun; Ikeda, Kokolo; Ono, Isao; Kobayashi, Shigenobu

113

The cerebellar cognitive affective syndrome.  

PubMed

Anatomical, physiological and functional neuroimaging studies suggest that the cerebellum participates in the organization of higher order function, but there are very few descriptions of clinically relevant cases that address this possibility. We performed neurological examinations, bedside mental state tests, neuropsychological studies and anatomical neuroimaging on 20 patients with diseases confined to the cerebellum, and evaluated the nature and severity of the changes in neurological and mental function. Behavioural changes were clinically prominent in patients with lesions involving the posterior lobe of the cerebellum and the vermis, and in some cases they were the most noticeable aspects of the presentation. These changes were characterized by: impairment of executive functions such as planning, set-shifting, verbal fluency, abstract reasoning and working memory; difficulties with spatial cognition including visual-spatial organization and memory; personality change with blunting of affect or disinhibited and inappropriate behaviour; and language deficits including agrammatism and dysprosodia. Lesions of the anterior lobe of the cerebellum produced only minor changes in executive and visual-spatial functions. We have called this newly defined clinical entity the 'cerebellar cognitive affective syndrome'. The constellation of deficits is suggestive of disruption of the cerebellar modulation of neural circuits that link prefrontal, posterior parietal, superior temporal and limbic cortices with the cerebellum. PMID:9577385

Schmahmann, J D; Sherman, J C

1998-04-01

114

Surface erosion caused on Mars from Viking descent engine plume  

USGS Publications Warehouse

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 material, (2) crusty to cloddy material, (3) blocky material, and (4) rock. ?? 1980 D. Reidel Publishing Co.

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

1980-01-01

115

Tonsillar crypt epithelium is an important extra-central nervous system site for viral replication in EV71 encephalomyelitis.  

PubMed

Enterovirus 71 (EV71; family Picornaviridae, species human Enterovirus A) usually causes hand, foot, and mouth disease, which may rarely be complicated by fatal encephalomyelitis. We investigated extra-central nervous system (extra-CNS) tissues capable of supporting EV71 infection and replication, and have correlated tissue infection with expression of putative viral entry receptors, scavenger receptor B2 (SCARB2), and P-selectin glycoprotein ligand-1 (PSGL-1). Formalin-fixed, paraffin-embedded CNS and extra-CNS tissues from seven autopsy cases were examined by IHC and in situ hybridization to evaluate viral antigens and RNA. Viral receptors were identified with IHC. In all seven cases, the CNS showed stereotypical distribution of inflammation and neuronal localization of viral antigens and RNA, confirming the clinical diagnosis of EV71 encephalomyelitis. In six cases in which tonsillar tissues were available, viral antigens and/or RNA were localized to squamous epithelium lining the tonsillar crypts. Tissues from the gastrointestinal tract, pancreas, mesenteric nodes, spleen, and skin were all negative for viral antigens/RNA. Our novel findings strongly suggest that tonsillar crypt squamous epithelium supports active viral replication and represents an important source of viral shedding that facilitates person-to-person transmission by both the fecal-oral or oral-oral routes. It may also be a portal for viral entry. A correlation between viral infection and SCARB2 expression appears to be more significant than for PSGL-1 expression. PMID:24378407

He, Yaoxin; Ong, Kien Chai; Gao, Zifen; Zhao, Xishun; Anderson, Virginia M; McNutt, Michael A; Wong, Kum Thong; Lu, Min

2014-03-01

116

Transmission of Actinobacillus pleuropneumoniae in pigs under field-like conditions: emphasis on tonsillar colonisation and passively acquired colostral antibodies.  

PubMed

The objectives of this study were to elucidate at which age tonsillar colonisation by Actinobacillus pleuropneumoniae occurs in pigs and relate this occurrence to the presence of colostral antibodies to A. pleuropneumoniae. The infection patterns were studied in an isolated cohort of pigs, which consisted of the offspring from five sows originating from a conventional pig herd. The sows were transferred to isolated research facilities before farrowing. A. pleuropneumoniae was detected on the tonsils of all sows. After a nursing period of 3 weeks, the pigs were weaned and reared isolated from other pigs until slaughter. The pigs were examined repeatedly for the presence of A. pleuropneumoniae on the tonsils and for antibodies to A. pleuropneumoniae using bacteriological and serological techniques, respectively.A. pleuropneumoniae was detected in the tonsils of one pig as early as 11 days after birth, showing that A. pleuropneumoniae can be transmitted from sow to offspring during a 3-week nursing period. The cumulative proportion of pigs carrying A. pleuropneumoniae in their tonsils increased significantly between the age of 4-12 weeks. This age period corresponded to the age at which the proportion of pigs with detectable levels of colostral antibodies to the different serotypes of A. pleuropneumoniae was declining. Since these two events take place in the same age period, we expect a possible biological association between the level of the passive immunity and the degree of tonsillar colonisation. The median duration of tonsillar colonisation was estimated to approximately 7-8 weeks. PMID:12243892

Vigre, Håkan; Angen, Øystein; Barfod, Kristen; Lavritsen, Dorte Thanning; Sørensen, Vibeke

2002-10-22

117

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.

2011-01-01

118

Origin, lineage and function of cerebellar glia.  

PubMed

The glial cells of the cerebellum, and particularly astrocytes and oligodendrocytes, are characterized by a remarkable phenotypic variety, in which highly peculiar morphological features are associated with specific functional features, unique among the glial cells of the entire CNS. Here, we provide a critical report about the present knowledge of the development of cerebellar glia, including lineage relationships between cerebellar neurons, astrocytes and oligodendrocytes, the origins and the genesis of the repertoire of glial types, and the processes underlying their acquisition of mature morphological and functional traits. In parallel, we describe and discuss some fundamental roles played by specific categories of glial cells during cerebellar development. In particular, we propose that Bergmann glia exerts a crucial scaffolding activity that, together with the organizing function of Purkinje cells, is necessary to achieve the normal pattern of foliation and layering of the cerebellar cortex. Moreover, we discuss some of the functional tasks of cerebellar astrocytes and oligodendrocytes that are distinctive of cerebellar glia throughout the CNS. Notably, we report about the regulation of synaptic signalling in the molecular and granular layer mediated by Bergmann glia and parenchymal astrocytes, and the functional interaction between oligodendrocyte precursor cells and neurons. On the whole, this review provides an extensive overview of the available literature and some novel insights about the origin and differentiation of the variety of cerebellar glial cells and their function in the developing and mature cerebellum. PMID:23981535

Buffo, Annalisa; Rossi, Ferdinando

2013-10-01

119

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.

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

2010-01-01

120

Cerebellar contributions to verbal working memory.  

PubMed

There is increasing evidence for a cerebellar role in working memory. Clinical research has shown that working memory impairments after cerebellar damage and neuroimaging studies have revealed task-specific activation in the cerebellum during working memory processing. A lateralisation of cerebellar function within working memory has been proposed with the right hemisphere making the greater contribution to verbal processing and the left hemisphere for visuospatial tasks. We used continuous theta burst stimulation (cTBS) to examine whether differences in post-stimulation performance could be observed based on the cerebellar hemisphere stimulated and the type of data presented. We observed that participants were significantly less accurate on a verbal version of a Sternberg task after stimulation to the right cerebellar hemisphere when compared to left hemisphere stimulation. Performance on a visual Sternberg task was unaffected by stimulation of either hemisphere. We discuss our results in the context of prior studies that have used cerebellar stimulation to investigate working memory and highlight the cerebellar role in phonological encoding. PMID:24338673

Tomlinson, Simon P; Davis, Nick J; Morgan, Helen M; Bracewell, R Martyn

2014-06-01

121

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

122

Cerebellar involvement in metabolic disorders: a pattern-recognition approach  

Microsoft Academic Search

Inborn errors of metabolism can affect the cerebellum during development, maturation and later during life. We have established\\u000a criteria for pattern recognition of cerebellar abnormalities in metabolic disorders. The abnormalities can be divided into\\u000a four major groups: cerebellar hypoplasia (CH), hyperplasia, cerebellar atrophy (CA), cerebellar white matter abnormalities\\u000a (WMA) or swelling, and involvement of the dentate nuclei (DN) or cerebellar

M. Steinlin; S. Blaser; E. Boltshauser

1998-01-01

123

Cerebellar atrophy in systemic lupus erythematosus.  

PubMed

Central nervous system involvement in systemic lupus erythematosus (SLE) is common; this is especially so in patients with positive antiphospholipid antibody. However, cerebellar involvement is very unusual. In our institution, we have seen 150 cases of SLE over the last 10 years; however, this is the only patient who has cerebellar involvement due to SLE. The patient had no other neurological deficit, and no other cause apart from her SLE to explain her cerebellar ataxia. Her antiphospholipid antibody was negative. The patient showed some improvement on high-dose steroids and azathioprin. PMID:8563737

al-Arfaj, H F; Naddaf, H O

1995-10-01

124

Titan Explorer Entry, Descent and Landing Trajectory Design.  

National Technical Information Service (NTIS)

The Titan Explorer mission concept includes an orbiter, entry probe and inflatable airship designed to take remote and in-situ measurements of Titan's atmosphere. A modified entry, descent and landing trajectory at Titan that incorporates mid-air airship ...

J. L. Fisher M. K. Lockwood R. E. Lindberg

2006-01-01

125

14 CFR 31.19 - Performance: Uncontrolled descent.  

Code of Federal Regulations, 2010 CFR

... Performance: Uncontrolled descent. 31.19 Section 31.19 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION...AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.19 Performance: Uncontrolled...

2010-01-01

126

14 CFR 31.19 - Performance: Uncontrolled descent.  

Code of Federal Regulations, 2010 CFR

... Performance: Uncontrolled descent. 31.19 Section 31.19 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION...AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Flight Requirements § 31.19 Performance: Uncontrolled...

2009-01-01

127

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

128

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

129

Mathematica (Trademark) and the Method of Steepest Descents. Part 1.  

National Technical Information Service (NTIS)

Mathematica is a symbolic manipulator with graphical capabilities. During the fall 1990 semester, I used Mathematica on my NeXT workstation to create graphics for teaching the method of steepest descents. This required level curve plots and surface plots ...

N. Bleistein

1992-01-01

130

Thermal control for planetary probes. [during descent phase  

NASA Technical Reports Server (NTRS)

Thermal control of planetary probes during the descent phase of a mission is examined. Emphasis was placed on the problems of atmospheric uncertainties to be encountered by the probes, insulation performance, and equipment temperature limits.

Mcmordie, R.

1974-01-01

131

A general descent framework for the monotone variational inequality problem  

Microsoft Academic Search

We present a framework for descent algorithms that solve the monotone variational inequalityproblem V IP v which consists in finding a solution v2\\\\Omegav which satisfies s(v)T(u \\\\Gamma v) 0, for allu2\\\\Omegav . This unified framework includes, as special cases, some well known iterative methodsand equivalent optimization formulations. A descent method is developed for an equivalentgeneral optimization formulation and a proof

Jia Hao Wu; Michael Florian; Patrice Marcotte

1993-01-01

132

Air-Traffic Controllers Evaluate The Descent Advisor  

NASA Technical Reports Server (NTRS)

Report describes study of Descent Advisor algorithm: software automation aid intended to assist air-traffic controllers in spacing traffic and meeting specified times or arrival. Based partly on mathematical models of weather conditions and performances of aircraft, it generates suggested clearances, including top-of-descent points and speed-profile data to attain objectives. Study focused on operational characteristics with specific attention to how it can be used for prediction, spacing, and metering.

Tobias, Leonard; Volckers, Uwe; Erzberger, Heinz

1992-01-01

133

Testicular descent: INSL3, testosterone, genes and the intrauterine milieu  

Microsoft Academic Search

Complete testicular descent is a sign of, and a prerequisite for, normal testicular function in adult life. The process of testis descent is dependent on gubernacular growth and reorganization, which is regulated by the Leydig cell hormones insulin-like peptide 3 (INSL3) and testosterone. Investigation of the role of INSL3 and its receptor, relaxin-family peptide receptor 2 (RXFP2), has contributed substantially

Katharina M. Main; Jorma Toppari; Niels E. Skakkebæk; Katrine Bay

2011-01-01

134

Effects of flutamide and finasteride on rat testicular descent.  

PubMed

The endocrine control of descent of the testis in mammalian species is poorly understood. The androgen dependency of testicular descent was studied in the rat using an antiandrogen (flutamide) and an inhibitor of the enzyme 5 alpha-reductase (finasteride). Androgen receptor blockade inhibited testicular descent more effectively than inhibition of 5 alpha-reductase activity. Moreover, its inhibitory effect was limited to the outgrowth phase of the gubernaculum testis, particularly the earliest stages of outgrowth. Gubernacular size was also significantly reduced in fetuses exposed to flutamide during the outgrowth period. In contrast, androgen receptor blockade or 5 alpha-reductase inhibition applied after the initiation of gubernacular outgrowth or during the regression phase did not affect testicular descent. Successful inhibition of the development of epididymis and vas by prenatal flutamide did not correlate with ipsilateral testicular maldescent, suggesting that an intact epididymis is not required for descent of the testis. Plasma androgen assays confirmed significant inhibition of dihydrotestosterone formation in finasteride-treated rats. These data suggest that androgens, primarily testosterone, are required during the early phases of gubernacular outgrowth for subsequent successful completion of testicular descent. PMID:1677329

Spencer, J R; Torrado, T; Sanchez, R S; Vaughan, E D; Imperato-McGinley, J

1991-08-01

135

A descent of the aurora over Lapland  

NASA Astrophysics Data System (ADS)

A very large statistical study (? 4 × 105 measurements) into the peak emission height of the aurora has shown that the aurora over Lapland descended significantly between 1996 and 2007. The study was performed using images from a network of ground-based all-sky cameras which form part of the MIRACLE (Magnetometers-Ionospheric Radar-All-sky Cameras Large Experiment) network, and are located at various observation stations across northern Finland and Sweden. The height of the aurora was first measured about a century ago. Since then, it has generally been assumed that the peak emission height of any particular auroral emission is constant for similar geomagnetic conditions. The present work was motivated by the need to improve estimates of the height of the aurora used to calculate other ionospheric and auroral properties, such as optical flow velocities and auroral arc widths. In recent years MIRACLE has produced approximately 105 images of the aurora per station per year. In order to analyse such a large number of images, a novel fast and automatic method was developed for finding the peak emission height of an auroral structure from a pair of all-sky camera images with overlapping fields of view. This method has been applied to all auroral images recorded by the MIRACLE intensified CCD cameras in operation between 1996 and 2007. Such a large data set allows the study of variations in the height of the aurora with time (yearly, monthly, hourly) and with solar and geomagnetic indices such as F10.7 and Kp. Results from the statistical study show that the peak emission height of green (557.7 nm, O1S - O1D transition) aurora over Lapland descended by about 10 km between 1996 and 2007. This descent occurred independently of the solar cycle, and is thought to be due to a cooling and contraction of the mesosphere and lower thermosphere.

Whiter, Daniel; Partamies, Noora

2014-05-01

136

[Bilateral cerebellar hematoma after supratentorial glioma surgery].  

PubMed

We present a case of bilateral hematoma in cerebellar hemispheres in a 30-year-old man after surgical treatment of extensive left frontal glioma. 16 hours after surgery the patient lost consciousness. An immediate CT revealed hematoma in both cerebellar hemispheres. The hematoma was subsequently removed via bilateral suboccipital craniectomy. After the operation the clinical status of the patient gradually improved - he was discharged in a good general condition. In the presented case the hematoma developed presumably as a consequence of extensive cerebrospinal fluid (CSF) loss (670 ml) via postoperative wound drainage. The resulting cerebellar displacement caused strain of the draining veins, affecting blood outflow, and causing parenchymal hemorrhage. In order to prevent the complication, massive CSF loss during and after operation should be avoided. Careful monitoring of the patient's condition in the postoperative period, even if the general status is good, is important because only an immediate intervention may prevent the development of irreversible consequences of cerebellar hematoma formation. PMID:15354240

Czepko, Ryszard; Kwinta, Borys; Uhl, Henryka; Urbanik, Andrzej; Libionka, Witold; Pietraszko, Wojciech

2004-01-01

137

A dynamical system view of cerebellar function  

NASA Astrophysics Data System (ADS)

First some previous theories of cerebellar function are reviewed, and deficiencies in how they map onto the neurophysiological structure are pointed out. I hypothesize that the cerebellar cortex builds an internal model, or prediction, of the dynamics of the animal. A class of algorithms for doing prediction based on local reconstruction of attractors are described, and it is shown how this class maps very well onto the structure of the cerebellar cortex. I hypothesize that the climbing fibers multiplex between different trajectories corresponding to different modes of operation. Then the vestibulo-ocular reflex is examined, and experiments to test the proposed model are suggested. The purpose of the presentation here is twofold: (1) To enlighten physiologists to the mathematics of a class of prediction algorithms that map well onto cerebellar architecture. (2) To enlighten dynamical system theorists to the physiological and anatomical details of the cerebellum.

Keeler, James D.

1990-06-01

138

Heterozygous alterations of TNFRSF13B/TACI in tonsillar hypertrophy and sarcoidosis.  

PubMed

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

Speletas, Matthaios; Salzer, Ulrich; Florou, Zoe; Petinaki, Efthimia; Daniil, Zoe; Bardaka, Fotini; Gourgoulianis, Konstantinos I; Skoulakis, Charalampos; Germenis, Anastasios E

2013-01-01

139

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.

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

2013-01-01

140

Tonsillar application of AT-2 SIV affords partial protection against rectal challenge with SIVmac239  

PubMed Central

While mucosal responses are important for preventing infections with HIV, the optimal strategies for inducing them remain unclear. To evaluate vaccine strategies targeting the oral mucosal lymphoid tissue inductive sites as an approach to provide immunity at distal sites, we vaccinated healthy macaques via the palatine/lingual tonsils with aldrithiol 2 (AT-2) inactivated SIVmac239, combined with CpG-C immunostimulatory oligonucleotide (CpG-C ISS-ODN , C274) as the adjuvant. Macaques received 5 doses of C274 or control ODN C661 and AT-2 SIV on the tonsillar tissues every 6 weeks before being challenged rectally with SIVmac239, 8 weeks after the last immunization. Although no T or B cell responses were detected in the blood prior to challenge, Ab responses were detected in the rectum . Immunization with AT-2 SIV significantly reduced the frequency of infection compared to non-immunized controls, irrespective of adjuvant. In the vaccinated animals that became infected, peak viremias were somewhat reduced. SIV-specific responses were detected in the blood once animals became infected with no detectable differences between the differently immunized groups and the controls. This work provides evidence that vaccine immunogens applied to the oral mucosal-associated lymphoid tissues can provide benefit against rectal challenge, a finding with important implications for mucosal vaccination strategies.

Vagenas, Panagiotis; Williams, Vennansha G.; Piatak, Michael; Bess, Julian W.; Lifson, Jeffrey D.; Blanchard, James L.; Gettie, Agegnehu; Robbiani, Melissa

2009-01-01

141

Neuropsychological functioning in unilateral cerebellar damage.  

PubMed

A woman had a left superior cerebellar artery infarct associated with reduced hexamethylpropileneamine oxime uptake on SPECT scan of the basal ganglia and frontoparietal areas of the opposite hemisphere performed poorly in some neuropsychological tests indicating right hemisphere dysfunction. There was a lengthening of reaction and movement times with the hand ipsilateral to the lesion. These deficits were temporary. A unilateral cerebellar lesion can produce neuropsychological deficits, possibly because of hypoperfusion in contralateral frontoparietal regions, but spontaneous neuropsychological remissions may occur. PMID:7874621

Botez-Marquard, T; Léveillé, J; Botez, M I

1994-11-01

142

Targeting the red nucleus for cerebellar tremor.  

PubMed

Deep brain stimulation of the thalamus (and especially the ventral intermediate nucleus) does not significantly improve a drug-resistant, disabling cerebellar tremor. The dentato-rubro-olivary tract (Guillain-Mollaret triangle, including the red nucleus) is a subcortical loop that is critically involved in tremor genesis. We report the case of a 48-year-old female patient presenting with generalized cerebellar tremor caused by alcohol-related cerebellar degeneration. Resistance to pharmacological treatment and the severity of the symptoms prompted us to investigate the effects of bilateral deep brain stimulation of the red nucleus. Intra-operative microrecordings of the red nucleus revealed intense, irregular, tonic background activity but no rhythmic components that were synchronous with upper limb tremor. The postural component of the cerebellar tremor disappeared during insertion of the macro-electrodes and for a few minutes after stimulation, with no changes in the intentional (kinetic) component. Stimulation per se did not reduce postural or intentional tremor and was associated with dysautonomic symptoms (the voltage threshold for which was inversed related to the stimulation frequency). Our observations suggest that the red nucleus is (1) an important centre for the genesis of cerebellar tremor and thus (2) a possible target for drug-refractory tremor. Future research must determine how neuromodulation of the red nucleus can best be implemented in patients with cerebellar degeneration. PMID:24415178

Lefranc, M; Manto, M; Merle, P; Tir, M; Montpellier, D; Constant, J-M; Le Gars, D; Macron, J-M; Krystkowiak, P

2014-06-01

143

Design of automation tools for management of descent traffic  

NASA Technical Reports Server (NTRS)

The design of an automated air traffic control system based on a hierarchy of advisory tools for controllers is described. Compatibility of the tools with the human controller, a key objective of the design, is achieved by a judicious selection of tasks to be automated and careful attention to the design of the controller system interface. The design comprises three interconnected subsystems referred to as the Traffic Management Advisor, the Descent Advisor, and the Final Approach Spacing Tool. Each of these subsystems provides a collection of tools for specific controller positions and tasks. This paper focuses primarily on the Descent Advisor which provides automation tools for managing descent traffic. The algorithms, automation modes, and graphical interfaces incorporated in the design are described. Information generated by the Descent Advisor tools is integrated into a plan view traffic display consisting of a high-resolution color monitor. Estimated arrival times of aircraft are presented graphically on a time line, which is also used interactively in combination with a mouse input device to select and schedule arrival times. Other graphical markers indicate the location of the fuel-optimum top-of-descent point and the predicted separation distances of aircraft at a designated time-control point. Computer generated advisories provide speed and descent clearances which the controller can issue to aircraft to help them arrive at the feeder gate at the scheduled times or with specified separation distances. Two types of horizontal guidance modes, selectable by the controller, provide markers for managing the horizontal flightpaths of aircraft under various conditions. The entire system consisting of descent advisor algorithm, a library of aircraft performance models, national airspace system data bases, and interactive display software has been implemented on a workstation made by Sun Microsystems, Inc. It is planned to use this configuration in operational evaluations at an en route center.

Erzberger, Heinz; Nedell, William

1988-01-01

144

Neuropsychological consequences of cerebellar tumour resection in children: cerebellar cognitive affective syndrome in a paediatric population.  

PubMed

Acquired cerebellar lesions in adults have been shown to produce impairments in higher function as exemplified by the cerebellar cognitive affective syndrome. It is not yet known whether similar findings occur in children with acquired cerebellar lesions, and whether developmental factors influence their presentation. In studies to date, survivors of childhood cerebellar tumours who demonstrate long-term deficits in cognitive functions have undergone surgery as well as cranial irradiation or methotrexate treatment. Investigation of the effects of the cerebellar lesion independent of the known deleterious effects of these agents is important for understanding the role of the cerebellum in cognitive and affective development and for informing treatment and rehabilitation strategies. If the cerebellar contribution to cognition and affect is significant, then damage in childhood may influence a wide range of psychological processes, both as an immediate consequence and as these processes fail to develop normally later on. In this study we evaluated neuropsychological data in 19 children who underwent resection of cerebellar tumours but who received neither cranial irradiation nor methotrexate chemotherapy. Impairments were noted in executive function, including planning and sequencing, and in visual-spatial function, expressive language, verbal memory and modulation of affect. These deficits were common and in some cases could be dissociated from motor deficits. Lesions of the vermis in particular were associated with dysregulation of affect. Behavioural deficits were more apparent in older than younger children. These results reveal that clinically relevant neuropsychological changes may occur following cerebellar tumour resection in children. Age at the time of surgery and the site of the cerebellar lesion influence the neurobehavioural outcome. The results of the present study indicate that the cerebellar cognitive affective syndrome is evident in children as well as in adults, and they provide further clinical evidence that the cerebellum is an essential node in the distributed neural circuitry subserving higher-order behaviours. PMID:10775548

Levisohn, L; Cronin-Golomb, A; Schmahmann, J D

2000-05-01

145

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

146

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

147

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

148

Cerebellar research: two centuries of discoveries.  

PubMed

Numerous laboratories currently focus their activities on cerebellar research. The cerebellum is attractive due to its sophisticated circuitry, high degree of modifiability combined with unique operational mechanisms, and the growing awareness of its multiple roles. Works of pioneers of these last two centuries, such as Rolando, Flourens, Magendie, Luciani, Lugaro, Babinski, Holmes, Cajal, Larsell, Eccles, Voogd, Llinas, or Ito, still exert a strong influence in the way we investigate cerebellar functions. The amount of knowledge is exploding, thanks to advances in genetics, molecular and cellular analyses, profusion of brain imaging techniques, novel behavioral assessments, and reshaping of models of cerebellar function. More than ever, strong and consistent intellectual efforts are required to generate homogeneous research outcomes that might exert a significant influence in the forthcoming domains of research. Because research is often based on the results of our predecessors, The Cerebellum has launched a section called Cerebellar Classics. Papers selected represent key steps for the discovery of some of the secrets of the cerebellar circuitry. These seminal contributions offer a portal to the past to modern scholars. PMID:22113501

Manto, Mario; Haines, Duane

2012-06-01

149

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

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

2014-01-01

150

Space shuttle descent design: From development to operations  

NASA Technical Reports Server (NTRS)

The descent guidance system, the descent trajectories design, and generating of the associated flight products are discussed. The programs which allow the successful transitions from development to STS operations, resulting in reduced manpower requirements and compressed schedules for flight design cycles are addressed. The topics include: (1) continually upgraded tools for the job, i.e., consolidating tools via electronic data transfers, tailoring general purpose software for needs, easy access to tools through an interactive approach, and appropriate flexibility to allow design changes and provide growth capability; (2) stabilizing the flight profile designs (I-loads) in an uncertain environment; and (3) standardizing external interfaces within performance and subsystems constraints of the Orbiter.

Crull, T. J.; Hite, R. E., III

1985-01-01

151

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

152

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

153

Relevance of the cerebellar hemispheres for executive functions  

Microsoft Academic Search

The aim of the present study was to elucidate the role of the cerebellar hemispheres in executive functions. The findings are relevant because of the large number of children who survive cerebellar tumors. Neuropsychologic assessments of four patients (8-21 years of age) who had undergone neurosurgery for removal of tumors in the cerebellar hemispheres were conducted and compared with the

Canan Karatekin; Jorge A. Lazareff; Robert F. Asarnow

2000-01-01

154

Transient orthostatic hypertension after partial cerebellar resection.  

PubMed

An effective baroreflex and autonomic pathways normally ensure that blood pressure (BP) is satisfactorily maintained, despite various stimuli in daily life that include postural changes. We describe a 20-year-old man with a cerebellar hematoma and acute hydrocephalus, who had a vermian and partial right cerebellar hemisphere resection followed by orthostatic hypertension (OHT) and mutism. On standing his systolic BP rose over 60 mmHg with a fivefold increase in plasma noradrenaline. After a period of 8 weeks, postural BP regulation improved along with his ability to communicate. We conclude that transient impairment of cerebellar autonomic modulation or dysfunction of the baroreflex medullary circuit, may have resulted in OHT. PMID:20845056

Idiaquez, Juan; Fadic, Ricardo; Mathias, Christopher J

2011-02-01

155

Differential diagnosis of cerebellar atrophy in childhood.  

PubMed

Starting from the imaging appearance of cerebellar atrophy (CA) we provide checklists for various groups of CA: hereditary CA, postnatally acquired CA, and unilateral CA. We also include a list of disorders with ataxia as symptom, but no evidence of CA on imaging. These checklists may be helpful in the evaluation of differential diagnosis and planning of additional investigations. However, the complete constellation of clinical (including history and neurological examination), imaging, and other information have to be considered. On the basis of a single study distinction between prenatal onset atrophy, postnatal onset atrophy, and cerebellar hypoplasia is not always possible. Apart from rare exceptions, neuroimaging findings of CA are nonspecific. A pattern-recognition approach is suggested, considering isolated (pure) CA, CA and hypomyelination, CA and progressive white matter abnormalities, CA and basal ganglia involvement, and cerebellar cortex hyperintensity. PMID:17869142

Poretti, Andrea; Wolf, Nicole I; Boltshauser, Eugen

2008-05-01

156

Diagnostic approach to cerebellar disease in children.  

PubMed

We reviewed the clinical records of 51 extensively investigated pediatric patients with structural abnormalities of the cerebellum as revealed by magnetic resonance imaging (MRI). Ten had hypoplasia of the vermis, 21 had hypoplasia of the vermis and cerebellar hemispheres, 2 had pontocerebellar hypoplasia, and 18 had progressive cerebellar atrophy. A clear diagnosis was reached in 37 (72.5%). Initial characterization of the cerebellar alterations by MRI separated hypoplastic from atrophic cases and confirmed MRI as an essential preliminary means for distinguishing malformations from metabolic-degenerative conditions. However, the diagnostic possibilities are so numerous that it is not feasible to propose a standardized diagnostic protocol for pediatric patients with an altered cerebellum. Subsequent investigations should be suggested by the neuroradiologic and clinical peculiarities of each case. PMID:16417854

D'Arrigo, Stefano; Viganò, Lucia; Grazia Bruzzone, Maria; Marzaroli, Michela; Nikas, Ioannis; Riva, Daria; Pantaleoni, Chiara

2005-11-01

157

Bilateral representation in the deep cerebellar nuclei  

PubMed Central

The cerebellum is normally assumed to represent ipsilateral movements. We tested this by making microelectrode penetrations into the deep cerebellar nuclei (mainly nucleus interpositus) of monkeys trained to perform a reach and grasp task with either hand. Following weak single electrical stimuli, many sites produced clear bilateral facilitation of multiple forelimb muscles. The short onset latencies, which were similar for each side, suggested that at least some of the muscle responses were mediated by descending tracts originating in the brainstem, rather than via the cerebral cortex. Additionally, cerebellar neurones modulated their discharge with both ipsilateral and contralateral movements. This was so, even when we carefully excluded contralateral trials with evidence of electromyogram modulation on the ipsilateral side. We conclude that the deep cerebellar nuclei have a bilateral movement representation, and relatively direct, powerful access to limb muscles on both sides of the body. This places the cerebellum in an ideal position to coordinate bilateral movements.

Soteropoulos, Demetris S; Baker, Stuart N

2008-01-01

158

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.

Pisotta, Iolanda; Molinari, Marco

2014-01-01

159

The anatomical substrate of cerebellar mutism.  

PubMed

Up to 39% of children operated for a posterior fossa tumor develop the cerebellar mutism syndrome. Although they are alert and cooperative, with normal language comprehension, they are unable to speak. In addition, patients may demonstrate apathy, bladder and bowel incontinence and long-term language and cognitive disturbances. This devastating syndrome is at the same time intriguing, because it confirms a role for the cerebellum in language and cognitive functions. Recent investigations have led to new insights regarding the cerebellar mutism syndrome. The commonly accepted hypothesis states that the mutism is caused by a hypofunction of cerebral hemispheres, due to damage to the superior cerebellar peduncle and functional disruption of the cerebello-cerebral circuitry. This article focuses on the evidence for and against this hypothesis and its clinical consequences. PMID:24735842

van Baarsen, Kirsten Margaretha; Grotenhuis, Joachim André

2014-06-01

160

Unilateral cerebellar hypoplasia with different clinical features.  

PubMed

Unilateral cerebellar hypoplasia (UCH) is a rare pathological condition characterized by the loss of volume in cerebellar hemispheres ranging from mild asymptomatic to severe symptomatic cases. As the designation of UCH remains problematic, the underlying etiopathogenesis also lacks explanation. We investigated the patients admitted to Departments of Child Neurology, Neurology, and Genetics between the years 1992 and 2010 and detected 12 patients with unilateral cerebellar volume loss, with the exclusion of all other cerebellar pathologies. The ages of patients ranged between 6 months to 55 years. Five patients had a delay in developmental milestones, and one of these was diagnosed with neurofibromatosis type 1. Two patients had epileptic seizures, one patient had peripheral facial paralysis as a component of Moebius syndrome, and four patients were incidentally diagnosed during etiological work-up for headache. The clinical outcomes of patients varied from healthy subjects to marked developmental impairment. Radiologically, five patients had severe disproportionate UCH, six had moderate disproportionate, and one had mild proportionate UCH. Cerebellar peduncles were affected in all, and vermis was partly hypoplastic in eight patients. Brainstem was involved in four patients, and seven patients showed involvement of white matter and/or corpus callosum. Imaging features supported that patients with severe disproportionate UCH also displayed additional cerebral and commissural changes, which were related to ischemic or vascular injuries, implying a prenatally acquired disruption. In the presence of such a wide spectrum of clinical and radiological features, a prenatally acquired lesion and, thus, a disruption seem to be more explanatory rather than a primary developmental process or malformation in the etiopathogenesis of unilateral cerebellar hypoplasia. PMID:20967575

Benbir, Gulcin; Kara, Simay; Yalcinkaya, Beyza Citci; Karhkaya, Geysu; Tuysuz, Beyhan; Kocer, Naci; Yalcinkaya, Cengiz

2011-03-01

161

Quasi-duo rings and stable range descent  

Microsoft Academic Search

In a recent paper, the first author introduced a general theory of corner rings in noncommutative rings that generalized the classical theory of Peirce decompositions. This theory is applied here to the study of the stable range of rings upon descent to corner rings. A ring is called quasi-duo if every maximal 1-sided ideal is 2-sided. Various new characterizations are

T. Y. Lam; Alex S. Dugas

2005-01-01

162

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

163

Quiver Presentations for Descent Algebras of Exceptional Type  

Microsoft Academic Search

The descent algebra of a finite Coxeter group $W$ is a basic algebra, and as such it has a presentation as quiver with relations. In recent work, we have developed a combinatorial framework which allows us to systematically compute such a quiver presentation for a Coxeter group of a given type. In this article, we use that framework to determine

Goetz Pfeiffer; Galway Ireland

2008-01-01

164

Descents and nodal load in scale-free networks.  

PubMed

The load of a node in a network is the total traffic going through it when every node pair sustains a uniform bidirectional traffic between them on shortest paths. We express nodal load in terms of the more elementary notion of a node's descents in breadth-first-search [(BFS) or shortest-path] trees and study both the descent and nodal-load distributions in the case of scale-free networks. Our treatment is both semianalytical (combining a generating-function formalism with simulation-derived BFS branching probabilities) and computational for the descent distribution; it is exclusively computational in the case of the load distribution. Our main result is that the load distribution, even though it can be disguised as a power law through subtle (but inappropriate) binning of the raw data, is in fact a succession of sharply delineated probability peaks, each of which can be clearly interpreted as a function of the underlying BFS descents. This find is in stark contrast with previously held belief, based on which a power law of exponent -2.2 was conjectured to be valid regardless of the exponent of the power-law distribution of node degrees. PMID:18517694

Bareinboim, Elias; Barbosa, Valmir C

2008-04-01

165

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

166

LANDER program manual: A lunar ascent and descent simulation  

NASA Technical Reports Server (NTRS)

LANDER is a computer program used to predict the trajectory and flight performance of a spacecraft ascending or descending between a low lunar orbit of 15 to 500 nautical miles (nm) and the lunar surface. It is a three degree-of-freedom simulation which is used to analyze the translational motion of the vehicle during descent. Attitude dynamics and rotational motion are not considered. The program can be used to simulate either an ascent from the Moon or a descent to the Moon. For an ascent, the spacecraft is initialized at the lunar surface and accelerates vertically away from the ground at full thrust. When the local velocity becomes 30 ft/s, the vehicle turns downrange with a pitch-over maneuver and proceeds to fly a gravity turn until Main Engine Cutoff (MECO). The spacecraft then coasts until it reaches the requested holding orbit where it performs an orbital insertion burn. During a descent simulation, the lander begins in the holding orbit and performs a deorbit burn. It then coasts to pericynthion, where it reignites its engines and begins a gravity turn descent. When the local horizontal velocity becomes zero, the lander pitches up to a vertical orientation and begins to hover in search of a landing site. The lander hovers for a period of time specified by the user, and then lands.

1988-01-01

167

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

168

Operation of CONSERT aboard Rosetta during the descent of Philae  

NASA Astrophysics Data System (ADS)

This paper presents a study investigating the performance of using the CONSERT instrument aboard the Rosetta spacecraft as a radar sounder during the Separation-Descent-Landing (SDL) phase of the Rosetta mission. Gathering scientifically valuable data during this phase will support CONSERT's primary target, the reconstruction of the 3D permittivity distribution within the comet 67P/Churyumov-Gerasimenko, by providing a permittivity map of the surface around the landing site. Simulation results will show the performance of the instrument, using a realistic setup including the antenna characteristics of both orbiter and landing unit as well as a realistic orbitography for the descent phase. It will be shown that operating the CONSERT instrument will indeed provide very valuable data, thereby providing tremendous aid to the experiment's main objective. Furthermore, by including knowledge of the antenna characteristics, it is possible to calculate attitude and descent profile of the Philae lander during descent, using the data of the line-of-sight propagation path and the echoes reflected from the comet's surface.

Hegler, Sebastian; Statz, Christoph; Hahnel, Ronny; Plettemeier, Dirk; Herique, Alain; Kofman, Wlodek

2013-12-01

169

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

170

Mars Smart Lander Simulations for Entry, Descent, and Landing.  

National Technical Information Service (NTIS)

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 Trajectori...

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

2002-01-01

171

Moral Darwinism: Ethical evidence for the descent of man  

Microsoft Academic Search

Could an ethical theory ever play a substantial evidential role in a scientific argument for an empirical hypothesis? InThe Descent of Man, Darwin includes an extended discussion of the nature of human morality, and the ethical theory which he sketches is not simply developed as an interesting ramification of his theory of evolution, but is used as a key part

Robert T. Pennock

1995-01-01

172

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

PubMed

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; Ismail, Salmah; Yusof, Mohd Yasim; Dhabaan, Ghulam N; Abdulla, Mahmood Ameen

2013-01-01

173

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

174

Measurement of CPAS Main Parachute Rate of Descent  

NASA Technical Reports Server (NTRS)

The Crew Exploration Vehicle Parachute Assembly System (CPAS) is being designed to land the Orion Crew Module (CM) at a safe rate of descent at splashdown. Flight test performance must be measured to a high degree of accuracy to ensure this requirement is met with the most efficient design possible. Although the design includes three CPAS Main parachutes, the requirement is that the system must not exceed 33 ft/s under two Main parachutes, should one of the Main parachutes fail. Therefore, several tests were conducted with clusters of two Mains. All of the steady-state rate of descent data are normalized to standard sea level conditions and checked against the limit. As the Orion design gains weight, the system is approaching this limit to within measurement precision. Parachute "breathing," cluster interactions, and atmospheric anomalies can cause the rate of descent to vary widely and lead to challenges in characterizing parachute terminal performance. An early test had contradictory rate of descent results from optical trajectory and Differential Global Positioning Systems (DGPS). A thorough analysis of the data sources and error propagation was conducted to determine the uncertainty in the trajectory. It was discovered that the Time Space Position Information (TSPI) from the optical tracking provided accurate position data. However, the velocity from TPSI must be computed via numerical differentiation, which is prone to large error. DGPS obtains position through pseudo-range calculations from multiple satellites and velocity through Doppler shift of the carrier frequency. Because the velocity from DGPS is a direct measurement, it is more accurate than TSPI velocity. To remedy the situation, a commercial off-the-shelf product that combines GPS and an Inertial Measurement Unit (IMU) was purchased to significantly improve rate of descent measurements. This had the added benefit of solving GPS dropouts during aircraft extraction. Statistical probability distributions for CPAS Main parachute rate of descent and drag coefficient were computed and plotted. Using test data, a terminal rate of descent at splashdown can be estimated as a function of canopy loading.

Ray, Eric S.

2011-01-01

175

Adult leptomeningeal cerebellar heterotopia in contact with the posterior inferior cerebellar artery.  

PubMed

A leptomeningeal mass was encountered during microdissection of a 63-year-old male cadaver, located dorsal to the left side of the medulla oblongata. The structure was compressing the posterior inferior cerebellar artery (PICA) and was composed of cerebellar-like tissue. Immunohistochemistry for S100 protein, glial fibrillary acidic protein and neurofilaments (NF, the triplet proteins and the 200 kD antibody) on paraffin-embedded samples confirmed the cerebellar heterotopion. Abundant Lewy-like degenerative bodies were also identified within the heterotopion; they were positive for the NF triplet and negative for the 200 kD neurofilaments. Purkinje cells were rare. This is the first evidence of a leptomeningeal cerebellar heterotopia in contact with PICA in adult. Such subtentorial heterotopias, even if rare, should be searched for during clinical, paraclinical and surgical explorations of the posterior fossa. PMID:22585456

Rusu, Mugurel Constantin

2013-03-01

176

Perinatal Cerebellar Injury in Human and Animal Models  

PubMed Central

Cerebellar injury is increasingly recognized through advanced neonatal brain imaging as a complication of premature birth. Survivors of preterm birth demonstrate a constellation of long-term neurodevelopmental deficits, many of which are potentially referable to cerebellar injury, including impaired motor functions such as fine motor incoordination, impaired motor sequencing and also cognitive, behavioral dysfunction among older patients. This paper reviews the morphogenesis and histogenesis of the human and rodent developing cerebellum, and its more frequent injuries in preterm. Most cerebellar lesions are cerebellar hemorrhage and infarction usually leading to cerebellar abnormalities and/or atrophy, but the exact pathogenesis of lesions of the cerebellum is unknown. The different mechanisms involved have been investigated with animal models and are primarily hypoxia, ischemia, infection, and inflammation Exposure to drugs and undernutrition can also induce cerebellar abnormalities. Different models are detailed to analyze these various disturbances of cerebellar development around birth.

Biran, Valerie; Verney, Catherine; Ferriero, Donna M.

2012-01-01

177

Perinatal cerebellar injury in human and animal models.  

PubMed

Cerebellar injury is increasingly recognized through advanced neonatal brain imaging as a complication of premature birth. Survivors of preterm birth demonstrate a constellation of long-term neurodevelopmental deficits, many of which are potentially referable to cerebellar injury, including impaired motor functions such as fine motor incoordination, impaired motor sequencing and also cognitive, behavioral dysfunction among older patients. This paper reviews the morphogenesis and histogenesis of the human and rodent developing cerebellum, and its more frequent injuries in preterm. Most cerebellar lesions are cerebellar hemorrhage and infarction usually leading to cerebellar abnormalities and/or atrophy, but the exact pathogenesis of lesions of the cerebellum is unknown. The different mechanisms involved have been investigated with animal models and are primarily hypoxia, ischemia, infection, and inflammation Exposure to drugs and undernutrition can also induce cerebellar abnormalities. Different models are detailed to analyze these various disturbances of cerebellar development around birth. PMID:22530126

Biran, Valerie; Verney, Catherine; Ferriero, Donna M

2012-01-01

178

Cerebellar Atrophy in Human and Murine Succinic Semialdehyde Dehydrogenase Deficiency  

PubMed Central

Human succinic semialdehyde dehydrogenase deficiency, an autosomal recessive disorder of ?-aminobutyric acid (GABA) catabolism, was modeled by a murine model sharing the phenotype of ataxia and seizures. Magnetic resonance imaging (MRI) with volumetry was obtained on 7 patients versus controls, and MRI with stereology was derived in 3 murine genotypes: null, wild-type, and heterozygous mutants. All patients had T1 hypointensity and T2 hyperintensity in globus pallidus, and 5 also had similar changes in subthalamic and cerebellar dentate nuclei. There was a trend for patients to have a smaller cerebellar vermis. Homozygous null mice had significantly lower total brain and cerebellar volumes than wild-types and heterozygotes. Stereology confirmed cerebellar atrophy and was otherwise normal in multiple regions. Cerebellar volume loss is present in the murine disorder with a trend for cerebellar atrophy in patients. Reduced cerebellar volume can reflect neurodegeneration and may be related to the clinical manifestations.

Acosta, Maria T.; Munasinghe, Jeeva; Pearl, Phillip L.; Gupta, Maneesh; Finegersh, Andrey; Gibson, K. Michael; Theodore, William H.

2010-01-01

179

HIV-1 pathogenesis differs in rectosigmoid and tonsillar tissues infected ex vivo with CCR5- and CXCR4-tropic HIV-1.  

PubMed

Gut-associated lymphoid tissue (GALT) has been identified as the primary target of HIV-1 infection. To investigate why GALT is especially vulnerable to HIV-1, and to determine whether the selective transmission of CCR5-using viral variants (R5) in vivo is the result of a greater susceptibility of GALT to this viral variant, we performed comparative studies of CXCR4-using (X4) and R5 HIV-1 infections of human lymphoid (tonsillar) and rectosigmoid tissues ex vivo under controlled laboratory conditions. We found that the relative level of R5 replication in rectosigmoid tissue is much greater than in tonsillar tissue. This difference is associated with the expression of the CCR5 co-receptor on approximately 70% of CD4 T cells in rectosigmoid tissue, whereas in tonsillar tissue it is expressed on fewer than 15% of CD4 T cells. Furthermore, tonsillar tissue responds to X4 HIV-1 infection by upregulating the secretion of CC-chemokines, providing a potential CCR5 blockade and further resistance to R5 infection, whereas gut tissue failed to increase such innate immune responses. Our results show that rectosigmoid tissue is more prone than tonsillar lymphoid tissue to R5 HIV-1 infection, primarily because of the high prevalence and availability of R5 cell targets and reduced chemokine blockade. The majority of CD4 T cells express CXCR4, however, and X4 HIV-1 readily replicates in both tissues, suggesting that although the differential expression of co-receptors contributes to the GALT vulnerability to R5 HIV-1, it alone cannot account for the selective R5 infection of the rectal mucosa in vivo. PMID:17545702

Grivel, Jean-Charles; Elliott, Julie; Lisco, Andrea; Biancotto, Angèlique; Condack, Cristian; Shattock, Robin J; McGowan, Ian; Margolis, Leonid; Anton, Peter

2007-06-19

180

Cerebellar Disease in an Adult Cow  

PubMed Central

This is the report of clinical signs and lesions of a cerebellar disorder in an adult four year old Limousin cow grazing perennial ryegrass (Lolium perenne). The most striking histopathological lesion was a marked paucity of Purkinje cells throughout the cerebellum. ImagesFigure 1.Figure 2.

Oz, H. H.; Nicholson, S. S.; Al-Bagdadi, F. K.; Zeman, D. H.

1986-01-01

181

TRPC channels promote cerebellar granule neuron survival  

Microsoft Academic Search

Channels formed by the transient receptor potential (TRP) family of proteins have a variety of physiological functions. Here we report that two members of the TRP cation channel (TRPC) subfamily, TRPC3 and 6, protected cerebellar granule neurons (CGNs) against serum deprivation–induced cell death in cultures and promoted CGN survival in rat brain. In CGN cultures, blocking TRPC channels or downregulating

Yichang Jia; Jian Zhou; Yilin Tai; Yizheng Wang

2007-01-01

182

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.??

Silveri, M; Misciagna, S; Terrezza, G

2001-01-01

183

Coccidioidomycosis with cerebral and cerebellar granulomas.  

PubMed

We discuss the diagnosis, treatment and prognosis of a Danish male with disseminated coccidioidomycosis. He presented with headaches and slight fever. Examination showed pulmonary, cutaneous and cerebral and cerebellar granulomas, a rare complication. He was treated with intravenously and subsequently orally administered fluconazole. Symptoms and clinical findings regressed during treatment. PMID:16798706

Rosendahl, Mikkel; Kvinesdal, Birgit

2006-01-01

184

Dendrite Formation of Cerebellar Purkinje Cells  

Microsoft Academic Search

During postnatal cerebellar development, Purkinje cells form the most elaborate dendritic trees among neurons in the brain,\\u000a which have been of great interest to many investigators. This article overviews various examples of cellular and molecular\\u000a mechanisms of formation of Purkinje cell dendrites as well as the methodological aspects of investigating those mechanisms.

Masahiko Tanaka

2009-01-01

185

Radiation-induced cerebellar chondrosarcoma. Case report  

SciTech Connect

The authors report a case of chondrosarcoma arising in the cerebellum 16 years after treatment of a cerebellar malignant astrocytoma by subtotal resection and irradiation. It is thought that the chondrosarcoma arising within the intracranial cavity was a probable consequence of previous ionizing radiation.

Bernstein, M.; Perrin, R.G.; Platts, M.E.; Simpson, W.J.

1984-07-01

186

Constrained trajectory optimization for lunar landing during the powered descent phase  

Microsoft Academic Search

To design the more accurate trajectory of a soft lunar landing, the constraints on the powered descent sub-phase, such as a breaking phase, an approach phase, a terminal descent phase, have to be considered. In this paper, the trajectory optimization of the lunar landing was performed considering constraints on the sub-phase of the powered descent phase. To convert the optimal

Bong-Gyun Park; Daekyu Sangt; Min-Jea Tahku

2009-01-01

187

Posterior fossa syndrome after cerebellar stroke.  

PubMed

Posterior fossa syndrome (PFS) due to vascular etiology is rare in children and adults. To the best of our knowledge, PFS due to cerebellar stroke has only been reported in patients who also underwent surgical treatment of the underlying vascular cause. We report longitudinal clinical, neurocognitive and neuroradiological findings in a 71-year-old right-handed patient who developed PFS following a right cerebellar haemorrhage that was not surgically evacuated. During follow-up, functional neuroimaging was conducted by means of quantified Tc-99m-ECD SPECT studies. After a 10-day period of akinetic mutism, the clinical picture developed into cerebellar cognitive affective syndrome (CCAS) with reversion to a previously learnt accent, consistent with neurogenic foreign accent syndrome (FAS). No psychometric evidence for dementia was found. Quantified Tc-99m-ECD SPECT studies consistently disclosed perfusional deficits in the anatomoclinically suspected but structurally intact bilateral prefrontal brain regions. Since no surgical treatment of the cerebellar haematoma was performed, this case report is presumably the first description of pure, "non-surgical vascular PFS". In addition, reversion to a previously learnt accent which represents a subtype of FAS has never been reported after cerebellar damage. The combination of this unique constellation of poststroke neurobehavioural changes reflected on SPECT shows that the cerebellum is crucially implicated in the modulation of neurocognitive and affective processes. A decrease of excitatory impulses from the lesioned cerebellum to the structurally intact supratentorial network subserving cognitive, behavioural and affective processes constitutes the likely pathophysiological mechanism underlying PFS and CCAS in this patient. PMID:23575947

Mariën, Peter; Verslegers, Lieven; Moens, Maarten; Dua, Guido; Herregods, Piet; Verhoeven, Jo

2013-10-01

188

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

PubMed Central

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.

Myoung, Jinjong; Ganem, Don

2011-01-01

189

Two descent hybrid conjugate gradient methods for optimization  

NASA Astrophysics Data System (ADS)

In this paper, we propose two new hybrid nonlinear conjugate gradient methods, which produce sufficient descent search direction at every iteration. This property depends neither on the line search used nor on the convexity of the objective function. Under suitable conditions, we prove that the proposed methods converge globally for general nonconvex functions. The numerical results show that both hybrid methods are efficient for the given test problems from the CUTE library.

Zhang, Li; Zhou, Weijun

2008-06-01

190

Exponentiated Gradient Versus Gradient Descent for Linear Predictors  

Microsoft Academic Search

We consider two algorithms for on-line prediction based on a linear model. The algorithms are the well-known gradient descent (GD) algorithm and a new algorithm, which we call EG±. They both maintain a weight vector using simple updates. For the GD algorithm, the update is based on subtracting the gradient of the squared error made on a prediction. The EG±algorithm

Jyrki Kivinen; Manfred K. Warmuth

1997-01-01

191

Numerical Simulation of Helicopter Aeromechanics in Slow Descent Flight  

Microsoft Academic Search

\\u000a In this paper we present numerical simulation results for a generic helicopter configuration in slow descent flight. The well\\u000a known HART-II test case has been chosen as the experimental reference, especially the baseline case. This test case is characterized\\u000a by the occurrence of Blade-Vortex Interactions (BVI) and can thus be considered as very ambitious with respect to the aerodynamic\\u000a simulation.

M. Embacher; M. Keßler; F. Bensing; E. Krämer

192

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.

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

2014-01-01

193

Entry, Descent, and Landing Performance of the Mars Phoenix Lander  

NASA Technical Reports Server (NTRS)

On May 25, 2008, the Mars Phoenix Lander successfully landed on the northern arctic plains of Mars. An overview of a preliminary reconstruction analysis performed on each entry, descent, and landing phase to assess the performance of Phoenix as it descended is presented and a comparison to pre-entry predictions is provided. The landing occurred 21 km further downrange than the predicted landing location. Analysis of the flight data revealed that the primary cause of Phoenix s downrange landing was a higher trim total angle of attack during the hypersonic phase of the entry, which resulted in Phoenix flying a slightly lifting trajectory. The cause of this higher trim attitude is not known at this time. Parachute deployment was 6.4 s later than prediction. This later deployment time was within the variations expected and is consistent with a lifting trajectory. The parachute deployment and inflation process occurred as expected with no anomalies identified. The subsequent parachute descent and powered terminal landing also behaved as expected. A preliminary reconstruction of the landing day atmospheric density profile was found to be lower than the best apriori prediction, ranging from a few percent less to a maximum of 8%. A comparison of the flight reconstructed trajectory parameters shows that the actual Phoenix entry, descent, and landing was close to pre-entry predictions. This reconstruction investigation is currently ongoing and the results to date are in the process of being refined.

Desai, Prasun N.; Prince, Jill L.; Wueen, Eric M.; Cruz, Juan R.; Grover, Myron R.

2008-01-01

194

Data-Analysis System for Entry, Descent, and Landing  

NASA Technical Reports Server (NTRS)

A report describes the Entry Descent Landing Data Analysis (EDA), which is a system of signal-processing software and computer hardware for acquiring status data conveyed by multiple-frequency-shift-keying tone signals transmitted by a spacecraft during descent to the surface of a remote planet. The design of the EDA meets the challenge of processing weak, fluctuating signals that are Doppler-shifted by amounts that are only partly predictable. The software supports both real-time and post processing. The software performs fast-Fourier-transform integration, parallel frequency tracking with prediction, and mapping of detected tones to specific events. The use of backtrack and refinement parallel-processing threads helps to minimize data gaps. The design affords flexibility to enable division of a descent track into segments, within each of which the EDA is configured optimally for processing in the face of signal conditions and uncertainties. A dynamic-lock-state feature enables the detection of signals using minimum required computing power less when signals are steadily detected, more when signals fluctuate. At present, the hardware comprises eight dual-processor personal-computer modules and a server. The hardware is modular, making it possible to increase computing power by adding computers.

Pham, Timothy; Chang, Christine; Sartorius, Edgar; Finley, Susan; White, Leslie; Estabrook, Polly; Fort, David

2005-01-01

195

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 minor mid-course corrections, a Lunar Orbit Insertion (LOI) burn, a de-orbit burn, and 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 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.

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

2008-01-01

196

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

197

Shadowing Pseudo-Orbits and Gradient Descent Noise Reduction  

NASA Astrophysics Data System (ADS)

Shadowing trajectories are one of the most powerful ideas of modern dynamical systems theory, providing a tool for proving some central theorems and a means to assess the relevance of models and numerically computed trajectories of chaotic systems. Shadowing has also been seen to have a role in state estimation and forecasting of nonlinear systems. Shadowing trajectories are guaranteed to exist in hyperbolic systems, but this is not true of nonhyperbolic systems, indeed it can be shown there are systems that cannot have long shadowing trajectories. In this paper we consider what might be called shadowing pseudo-orbits. These are pseudo-orbits that remain close to a given pseudo-orbit, but have smaller mismatches between forecast state and verifying state. Shadowing pseudo-orbits play a useful role in the understanding and analysis of gradient descent noise reduction, state estimation, and forecasting nonlinear systems, because their existence can be ensured for a wide class of nonhyperbolic systems. New theoretical results are presented that extend classical shadowing theorems to shadowing pseudo-orbits. These new results provide some insight into the convergence behaviour of gradient descent noise reduction methods. The paper also discusses, in the light of the new results, some recent numerical results for an operational weather forecasting model when gradient descent noise reduction was employed.

Judd, Kevin

2008-02-01

198

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.

Igawa, Tatsuya; Katsuhira, Junji

2014-01-01

199

Hazard avoidance via descent images for safe landing  

NASA Astrophysics Data System (ADS)

In planetary or lunar landing missions, hazard avoidance is critical for landing safety. Therefore, it is very important to correctly detect hazards and effectively find a safe landing area during the last stage of descent. In this paper, we propose a passive sensing based HDA (hazard detection and avoidance) approach via descent images to lower the landing risk. In hazard detection stage, a statistical probability model on the basis of the hazard similarity is adopted to evaluate the image and detect hazardous areas, so that a binary hazard image can be generated. Afterwards, a safety coefficient, which jointly utilized the proportion of hazards in the local region and the inside hazard distribution, is proposed to find potential regions with less hazards in the binary hazard image. By using the safety coefficient in a coarse-to-fine procedure and combining it with the local ISD (intensity standard deviation) measure, the safe landing area is determined. The algorithm is evaluated and verified with many simulated descent downward looking images rendered from lunar orbital satellite images.

Yan, Ruicheng; Cao, Zhiguo; Zhu, Lei; Fang, Zhiwen

2013-10-01

200

Titan Explorer Entry, Descent and Landing Trajectory Design  

NASA Technical Reports Server (NTRS)

The Titan Explorer mission concept includes an orbiter, entry probe and inflatable airship designed to take remote and in-situ measurements of Titan's atmosphere. A modified entry, descent and landing trajectory at Titan that incorporates mid-air airship inflation (under a parachute) and separation is developed and examined for Titan Explorer. The feasibility of mid-air inflation and deployment of an airship under a parachute is determined by implementing and validating an airship buoyancy and inflation model in the trajectory simulation program, Program to Optimize Simulated Trajectories II (POST2). A nominal POST2 trajectory simulation case study is generated which examines different descent scenarios by varying airship inflation duration, orientation, and separation. The buoyancy model incorporation into POST2 is new to the software and may be used in future trajectory simulations. Each case from the nominal POST2 trajectory case study simulates a successful separation between the parachute and airship systems with sufficient velocity change as to alter their paths to avoid collision throughout their descent. The airship and heatshield also separate acceptably with a minimum distance of separation from the parachute system of 1.5 km. This analysis shows the feasibility of airship inflation on a parachute for different orientations, airship separation at various inflation times, and preparation for level-flight at Titan.

Fisher, Jody L.; Lindberg, Robert E.; Lockwood, Mary Kae

2006-01-01

201

[Autoantibodies associated with autoimmune-mediated cerebellar ataxia].  

PubMed

Various autoantibodies are associated with autoimmune-mediated cerebellar ataxia. Anti-Yo, -Zic, -CARPVIII, -Tr, -Ri, -Hu, -Ma, -CRMP-5, -ANNA-3, -PCA-2, -VGCC, and -mGluR antibodies (Abs) are found in paraneoplastic cerebellar ataxia, whereas anti-GAD, -thyroid, and -gliadin Abs are found in non-paraneoplastic cerebellar ataxia. Most of these antibodies are not pathogenic but are diagnostic markers. However, anti-VGCC, anti-mGluR, and anti-GAD Abs have been shown to cause cerebellar ataxia, because administration of these Abs mimics cerebellar ataxia in vivo. Experiments using in vitro preparations show that anti-VGCC Ab depresses excitatory synaptic transmissions, and anti-GAD Ab suppresses inhibitory synaptic transmissions. Anti-mGluR Ab interferes with the induction of synaptic plasticity. These results suggest that pathogenic Abs elicit cerebellar synaptic dysfunction, and thereby cause ataxia in patients. PMID:23568983

Mitoma, Hiroshi; Nanri, Kazunori

2013-04-01

202

Cerebellar pathway changes following cerebral hemispherectomy.  

PubMed

Following unilateral cerebral injury, several patterns of cerebellar metabolism have been noted on positron emission tomography (PET); these changes have been attributed both to the distant diaschisis as well as to reorganizational changes within the cerebellum. We used diffusion tensor magnetic resonance imaging (MRI) to study 14 children who had undergone cerebral hemispherectomy because of intractable epilepsy and compared them with those from 17 controls. In 10 children who had preoperative and postoperative scans, a paired comparison was performed. Our findings showed significantly higher fractional anisotropy values in corticopontocerebellar pathways postoperatively compared to preoperatively. When compared to controls, we found a higher rate of age-related fractional anisotropy changes of corticopontocerebellar pathways in the postoperative scans. Our results indicate reorganizational changes in the contralateral (intact) corticopontocerebellar pathway and the cerebellar white matter. These changes likely contribute to the far better motor outcomes seen in children compared to adults sustaining such cortical injuries. PMID:22965564

Govindan, Rajkumar Munian; Brescoll, Jennifer; Chugani, Harry T

2013-12-01

203

Cerebellar cognitive affective syndrome associated with topiramate.  

PubMed

The cerebellar cognitive affective syndrome (CCAS) represents a spectrum of cerebellar-induced neurocognitive and affective disturbances. In this report a patient is described who developed CCAS under a treatment with standard daily dose of the anti-epileptic drug topiramate (TPM). Cognitive disturbances consisted of impaired visuo-spatial memory, concentration deficits and executive dysfunctions. Behavior and affect were characterized by marked mood-swings and several disinhibited symptoms. After a gradual discontinuation of treatment with topiramate, a complete remission of the cognitive and affective symptoms was observed within 6 weeks. Functional neuroimaging studies by means of SPECT were conducted 2 weeks and 8 months following TPM discontinuation. This case report seems to suggest that functional disruption of the cerebello-cerebral circuitry, leading to CCAS, can follow treatment with topiramate. PMID:18304728

Baillieux, Hanne; Verslegers, Werner; Paquier, Philippe; De Deyn, Peter P; Mariën, Peter

2008-05-01

204

Cerebellar venous angiomas. A continuing controversy.  

PubMed

We have studied three patients with angiographically documented cerebellar venous angioma (CVA). One patient had a subacute cerebellar hematoma and underwent posterior fossa craniotomy for evacuation of the hematoma and excision of the malformation. A hemorrhagic venous infarction of the brain stem and cerebellum occurred, and the patient died three weeks postoperatively. A second patient with an unruptured CVA had a history of headaches, tinnitus, and vertigo. Conservative treatment was elected, and the patient's condition remains unchanged after 11 months of follow-up. The third patient, recently diagnosed as having an unruptured CVA had episodic vertigo and disequilibrium. Conservative treatment was chosen, and he is asymptomatic after six months of follow-up. Based on a review of 24 other cases of CVA plus our experience we could not conclude any definite trend regarding natural history or treatment. However, conservative treatment seems the logical choice in patients with unruptured CVA. PMID:3985813

Biller, J; Toffol, G J; Shea, J F; Fine, M; Azar-Kia, B

1985-04-01

205

Traumatic hemorrhage within a cerebellar dermoid cyst.  

PubMed

Intracranial dermoid cysts with hemorrhage are fairly rare. Herein, we reported a 28-year-old female patient with a cerebellar dermoid cyst, which was found accidently on neuro-imaging after head trauma. MR scanning revealed that the lesion was located within the cerebellar vermis and was measured 3.5cm×3.9cm×3.0cm, with hyper-intensity on T1WI and hypo-intensity on T2WI. However, on CT imaging, it showed hyper-dense signals. It was removed completely via midline sub-occipital approach under surgical microscope. Histological examination proved it was a dermoid cyst with internal hemorrhage. In combination with literature review, we discussed the factors that might be responsible for the hemorrhage within dermoid cysts. PMID:22211083

Luan, Yongxin; Wang, Haifeng; Zhong, Yanping; Bian, Xinchao; Luo, Yinan; Ge, Pengfei

2012-01-01

206

Traumatic Hemorrhage within a Cerebellar Dermoid Cyst  

PubMed Central

Intracranial dermoid cysts with hemorrhage are fairly rare. Herein, we reported a 28-year-old female patient with a cerebellar dermoid cyst, which was found accidently on neuro-imaging after head trauma. MR scanning revealed that the lesion was located within the cerebellar vermis and was measured 3.5cm×3.9cm×3.0cm, with hyper-intensity on T1WI and hypo-intensity on T2WI. However, on CT imaging, it showed hyper-dense signals. It was removed completely via midline sub-occipital approach under surgical microscope. Histological examination proved it was a dermoid cyst with internal hemorrhage. In combination with literature review, we discussed the factors that might be responsible for the hemorrhage within dermoid cysts.

Luan, Yongxin; Wang, Haifeng; Zhong, Yanping; Bian, Xinchao; Luo, Yinan; Ge, Pengfei

2012-01-01

207

Isolated rhomboencephalosynapsis - a rare cerebellar anomaly  

PubMed Central

Summary Background: Rhomboencephalosynapsis (RES, RS) is a unique entity usually recognized in infancy based on neuroimaging. Cerebellar fusion and absence of cerebellar vermis is often associated with supratentorial findings. Since now there are about 50 cases described worldwide, with approximately 36 patients diagnosed by MRI. The authors present the first in Poland case of this uncommon malformation and review the literature. Case Report: The authors describe a 28-month-old-girl with microcephaly and proper psychomotor development. The family history was unrelevant. Based on MRI the congenital malformation of posterior fossa-rhombencephalosynapsis was confirmed Conclusions: Presented patient is a typical example of MRI usefulness especially in patients with RES. RES symptoms are mild and that is why the diagnosis is usually made only in adulthood.

Paprocka, Justyna; Jamroz, Ewa; Scieszka, Ewa; Kluczewska, Ewa

2012-01-01

208

Paraneoplastic cerebellar degeneration in Hodgkin's lymphoma.  

PubMed

Paraneoplastic cerebellar degeneration (PCD) is a rare disorder presenting typically with acute or subacute severe cerebellar ataxia. PCD is most commonly associated with small cell lung cancer followed by adenocarcinoma of breast and ovary, and Hogdkin's lymphoma. We report a case of a 54-year-old male with acute-onset pancerebellar syndrome with underlying Hodgkin's lymphoma. A high index of suspicion of PCD resulted in arriving at an early diagnosis of underlying Hodgkin's disease. The patient was managed with six cycles of chemotherapy, which resulted in clinical stabilization and reversal of magnetic resonance imaging abnormalities. Antitumor therapy appears to have a significant impact on reversing PCD and hence early diagnosis and intervention for the primary remains the corner stone in stabilizing the neurological condition. PMID:22919195

Suri, Vinit; Khan, Nadeem I; Jadhao, Nilesh; Gupta, Rohan

2012-07-01

209

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.

Pierard, Sophie; Vinetti, Marco

2014-01-01

210

An update on Spino-cerebellar ataxias  

PubMed Central

The dominantly inherited ataxias, also known as Spino-cerebellar ataxias (SCAs), are rapidly expanding entities. New mutations are being identified at remarkable regularity. Recent awareness of molecular abnormalities in SCAs has addressed some of the long sought questions, but gaps in knowledge still exist. Three major categories of SCAs, according to molecular mechanisms, have evolved over recent few years: Polyglutamate expansion ataxia, non-coding zone repeat ataxia, and ataxia due to conventional mutation. Using the fulcrum of these mechanisms, the article provides an update of SCAs. Shared and specific clinical features, genetic abnormalities, and possible links between molecular abnormalities and cerebellar degeneration have been discussed. Emphasis has been placed on the mechanisms of polyglutamate toxicity.

Mondal, Banashree; Paul, Pritikanta; Paul, Madhuparna; Kumar, Hrishikesh

2013-01-01

211

Cerebellar granule cell Cre recombinase expression.  

PubMed

The cerebellum maintains balance and orientation, refines motor action, stores motor memories, and contributes to the timing aspects of cognition. We generated two mouse lines for making Cre recombinase-mediated gene disruptions largely confined to adult cerebellar granule cells. For this purpose we chose the GABA(A) receptor alpha6 subunit gene, whose expression marks this cell type. Here we describe mouse lines expressing Cre recombinase generated by 1) Cre knocked into the native alpha6 subunit gene by homologous recombination in embryonic stem cells; and 2) Cre recombined into an alpha6 subunit gene carried on a bacterial artificial chromosome (BAC) genomic clone. The fidelity of Cre expression was tested by crossing the mouse lines with the ROSA26 reporter mice. The particular alpha6BAC clone we identified will be valuable for delivering other gene products to cerebellar granule cells. PMID:12820171

Aller, M I; Jones, A; Merlo, D; Paterlini, M; Meyer, A H; Amtmann, U; Brickley, S; Jolin, H E; McKenzie, A N J; Monyer, H; Farrant, M; Wisden, W

2003-06-01

212

Cerebellar hallmarks of conditioned preference for cocaine.  

PubMed

Pavlovian conditioning tunes the motivational drive of drug-associated stimuli, fostering the probability of those environmental stimuli to promote and trigger drug seeking and taking. Interestingly, different areas in the cerebellum are involved in the formation and long-lasting storage of Pavlovian emotional memory. Very recently, we have shown that conditioned preference for an odour associated with cocaine was directly correlated with cFOS expression in cells at the dorsal region of the granule cell layer of the cerebellar vermis. The main goal of the current investigation was to further extend the description of cFOS-IR patterns in cerebellar circuitry after training mice in a cocaine-odour Pavlovian conditioning procedure, including now the major inputs (the inferior olive and pontine nuclei) and one of the output nuclei (the medial deep nucleus) of the cerebellum. The results showed that the cerebellar hallmark of preference towards an odour cue associated to cocaine is an increase in cFOS expression in the dorsal part of the granule cell layer. cFOS-IR levels expressed in the granule cell layer of mice that did not show cocaine conditioned preference did not differ from the basal levels. Remarkably, mice subjected to a random cocaine-odour pairing procedure (the unpaired group) exhibited higher cFOS-IR in the inferior olive, the pontine nuclei and in the deep medial nucleus. Therefore, our findings suggest that inputs and the output of cerebellar circuitry are enhanced when contingency between the CS+ and cocaine is lacking. PMID:24813699

Carbo-Gas, Maria; Vazquez-Sanroman, Dolores; Gil-Miravet, Isis; De Las Heras-Chanes, Joan; Coria-Avila, Genaro A; Manzo, Jorge; Sanchis-Segura, Carla; Miquel, Marta

2014-06-10

213

Cerebellar hemorrhage associated with moyamoya disease.  

PubMed

A 60-year-old female was admitted with complaints of severe headache, nausea, and vomiting. Computed tomography demonstrated a right cerebellar hematoma, which was surgically removed. Bilateral carotid angiography showed occlusions of the anterior and middle cerebral arteries, and abnormal vascular networks. Vertebral angiography showed a well developed posterior pericallosal artery. Left encephalo-duro-arterio-synangiosis was performed. No cerebral vascular incident has been observed for 32 months. PMID:9631637

Ise, H; Tokunaga, H; Aizawa, M; Sawaura, H

1998-04-01

214

[Spontaneous cerebellar hematoma in adults. 44 cases].  

PubMed

Spontaneous cerebellar hematomas account for 10 p. 100 of all spontaneous intra-cranial hemorrhages. In this series of 44 cases, 3 clinico-pathological groups are described on the basis of clinical and pathological data (small, middle and massive hematomas). The mortality rate was high (50 p. 100). Nevertheless, early and direct draining of the hematomas provides the best chances of survival. PMID:2237092

Guillermain, P; Lena, G; Reynier, Y; Vincentelli, F; Jazzar, A

1990-01-01

215

Altered experimental pain perception after cerebellar infarction.  

PubMed

Animal studies have suggested that the cerebellum, in addition to its motor functions, also has a role in pain processing and modulation, possibly because of its extensive connections with the prefrontal cortex and with brainstem regions involved in descending pain control. Consistently, human imaging studies have shown cerebellar activation in response to painful stimulation. However, it is presently not clear whether cerebellar lesions affect pain perception in humans. In the present study, we used experimental pain testing to compare acute pain perception and endogenous pain inhibition in 30 patients 1 to 11years after cerebellar infarction and in 30 sex- and age-matched healthy control subjects. Compared to controls, patients exhibited a significantly increased pain perception in response to acute heat stimuli (44°C-48°C, average pain intensity rating for patients 3.4±2.8 and for controls 1.5±1.7 [on a numeric rating scale of 0-10], P<.01) and to repeated 256mN pinprick stimuli (1.3±1.9 vs 0.6±1.0 [0-10], P<.05). Heat hyperalgesia in patients was more pronounced on the body side ipsilateral to the infarction. In addition, patients showed reduced offset analgesia (change in pain intensity rating: 0.0%±15.8% vs -16.9%±36.3%, P<.05) and reduced placebo analgesia (change in pain intensity rating: -1.0±1.1 vs -1.8±1.3 [0-10], P<.05) compared to controls. In contrast, heat and pressure pain thresholds were not significantly different between groups. These results show that, after cerebellar infarction, patients perceive heat and repeated mechanical stimuli as more painful than do healthy control subjects and have deficient activation of endogenous pain inhibitory mechanisms (offset and placebo analgesia). This suggests that the cerebellum has a previously underestimated role in human pain perception and modulation. PMID:24721690

Ruscheweyh, Ruth; Kühnel, Maria; Filippopulos, Filipp; Blum, Bernhard; Eggert, Thomas; Straube, Andreas

2014-07-01

216

Cerebellar Dermoid Cyst with Occipital Dermal Sinus  

Microsoft Academic Search

Intracranial dermoid cyst is a rare entity accounting for 0.1–0.7% of all intracranial tumors. The most common location is in the posterior fossa, at or near the midline. We present 2 pediatric cases with dermal sinus. The first case presented with clinical signs of increased intracranial pressure and cerebellar symptoms. CT scan showed a large and regular midline posterior fossa

F. Layadi; N. Louhab; M. Lmejjati; K. Aniba; A. Aït Elqadi; S. Aït Benali

2006-01-01

217

Ultrasonically detectable cerebellar haemorrhage in preterm infants  

Microsoft Academic Search

ObjectiveTo determine the frequency and pattern of cerebellar haemorrhage (CBH) on routine cranial ultrasound (cUS) imaging in infants of ?32 weeks gestation, and to investigate how extremely preterm infants with CBH differ from those with severe intraventricular haemorrhage (IVH).Methods672 infants of ?32 weeks gestation were prospectively examined for CBH on serial cUS imaging. In a separate case–control analysis, the clinical

L K McCarthy; V Donoghue; J F A Murphy

2011-01-01

218

Chronic cerebellar stimulation and developmental reflexes.  

PubMed

The changes in motor function in cerebral palsy patients produced by chronic anterior lobe cerebellar stimulation were documented with the Milani-Comparetti developmental scale, which allows comparison betweenfunctional gains and reflex patterns. Two patients with marked motor retardation and primitive reflexes were followed serially over several months of stimulation. Using these measures, the efficiency of chronic stimulation can be assessed, although many years will be needed to evaluate its role in treating motor disabilities. PMID:300429

Penn, R D; Etzel, M L

1977-04-01

219

Paraneoplastic cerebellar degeneration associated with ovarian cancer  

PubMed Central

Paraneoplastic cerebellar degeneration (PCD) is a rare neurological disorder characterized by a widespread loss of Purkinje cells associated with a progressive pancerebellar dysfunction. PCD often precedes the cancer diagnosis by months to years. Here, we report the case of a 64-year-old woman who developed PCD symptoms, associated with high levels of anti-Yo antibodies, one year after a previous diagnosis of ovarian cancer. Clinical features, pathogenesis and treatment of PCD associated with cancer are discussed according to previous studies.

RUSSO, ALESSIA ERIKA; SCALONE, SIMONA; LEONARDI, GIULIA COSTANZA; SCALISI, AURORA; GIORDA, GIORGIO; SORIO, ROBERTO

2013-01-01

220

Post-infarct cerebellar cognitive affective syndrome: a case report.  

PubMed

Post Infarct cerebellar cognitive affective syndrome is a rare disorder, characterized by cognitive impairment in the domains of memory, language, visuo-spatial functioning and affect after cerebellar stroke. We report a case of young female who developed mood alteration and cognitive disturbance following isolated cerebellar infarct. We, therefore, advocate a potential role of cerebellum in regulation of cognition and behaviour in humans. PMID:18988420

Jawaid, Ali; Rauf, Muhammad Ameen; Usman, Uzma; Khealani, Bhojo A

2008-07-01

221

Cerebellar synaptic protein expression in schizophrenia.  

PubMed

A cortico-subcortico-cerebellar neural circuit has been postulated to be important in the pathophysiology of schizophrenia. This study investigated whether there are synaptic changes in the cerebellum to accompany its putative involvement in the disorder. We measured the expression of three synaptic proteins (synaptophysin, complexin I and complexin II) in the cerebellar cortex of 16 subjects with schizophrenia and 16 controls using in situ hybridisation histochemistry and immunoautoradiography. Complexin I and II are expressed predominantly by inhibitory and excitatory neurones respectively. In schizophrenia, synaptophysin mRNA was decreased, as was complexin II and its mRNA. Complexin I mRNA and protein levels were unaltered. Expression of the mRNAs in the rat cerebellum was unaffected by 2 weeks administration of antipsychotic drugs (haloperidol, chlorpromazine, risperidone, olanzapine or clozapine). We conclude that there is synaptic pathology in the cerebellum in schizophrenia. By disrupting neural circuits, the alterations may contribute to the cerebellar dysfunction thought to occur in the disorder. PMID:11483314

Eastwood, S L; Cotter, D; Harrison, P J

2001-01-01

222

[Diagnostic and treatment of hypertensive cerebellar hematomas].  

PubMed

Authors analyzed the results of treatment of 56 patients with hypertensive cerebellar hemorrhages (volume 0,5-41 cm3). Brain stem symptoms were found in 45 (80%) of patients. The dislocation of brain stem was observed in 38 (68%) cases, occlusive hydrocephaly - in 22 (39%), intraventricular hemorrhage - in 26 (46%). Severity of state depended on character of disease course, presence of stem symptoms, awakening level, volume and localization of cerebellar hematoma, development of intraventricular hemorrhage, occlusive hydrocephaly and dislocation of brain stem. Thirty-six patients were operated. After the neurosurgical intervention, 22 (61%) patients were discharged without or with the minimal neurological deficit, 1 (3%) with marked disability and 13 (36%) patients died. In conclusion, the removal of hematoma is recommended in dislocation of brain stem and disturbance of consiousnes: the ventricular drainage - in occlusive hydrocephaly developed as a consequence of hemotamponade of IV ventricular. The surgical treatment is not recommended to patients with cerebellar hematomas with the volume less than 7 cm3. PMID:19491806

Krylov, V V; Dash'ian, V G; Murashko, A A; Burov, S A

2009-01-01

223

Learning of Sensory Sequences in Cerebellar Patients  

PubMed Central

A possible role of the cerebellum in detecting and recognizing event sequences has been proposed. The present study sought to determine whether patients with cerebellar lesions are impaired in the acquisition and discrimination of sequences of sensory stimuli of different modalities. A group of 26 cerebellar patients and 26 controls matched for age, sex, handedness, musicality, and level of education were tested. Auditory and visual sensory sequences were presented out of different sensory pattern categories (tones with different acoustic frequencies and durations, visual stimuli with different spatial locations and colors, sequential vision of irregular shapes) and different ranges of inter-cue time intervals (fast and slow). Motor requirements were small, with vocal responses and no time restrictions. Perception of visual and acoustic stimuli was generally preserved in patients and controls. The number of errors was significantly higher in the faster tempo of sequence presentation in learning of sequences of tones of different frequencies and in learning of sequences of visual stimuli of different spatial locations and different colors. No difference in tempo between the groups was shown. The total number of errors between the two groups was identical in the sequence conditions. No major disturbances in acquisition or discrimination of various sensory sequences were observed in the group of cerebellar patients. Sequence learning may be impaired only in tasks with significant motor demands.

Frings, Markus; Boenisch, Raoul; Gerwig, Marcus; Diener, Hans-Christoph; Timmann, Dagmar

2004-01-01

224

Cerebellar Degeneration Associated with Sj?gren's Syndrome  

PubMed Central

Background Neurologic manifestations of primary Sjögren's syndrome (PSS) have been reported to vary from sensory polyneuropathy to encephalopathy or psychiatric problems. However, marked cerebellar degeneration associated with PSS has rarely been reported. Case Report We describe a patient with Sjögren's syndrome who exhibited rapidly progressive cerebellar ataxia, nystagmus, cognitive decline, and psychiatric problems. Brain magnetic resonance imaging revealed marked atrophy of the cerebellum, and 18F-fluorodeoxyglucose positron-emission tomography demonstrated glucose hypometabolism of the cerebellum. Conclusions Our PSS patient exhibited a progressive course of cerebellar syndrome, as evidenced by cerebellar atrophy on serial brain images.

Kim, Mi Jung; Lee, Myoung Chong; Lee, Jae-Hong

2012-01-01

225

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

226

Sonographic detection of in utero isolated cerebellar hemorrhage.  

PubMed

Cerebellar hemorrhage is a relatively rare phenomenon in neonates, and most cases are associated with intraventricular hemorrhage (IVH). Prenatally diagnosed intracranial hemorrhage is rare, and diagnoses of cerebellar hemorrhage are even rarer. In our literature search, we discovered 3 cases of prenatal diagnosis of cerebellar hemorrhage, all accompanied by IVH. None of the neonates survived. We report a case initially observed in utero by sonography of cerebellar hemorrhage without evidence of IVH, causing ventriculomegaly in a 32-week twin fetus who was subsequently successfully treated. PMID:12795563

Hiller, Luke; McGahan, John P; Bijan, Bijan; Melendres, Giselle; Towner, Dena

2003-06-01

227

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

228

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

229

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

230

A piloted simulator evaluation of a ground-based 4D descent advisor algorithm  

NASA Technical Reports Server (NTRS)

A ground-based, four-dimensional (4D) descent-advisor algorithm is under development at NASA Ames Research Center. The algorithm combines detailed aerodynamic, propulsive, and atmospheric models with an efficient numerical integration scheme to generate 4D descent advisories. This paper investigates the ability of the 4D descent advisor algorithm to provide adequate control of arrival time for aircraft not equipped with on-board 4D guidance systems. A piloted simulation was conducted to determine the precision with which the descent advisor could predict the 4D trajectories of typical straight-in descents flown by airline pilots under different wind conditions. The effects of errors in the estimation of wind and initial aircraft weight were also studied. A description of the descent advisor as well as the results of the simulation studies are presented.

Green, Steven M.; Davis, Thomas J.; Erzberger, Heinz

1987-01-01

231

A piloted simulator evaluation of a ground-based 4-D descent advisor algorithm  

NASA Technical Reports Server (NTRS)

A ground-based, four dimensional (4D) descent-advisor algorithm is under development at NASA-Ames. The algorithm combines detailed aerodynamic, propulsive, and atmospheric models with an efficient numerical integration scheme to generate 4D descent advisories. The ability is investigated of the 4D descent advisor algorithm to provide adequate control of arrival time for aircraft not equipped with on-board 4D guidance systems. A piloted simulation was conducted to determine the precision with which the descent advisor could predict the 4D trajectories of typical straight-in descents flown by airline pilots under different wind conditions. The effects of errors in the estimation of wind and initial aircraft weight were also studied. A description of the descent advisor as well as the result of the simulation studies are presented.

Davis, Thomas J.; Green, Steven M.; Erzberger, Heinz

1990-01-01

232

Descent equations of Yang-Mills anomalies in noncommutative geometry  

Microsoft Academic Search

Consistent Yang-Mills anomalies ? ?2n?kk?1 (n?N, k = 1,2,…, 2n) as described collectively by Zumino's descent equations ??2n?kk?1 + d?2n?k?1k = 0 starting with the Chern character Ch2n = d?2n?10 of a principal SU (N) bundle over a 2n-dimensional manifold are considered (i.e. ? ?2n?kk?1 are the Chern-Simons terms (k = 1), axial anomalies (k = 2), Schwinger terms (k

Edwin Langmann

1997-01-01

233

Apollo 16, LM-11 descent propulsion system final flight evaluation  

NASA Technical Reports Server (NTRS)

The performance of the LM-11 descent propulsion system during the Apollo 16 missions was evaluated and found satisfactory. The average engine effective specific impulse was 0.1 second higher than predicted, but well within the predicted one sigma uncertainty of 0.2 seconds. Several flight measurement discrepancies existed during the flight as follows: (1) the chamber pressure transducer had a noticeable drift, exhibiting a maximum error of about 1.5 psi at approximately 130 seconds after engine ignition, (2) the fuel and oxidizer interface pressure measurements appeared to be low during the entire flight, and (3) the fuel propellant quantity gaging system did not perform within expected accuracies.

Avvenire, A. T.

1974-01-01

234

Factored form descent: a practical algorithm for coherence retrieval.  

PubMed

We formulate coherence retrieval, the process of recovering via intensity measurements the two-point correlation function of a partially coherent field, as a convex weighted least-squares problem and show that it can be solved with a novel iterated descent algorithm using a coherent-modes factorization of the mutual intensity. This algorithm is more memory-efficient than the standard interior point methods used to solve convex problems, and we verify its feasibility by reconstructing the mutual intensity of a Schell-model source from both simulated data and experimental measurements. PMID:23482147

Zhang, Zhengyun; Chen, Zhi; Rehman, Shakil; Barbastathis, George

2013-03-11

235

An evaluation of descent strategies for TNAV-equipped aircraft in an advanced metering environment  

NASA Technical Reports Server (NTRS)

Investigated were the effects on system throughput and fleet fuel usage of arrival aircraft utilizing three 4D RNAV descent strategies (cost optimal, clean-idle Mach/CAS and constant descent angle Mach/CAS), both individually and in combination, in an advanced air traffic control metering environment. Results are presented for all mixtures of arrival traffic consisting of three Boeing commercial jet types and for all combinations of the three descent strategies for a typical en route metering airport arrival distribution.

Izumi, K. H.; Schwab, R. W.; Groce, J. L.; Coote, M. A.

1986-01-01

236

A Case of Adrenoleukodystrophy Presenting as Progressive Cerebellar Dysfunction  

PubMed Central

X-linked adrenoleukodystrophy (X-ALD) is a hereditary neurological disorder affecting the nervous system and adrenal cortex. The phenotype of X-ALD ranges from the rapidly progressive cerebral form to milder adrenomyeloneuropathy. However, cerebellar manifestations are rare. We report a case of adrenoleukodystrophy presenting as progressive cerebellar dysfunction resembling olivopontocerebellar degeneration, with a review of the literature

Jung, Seunguk; Chung, Jong Won; Yun, Ji Young; Kim, Han-Joon; Jeon, Beom Seok

2009-01-01

237

Cerebellar neurocognition: insights into the bottom of the brain.  

PubMed

The traditional view on the core functions of the cerebellum consists of the regulation of motor coordination, balance and motor speech. However, during the past decades results from neuroanatomical, neuroimaging and clinical studies have substantially extended the functional role of the cerebellum to cognitive and affective regulation. Neuroanatomical studies convincingly showed cerebellar connectivity with associative areas of the cerebral cortex involved in higher cognitive functioning, while functional neuroimaging provided evidence of cerebellar activation during a variety of cognitive tasks. In addition, more systematic neuropsychological research performed in patients with cerebellar lesions and the development of more sensitive neuropsychological tests allowed clinicians to identify significant cognitive and affective disturbances following cerebellar damage. In this review, an overview is presented of the cerebellar role in a variety of cognitive processes, such as executive functioning, memory, learning, attention, visuo-spatial regulation, language and behavioral-affective modulation. In addition, recent evidence with regard to cerebellar induced clinical entities such as the cerebellar cognitive affective syndrome (CCAS) and the posterior fossa syndrome (PFS), will be discussed. Although extensive research has substantially broadened the insights in the cognitive and affective role of the cerebellum, the precise nature of the cerebellar contribution to cognitive and affective regulation is not yet clear. In this review experimental and clinical data will be discussed that substantiate the presumed neurobiological mechanisms underlying the cognitive and affective modulatory role of the cerebellum. PMID:18602745

Baillieux, Hanne; De Smet, Hyo Jung; Paquier, Philippe F; De Deyn, Peter P; Mariën, Peter

2008-09-01

238

Congenital Cerebellar Cortical Degeneration in Holstein Cattle in Southern Brazil  

Microsoft Academic Search

A congenital progressive cerebellar disorder is described in Holstein calves. The clinical signs were progressive and were characterized by ataxia, hypermetria, a wide stance and fine head tremors. When the affected cattle were forced to run, the signs were exacerbated, leading to epileptiform attacks. Histological lesions consisted of a very selective cerebellar cortical degeneration, almost exclusively affecting the Purkinje cells.

A. L. Schild; F. Riet-Correa; E. L. Portiansky; M. C. Méndez; D. L. Graça

2001-01-01

239

Multifocal eosinophilic granuloma presenting as progressive brainstem and cerebellar dysfunction  

Microsoft Academic Search

A 55 year old woman with multifocal eosinophilic granuloma (MEG) is described. She developed facial numbness and twitching followed by slowly progressive cerebellar symptoms. Two years later polyuria and polydipsia were noted. A CT of the brain showed multifocal enhancing lesions, and MRI showed areas of hyperintensity on T2 weighted studies in the cerebellar peduncles, pons, and midbrain. Radiographs of

T Fukazawa; T Yanagihara; K Hamada; T Hamada

1994-01-01

240

[Clinical study of two cases of traumatic cerebellar injury].  

PubMed

Two cases of traumatic cerebellar injury complicated with a traumatic medial longitudinal fasciculus (MLF) syndrome or cerebellar mutism were reported, and the cause of these mechanisms was discussed: Case 1: A 9-year-old boy who struck his head in the occipital region during an automobile accident was operated on for a delayed traumatic intracerebellar hematoma. The operation improved the level of his consciousness but MLF syndrome was noticed. The mechanism of traumatic MLF syndrome was discussed in relation to vascular injury and to neurovascular friction. The outcome of the syndrome including our case, which recovered spontaneously, seemed to support the theory of neurovascular injury. Case 2: A 6-year-old boy who struck his head in the temporooccipital region during an automobile accident was admitted to our hospital without conciousness. On admission, contusion of the temporal lobe and left cerebellar hemisphere was demonstrated by a computerized tomography (CT) and magnetic resonance imaging (MRI). A mute state (cerebellar mutism) was recognized after his recovery of consciousness. The cause of the cerebellar mutism was thought to be an injury of the cerebellar vermis or left cerebellar hemisphere. The findings of CT scan and MRI in our case suggested that the cause of the cerebellar mutism was the contusion of these areas. PMID:2406638

Yokota, H; Nakazawa, S; Kobayashi, S; Taniguchi, Y; Yukihide, T

1990-01-01

241

Cerebellar atrophy and prognosis after temporal lobe resection.  

PubMed Central

OBJECTIVE: Experimental data indicate inhibitory effects of the cerebellum on seizure activity. Structural damage such as cerebellar atrophy, which is a common finding in patients with chronic epilepsy, may reduce these effects. METHODS: Outcome after temporal lobectomy was studied in 78 consecutive patients, with or without cerebellar atrophy diagnosed by MRI. RESULTS: Thirty five patients (45%) showed cerebellar atrophy. At a mean follow up of 14.6 (range, 6-40) months, 50 patients (64%) had no postoperative seizures. In these patients, the frequency of cerebellar atrophy was significantly lower (34%) than in patients who relapsed (64%, p < 0.01). Occurrence of generalised tonic-clonic seizures (GTCS) within two years before surgery, occurrence of GTCS at any time preoperatively, long duration of epilepsy, and older age at surgery were also associated with recurrence of seizures. Multiple logistic regression analysis suggested occurrence of GTCS within two years before surgery and cerebellar atrophy as the main predictive indicators. When both factors were present, the percentage of patients remaining seizure free since surgery fell to 30%, compared with 60% when only GTCS were present, 78.6% when only cerebellar atrophy was present, and 87.5% when both factors were absent. CONCLUSIONS: Cerebellar atrophy shown by MRI was a frequent finding in surgically treated patients with temporal lobe epilepsy. The presence of cerebellar atrophy seems to worsen the prognosis after temporal lobe resection. Images

Specht, U; May, T; Schulz, R; Rohde, M; Ebner, A; Schmidt, R C; Schutz, M; Wolf, P

1997-01-01

242

Cerebellar dysfunction in patients with bronchogenic carcinoma: immunological investigations  

Microsoft Academic Search

Sera from seven patients with bronchogenic carcinoma and cerebellar dysfunction were tested for anti-Purkinje cell antibodies (APCA) by indirect immunofluorescence and indirect immunoperoxidase reaction. Specific APCA as described in paraneoplastic cerebellar degeneration (PCD) were not detected in any of these patients or in control patients. The lack of APCA in patients with bronchogenic carcinoma and their presence in association with

K. Wessel; C. Budde-Steffen; H. Wiethölter; H. C. Diener; J. Dichgans

1988-01-01

243

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

244

Evaluating the affective component of the cerebellar cognitive affective syndrome.  

PubMed

The authors performed a systematic review and meta-analysis of studies evaluating the affective component of the cerebellar cognitive affective syndrome. Depressive and anxiety symptoms and personality changes were more frequent in patients with spinocerebellar ataxia. Patients with cerebellar lesions were more likely to have depression, deficits in the ability to experience emotions, and behavioral difficulties. A meta-analysis revealed modestly higher scores on the Hamilton Depression Rating Scale (HAM-D) among patients with cerebellar disease. This review highlights the need for cohort studies using noncerebellar comparison groups, more sensitive measures, and appropriate-sized populations with isolated cerebellar lesions to thoroughly assess the affective component of the cerebellar cognitive affective syndrome. PMID:19776302

Wolf, Uri; Rapoport, Mark J; Schweizer, Tom A

2009-01-01

245

New evidence for the cerebellar involvement in personality traits  

PubMed Central

Following the recognition of its role in sensory-motor coordination and learning, the cerebellum has been involved in cognitive, emotional, and even personality domains. This study investigated the relationships between cerebellar macro- and micro-structural variations and temperamental traits measured by Temperament and Character Inventory (TCI). High resolution T1-weighted, and Diffusion Tensor Images of 100 healthy subjects aged 18–59 years were acquired by 3 Tesla Magnetic Resonance scanner. In multiple regression analyses, cerebellar Gray Matter (GM) or White Matter (WM) volumes, GM Mean Diffusivity (MD), and WM Fractional Anisotropy (FA) were used as dependent variables, TCI scores as regressors, gender, age, and education years as covariates. Novelty Seeking scores were associated positively with the cerebellar GM volumes and FA, and negatively with MD. No significant association between Harm Avoidance, Reward Dependence or Persistence scores and cerebellar structural measures was found. The present data put toward a cerebellar involvement in the management of novelty.

Picerni, Eleonora; Petrosini, Laura; Piras, Fabrizio; Laricchiuta, Daniela; Cutuli, Debora; Chiapponi, Chiara; Fagioli, Sabrina; Girardi, Paolo; Caltagirone, Carlo; Spalletta, Gianfranco

2013-01-01

246

Distinct critical cerebellar subregions for components of verbal working memory  

PubMed Central

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 cognitive performance and cerebellar integrity in a specific degeneration of the cerebellar cortex: Spinocerebellar Ataxia type 6 (SCA6). The results demonstrate a critical relationship between verbal working memory and grey matter density in superior (bilateral lobules VI and crus I of lobule VII) and inferior (bilateral lobules VIIIa and VIIIb, and right lobule IX) parts of the cerebellum. We demonstrate that distinct cerebellar regions subserve different components of the prevalent psychological model for verbal working memory based on a phonological loop. The work confirms the involvement of the cerebellum in verbal working memory and defines specific subsystems for this within the cerebellum.

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

2014-01-01

247

Cerebellar loops: a review of the nucleocortical pathway.  

PubMed

Feedback pathways are a common circuit motif in vertebrate brains. Reciprocal interconnectivity is seen between the cerebral cortex and thalamus as well as between basal ganglia structures, for example. Here, we review the literature on the nucleocortical pathway, a feedback pathway from the cerebellar nuclei to the cerebellar cortex, which has been studied anatomically but has remained somewhat obscure. This review covers the work examining this pathway on a number of levels, ranging from its existence in numerous species, its organization within cerebellar circuits, its cellular composition, and a discussion of its potential roles in motor control. Recent interest in cerebellar modular organization raises the profile of this neglected cerebellar pathway, and it is hoped that this review will consolidate knowledge gained over several decades of research into a useful format, spurring new investigations into this evolutionarily conserved pathway. PMID:24362758

Houck, Brenda D; Person, Abigail L

2014-06-01

248

Nicotine increases cerebellar activity during finger tapping.  

PubMed

Nicotine improves performance on several cognitive and sensorimotor tasks. The neuronal mechanisms associated with these changes in performance are, however, largely unknown. Functional magnetic resonance imaging (fMRI) was used to examine the effect of nicotine on neuronal response in nineteen healthy subjects while they performed an auditory-paced finger tapping task. Subjects performed the task, after receiving either a nicotine patch or placebo treatment, in a single blind, crossover design. Compared to placebo, nicotine treatment increased response in the cerebellar vermis. Increased vermal activity, in the absence of changes in other task-related regions suggests specificity in nicotine's effects. PMID:24358367

Wylie, Korey P; Tanabe, Jody; Martin, Laura F; Wongngamnit, Narin; Tregellas, Jason R

2013-01-01

249

The cerebellar mutism syndrome and its relation to cerebellar cognitive function and the cerebellar cognitive affective disorder.  

PubMed

The postoperative cerebellar mutism syndrome (CMS), consisting of diminished speech output, hypotonia, ataxia, and emotional lability, occurs after surgery in up to 25% of patients with medulloblastoma and occasionally after removal of other posterior fossa tumors. Although the mutism is transient, speech rarely normalizes and the syndrome is associated with long-term adverse neurological, cognitive, and psychological sequelae. The clinical, neuroradiographic, and neuropsychological findings associated with CMS as well as possible mechanisms of injury are reviewed. Theories about the pathophysiology of CMS have evolved along with our understanding of the cerebellum as an important structure in the distributive neurocircuitry underlying complex speech, cognition, and behavior. CMS shares many similarities with the cerebellar cognitive affective syndrome, more commonly described in adults and consisting of disturbances of executive function, visuospatial skills, nonmotor language, and affect regulation. Future directions include more thorough neuropsychological characterization, functional and diffusion tensor imaging studies, and investigations into the underlying differences that may make some patients more vulnerable to CMS. PMID:18924161

Wells, Elizabeth M; Walsh, Karin S; Khademian, Zarir P; Keating, Robert F; Packer, Roger J

2008-01-01

250

Vascular considerations in glaucoma patients of African and European descent.  

PubMed

Glaucoma is the leading cause of blindness in individuals of African descent (AD). While open-angle glaucoma (OAG) disproportionately affects individuals of AD compared with persons of European descent (ED), the physiological mechanisms behind this disparity are largely unknown. The more rapid progression and greater severity of the disease in persons of AD further raise the concern for identifying these underlying differences in disease pathophysiology between AD and ED glaucoma patients. Ocular structural differences between AD and ED patients, including larger optic disc area, cup:disc ratio and thinner corneas, have been found. AD individuals are also disproportionately affected by systemic vascular diseases, including hypertension, cardiovascular disease, stroke and diabetes mellitus. Abnormal ocular blood flow has been implicated as a risk factor for glaucoma, and pilot research is beginning to identify localized ocular vascular differences between AD and ED OAG patients. Given the known systemic vascular deficits and the relationship between glaucoma and ocular blood flow, exploring these concepts in terms of glaucoma risk factors may have a significant impact in elucidating the mechanisms behind the disease disparity in the AD population. PMID:24460758

Huck, Andrew; Harris, Alon; Siesky, Brent; Kim, Nathaniel; Muchnik, Michael; Kanakamedala, Priyanka; Amireskandari, Annahita; Abrams-Tobe, Leslie

2014-08-01

251

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

252

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

253

High mammographic density in women of Ashkenazi Jewish descent  

PubMed Central

Introduction Percent mammographic density (PMD) adjusted for age and body mass index is one of the strongest risk factors for breast cancer and is known to be approximately 60% heritable. Here we report a finding of an association between genetic ancestry and adjusted PMD. Methods We selected self-identified Caucasian women in the California Pacific Medical Center Research Institute Cohort whose screening mammograms placed them in the top or bottom quintiles of age-adjusted and body mass index-adjusted PMD. Our final dataset included 474 women with the highest adjusted PMD and 469 with the lowest genotyped on the Illumina 1 M platform. Principal component analysis (PCA) and identity-by-descent analyses allowed us to infer the women's genetic ancestry and correlate it with adjusted PMD. Results Women of Ashkenazi Jewish ancestry, as defined by the first principal component of PCA and identity-by-descent analyses, represented approximately 15% of the sample. Ashkenazi Jewish ancestry, defined by the first principal component of PCA, was associated with higher adjusted PMD (P = 0.004). Using multivariate regression to adjust for epidemiologic factors associated with PMD, including age at parity and use of postmenopausal hormone therapy, did not attenuate the association. Conclusions Women of Ashkenazi Jewish ancestry, based on genetic analysis, are more likely to have high age-adjusted and body mass index-adjusted PMD. Ashkenazi Jews may have a unique set of genetic variants or environmental risk factors that increase mammographic density.

2013-01-01

254

Chronic tonsillar herniation in Crouzon's and Apert's syndromes: the role of premature synostosis of the lambdoid suture.  

PubMed

The incidence of chronic tonsillar herniation (CTH) was evaluated with magnetic resonance imaging in 44 patients with Crouzon's syndrome and 51 with Apert's syndrome; the incidence was 72.7% in Crouzon's syndrome and 1.9% in Apert's syndrome. All the patients with Crouzon's syndrome and progressive hydrocephalus had CTH, but of 32 individuals with Crouzon's syndrome and CTH, only 15 had progressive hydrocephalus. Five patients with Apert's syndrome were treated for progressive hydrocephalus; none had CTH. The patterns of suture closure in these two groups of patients were studied, and significant differences in coronal, sagittal, and lambdoid sutures were found between patients with Crouzon's and Apert's syndromes. In Crouzon's syndrome, significant differences in the pattern of lambdoid suture closure were found between the groups with and without CTH; in the group with CTH, the lambdoid closure appeared earlier. The authors propose that the high incidence of individuals with CTH who have Crouzon's syndrome is related to the premature synostosis of the lambdoid suture in the first 24 months of age. PMID:7674004

Cinalli, G; Renier, D; Sebag, G; Sainte-Rose, C; Arnaud, E; Pierre-Kahn, A

1995-10-01

255

Cerebellar agenesis II: motor and language functions.  

PubMed

In a former study of a patient with cerebellar agenesis (HK) mild motor deficits, problems in delay eyeblink conditioning and mild to moderate deficits in IQ, planning behavior, visuospatial abilities, visual memory, and attention were found. The present study reports additional findings in the same patient. In the motor domain, impairments in fine motor manipulations, trace eyeblink conditioning and motor imagination in a functional magnetic resonance (fMRI) study were found. Based on fMRI findings; however, cortical areas involved in a tapping task did not significantly differ from a healthy control group. In the cognitive domain, deficits in speech comprehension as well as verbal learning and declarative memory were present. No significant affective symptoms were observed. Although problems in executive, visuospatial and language tasks are in agreement with the so-called cerebellar cognitive affective syndrome-other possibilities remain. Non-motor impairments in HK might also be a consequence of lacking motor abilities in development and motor deficits may interfere with the performance of parts of the cognitive tasks. In addition, lack of promotion and learning opportunities in childhood may contribute and mental retardation based on extracerebellar dysfunction cannot be excluded. PMID:16036465

Richter, S; Dimitrova, A; Hein-Kropp, C; Wilhelm, H; Gizewski, E; Timmann, D

2005-04-01

256

Cerebellar Telomere Length and Psychiatric Disorders  

PubMed Central

We tested whether telomere length is altered in the brains of patients diagnosed with major depression (MD), bipolar disorder (BD) and schizophrenia (SZ) by measuring mean telomere length (mTL) with real-time PCR. The samples are cerebellar gray matter from 46 SZ, 46 BP, and 15 MD patients, and 48 healthy controls. We found no difference in mTL between SZ and controls, BD and controls, MD and controls, or all cases and controls; no correlation between mTL and age was observed, either. This suggests that brain gray matter is unlikely to be related to the telomere length shortening reported in blood of psychiatric patients. White matter deserves further investigation as it has been reported to have a different mTL dynamic from gray matter. Since mTL has been reported to be a heritable quantitative trait, we also carried out genome-wide mapping of genetic factors for mTL, treating mTL as a quantitative trait. No association survived correction of multiple testing for the number of SNPs studied. The previously reported rs2630578 (BICD1) association was not replicated. This suggests that telomere length of cerebellar gray matter is determined by multiple loci with “weak effects.”

Zhang, Dandan; Cheng, Lijun; Craig, David W.; Redman, Margot

2011-01-01

257

The olivo-cerebellar circuit as a universal motor control system  

Microsoft Academic Search

The olivo-cerebellar system is one of the central networks organizing movement coordination in vertebrates. This system consists of three main anatomical structures: the inferior olive (IO), the cerebellar nuclei, and the cerebellar cortex. Over the last four decades studies in many laboratories have contributed significantly to our understanding of the electrophysiology of IO and cerebellar neurons. However, addressing the dynamic

Rodolfo R. Llinás; Elena Leznik; Vladimir I. Makarenko

2004-01-01

258

Development of an analytical guidance algorithm for lunar descent  

NASA Astrophysics Data System (ADS)

In recent years, NASA has indicated a desire to return humans to the moon. With NASA planning manned missions within the next couple of decades, the concept development for these lunar vehicles has begun. The guidance, navigation, and control (GN&C) computer programs that will perform the function of safely landing a spacecraft on the moon are part of that development. The lunar descent guidance algorithm takes the horizontally oriented spacecraft from orbital speeds hundreds of kilometers from the desired landing point to the landing point at an almost vertical orientation and very low speed. Existing lunar descent GN&C algorithms date back to the Apollo era with little work available for implementation since then. Though these algorithms met the criteria of the 1960's, they are cumbersome today. At the basis of the lunar descent phase are two elements: the targeting, which generates a reference trajectory, and the real-time guidance, which forces the spacecraft to fly that trajectory. The Apollo algorithm utilizes a complex, iterative, numerical optimization scheme for developing the reference trajectory. The real-time guidance utilizes this reference trajectory in the form of a quartic rather than a more general format to force the real-time trajectory errors to converge to zero; however, there exist no guarantees under any conditions for this convergence. The proposed algorithm implements a purely analytical targeting algorithm used to generate two-dimensional trajectories "on-the-fly"' or to retarget the spacecraft to another landing site altogether. It is based on the analytical solutions to the equations for speed, downrange, and altitude as a function of flight path angle and assumes two constant thrust acceleration curves. The proposed real-time guidance algorithm has at its basis the three-dimensional non-linear equations of motion and a control law that is proven to converge under certain conditions through Lyapunov analysis to a reference trajectory formatted as a function of downrange, altitude, speed, and flight path angle. The two elements of the guidance algorithm are joined in Monte Carlo analysis to prove their robustness to initial state dispersions and mass and thrust errors. The robustness of the retargeting algorithm is also demonstrated.

Chomel, Christina Tvrdik

259

Recent binge drinking predicts smaller cerebellar volumes in adolescents  

PubMed Central

Background The current study examined the effects of recent binge drinking on cerebellar morphometry in a sample of healthy adolescents. Methods Participants were 106 teenagers (46 bingers and 60 controls) aged 16–19 who received a high-resolution magnetic resonance imaging (MRI) scan. FreeSurfer segmented and quantified the volume of each cerebellum. Maximum drinks during a binge in the past three months and duration since last binge were examined as predictors of cerebellar volume, after controlling for potentially confounding variables. Results In the 106 teens, higher peak drinks predicted smaller left hemisphere cerebellar gray (f2=.06, p = .02) and white matter (f2=.08, p = .02) and right hemisphere cerebellar gray matter (f2=.08, p = .006), and marginally predicted smaller right hemisphere cerebellar white matter (f2=.05, p = .09). Gender did not moderate these effects. Conclusion More intense adolescent binge drinking is linked to smaller cerebellar volumes even in healthy teens, above and beyond variability attributable to risk factors for binge drinking. Longitudinal research is needed to see if cerebellar volumes worsen with protracted drinking and recover with abstinence. Interventions aimed at improving brain structure in adolescent binge drinkers are necessary given the high prevalence of risky drinking in youth

Lisdahl, Krista M.; Thayer, Rachel; Squeglia, Lindsay M.; McQueeny, Tim M.; Tapert, Susan F.

2012-01-01

260

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.

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

2010-01-01

261

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.

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

2012-01-01

262

Field Testing of the Mars Exploration Rovers Descent Image Motion Estimation System  

Microsoft Academic Search

Abstract ? The Mars Exploration Rover (MER) Descent Image Motion Estimation System (DIMES) is the first autonomous machine vision system used to safely land a robotics payload on another planet. DIMES consists of a descent camera and an algorithm for estimating horizontal velocity using image, inertial and altitude measurements. Before DIMES was accepted by MER for inclusion in the mission,

Andrew Edie Johnson; Reg G. Willson; Jay Goguen; James Alexander; David Meller

2005-01-01

263

Mitral annular descent velocity by tissue Doppler echocardiography as an index of global left ventricular function  

Microsoft Academic Search

Mitral annular descent has been described as an index of left ventricular (LV) systolic function, which is independent of endocardial definition. Echocardiographic tissue Doppler imaging is a new technique that calculates and displays color-coded cardiac tissue velocities on-line. To evaluate mitral annular descent velocity as a rapid index of global LV function, we performed tissue Doppler imaging studies in 55

Vijay K. Gulati; William E. Katz; William P. Follansbee; John Gorcsan

1996-01-01

264

Parallel tracing of multiple trajectories in gradient descent algorithm with Cell Broadband Engine  

Microsoft Academic Search

Explored here is t he ability of Cell B.E. to efficiently reveal viable solutions of nonlinear function approximation with multilayer perceptron (MLP) employing gradient descent algorithm. The capacity of Cell BE to asynchronously trace several trajectories of implemented gradient descent algorithm from random set of starting points offers advantage of revealing statistical trends and classifying viable optimal approximations delivered by

Yuri Boiko; Gabriel A. Wainer

2009-01-01

265

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.

266

From Psychology of Race to Issue of Skin Color: Western Trivialization and Peoples of African Descent  

Microsoft Academic Search

In the aftermath of Western colonization is the trivialization of skin color as significant issue in the psychology of peoples of African descent. Although social scientists use race as a key factor in elucidating and understanding human social conditions, skin color and its impact on the social and psychological disposition of people of African descent have been understudied. Oblivious to

Ronald E. Hall

2005-01-01

267

Effects of the Phoenix Lander descent thruster plume on the Martian surface  

Microsoft Academic Search

The exhaust plume of Phoenix's hydrazine monopropellant pulsed descent thrusters will impact the surface of Mars during its descent and landing phase in the northern polar region. Experimental and computational studies have been performed to characterize the chemical compounds in the thruster exhausts. No undecomposed hydrazine is observed above the instrument detection limit of 0.2%. Forty-five percent ammonia is measured

D. H. Plemmons; M. Mehta; B. C. Clark; S. P. Kounaves; L. L. Peach; N. O. Renno; L. Tamppari; S. M. M. Young

2008-01-01

268

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

269

Mars Exploration Rovers Entry, Descent, and Landing Trajectory Analysis  

NASA Technical Reports Server (NTRS)

The Mars Exploration Rover mission successfully landed two rovers "Spirit" and "Opportunity" on Mars on January 4th and 25th of 2004, respectively. The trajectory analysis performed to define the entry, descent, and landing (EDL) scenario is described. The entry requirements and constraints are presented, as well as uncertainties used in a Monte Carlo dispersion analysis to statistically assess the robustness of the entry design to off-nominal conditions. In the analysis, six-degree-of-freedom and three-degree-of-freedom trajectory results are compared to assess the entry characteristics of the capsule. Comparison of the preentry results to preliminary post-landing reconstruction data shows that all EDL parameters were within the requirements. In addition, the final landing position for both "Spirit" and "Opportunity" were within 15 km of the predicted landing location.

Desai, Prasun N.; Knocke, Philip C.

2004-01-01

270

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

271

Embryology and physiology of testicular development and descent.  

PubMed

Sexual differentiation starts with the development of bipotential gonads that further differentiate into testes or ovaries. The fetal testis secretes hormones that guide the differentiation of internal and external sex organs, whereas the fetal ovary remains rather inactive hormonally. Defects in gonadal differentiation or hormone secretion and action result in disorders of sex development (DSD). Testicular descent is a continuum that has often been described to occur in two main phases: the transabdominal phase and the inguinoscrotal phase. The first phase is according to animal studies dependent on Leydig cell-derived insulin-like peptide 3 (INSL3) that induces male-like development of the gubernaculum. This phase is rarely disrupted in man. The inguinoscrotal phase is dependent on androgens, also secreted by Leydig cells. PMID:24683945

Virtanen, Helena E; Toppari, Jorma

2014-02-01

272

Overview of the Phoenix Entry, Descent and Landing System Architecture  

NASA Technical Reports Server (NTRS)

NASA s Phoenix Mars Lander began its journey to Mars from Cape Canaveral, Florida in August 2007, but its journey to the launch pad began many years earlier in 1997 as NASA s Mars Surveyor Program 2001 Lander. In the intervening years, the entry, descent and landing (EDL) system architecture went through a series of changes, resulting in the system flown to the surface of Mars on May 25th, 2008. Some changes, such as entry velocity and landing site elevation, were the result of differences in mission design. Other changes, including the removal of hypersonic guidance, the reformulation of the parachute deployment algorithm, and the addition of the backshell avoidance maneuver, were driven by constant efforts to augment system robustness. An overview of the Phoenix EDL system architecture is presented along with rationales driving these architectural changes.

Grover, Myron R., III; Cichy, Benjamin D.; Desai, Prasun N.

2008-01-01

273

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

274

Mars Exploration Rover Mission: Entry, Descent, and Landing System Validation  

NASA Technical Reports Server (NTRS)

System validation for a Mars entry, descent, and landing system is not simply a demonstration that the electrical system functions in the associated environments. The function of this system is its interaction with the atmospheric and surface environment. Thus, in addition to traditional test-bed, hardware-in-the-loop, testing, a validation program that confirms the environmental interaction is required. Unfortunately, it is not possible to conduct a meaningful end-to-end test of a Mars landing system on Earth. The validation plan must be constructed from an interconnected combination of simulation, analysis and test. For the Mars Exploration Rover mission, this combination of activities and the logic of how they combined to the system's validation was explicitly stated, reviewed, and tracked as part of the development plan.

Mitcheltree, Robert A.; Lee, Wayne; Steltzner, Adam; SanMartin, Alejanhdro

2004-01-01

275

Mars Exploration Rover: Launch, Cruise, Entry, Descent, and Landing  

NASA Technical Reports Server (NTRS)

The Mars Exploration Rover Project was an ambitious effort to land two highly capable rovers on Mars and concurrently explore the Martian surface for three months each. Launched in June and July of 2003, cruise operations were conducted through January 4, 2004 with the first landing, followed by the second landing on January 25. The prime mission for the second rover ended on April 27, 2004. This paper will provide an overview of the launch, cruise, and landing phases of the mission, including the engineering and science objectives and challenges involved in the selection and targeting of the landing sites, as well as the excitement and challenges of atmospheric entry, descent and landing execution.

Erickson, James K.; Manning, Robert M.; Adler, M.

2004-01-01

276

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

277

Long-term survival in cerebellar glioblastoma multiforme. Case report.  

PubMed

Primary cerebellar glioblastoma multiforme (GBM) is a rare tumor in adults that accounts for just 1% of all cases of GBM. Cerebellar GBMs are not yet completely understood also as far as the prognosis. We report a case of cerebellar GBM in a 27-year-old woman. Magnetic resonance imaging (MRI) showed a 3x3.6 cm-sized, ill-defined, heterogeneously enhancing mass in the left cerebellum. GBM was histologically confirmed following radical surgery. Postoperative radiotherapy with concomitant and adjuvant temozolomide chemotherapy was subsequently administrated. She has no evidence of recurrence and is in good clinical conditions up-to date, three years after surgery. PMID:23111300

Hernandez-Gonzalez, G; Marchione, P; De Angelis, F; Giannone, C; Kouleridou, A; Spallone, A

2012-12-01

278

A severe frontal-parietal lobe syndrome following cerebellar damage.  

PubMed

We report a case study of a frontal and parietal lobe syndrome with memory loss after unilateral left-sided cerebellar damage caused by a stroke in a patient with right cerebellar unusual developmental agenesis. The syndrome consisted of severe deficits in planning an organized sequence of events, in visuo-constructive abilities and inappropriate jocularity. These changes are ascribed in part to cerebellar-pontine lesions with resulting frontal lobe diaschisis as documented by single-photon emission computed tomography in the absence of morphological damage to the neocortex. PMID:11422432

Botez-Marquard, T; Bard, C; Léveillé, J; Botez, M I

2001-07-01

279

25 CFR 18.104 - May a tribe include provisions in its tribal probate code regarding the distribution and descent...  

Code of Federal Regulations, 2011 CFR

...include provisions in its tribal probate code regarding the distribution and descent of trust personalty? 18.104 Section 18...include provisions in its tribal probate code regarding the distribution and descent of trust personalty? No. All trust...

2011-04-01

280

[Spontaneous cerebellar hematoma. Analysis of 23 cases].  

PubMed

A series of 23 patients with spontaneous cerebellar hematoma is analysed retrospectively. Several degrees of consciousness impairment, and headache occurred in all; 12 patients presented motor deficits among the more important clinical signs. Arterial hypertension (69.5%) and diabetes (34%) stand out in the pathological background, and their association was frequent (30%). Computerized tomography (CT) disclosing severe ventricular dilatation (69.5%) associated or not with intraventricular presence of blood is considered as an unsatisfactory prognosis sign, and indicative for emergency therapy. Emergency external ventricular draining is the best indication for the majority of these cases. Posterior fossa craniectomy for emptying the hematoma may be the indication in severe cases. Death and morbidity in this pathology are high as yet. However, CT contribution for diagnosis is quicker and better than benefits obtained through other methods. Results observed in the present series are illustrative on this statement, when compared to data of other series diagnosed through other methods. PMID:3408383

Rial, J P; Vilalta, J; Guitart, J M; Rubio, E

1988-03-01

281

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

282

Note on Cerebellar Evoked Potentials Related to Extraocular Muscle Stretch.  

National Technical Information Service (NTIS)

The studies of both Hermann and Wolfe, employing bipolar recordings in two different species (goldfish and cat), have demonstrated that there are slow cerebellar potentials related to saccadic eye movements, but they precede the saccades. This type of ana...

J. W. Wolfe

1971-01-01

283

Novel Approaches to Studying the Genetic Basis of Cerebellar Development  

PubMed Central

The list of genes that when mutated cause disruptions in cerebellar development is rapidly increasing. The study of both spontaneous and engineered mouse mutants has been essential to this progress, as it has revealed much of our current understanding of the developmental processes required to construct the mature cerebellum. Improvements in brain imaging, such as magnetic resonance imaging (MRI) and the emergence of better classification schemes for human cerebellar malformations, have recently led to the identification of a number of genes which cause human cerebellar disorders. In this review we argue that synergistic approaches combining classical molecular techniques, genomics, and mouse models of human malformations will be essential to fuel additional discoveries of cerebellar developmental genes and mechanisms.

Sajan, Samin A.; Waimey, Kathryn E.

2010-01-01

284

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.

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

2014-01-01

285

Remote cerebellar hemorrhage (zebra sign) in vascular neurosurgery: pathophysiological insights.  

PubMed

Hemorrhage in regions remote from the site of initial intracranial operations is rare, but may be fatal. Postoperative cerebellar hemorrhage as a complication of supratentorial surgery, with a radiological appearance known as zebra sign, is an increasingly recognized clinical entity and is associated mainly with vascular neurosurgery or temporal lobe resection. The pathophysiology remains unclear. Three cases of remote cerebellar hematoma occurred after neck clipping of anterior communicating artery aneurysms. All patients had similar clinical findings and underwent pterional craniotomy with the head in accentuated extension. One patient died and the two were discharged without symptoms. Cerebellar hemorrhage probably has a multifactorial origin involving positioning associated with abundant cerebrospinal fluid drainage causing cerebellar sag with resultant vein stretching and bleeding, and use of aspirin or other antiplatelet agents. PMID:19556730

Figueiredo, Eberval Gadelha; de Amorim, Robson Luis Oliveira; Teixeira, Manoel Jacobsen

2009-06-01

286

Prolonged Cerebellar Ataxia: An Unusual Complication of Hypoglycemia  

PubMed Central

A 51-year-old male with a history of insulin-dependent diabetes and polysubstance abuse presented after overdose on insulin. Soon after resuscitation, he displayed a severe ataxia in all 4 limbs and was unable to walk; all of which persisted for at least 5 days. Laboratory testing was unrevealing, including relatively normal brain magnetic resonance imaging. He had recovered full neurologic function 3 months after the event. This report describes a case of reversible cerebellar ataxia as a rare complication of severe hypoglycemia that may occur in patients with abnormal cerebellar glucose metabolism. Thus, this phenomenon should be included in the differential diagnosis of patients with a history of hypoglycemia who present with ataxia. In this context, the differential diagnosis of cerebellar ataxia is discussed, as is the proposed mechanism for hypoglycemia-induced cerebellar dysfunction.

Orlander, Jay D.

2007-01-01

287

Bipolar disorder associated with paraneoplastic cerebellar degeneration: a case report.  

PubMed

We Present a case report of a patient who suffers from Paraneoplastic cerebellar degeneration (PCD) secondary to which the patient, a young woman, developed Bipolar Affective Disorder. Here we focus on the mental health aspects of this case. PMID:21057423

Slattery, Catherine; Agius, Mark; Zaman, Rashid

2010-11-01

288

21 CFR 882.5820 - Implanted cerebellar stimulator.  

Code of Federal Regulations, 2010 CFR

...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 placed on...

2010-04-01

289

21 CFR 882.5820 - Implanted cerebellar stimulator.  

Code of Federal Regulations, 2010 CFR

...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 placed on...

2009-04-01

290

Past, Present and Future Therapeutics for Cerebellar Ataxias  

PubMed Central

Cerebellar ataxias are a group of disabling neurological disorders. Patients exhibit a cerebellar syndrome and can also present with extra-cerebellar deficits, namely pigmentary retinopathy, extrapyramidal movement disorders, pyramidal signs, cortical symptoms (seizures, cognitive impairment/behavioural symptoms), and peripheral neuropathy. Recently, deficits in cognitive operations have been unraveled. Cerebellar ataxias are heterogeneous both at the phenotypic and genotypic point of view. Therapeutical trials performed during these last 4 decades have failed in most cases, in particular because drugs were not targeting a deleterious pathway, but were given to counteract putative defects in neurotransmission. The identification of the causative mutations of many hereditary ataxias, the development of relevant animal models and the recent identifications of the molecular mechanisms underlying ataxias are impacting on the development of new drugs. We provide an overview of the pharmacological treatments currently used in the clinical practice and we discuss the drugs under development.

Marmolino, D; Manto, M

2010-01-01

291

Genetics Home Reference: VLDLR-associated cerebellar hypoplasia  

MedlinePLUS

... and Families Resources for Health Professionals What glossary definitions help with understanding VLDLR-associated cerebellar hypoplasia? ataxia ; ... very low density lipoprotein ; VLDL You may find definitions for these and many other terms in the ...

292

Chromosome stability in tonsillar squamous cell carcinoma is associated with HPV16 integration and indicates a favorable prognosis.  

PubMed

Tonsillar squamous cell carcinoma (TSCC) is frequently associated with human papillomavirus (HPV) and chromosome instability. Data from cellular model systems are, however, controversial concerning a relation between HPV and chromosome instability development. Here we studied this association in 77 primary TSCC with known clinical outcome and cell cycle protein expression profiles. Thirty-two tumors (42%) showed HPV16-integration. All 77 cases were analyzed by fluorescence in situ hybridization using chromosome 1- and 7-specific centromere DNA probes to detect chromosome instability, indicated by the presence of chromosome imbalances and/or polyploidization for these chromosomes. In addition, eight HPV-positive dysplasias, seven of which were adjacent to a carcinoma, were analyzed. Disomy for chromosome 1 and 7 was present in 29 out of 77 TSCC (38%), of which 19 were HPV16-positive (p = 0.002). Aneusomy was observed in the remaining 48 TSCC, of which 13 were HPV-positive. Aneusomies correlated significantly with tobacco- and alcohol consumption (p = 0.001 and p = 0.016, respectively) and a higher T-stage (p = 0.018). Both HPV-positivity and chromosome disomy were significantly associated with a favorable disease-free survival (p = 0.001 and p = 0.025, respectively). Particularly in the HPV16-positive group chromosome instability is a very strong indicator for an unfavorable prognosis (p = 0.032). In the dysplasias an identical HPV and chromosome copy number status was identified as in the adjacent tumors. We conclude that HPV-positive TSCC and their precursor lesions are more often genetically stable than HPV-negative lesions and that these tumors are associated with a favorable prognosis. Chromosome instability is an indicator for unfavorable prognosis, particularly in the HPV-positive patient group. PMID:22987500

Mooren, Jeroen J; Kremer, Bernd; Claessen, Sandra M H; Voogd, Adri C; Bot, Fredrik J; Peter Klussmann, J; Huebbers, Christian U; Hopman, Anton H N; Ramaekers, Frans C S; Speel, Ernst-Jan M

2013-04-15

293

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.

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

2013-01-01

294

Cerebellar transcranial magnetic stimulation impairs verbal working memory  

Microsoft Academic Search

Previous functional magnetic resonance imaging and patient studies indicate cerebellar participation in verbal working memory. In particular, event-related functional magnetic resonance imaging showed superior cerebellar activation during the initial encoding phase of the Sternberg task. This study used functional magnetic resonance imaging-guided trans- cranial magnetic stimulation (TMS) to test whether disruption of the right superior cerebellum (hemispheric lobule VI\\/Crus I)

John E. Desmond; S. H. Annabel Chen; Perry B. Shieh

2005-01-01

295

Cerebellar abscesses secondary to occipital dermoid cyst with dermal sinus  

Microsoft Academic Search

BACKGROUNDHydrocephalus and cerebellar abscesses as the principal manifestations of posterior fossa dermoid cyst are rare. In addition, extradural dermoid cyst of the posterior fossa has been described in only 9 cases in the literature. We present an unusual case of obstructive hydrocephalus due to cerebellar abscesses induced by an adjacent extradural dermoid cyst with complete occipital dermal sinus.CASE DESCRIPTIONA 14-month-old

Ali Akhaddar; Mohamed Jiddane; Noureddine Chakir; Rachid El Hassani; Brahim Moustarchid; Fouad Bellakhdar

2002-01-01

296

Hypertrophic olivary degeneration after resection of a cerebellar tumor  

Microsoft Academic Search

We report a case of hypertrophic olivary degeneration due to cerebellar surgery for a low-grade tumor. A 27-year-old female\\u000a presented with right-sided paresthesias and intermittent leg paresis following a right cerebellar resection of a tumor 2 weeks\\u000a prior. One month later, her symptoms remained stable while her neurological examination demonstrated slight right hemi-body\\u000a hypoesthesia and subtle appendicular ataxia in her right

Serra Akar; Jan Drappatz; Liangge Hsu; Russell A. Blinder; Peter Mc L. Black; Santosh Kesari

2008-01-01

297

Systems Biology Perspectives on Cerebellar Long-Term Depression  

Microsoft Academic Search

Long-term depression (LTD) at parallel fiber-Purkinje cell (PF-PC) synapses is thought to be the cellular correlate of cerebellar associative learning. The molecular processes are, in brief, phosphorylation of AMPA-type glutamate receptors (AMPARs) and their subsequent removal from the surface of the PF-PC synapse. In order to elucidate the fundamental mechanisms for cerebellar LTD and further the understanding of its computational

Hideaki Ogasawara; Tomokazu Doi; Mitsuo Kawato

2008-01-01

298

Emotions and their cognitive control in children with cerebellar tumors.  

PubMed

A constellation of deficits, termed the cerebellar cognitive affective syndrome (CCAS), has been reported following acquired cerebellar lesions. We studied emotion identification and the cognitive control of emotion in children treated for acquired tumors of the cerebellum. Participants were 37 children (7-16 years) treated for cerebellar tumors (19 benign astrocytomas (AST), 18 malignant medulloblastomas (MB), and 37 matched controls (CON). The Emotion Identification Task investigated recognition of happy and sad emotions in music. In two cognitive control tasks, we investigated whether children could identify emotion in situations in which the emotion in the music and the emotion in the lyrics was either congruent or incongruent. Children with cerebellar tumors identified emotion as accurately and quickly as controls (p > .05), although there was a significant interaction of emotions and group (p < .01), with the MB group performing less accurately identifying sad emotions, and both cerebellar tumor groups were impaired in the cognitive control of emotions (p < .01). The fact that childhood acquired cerebellar tumors disrupt cognitive control of emotion rather than emotion identification provides some support for a model of the CCAS as a disorder, not so much of emotion as of the regulation of emotion by cognition. PMID:20887648

Hopyan, Talar; Laughlin, Suzanne; Dennis, Maureen

2010-11-01

299

TRPC3 channel underlies cerebellar long-term depression.  

PubMed

Cerebellar long-term depression (LTD) is induced by repetitive pairing of both synaptic inputs provided by climbing fibers (CFs) and parallel fibers (PFs), especially when CF stimulation followed by burst of PFs. Metabotropic glutamate receptor type 1 (mGluR1)-dependent signaling in Purkinje cells is critically involved in the induction of cerebellar LTD. Signaling pathway of mGluR1 has two limbs: one is IP3 receptor-mediated Ca release from intracellular Ca store and the other is activation of transient receptor potential canonical (TRPC) channels. Here, we hypothesized that TRPC3, which is reported to be responsible for mGluR1-evoked slow currents, mediates the induction of the cerebellar LTD. Purkinje cells were loaded with antibodies which act against a cytoplasmic epitope of TRPC3 channels, acting as a specific antagonist of TRPC3. About 30 min after achieving a whole-cell configuration, mGluR1-evoked slow currents were significantly reduced; a possible cause of this time delay might be the diffusion time course from patch pipette to the dendrite site of mGluR1 activation. Taking this delay into consideration, we next attempted to induce cerebellar LTD by pairing PFs and CF. It was found that cerebellar LTD was hindered in the presence of TRPC3 antibodies. Taken together, our data suggest that TRPC3 activation may be essential for the induction of LTD in cerebellar Purkinje cells. PMID:23408143

Kim, Sang Jeong

2013-06-01

300

Cerebellar atrophy without cerebellar cortex hyperintensity in infantile neuroaxonal dystrophy (INAD) due to PLA2G6 mutation  

Microsoft Academic Search

Infantile neuroaxonal dystrophy (INAD) is a rare neurodegenerative disorder characterized by infantile onset and rapid progression of psychomotor regression and hypotonia evolving into spasticity. The neuroradiologic hallmark of the disease is represented by cerebellar atrophy and signal hyperintensity in the cerebellar cortex on MR T2-weighted images. We report a 2-year-old boy with psychomotor regression and hypotonia carrying a homozygous 5?

Roberta Biancheri; Andrea Rossi; Giannina Alpigiani; Mirella Filocamo; Carlo Gandolfo; Renata Lorini; Carlo Minetti

2007-01-01

301

Descent strategy comparisons for TNAV-equipped aircraft under airplane-preferred operating conditions  

NASA Technical Reports Server (NTRS)

Three 4-D descent strategies were evaluated which were employed by TNAV-equipped aircraft in an advanced metering air traffic control environment. The Flow Management Evaluation Model (FMEM) was used to assess performance using three criteria when traffic enters the simulation under preferred cruise operating conditions (altitude and speed): throughput, fuel usage, and conflict probability. In comparison to an evaluation previously performed under NASA contract, the current analysis indicates that the optimal descent strategy is preferred over the clean-idle and constant descent angle (CFPA) strategies when all three criteria are considered.

Izumi, K. H.

1989-01-01

302

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

303

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

304

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

305

Estimating the degree of identity by descent in consanguineous couples.  

PubMed

In some clinical and research settings, it is often necessary to identify the true level of "identity by descent" (IBD) between two individuals. However, as the individuals become more distantly related, it is increasingly difficult to accurately calculate this value. Consequently, we have developed a computer program that uses genome-wide SNP genotype data from related individuals to estimate the size and extent of IBD in their genomes. In addition, the software can compare a couple's IBD regions with either the autozygous regions of a relative affected by an autosomal recessive disease of unknown cause, or the IBD regions in the parents of the affected relative. It is then possible to calculate the probability of one of the couple's children suffering from the same disease. The software works by finding SNPs that exclude any possible IBD and then identifies regions that lack these SNPs, while exceeding a minimum size and number of SNPs. The accuracy of the algorithm was established by estimating the pairwise IBD between different members of a large pedigree with varying known coefficients of genetic relationship (CGR). PMID:21901788

Carr, Ian M; Markham, Sir Alexander F; Pena, Sérgio D J

2011-12-01

306

STS-40 descent BET products: Development and results  

NASA Technical Reports Server (NTRS)

Descent Best Estimate Trajectory (BET) Data were generated for the final Orbiter Experiments Flight, STS-40. This report discusses the actual development of these post-flight products: the inertial BET, the Extended BET, and the Aerodynamic BET. Summary results are also included. The inertial BET was determined based on processing Tracking and Data Relay Satellite (TDRSS) coherent Doppler data in conjunction with observations from eleven C-band stations, to include data from the Kwajalein Atoll and the usual California coastal radars, as well as data from five cinetheodolite cameras in the vicinity of the runways at EAFB. The anchor epoch utilized for the trajectory reconstruction was 53,904 Greenwich Mean Time (GMT) seconds which corresponds to an altitude at epoch of approximately 708 kft. Atmospheric data to enable development of an Extended BET for this mission were upsurped from the JSC operational post-flight BET. These data were evaluated based on Space Shuttle-derived considerations as well as model comparisons. The Aerodynamic BET includes configuration information, final mass properties, and both flight-determined and predicted aerodynamic performance estimates. The predicted data were based on the final pre-operational databook, updated to include flight determined incrementals based on an earlier ensemble of flights. Aerodynamic performance comparisons are presented and correlated versus statistical results based on twenty-two previous missions.

Oakes, Kevin F.; Wood, James S.; Findlay, John T.

1991-01-01

307

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

308

Mars Science Laboratory Entry, Descent, and Landing System Overview  

NASA Technical Reports Server (NTRS)

In 2012, 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. Thus, there are many design challenges that must be solved for the mission to be successful. Several pieces of the EDL design are technological firsts, such as guided entry and precision landing on another planet, as well as the entire Sky Crane maneuver. This paper discusses the MSL EDL architecture and discusses some of the challenges faced in delivering an unprecedented rover payload to the surface of Mars.

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

2010-01-01

309

Preliminary Study of a Model Rotor in Descent  

NASA Technical Reports Server (NTRS)

Within a program designed to develop experimental techniques for measuring the trajectory and structure of vortices trailing from the tips of rotor blades, the present preliminary study focuses on a method for quantifying the trajectory of the trailing vortex during descent flight conditions. This study also presents rotor loads and blade surface pressures for a range of tip-path plane angles and Mach numbers. Blade pressures near the leading edge and along the outer radius are compared with data obtained on the same model rotor, but in open jet facilities. A triangulation procedure based on two directable laser-light sheets, each containing an embedded reference, proved effective in defining the spatial coordinates of the trailing vortex. When interrogating a cross section of the flow that contains several trailing vortices, the greatest clarity was found to result when the flow is uniformly seeded. Surface pressure responses during blade-vortex interactions appeared equally sensitive near the leading edge and along the outer portion of the blade, but diminished rapidly as the distance along the blade chord increased. The pressure response was virtually independent of whether the tip-path plane angle was obtained through shaft tilt or cyclic pitch. Although the shape and frequency of the pressure perturbations on the advancing blade during blade-vortex interaction are similar to those obtained in open-jet facilities, the angle of the tip-path plane may need to be lower than the range covered in this study.

McAlister, K. W.; Tung, C.; Sharpe, D. L.; Huang, S.; Hendley, E. M.

2000-01-01

310

Engineering description of the ascent/descent bet product  

NASA Technical Reports Server (NTRS)

The Ascent/Descent output product is produced in the OPIP routine from three files which constitute its input. One of these, OPIP.IN, contains mission specific parameters. Meteorological data, such as atmospheric wind velocities, temperatures, and density, are obtained from the second file, the Corrected Meteorological Data File (METDATA). The third file is the TRJATTDATA file which contains the time-tagged state vectors that combine trajectory information from the Best Estimate of Trajectory (BET) filter, LBRET5, and Best Estimate of Attitude (BEA) derived from IMU telemetry. Each term in the two output data files (BETDATA and the Navigation Block, or NAVBLK) are defined. The description of the BETDATA file includes an outline of the algorithm used to calculate each term. To facilitate describing the algorithms, a nomenclature is defined. The description of the nomenclature includes a definition of the coordinate systems used. The NAVBLK file contains navigation input parameters. Each term in NAVBLK is defined and its source is listed. The production of NAVBLK requires only two computational algorithms. These two algorithms, which compute the terms DELTA and RSUBO, are described. Finally, the distribution of data in the NAVBLK records is listed.

Seacord, A. W., II

1986-01-01

311

Direct Temperature Measurements during Netlander Descent on Mars  

NASA Astrophysics Data System (ADS)

A new design for a platinum thermoresistance temperature sensor has been developed and tested in Earth's atmosphere and stratosphere. It will be one of the sensors equipping the scientific package ATMIS (Atmospheric and Meteorology Instrument System), which will be devoted to the measurement of the meteorological parameters during both the entry/descent phase and the surface phase, aboard the Netlanders. In particular vertical profiles of temperature, density and pressure will allow the resolution of vertical gradients to investigate the atmospheric structure and dynamics. In view of the future missions to Mars, Netlander represents a unique chance to increase significantly the climate record both in time and in space, doubling the current knowledge of the atmospheric parameters. Furthermore is the only opportunity to conduct direct measurement of temperature and pressure (outside the boundary layer of the airbags used for the landing). The temperature sensor proposed is a platinum thermoresistance, enhancement of HASI TEM (Cassini/Huygens Mission); a substantial improvement of the performances, i.e. a faster dynamic response, has been obtained. Two different prototypes of new design sensor have been built, laboratory test are proceeding and the second one has been already flown aboard a stratospheric balloon.

Colombatti, G.; Angrilli, F.; Ferri, F.; Francesconi, A.; Fulchignoni, M.; Lion Stoppato, P. F.; Saggi, B.

1999-09-01

312

HLA type inference via haplotypes identical by descent.  

PubMed

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 hypervariable 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. PMID:21385049

Setty, Manu N; Gusev, Alexander; Pe'er, Itsik

2011-03-01

313

Orion Entry, Descent, and Landing Performance and Mission Design  

NASA Technical Reports Server (NTRS)

The Orion Vehicle is the next spacecraft to take humans into space and will include missions to ISS as well as missions to the Moon. As part of that challenge, the vehicle will have to accommodate multiple mission design concepts, since return from Low Earth Orbit and return from the Moon can be quite different. Commonality between the different missions as it relates to vehicle systems, guidance capability, and operations concepts is the goal. Several unique mission design concepts include the specification of multiple land-based landing sites for a vehicle with closed-loop direct and skip entry guidance, followed by a parachute descent and landing attenuation system. This includes the ability of the vehicle to accurately target and land at a designated landing site, including site location aspects, landing site size, and landing opportunities assessments. Analyses associated with these mission design and flight performance challenges and constraints will be discussed as well as potential operational concepts to provide feasibility and/or mission commonality.

Broome, Joel M.; Johnson, Wyatt

2007-01-01

314

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

315

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

316

Defective cerebellar control of cortical plasticity in writer's cramp  

PubMed Central

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.

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

2013-01-01

317

Developmental origins of diversity in cerebellar output nuclei  

PubMed Central

Background The functional integration of the cerebellum into a number of different neural systems is governed by the connection of its output axons. In amniotes, the majority of this output is mediated by an evolutionarily diverse array of cerebellar nuclei that, in mice, are derived from the embryonic rhombic lip. To understand the origins of cerebellar nucleus diversity, we have explored how nucleus development is patterned in birds, which notably lack a dentate-like nucleus output to the dorsal thalamus. Results Using targeted in ovo electoroporation of green fluorescent protein (GFP) and red fluorescent protein (RFP) in a variety of combinations and with different conditional enhancers, we show that cerebellar nuclei in chicks are produced, as in the mouse, at the rhombic lip. Furthermore, the comparison of fate-mapped neurons with molecular markers reveals a strict temporal sequence of cell fate allocation in establishing the avian lateral and medial cerebellar nuclei. In contrast to the mouse cerebellum, Lhx9 expression is confined to extracerebellar thalamic afferent nuclei corresponding to the absence, in chicks, of a dentate nucleus. Spatiotemporally targeted over-expression of Lhx9 in chick cerebellar nuclei (recapitulating in part the mammalian expression pattern) results in a loss of distinct nuclear boundaries and a change in axon initial trajectories consistent with a role for Lhx9 specifying targeting. Conclusions Our results confirm the relationship between cell fate and a fine grain temporal patterning at the rhombic lip. This suggests that the lack of a cerebellar output to the dorsal thalamus of birds corresponds with a restricted expression of the LIM-homeodomain gene Lhx9 to earlier born rhombic lip cohorts when compared to mice. The evolution of cerebellar nucleus diversity in amniotes may hence reflect a heterochronic adaptation of gene expression with respect to the sequential production of rhombic lip derivatives resulting in altered axonal targeting.

2014-01-01

318

Cerebellar development in the absence of Gbx function in zebrafish.  

PubMed

The midbrain-hindbrain boundary (MHB) is a well-known organizing center during vertebrate brain development. The MHB forms at the expression boundary of Otx2 and Gbx2, mutually repressive homeodomain transcription factors expressed in the midbrain/forebrain and anterior hindbrain, respectively. The genetic hierarchy of gene expression at the MHB is complex, involving multiple positive and negative feedback loops that result in the establishment of non-overlapping domains of Wnt1 and Fgf8 on either side of the boundary and the consequent specification of the cerebellum. The cerebellum derives from the dorsal part of the anterior-most hindbrain segment, rhombomere 1 (r1), which undergoes a distinctive morphogenesis to give rise to the cerebellar primordium within which the various cerebellar neuron types are specified. Previous studies in the mouse have shown that Gbx2 is essential for cerebellar development. Using zebrafish mutants we show here that in the zebrafish gbx1 and gbx2 are required redundantly for morphogenesis of the cerebellar primordium and subsequent cerebellar differentiation, but that this requirement is alleviated by knocking down Otx. Expression of fgf8, wnt1 and the entire MHB genetic program is progressively lost in gbx1-;gbx2- double mutants but is rescued by Otx knock-down. This rescue of the MHB genetic program depends on rescued Fgf signaling, however the rescue of cerebellar primordium morphogenesis is independent of both Gbx and Fgf. Based on our findings we propose a revised model for the role of Gbx in cerebellar development. PMID:24183937

Su, Chen-Ying; Kemp, Hilary A; Moens, Cecilia B

2014-02-01

319

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

320

Final STS-35 Columbia Descent BET Products and Results for LaRC OEX Investigations.  

National Technical Information Service (NTIS)

Final STS-35 'Columbia' descent Best Estimate Trajectory (BET) products have been developed for Langley Research Center (LaRC) Orbiter Experiments (OEX) investigations. Included are the reconstructed inertial trajectory profile; the Extended BET, which co...

K. F. Oakes J. T. Findlay R. A. Jasinski J. S. Wood

1991-01-01

321

Atmosphere Assessment for MARS Science Laboratory Entry, Descent and Landing Operations.  

National Technical Information Service (NTIS)

On August 6, 2012, the Mars Science Laboratory rover, Curiosity, successfully landed on the surface of Mars. The Entry, Descent and Landing (EDL) sequence was designed using atmospheric conditions estimated from mesoscale numerical models. The models, dev...

A. Chen A. D. Cianciolo A. R. Vasavada B. Cantor D. Kass D. Tyler J. Barnes M. Mischna S. Rafkin

2013-01-01

322

2007 Mars Phoenix Entry, Descent, and Landing Simulation and Modeling Analysis  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the entry, descent, and landing of the 2007 Mars Phoenix lander. Aerodynamics characteristics along with Monte Carlo analyses are also presented for launch and landing site opportunities.

Prince, Jill L.; Grover, Myron R.; Desai, Prasun N.; Queen, Eric M.

2007-01-01

323

Entry, Descent and Landing (EDL) Technology Investments Within NASA's Space Technology Mission Directorate (STMD)  

NASA Astrophysics Data System (ADS)

NASA’s Space Technology Mission Directorate has several investments in entry, descent and landing technologies, across its nine programs. This presentation will give a top-level view of the various investments.

Munk, M. M.

2014-06-01

324

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

325

Cerebellar hypoplasia: Differential diagnosis and diagnostic approach.  

PubMed

Cerebellar hypoplasia (CH) refers to a cerebellum with a reduced volume, and is a common, but non-specific neuroimaging finding. The etiological spectrum of CH is wide and includes both primary (malformative) and secondary (disruptive) conditions. Primary conditions include chromosomal aberrations (e.g., trisomy 13 and 18), metabolic disorders (e.g., molybdenum cofactor deficiency, Smith-Lemli-Opitz syndrome, and adenylosuccinase deficiency), genetic syndromes (e.g., Ritscher-Schinzel, Joubert, and CHARGE syndromes), and brain malformations (primary posterior fossa malformations e.g., Dandy-Walker malformation, pontine tegmental cap dysplasia and rhombencephalosynapsis, or global brain malformations such as tubulinopathies and ?-dystroglycanopathies). Secondary (disruptive) conditions include prenatal infections (e.g., cytomegalovirus), exposure to teratogens, and extreme prematurity. The distinction between malformations and disruptions is important for pathogenesis and genetic counseling. Neuroimaging provides key information to categorize CH based on the pattern of involvement: unilateral CH, CH with mainly vermis involvement, global CH with involvement of both vermis and hemispheres, and pontocerebellar hypoplasia. The category of CH, associated neuroimaging findings and clinical features may suggest a specific disorder or help plan further investigations and interpret their results. Over the past decade, advances in neuroimaging and genetic testing have greatly improved clinical diagnosis, diagnostic testing, recurrence risk counseling, and information about prognosis for patients and their families. In the next decade, these advances will be translated into deeper understanding of these disorders and more specific treatments. © 2014 Wiley Periodicals, Inc. PMID:24839100

Poretti, Andrea; Boltshauser, Eugen; Doherty, Dan

2014-06-01

326

?6 integrin subunit regulates cerebellar development  

PubMed Central

Mutations in genes encoding several basal lamina components as well as their cellular receptors disrupt normal deposition and remodeling of the cortical basement membrane resulting in a disorganized cerebral and cerebellar cortex. The ?6 integrin was the first ? subunit associated with cortical lamination defects and formation of neural ectopias. In order to understand the precise role of ?6 integrin in the central nervous system (CNS), we have generated mutant mice carrying specific deletion of ?6 integrin in neuronal and glia precursors by crossing ?6 conditional knockout mice with Nestin-Cre line. Cerebral cortex development occurred properly in the resulting ?6fl/fl;nestin-Cre mutant animals. Interestingly, however, cerebellum displayed foliation pattern defects although granule cell (GC) proliferation and migration were not affected. Intriguingly, analysis of Bergmann glial (BG) scaffold revealed abnormalities in fibers morphology associated with reduced processes outgrowth and altered actin cytoskeleton. Overall, these data show that ?6 integrin receptors are required in BG cells to provide a proper fissure formation during cerebellum morphogenesis.

Marchetti, Giovanni; De Arcangelis, Adele; Pfister, Veronique; Georges-Labouesse, Elisabeth

2013-01-01

327

Rapidly progressive cerebellar ataxia in West Wales.  

PubMed

Progressive multifocal leucoencephalopathy (PML) is a severe demyelinating disease of the central nervous system that is caused by the JC virus infection. It is often fatal or severely disabling. PML exclusively happens in the context of cell-mediated immunosuppression. Prior to the era of HIV, PML was mainly confined to patients with haematological malignancies and rheumatological diseases. The HIV epidemic in the early eighties led to massive expansion in the incidence and prevalence of the disease. PML has also been recognised to happen due to treatment with monoclonal antibodies such as natalizumab, which is used as a disease-modifying agent for relapsing remitting multiple sclerosis and other monoclonal antibodies used in dermatological and haematological conditions. The clinical picture is that of cognitive decline, visual disturbance and hemiparesis. The correct clinicoradiological picture combined with demonstrating the JC virus DNA in the cerebrospinal fluid (CSF) using PCR (PMR) is enough to establish the diagnosis. Brain biopsy is rarely needed. Immune reconstitution represents the mainstay in the treatment of PML. We present a case of a 47-year-old man who presented with progressive cerebellar ataxia. Investigations confirmed PML. He was found to be HIV positive. We also review the literature. PMID:24265345

Ali, Khalid; Amin, Reem; Yoganathan, Kathir G; Powell, Rob

2013-01-01

328

Organotypic Cerebellar Cultures: Apoptotic Challenges and Detection  

PubMed Central

Organotypic cultures of neuronal tissue were first introduced by Hogue in 1947 1,2 and have constituted a major breakthrough in the field of neuroscience. Since then, the technique was developed further and currently there are many different ways to prepare organotypic cultures. The method presented here was adapted from the one described by Stoppini et al. for the preparation of the slices and from Gogolla et al. for the staining procedure 3,4. A unique feature of this technique is that it allows you to study different parts of the brain such as hippocampus or cerebellum in their original structure, providing a big advantage over dissociated cultures in which all the cellular organization and neuronal networks are disrupted. In the case of the cerebellum it is even more advantageous because it allows the study of Purkinje cells, extremely difficult to obtain as dissociated primary culture. This method can be used to study certain developmental features of the cerebellum in vitro, as well as for electrophysiological and pharmacological experiments in both wild type and mutant mice. The method described here was designed to study the effect of apoptotic stimuli such as Fas ligand in the developing cerebellum, using TUNEL staining to measure apoptotic cell death. If TUNEL staining is combined with cell type specific markers, such as Calbindin for Purkinje cells, it is possible to evaluate cell death in a cell population specific manner. The Calbindin staining also serves the purpose of evaluating the quality of the cerebellar cultures.

Hurtado de Mendoza, Tatiana; Balana, Bartosz; Slesinger, Paul A.; Verma, Inder M.

2011-01-01

329

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

330

Glaucoma detection: the content of optometric eye examinations for a presbyopic patient of African racial descent  

Microsoft Academic Search

Aims:Standardised patient (SP) methodology is the gold standard for evaluating clinical practice. We investigated the content of optometric eyecare for an early presbyopic SP of African racial descent, an “at-risk” patient group for primary open-angle glaucoma (POAG).Methods:A trained actor presented unannounced as a 44-year-old patient of African racial descent, complaining of recent near vision difficulties, to 100 community optometrists for

R Shah; D F Edgar; P G Spry; R A Harper; A Kotecha; S Rughani; B J W Evans

2009-01-01

331

Relation between perineal descent and pudendal nerve damage in idiopathic faecal incontinence  

Microsoft Academic Search

In 60 patients with idiopathic anorectal incontinence, without neurological disease, there was a significant relationship, shown by regression analysis, between the pudendal nerve terminal motor latency and the extent of perineal descent during straining (r0.59;p<0.001), and the plane of the perineum on straining (r-0.61;p<0.001). These data are consistent with the suggestion that perineal descent can lead to stretch-induced damage to

P. N. Jones; D. Z. Lubowski; M. Swash; M. M. Henry

1987-01-01

332

Analysis of Flight Management System Predictions of 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 predictor and its uncertainty models, descents from cruise to the meter fix were executed using vertical navigation in a B737-700 simulator and a B777-200 simulator, both with commercial FMSs. For both aircraft types, the FMS computed the intended descent path for a specified speed profile assuming idle thrust after top of descent (TOD), and then it controlled the avionics without human intervention. The test matrix varied aircraft weight, descent speed, and wind conditions. The first analysis in this paper determined the effect of the test matrix parameters on the FMS computation of TOD location, and it compared the results to those for the current ground predictor in the Efficient Descent Advisor (EDA). The second analysis was similar but considered the time to fly a specified distance to the meter fix. The effects of the test matrix variables together with the accuracy requirements for the predictor will determine the allowable error for the predictor inputs. For the B737, the EDA prediction of meter fix crossing time agreed well with the FMS; but its prediction of TOD location probably was not sufficiently accurate to enable idle-thrust descents in congested airspace, even though the FMS and EDA gave similar shapes for TOD location as a function of the test matrix variables. For the B777, the FMS and EDA gave different shapes for the TOD location function, and the EDA prediction of the TOD location is not accurate enough to fully enable the concept. Furthermore, the differences between the FMS and EDA predictions of meter fix crossing time for the B777 indicated that at least one of them was not sufficiently accurate.

Stell, Laurel

2010-01-01

333

The Descent Rates of the Shear Zones of the Equatorial QBO.  

NASA Astrophysics Data System (ADS)

The influence of vertical advection on the descent rate of the zero-wind line in both phases of the equatorial quasi-biennial oscillation (QBO) is investigated with the help of the `THIN AIR' stratosphere two-and-a-half-dimensional model. The model QBO is forced by two symmetric easterly and westerly waves, and yet the model reproduces qualitatively the observed asymmetry in the descent rates of the two shear zones due to the enhanced heating during easterly descent combined with the equatorial heating induced by the extratropical planetary waves. Observations show that the maximum easterly accelerations occur predominantly from May until July, which is when the modeled equatorial planetary-wave-induced heating rates are weakest. Hence, model results are consistent with the theory that vertical advection induced by extratropical planetary waves slows significantly the descent of the easterly shear zone. The model also shows the observed increase in vertical wind shear during stalling of the easterly descent (which increases the impact of vertical advection). In the model, the effect of cross-equatorial advection of momentum by the mean flow is negligible compared to the vertical advection. Changes in the propagation of planetary waves depending on the sign of the equatorial zonal wind have a small effect on the modeled equatorial heating rates and therefore do not play a large part in producing the modeled asymmetry in descent rates.

Kinnersley, Jonathan S.; Pawson, Steven

1996-07-01

334

Pharmacogenomics of warfarin in populations of African descent.  

PubMed

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

2013-02-01

335

Experiments on liquid immiscibility along tholeiitic liquid lines of descent  

NASA Astrophysics Data System (ADS)

Crystallization experiments have been conducted on compositions along tholeiitic liquid lines of descent to define the compositional space for the development of silicate liquid immiscibility. Starting materials have 46-56 wt% SiO2, 11.7-17.7 wt% FeOtot, and Mg-number between 0.29 and 0.36. These melts fall on the basaltic trends relevant for Mull, Iceland, Snake River Plain lavas and for the Sept Iles layered intrusion, where large-scale liquid immiscibility has been recognized. At one atmosphere under anhydrous conditions, immiscibility develops below 1,000-1,020°C in all of these compositionally diverse lavas. Extreme iron enrichment is not necessary; immiscibility also develops during iron depletion and silica enrichment. Variations in melt composition control the development of silicate liquid immiscibility along the tholeiitic trend. Elevation of Na2O + K2O + P2O5 + TiO2 promotes the development of two immiscible liquids. Increasing melt CaO and Al2O3 stabilizes a single-liquid field. New data and published phase equilibria show that anhydrous, low-pressure fractional crystallization is the most favorable condition for unmixing during differentiation. Pressure inhibits immiscibility because it expands the stability field of high-Ca clinopyroxene, which reduces the proportion of plagioclase in the crystallizing assemblage, thus enhancing early iron depletion. Magma mixing between primitive basalt and Fe-Ti-P-rich ferrobasalts can serve to elevate phosphorous and alkali contents and thereby promote unmixing. Water might decrease the temperature and size of the two-liquid field, potentially shifting the binodal (solvus) below the liquidus, leading the system to evolve as a single-melt phase.

Charlier, Bernard; Grove, Timothy L.

2012-07-01

336

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.

Suarez-Kurtz, Guilherme; Botton, Mariana R

2013-01-01

337

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

338

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.

Canutescu, Adrian A.; Dunbrack, Roland L.

2003-01-01

339

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

340

Cerebellar vermis abnormalities and cognitive functions in individuals with Williams syndrome.  

PubMed

In Williams syndrome (WS) cerebellar measures were only indirectly related to behavioral outcomes. T1-weighted magnetic resonance images and neuropsychological data were acquired to investigate whether cerebellar vermis differences were present in 12 WS individuals compared with 13 chronological age-matched controls and whether WS cerebellar vermis measures were related to cognitive scores. In WS participants, we observed a significant increase in the volume of the posterior superior cerebellar vermis (lobules VI-VII) and an atypical ratio between width and height of the cerebellar vermis. Furthermore, we found an inverse correlation between cerebellar posterior vermis volume and scores on implicit learning, phonological fluency and the verbal short-term memory tasks. The present study supported a role for the posterior cerebellar vermis in higher cognitive processes and indicated that the cerebellar vermis abnormalities (enlargement) in WS individuals have an effect in worsening the cognitive performance in specific domains. PMID:23643765

Menghini, Deny; Di Paola, Margherita; Murri, Riccardo; Costanzo, Floriana; Caltagirone, Carlo; Vicari, Stefano; Petrosini, Laura

2013-07-01

341

An Acute Cerebro-Cerebellar Ataxic Form of Epilepsy in Childhood.  

National Technical Information Service (NTIS)

There are several types of acute cerebral ataxia which differ mainly in clinical course, most common site of lesion, and long term prognosis. Cases in which cerebellar symptoms predominate are sometimes called acute cerebellar ataxia. This syndrome must n...

I. S. Tets

1970-01-01

342

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.

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

2014-01-01

343

Interval Timing Disruptions in Subjects with Cerebellar Lesions  

PubMed Central

The cerebellum has long been implicated in time perception, particularly in the subsecond range. The current set of studies examines the role of the cerebellum in suprasecond timing, using analysis of behavioral data in subjects with cerebellar lesions. Eleven cerebellar lesion subjects and 17 controls were tested on temporal estimation, reproduction and production, for times ranging from 2 to 12 s. Cerebellar patients overproduced times on both the reproduction and production tasks; the effect was greatest at the shortest duration. A subset of patients also underestimated intervals. Cerebellar patients were significantly more variable on the estimation and reproduction tasks. No significant differences between normal and cerebellar patients were found on temporal discrimination tasks with either sub- or suprasecond times. Patients with damage to the lateral superior hemispheres or the dentate nuclei showed more significant impairments than those with damage elsewhere in the cerebellum, and patients with damage to the left cerebellum had more significant differences from controls than those with damage to the right. These data suggest that damage to the middle-to-superior lobules or the left hemisphere is especially detrimental to timing suprasecond intervals. We suggest that this region be considered part of a network of brain structures including the DLPFC that is crucial for interval timing.

Gooch, Cynthia M.; Wiener, Martin; Wencil, Elaine B.; Coslett, H. Branch

2009-01-01

344

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.

Porras-Garcia, M. Elena; Ruiz, Rocio; Perez-Villegas, Eva M.; Armengol, Jose A.

2013-01-01

345

[A case of hemifacial spasm associated with a cerebellar hematoma].  

PubMed

This is a report of a hemifacial spasm associated with a cerebellar hematoma. A 60 year-old female was admitted to our hospital due to severe vertigo and nausea. On admission, the neurological examination showed drowsy conscious level, cerebellar sign dominant on the left side, and left hemifacial spasm. CT scans disclosed a large hematoma in the left cerebellar hemisphere. An angiography revealed a dominant left PICA, but showed neither vascular malformation nor aneurysm. An emergency removal of the hematoma was carried out by using suboccipital craniectomy. Three days after the surgery, the patient's left hemifacial spasm disappeared completely. She had never suffered from left hemifacial spasm prior to this cerebellar bleeding. The hemifacial spasm was thought to be due to either the compression of the left facial nerve by the PICA which had been displaced by the cerebellar hematoma, or to the fact that the nucleus of the left facial nerve might have been stimulated by the hematoma, and the hemifacial spasm might have been caused as a result of the stimulation. The total removal of the hematoma and the postoperative CSF leakage might have decompressed the facial nerve. It was considered that this might be similar to microvascular decompression. PMID:7845513

Hirano, A; Ochi, S; Kanno, K

1994-12-01

346

Modeling the generation of output by the cerebellar nuclei.  

PubMed

Functional aspects of network integration in the cerebellar cortex have been studied experimentally and modeled in much detail ever since the early work by theoreticians such as Marr, Albus and Braitenberg more than 40 years ago. In contrast, much less is known about cerebellar processing at the output stage, namely in the cerebellar nuclei (CN). Here, input from Purkinje cells converges to control CN neuron spiking via GABAergic inhibition, before the output from the CN reaches cerebellar targets such as the brainstem and the motor thalamus. In this article we review modeling studies that address how the CN may integrate cerebellar cortical inputs, and what kind of signals may be transmitted. Specific hypotheses in the literature contrast rate coding and temporal coding of information in the spiking output from the CN. One popular hypothesis states that post-inhibitory rebound spiking may be an important mechanism by which Purkinje cell inhibition is turned into CN output spiking, but this hypothesis remains controversial. Rate coding clearly does take place, but in what way it may be augmented by temporal codes remains to be more clearly established. Several candidate mechanisms distinct from rebound spiking are discussed, such as the significance of spike time correlations between Purkinje cell pools to determine CN spike timing, irregularity of Purkinje cell spiking as a determinant of CN firing rate, and shared brief pauses between Purkinje cell pools that may trigger individual CN spikes precisely. PMID:23200193

Steuber, Volker; Jaeger, Dieter

2013-11-01

347

Structural basis of cerebellar microcircuits in the rat.  

PubMed

The topography of the cerebellar cortex is described by at least three different maps, with the basic units of each map termed "microzones," "patches," and "bands." These are defined, respectively, by different patterns of climbing fiber input, mossy fiber input, and Purkinje cell (PC) phenotype. Based on embryological development, the "one-map" hypothesis proposes that the basic units of each map align in the adult animal and the aim of the present study was to test this possibility. In barbiturate anesthetized adult rats, nanoinjections of bidirectional tracer (Retrobeads and biotinylated dextran amine) were made into somatotopically identified regions within the hindlimb C1 zone in copula pyramidis. Injection sites were mapped relative to PC bands defined by the molecular marker zebrin II and were correlated with the pattern of retrograde cell labeling within the inferior olive and in the basilar pontine nuclei to determine connectivity of microzones and patches, respectively, and also with the distributions of biotinylated dextran amine-labeled PC terminals in the cerebellar nuclei. Zebrin bands were found to be related to both climbing fiber and mossy fiber inputs and also to cortical representation of different parts of the ipsilateral hindpaw, indicating a precise spatial organization within cerebellar microcircuitry. This precise connectivity extends to PC terminal fields in the cerebellar nuclei and olivonuclear projections. These findings strongly support the one-map hypothesis and suggest that, at the microcircuit level of resolution, the cerebellar cortex has a common plan of spatial organization for major inputs, outputs, and PC phenotype. PMID:24133249

Cerminara, Nadia L; Aoki, Hanako; Loft, Michaela; Sugihara, Izumi; Apps, Richard

2013-10-16

348

Structural Basis of Cerebellar Microcircuits in the Rat  

PubMed Central

The topography of the cerebellar cortex is described by at least three different maps, with the basic units of each map termed “microzones,” “patches,” and “bands.” These are defined, respectively, by different patterns of climbing fiber input, mossy fiber input, and Purkinje cell (PC) phenotype. Based on embryological development, the “one-map” hypothesis proposes that the basic units of each map align in the adult animal and the aim of the present study was to test this possibility. In barbiturate anesthetized adult rats, nanoinjections of bidirectional tracer (Retrobeads and biotinylated dextran amine) were made into somatotopically identified regions within the hindlimb C1 zone in copula pyramidis. Injection sites were mapped relative to PC bands defined by the molecular marker zebrin II and were correlated with the pattern of retrograde cell labeling within the inferior olive and in the basilar pontine nuclei to determine connectivity of microzones and patches, respectively, and also with the distributions of biotinylated dextran amine-labeled PC terminals in the cerebellar nuclei. Zebrin bands were found to be related to both climbing fiber and mossy fiber inputs and also to cortical representation of different parts of the ipsilateral hindpaw, indicating a precise spatial organization within cerebellar microcircuitry. This precise connectivity extends to PC terminal fields in the cerebellar nuclei and olivonuclear projections. These findings strongly support the one-map hypothesis and suggest that, at the microcircuit level of resolution, the cerebellar cortex has a common plan of spatial organization for major inputs, outputs, and PC phenotype.

Cerminara, Nadia L.; Aoki, Hanako; Loft, Michaela; Apps, Richard

2013-01-01

349

A Case of Cerebral Erdheim-Chester Disease With Progressive Cerebellar Syndrome  

Microsoft Academic Search

Erdheim-Chester disease (ECD) is a rare non-Langerhans form of histiocytosis. Cerebellar involvement is rare in this syndrome. We report a 37-year-old woman with slowly progressive cerebellar ataxia, dysmetria of limbs, nystagmus, and dysarthria, bilateral painful axillary masses, and generalized arthralgia. Brain MRI revealed cerebellar atrophy with focal lesions in the pons, middle cerebellar peduncle, and the cerebellum. She underwent incisional

Sang-Jun Na; Kee Ook Lee; Jung Eun Kim; Yong-Duk Kim

2008-01-01

350

Mammillary Body and Cerebellar Shrinkage in Chronic Alcoholics: An MRI and Neuropsychological Study  

Microsoft Academic Search

Mammillary body and cerebellar volume loss are common in Korsakoff's syndrome but are more controversial in chronic alcoholics without frank amnesia or ataxia. This study related magnetic resonance imaging (MRI) derived ratings of tissue volume reduction in the mammillary bodies, cerebellar hemispheres, and cerebellar vermis to tests of verbal and nonverbal long-term declarative memory and ataxia. Ss were 33 chronic

Maria D. Davila; Paula K. Shear; Edith V. Sullivan; Adolf Pfefferbaum

1994-01-01

351

Acute cerebellar hemorrhage secondary to capillary telangiectasia in an infant. A case report.  

PubMed

We encountered an unusual case of an acute cerebellar hemorrhage secondary to a capillary telangiectasia in a 4-month-old infant. Prompt surgical evacuation of the cerebellar hematoma resulted in an excellent neurologic outcome. To the best of our knowledge, ours represents the only clinical case report of massive cerebellar bleed due to a capillary telangiectasia. PMID:7980112

Bland, L I; Lapham, L W; Ketonen, L; Okawara, S H

1994-11-01

352

Paraneoplastic cerebellar degeneration associated with multiple myeloma —3.4 years follow up  

Microsoft Academic Search

A 57 year old female patient demonstrated subacute generalized cerebellar symptoms and the investigations which were done exhibited that the clinical picture was due to the remote effect of multiple myeloma. In this case of paraneoplastic cerebellar degeneration, MRI showed cerebellar vermian atrophy when the brain CT scan was negative.

Sevket Akpinar; Önder Berk; Levent Karaca

1990-01-01

353

Reversible cerebellar ataxia with thyrotoxicosis: An autoimmune brain disease in remission due to Graves' disease  

PubMed Central

We hereby report a patient with seizure disorder who was on long term carbamazepine, admitted with features of thyrotoxicosis and cerebellar dysfunction. Anticonvulsant medications are cerebellar toxins; but in this case, reversal of cerebellar dysfunction was noted upon treatment of thyrotoxicosis with antithyroid drugs.

Prakasha, S. Rama; Suresh, G.; Prakash, P. S.; D'sa, Ivor Peter

2013-01-01

354

International Cooperative Ataxia Rating Scale for pharmacological assessment of the cerebellar syndrome  

Microsoft Academic Search

Despite the involvement of cerebellar ataxia in a large variety of conditions and its frequent association with other neurological symptoms, the quantification of the specific core of the cerebellar syndrome is possible and useful in Neurology. Recent studies have shown that cerebellar ataxia might be sensitive to various types of pharmacological agents, but the scales used for assessment were all

P. Trouillas; T. Takayanagi; M. Hallett; R. D. Currier; S. H. Subramony; K. Wessel; A. Bryer; H. C. Diener; S. Massaquoi; C. M. Gomez; P. Coutinho; M. Ben Hamida; G. Campanella; A. Filla; L. Schut; D. Timann; J. Honnorat; N. Nighoghossian; B. Manyam

1997-01-01

355

Presynaptic Calcium Signalling in Cerebellar Mossy Fibres  

PubMed Central

Whole-cell recordings were obtained from mossy fibre terminals in adult turtles in order to characterize the basic membrane properties. Calcium imaging of presynaptic calcium signals was carried out in order to analyse calcium dynamics and presynaptic GABA B inhibition. A tetrodotoxin (TTX)-sensitive fast Na+ spike faithfully followed repetitive depolarizing pulses with little change in spike duration or amplitude, while a strong outward rectification dominated responses to long-lasting depolarizations. High-threshold calcium spikes were uncovered following addition of potassium channel blockers. Calcium imaging using Calcium-Green dextran revealed a stimulus-evoked all-or-none TTX-sensitive calcium signal in simple and complex rosettes. All compartments of a complex rosette were activated during electrical activation of the mossy fibre, while individual simple and complex rosettes along an axon appeared to be isolated from one another in terms of calcium signalling. CGP55845 application showed that GABA B receptors mediated presynaptic inhibition of the calcium signal over the entire firing frequency range of mossy fibres. A paired-pulse depression of the calcium signal lasting more than 1?s affected burst firing in mossy fibres; this paired-pulse depression was reduced by GABA B antagonists. While our results indicated that a presynaptic rosette electrophysiologically functioned as a unit, topical GABA application showed that calcium signals in the branches of complex rosettes could be modulated locally, suggesting that cerebellar glomeruli may be dynamically sub-compartmentalized due to ongoing inhibition mediated by Golgi cells. This could provide a fine-grained control of mossy fibre-granule cell information transfer and synaptic plasticity within a mossy fibre rosette.

Thomsen, Louiza B.; Jorntell, Henrik; Midtgaard, Jens

2009-01-01

356

[Non-surgical forms of cerebellar hematoma (author's transl)].  

PubMed

Spontaneous cerebellar hemorrhage is a significant clinical entity because of its important incidence (more than 10 percent of intracranial hemorrhages) and its therapeutic possibilities. The diagnosis of this condition is difficult, but at the presnet time the Emi-scanner easily confirms the diagnosis. The surgical treatment was up until recently the only possible therapeutic approach, and it has been indiscriminately applied to all patients because of the high mortiality rate of this condition (80 percent). Two hypertensive patients who presented spontaneous cerebellar hematomas, verified by the scanner, were not submitted to surgery and both recovered spontaneously without sequelae. The existence of non-surgical forms of spontaneous cerebellar hemorrhage is discussed. Special attention is placed upon the variations in the level of consciousness and the presence or absence of acute hydrocephalus in the scanner in order to indicate the convenience of a surgical procedure. PMID:7366272

Jiménez García, M; Galdós Alcelay, L; Feijoo de Freixo, M

1980-02-10

357

Paraneoplastic cerebellar degeneration associated with lymphoepithelial carcinoma of the tonsil  

PubMed Central

Background Paraneoplastic cerebellar degeneration (PCD) is a classical tumor-associated, immune-mediated disease typically associated with gynecological malignancies, small-cell lung-cancer or lymphoma. Case presentation Here we present the case of a 38-year old male with an over 12 months rapidly progressive cerebellar syndrome. Extensive diagnostic workup revealed selective hypermetabolism of the right tonsil in whole-body PET. Histological examination after tonsillectomy demonstrated a lymphoepithelial carcinoma of the tonsil and the tongue base strongly suggesting a paraneoplastic cause of the cerebellar syndrome. To the best of our knowledge this is the first case of an association of a lymphoepithelial carcinoma, a rare pharyngeal tumor, with PCD. Conclusions In cases of classical paraneoplastic syndromes an extensive search for neoplasms should be performed including whole-body PET to detect tumors early in the course of the disease.

2013-01-01

358

An unusual cause of adult onset cerebellar ataxia with hypogonadism  

PubMed Central

We report an unusual case of sporadic adult onset cerebellar ataxia with hypogonadism. A 40-year-old unmarried man presented with progressive ataxia and dysarthria along with complaints of non-development of secondary sexual characteristics and erectile dysfunction. There were complaints of intermittent diarrhea. Clinical examination revealed a pan-cerebellar syndrome with features of hypoandrogenism. No eye movement abnormalities were evident. There were signs of malabsorption. Investigations confirmed the presence of auto-antibodies found in celiac disease, and a duodenal biopsy confirmed the same. Hypoandrogenism was postulated to be due to hypergonadotropic hypogonadism which has been mentioned in a few patients of celiac disease. However, the pattern seen in our patient was of a hypogonadotropic hypogonadism. This is probably secondary to an autoimmune hypophysitis seen in some patients in the absence of other clinical manifestations. Autoantibody testing should be a diagnostic necessity in any adult with a sporadic cerebellar ataxia.

Menon, Ramshekhar N.; Sanghani, Nirav; Javali, Mahendra; Jain, Neeraj; Shah, Arun B.

2009-01-01

359

An unusual cause of adult onset cerebellar ataxia with hypogonadism.  

PubMed

We report an unusual case of sporadic adult onset cerebellar ataxia with hypogonadism. A 40-year-old unmarried man presented with progressive ataxia and dysarthria along with complaints of non-development of secondary sexual characteristics and erectile dysfunction. There were complaints of intermittent diarrhea. Clinical examination revealed a pan-cerebellar syndrome with features of hypoandrogenism. No eye movement abnormalities were evident. There were signs of malabsorption. Investigations confirmed the presence of auto-antibodies found in celiac disease, and a duodenal biopsy confirmed the same. Hypoandrogenism was postulated to be due to hypergonadotropic hypogonadism which has been mentioned in a few patients of celiac disease. However, the pattern seen in our patient was of a hypogonadotropic hypogonadism. This is probably secondary to an autoimmune hypophysitis seen in some patients in the absence of other clinical manifestations. Autoantibody testing should be a diagnostic necessity in any adult with a sporadic cerebellar ataxia. PMID:20151008

Menon, Ramshekhar N; Sanghani, Nirav; Javali, Mahendra; Jain, Neeraj; Shah, Arun B

2009-01-01

360

Alpha-dystroglycan interactions affect cerebellar granule neuron migration.  

PubMed

The interaction of alpha-dystroglycan (a-DG) with its extracellular binding partners requires glycans attached to its mucin core domain, and defects in the glycosylation of a-DG are associated with both muscular dystrophy and neuronal migration defects. The involvement of a-DG and one of its ligands, agrin, in cerebellar neuronal migration was investigated. Antibodies directed against glycosylated a-DG inhibited granule neuron migration in cerebellar slice cultures. a-DG interactions did not appear to influence neurite outgrowth in cerebellar explant cultures, but enhanced granule neuron binding was observed on cells transfected with a-DG. These results suggest that interactions involving a-DG influence the strength of attachment of granule neurons to the a-DG-expressing Bergmann glial cells that guide granule neuron migration in the cerebellum. Experiments using anti-agrin antibodies suggest that agrin is not involved in these interactions. PMID:15160389

Qu, Qiang; Smith, Frances I

2004-06-15

361

Modulatory effects of theta burst stimulation on cerebellar nonsomatic functions.  

PubMed

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

2011-09-01

362

Disorders of cognitive and affective development in cerebellar malformations.  

PubMed

Acquired cerebellar lesions in adults and children can lead to the development of a complex behavioural pattern termed 'Cerebellar Cognitive Affective Syndrome' (Schmahmann and Sherman, Brain, 1998; 121: 561-79), which is characterized by reduced cognitive efficiency associated with specific neuropsychological deficits (executive and visuospatial disorders), expressive language disorders (mild agrammatism and anomia) and affective disorders with blunting of affect. It is not known whether a symptomatological picture such as this can also be found in congenital cerebellar malformations. We studied the behavioural developmental profile of 27 patients including children and adults with congenital malformations confined to the cerebellum, the largest studied sample to date. Extensive clinical and neuropsychological investigations highlight the presence of a wide range of disorders supporting the important role played by the cerebellum in the acquisition of higher-order cognitive and affective skills. The type and extent of cerebral reorganization processes in the presence of malformative lesions are difficult to predict and may possibly account for the variability of clinical phenotypes. It is, therefore, more difficult to identify a syndromic picture defined as exactly as is the case with acquired lesions. However, the pattern of deficits that we document is in remarkable agreement with the general profile of the Cerebellar Cognitive Affective Syndrome. Malformations affecting the cerebellar vermis induce affective and social disorders and evolve towards more unfavourable pictures often associated with an autistic symptomatology. Malformations of cerebellar hemispheres are more frequently associated with selective neuropsychological deficits involving mainly executive functions and visuospatial and linguistic abilities. Motor deficits are generally less severe, and tend to improve slowly and progressively, in some cases reaching almost complete functionality. Finally, the overall favourable evolution with an onset of skills in advanced age in a consistent subset of subjects suggests that individual follow-ups should be performed in order to monitor the quality and stability of impairments and acquired abilities over time. PMID:17872929

Tavano, Alessandro; Grasso, Rita; Gagliardi, Chiara; Triulzi, Fabio; Bresolin, Nereo; Fabbro, Franco; Borgatti, Renato

2007-10-01

363

Stereotactic evacuation of hypertensive cerebellar hemorrhage using plasminogen activator.  

PubMed

Treatment for hypertensive cerebellar hemorrhage still remains controversial as to whether direct surgical procedure is indicated or not. This is so even after the introduction of CT scan which easily demonstrates the location and size of the hematoma and the presence of hydrocephalus. In this paper, we present our experience of 20 patients with cerebellar hemorrhage treated by stereotactic evacuation using Komai's CT-stereotactic apparatus. All the patients had vertigo, cerebellar symptoms, dysfunction of brain stem or consciousness disturbance. The hematomas on CT scan were more than 28 mm in diameter. Acute obstructive hydrocephalus occurred in 90% of the patients with hematoma 40 mm or larger in size. The patients with consciousness disturbance were immediately operated on after the attack, and a drainage tube was placed in the hematoma cavity to drain cerebrospinal fluid and liquefied hematoma for one to eight days. On the other hand, when patients with hematoma around 30 mm in diameter complained vertigo for about two weeks, they also were operated on stereotactically. After the operation, their symptoms improved rapidly. The stereotactic operation could aspirate about 85% of the estimated hematoma volume and improved the hydrocephalus, except in one case in which the patient rapidly deteriorated to coma level with a large cerebellar hemorrhage and brain stem damage. This stereotactic evacuation of cerebellar hematoma using a plasminogen activator is effective for not only the removal of hematoma, but also for the treatment of secondary hydrocephalus following obstruction of the fourth ventricle by cerebellar hemorrhage.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2674756

Yokote, H; Komai, N; Nakai, E; Ueno, M; Hayashi, S; Terashita, T

1989-05-01

364

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.

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

2011-01-01

365

[Pediatric medulloblastoma presenting as cerebellar hemorrhage: a case report].  

PubMed

Medulloblastomas usually cause cerebellar ataxia and acute hydrocephalus owing to their increase in size. Cerebellar hemorrhage is an extremely rare initial clinical presentation of medulloblastoma. Herein, we report a case of medulloblastoma in an 8-year-old girl who presented with initial cerebellar intratumoral hemorrhage. The patient initially presented with mild headache;the differential diagnosis by using the initial computed tomography and magnetic resonance images was difficult, as bleeding from a cerebellar vascular malformation(cavernous angioma or arteriovenous malformation)was considered more likely. Hydrocephalus or typical findings indicative of medulloblastoma were not observed. We initially only observed the patient at another institution because the hematoma was relatively small(1.5×1×1cm). After follow-up imaging for pathological diagnosis, surgical removal was performed at our institute 49 days after the hemorrhage was observed. Complete tumor removal was achieved, and the histopathological diagnosis was medulloblastoma. The patient received whole brain and spinal irradiation(23.4Gy;posterior fossa local:50.4Gy)and chemotherapy(cyclophosphamide, 1,000mg/m2/day on day 1;vincristine, 1.5mg/m2/day on day 1;etoposide, 100mg/m2/day on days 1-3;cisplatin, 90mg/m2/day on day 2). No recurrences or neurological deficits were observed during a 2-year follow-up. This was a rare case of medulloblastoma presenting as cerebellar hemorrhage. Cerebellar medulloblastoma is among the common pediatric brain tumors;therefore, it should be diagnosed accurately and quickly. PMID:24920742

Furuhata, Masanori; Aihara, Yasuo; Eguchi, Seiichiro; Horiba, Ayako; Tanaka, Masahiko; Komori, Takashi; Okada, Yoshikazu

2014-06-01

366

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

367

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

368

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

369

An autopsied case of progressive supranuclear palsy presenting with cerebellar ataxia and severe cerebellar involvement.  

PubMed

A Japanese male patient presented with gait disturbance at the age of 69 years. His principal symptom was cerebellar ataxia for several years. He was initially diagnosed as having olivopontocerebellar atrophy because dysarthria and ataxia gradually developed, and head CT scan showed apparent atrophy of the cerebellum and brainstem and dilatation of the fourth ventricle. Later, he showed vertical gaze palsy, dysphagia, retrocollis, parkinsonism, axial dominant rigidity and grasp reflex, and therefore, the diagnosis was modified to progressive supranuclear palsy (PSP). Progressive atrophy of the frontotemporal lobe, cerebellum and brainstem, and dilatation of the lateral, third and fourth ventricles were evident on MRI. Gastrostomy and tracheotomy were performed 9 and 10 years after onset, respectively, and the patient died after 11 years disease duration. At autopsy the brain weighed 1000 g and showed atrophy of the frontotemporal lobe, cerebellum and brainstem. Neurofibrillary tangles, mainly globose-type revealed by Gallyas-Braak silver staining, were extensively observed in the cerebral cortex and subcortical grey matter. Numerous glial fibrillary tangles, including tuft-shaped astrocytes and coiled bodies, and extensive argyrophilic threads were also recognized, particularly in the frontal lobe, basal ganglia, cerebellar white matter, brainstem and spinal cord. The Purkinje cell layer showed severe neuron loss with Bergmann's gliosis, and the dentate nucleus showed severe neuron loss with grumose degeneration. Tau-positive/Gallyas-positive inclusions in the Purkinje cells and the glial cells of the Purkinje cell layer were observed. Pathological findings of the present patient were consistent with the diagnosis of PSP, but the olivopontocerebellar involvement, particularly in the cerebellum, was generally more severe, and the quantity of tau-positive/Gallyas-positive structures were more abundant than in typical PSP cases. The existence of a distinct, rare PSP subtype with severe olivopontocerebellar involvement, "PSP-C", which tends to be clinically misdiagnosed as spinocerebellar degeneration in the early disease stage, is noteworthy. The present case corresponded to this rare subtype of PSP. PMID:23320789

Iwasaki, Yasushi; Mori, Keiko; Ito, Masumi; Tatsumi, Shinsui; Mimuro, Maya; Yoshida, Mari

2013-10-01

370

Preserved Glucose Metabolism of Deep Cerebellar Nuclei in a Case of Multiple System Atrophy with Predominant Cerebellar Ataxia: F-18 Fluorodeoxyglucose Positron Emission Tomography Study  

PubMed Central

The cerebellar glucose metabolism of multiple system atrophy with predominant cerebellar ataxia (MSA-C) is known to be decreased but is not defined among areas of cerebellum. We encountered a 54-year-old man who developed dizziness and progressive ataxia followed by urinary incontinence and orthostatic hypotension, all of those symptoms progressed relentlessly and the symptoms responded poorly to levodopa therapy. Visual analysis and statistical parametric mapping analysis of F-18 fluorodeoxyglucose positron emission tomography showed hypometabolism of both cerebellar hemisphere, severe at cortical area, and pons. There was clear sparing of deep cerebellar nuclei. Our report, as we know, shows the first case of preserved glucose metabolism of deep cerebellar nuclei relative to cerebellar cortex in an MSA-C patient.

Kwon, Oh Dae; Ki, Chang-Seok

2010-01-01

371

Pure post-stroke cerebellar cognitive affective syndrome: a case report.  

PubMed

Cerebellar pathology commonly shows important motor signs and less evident cognitive dysfunction. The 'cerebellar cognitive affective syndrome' is characterised by impairment on executive function, spatial cognition, language and behaviour. We report the case of a man with acute onset of transitory motor features and severe mental disorders. Cranial CT and brain MRI revealed extended cerebellar lesions. Neuropsychological assessment disclosed deficits of attention, executive function and memory. Auditory event-related potentials showed abnormal P300. These data suggest a pure "cerebellar cognitive affective syndrome"and strengthen the hypothesis of cerebellar cognitive function modulation. PMID:15549508

Paulus, K S; Magnano, I; Conti, M; Galistu, P; D'Onofrio, M; Satta, W; Aiello, I

2004-10-01

372

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

373

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 26 November 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 26 November: as much as 397 plus or minus 15 K (lsigma) at 30 ppbv N2O and 640 ppbv CH4, and falling to 28 plus or minus 13 K above 200 ppbv N2O and 1280 ppbv CH4. Changes in theta were determined on five N2O and CH4 isopleths from 26 November through 12 March, and descent rates were calculated on each N2O isopleth for several time intervals. The maximum descent rates were seen between 26 November and 27 January: 0.82 plus or minus 0.20 K/day averaged over 50- 250 ppbv N2O. By late winter (26 February to 12 March), the average rate had decreased to 0.10 plus or minus 0.25 K/day. Descent rates also decreased with increasing N2O; the winter average (26 November to 5 March) descent rate varied from 0.75 plus or minus 0.10 K/day at 50 ppbv to 0.40 plus or minus 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, Jeffrey 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, Chrisotopher R.

2002-01-01

374

Cerebellar TMS in treatment of a patient with cerebellar ataxia: evidence from clinical, biomechanics and neurophysiological assessments.  

PubMed

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 cerebellar-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

2013-10-01

375

Cerebellar connections to the rostral reticular nucleus of the thalamus in the rat  

PubMed Central

We studied the cerebellar connections to the reticular nucleus thalamus (RNT) by means of retrograde axonal transport of horseradish peroxidase (HRP) in the rat. Specific HRP pressure injections to the rostral RNT (1.6–1.8 mm caudal to bregma) resulted in retrograde labelling of neurones in the cerebellar nuclei. The rostral RNT showed specific topographical organization of its cerebellar connections. Microinjections into the rostral RNT, 1.6 mm caudal to bregma, produced numerous HRP-labelled neurones within the anterior interposed (emboliform nucleus) and scarce HRP-labelled neurones within the lateral (dentate nucleus) cerebellar nuclei, whereas injections into the rostral RNT, 1.8 mm caudal to bregma, produced numerous HRP-labelled neurones within the posterior interposed (globose nucleus) and scarce lightly HRP-labelled neurones within the lateral (dentate nucleus) cerebellar nuclei. Cerebellar connections with the rostral RNT were exclusively ipsilateral to the injection site. No HRP-labelled cells were detected in the medial (fastigial nucleus) cerebellar nucleus. The cerebellar connections reach the RNT via the superior cerebellar peduncle. By contrast, HRP injections into the anterior, posterior interposed and lateral cerebellar nuclei produced no labelled cells within the RNT. This study demonstrates the existence of direct cerebello-RNT but not RNT-cerebellar connections. The presence of the cerebello-RNT connections introduces a new route through which the cerebellum may influence RNT and thus cerebral cortical activity.

Cavdar, Safiye; Onat, F Yilmaz lyz; Yananli, Hasan R; Sehirli, Umit S; Tulay, Cumhur; Saka, Erdin,; Gurdal, Esra

2002-01-01

376

Cerebellar connections to the rostral reticular nucleus of the thalamus in the rat.  

PubMed

We studied the cerebellar connections to the reticular nucleus thalamus (RNT) by means of retrograde axonal transport of horseradish peroxidase (HRP) in the rat. Specific HRP pressure injections to the rostral RNT (1.6-1.8 mm caudal to bregma) resulted in retrograde labelling of neurones in the cerebellar nuclei. The rostral RNT showed specific topographical organization of its cerebellar connections. Microinjections into the rostral RNT, 1.6 mm caudal to bregma, produced numerous HRP-labelled neurones within the anterior interposed (emboliform nucleus) and scarce HRP-labelled neurones within the lateral (dentate nucleus) cerebellar nuclei, whereas injections into the rostral RNT, 1.8 mm caudal to bregma, produced numerous HRP-labelled neurones within the posterior interposed (globose nucleus) and scarce lightly HRP-labelled neurones within the lateral (dentate nucleus) cerebellar nuclei. Cerebellar connections with the rostral RNT were exclusively ipsilateral to the injection site. No HRP-labelled cells were detected in the medial (fastigial nucleus) cerebellar nucleus. The cerebellar connections reach the RNT via the superior cerebellar peduncle. By contrast, HRP injections into the anterior, posterior interposed and lateral cerebellar nuclei produced no labelled cells within the RNT. This study demonstrates the existence of direct cerebello-RNT but not RNT-cerebellar connections. The presence of the cerebello-RNT connections introduces a new route through which the cerebellum may influence RNT and thus cerebral cortical activity. PMID:12489760

Cavdar, Safiye; Onat, Filiz Yilmaz; Yananli, Hasan R; Sehirli, Umit S; Tulay, Cumhur; Saka, Erdinç; Gürdal, Esra; Filiz, Y O

2002-12-01

377

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

PubMed

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 ([18F]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. PMID:3499490

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

1987-11-01

378

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.

van Dorp, Stijn; De Zeeuw, Chris I.

2014-01-01

379

Cerebellar Vermian Atrophy after Neonatal Hypoxic-Ischemic Encephalopathy  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Although pathologic evidence of cerebellar injury due to birth asphyxia is well described, neuroimaging evidence is sparse. The primary purpose of this retrospective study was to evaluate the early and late imaging findings in the cerebellum of patients who had neonatal hypoxic-ischemic encephalopathy with thalamic edema shown by neonatal CT. The secondary aims were to validate thalamic

Michael A. Sargent; Kenneth J. Poskitt; Elke H. Roland; Alan Hill; Glenda Hendson

380

Cerebellar Damage Produces Selective Deficits in Verbal Working Memory  

ERIC Educational Resources Information Center

The cerebellum is often active in imaging studies of verbal working memory, consistent with a putative role in articulatory rehearsal. While patients with cerebellar damage occasionally exhibit a mild impairment on standard neuropsychological tests of working memory, these tests are not diagnostic for exploring these processes in detail. The…

Ravizza, Susan M.; Mccormick, Cristin A.; Schlerf, John E.; Justus, Timothy; Ivry, Richard B.; Fiez, Julie A.

2006-01-01

381

Resistance to hypoglycemia of cerebellar transplants in the rat forebrain  

Microsoft Academic Search

Prolonged insulin-induced hypoglycemia causes widespread loss of neurons and permanent brain damage with irreversible coma. Although the deprivation of carbohydrate stores affects all brain regions, the breakdown of energy metabolism and cessation of protein synthesis occur predominantly in the cerebral cortex, caudoputamen and hippocampus. The cerebellum, brain stem and hypothalamus are largely resistant. Following transplantation of the cerebellar anlage of

P. Kleihues; M. Kiessling; R. Thilmann; Y. Xie; A. Uozumi; B. Volk

1986-01-01

382

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

383

Bilateral intracerebellar calcification associated with cerebellar hematoma. Case report.  

PubMed

A case of bilateral intracerebellar calcificaiton associated with cerebellar hematoma on the left side is reported. Clinical and microscopic examination failed to clarify the causes of calcification and hematoma. It is postulated that hemorrhage occurred from time to time through the fragile calcified vessel walls, since some portions of the organized hematoma were composed of massive erythrocytes. PMID:712397

Kawakami, Y; Nakao, Y; Tabuchi, K; Nosaka, Y; Ohmoto, T

1978-11-01

384

Distal posterior inferior cerebellar artery aneurysm: case report  

Microsoft Academic Search

The majority of posterior inferior cerebellar artery (PICA) aneurysms are usually found on the bifurcation of the vertebral artery (VA) - PICA junction. Aneurysms arising from more peripheral PICA seg- ments named distal PICA aneurysm are uncommon. The major clinical manifestation is that of an intracra- nial bleeding and the site of hemorrhage is related to the PICA segment originating

Ricardo Ramina; Viviane Aline Buffon; Jerônimo Buzetti Milano; Erasmo Barros da Silva Jr; Kelly Cristina Bordignon

2005-01-01

385

Angioarchitectonics of rat cerebellar cortex during pre- and postnatal development  

Microsoft Academic Search

The adult arrangement and the development of stem vessels and capillaries was studied in the rat cerebellum. In principle, stem vessels branch and terminate at three levels: (1) the molecular layer, (2) the Purkinje cell-granular layer, and (3) the cerebellar white matter. All stem vessels are interconnected by the capillary network which is most dense in the Purkinje cell—granular layer.

N. G. Conradi; J. Engvall; J. R. Wolff

1980-01-01

386

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

387

Cerebellar damage impairs executive control and monitoring of movement generation.  

PubMed

Executive control of motor responses is a psychological construct of the executive system. Several studies have demonstrated the involvement of the cerebral cortex, basal ganglia, and thalamus in the inhibition of actions and monitoring of performance. The involvement of the cerebellum in cognitive function and its functional interaction with basal ganglia have recently been reported. Based on these findings, we examined the hypothesis of cerebellar involvement in executive control by administering a countermanding task in patients with focal cerebellar damage. The countermanding task requires one to make a movement in response to a 'go' signal and to halt it when a 'stop' signal is presented. The duration of the go process (reaction time; RT), the duration of the stop process (stop signal reaction time; SSRT), and their relationship, expressed by a psychometric function, are recorded as measures of executive control. All patients had longer go process duration in general and in particular, as a proactive control, as demonstrated by the increase in RT after erroneously performed stop trials. Further, they were defective in the slope of the psychometric function indicating a difficulty on triggering the stop process, although the SSRT did not differ from controls. Notably, their performance was worse when lesions affected deep cerebellar nuclei. Our results support the hypothesis that the cerebellum regulates the executive control of voluntary actions. We speculate that its activity is attributed to specific cerebellar influence over the cortico-striatal loop. PMID:24465830

Brunamonti, Emiliano; Chiricozzi, Francesca R; Clausi, Silvia; Olivito, Giusy; Giusti, Maria Assunta; Molinari, Marco; Ferraina, Stefano; Leggio, Maria

2014-01-01

388

Motor learning induces astrocytic hypertrophy in the cerebellar cortex  

Microsoft Academic Search

Motor skill learning, but not mere motor activity, is associated with an increase in both synapse number and glial cell volume within the cerebellar cortex. The increase in synapse number has been shown to persist for at least 4 weeks in the absence of continued training. The present experiment similarly examined how a prolonged interruption in training affects the training-induced

Jeffrey A. Kleim; Julie A. Markham; Kapil Vij; Jennifer L. Freese; David H. Ballard; William T. Greenough

2007-01-01

389

Serous Adenocarcinoma of the Uterus Presenting as Paraneoplastic Cerebellar Degeneration  

Microsoft Academic Search

Paraneoplastic cerebellar degeneration is a rare complication of cancer and is most frequently associated with lung, ovary, and breast cancers as well as Hodgkins lymphoma. A 74-year-old female with a past history of breast cancer presented with vomiting, ataxia, slurred speech, and dizziness. Her serum chemistry, thyroid and liver function tests, acetylcholine antibodies, serum cortisol, CT, and MRI imaging were

J. Bram Johns; Kunle O. Odunsi; S. Fleischman; Masoud Azodi; Peter E. Schwartz

1999-01-01

390

Learning convergence in the cerebellar model articulation controller  

Microsoft Academic Search

A new way to look at the learning algorithm in the cerebellar model articulation controller (CMAC) proposed by J.S. Albus (1975) is presented. A proof that the CMAC learning always converges with arbitrary accuracy on any set of training data is obtained. An alternative way to implement CMAC based on the insights obtained in the process is proposed. The scheme

Yiu-fai Wong; Athanasios Sideris

1992-01-01

391

Verb Generation in Children and Adolescents with Acute Cerebellar Lesions  

ERIC Educational Resources Information Center

The aim of the present study was to examine verb generation in a larger group of children and adolescents with acute focal lesions of the cerebellum. Nine children and adolescents with cerebellar tumours participated. Subjects were tested a few days after tumour surgery. For comparison, a subgroup was tested also 1 or 2 days before surgery. None…

Frank, B.; Schoch, B.; Hein-Kropp, C.; Dimitrova, A.; Hovel, M.; Ziegler, W.; Gizewski, E. R.; Timmann, D.

2007-01-01

392

Caytaxin Deficiency Disrupts Signaling Pathways in Cerebellar Cortex  

PubMed Central

The genetically dystonic (dt) rat, an autosomal recessive model of generalized dystonia, harbors an insertional mutation in Atcay. As a result, dt rats are deficient in Atcay transcript and the neuronally-restricted protein caytaxin. Previous electrophysiological and biochemical studies have defined olivocerebellar pathways, particularly the climbing fiber projection to Purkinje cells, as a site of significant functional abnormality in dt rats. In normal rats, Atcay transcript is abundantly expressed in the granular and Purkinje cell layers of cerebellar cortex. To better understand the consequences of caytaxin deficiency in cerebellar cortex, differential gene expression was examined in dt rats and their normal littermates. Data from oligonucleotide microarrays and quantitative real-time RT-PCR (QRT-PCR) identified phosphatidylinositol signaling pathways, calcium homeostasis, and extracellular matrix interactions as domains of cellular dysfunction in dt rats. In dt rats, genes encoding the corticotropin-releasing hormone receptor 1 (CRH-R1, Crhr1) and calcium-transporting plasma membrane ATPase 4 (PMCA4, Atp2b4) showed the greatest up-regulation with QRT-PCR. Immunocytochemical experiments demonstrated that CRH-R1, CRH, and PMCA4 were up-regulated in cerebellar cortex of mutant rats. Along with previous electrophysiological and pharmacological studies, our data indicate that caytaxin plays a critical role in the molecular response of Purkinje cells to climbing fiber input. Caytaxin may also contribute to maturational events in cerebellar cortex.

Xiao, Jianfeng; Gong, Suzhen; LeDoux, Mark S.

2007-01-01

393

Cerebellar zonal patterning relies on purkinje cell neurotransmission.  

PubMed

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; Sillitoe, Roy V

2014-06-11

394

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

395

Cerebellar hyperactivity during smooth pursuit eye movements in bipolar disorder  

Microsoft Academic Search

IntroductionSmooth pursuit eye movements (SPEM) are abnormal in individuals with schizophrenia and individuals with bipolar disorder. Functional imaging methods have revealed greater hippocampal activity and less frontotemporal, visual, and posterior cerebellar activity in individuals with schizophrenia when performing a SPEM task. The underlying neurobiology of SPEM deficits in bipolar disorder is unknown.

Laura Frances Martin; Ann Olincy; Randy G. Ross; Yiping P. Du; Debra Singel; Shireen Shatti; Jason R. Tregellas

2011-01-01

396

Predicting and correcting ataxia using a model of cerebellar function.  

PubMed

Cerebellar damage results in uncoordinated, variable and dysmetric movements known as ataxia. Here we show that we can reliably model single-joint reaching trajectories of patients (n = 10), reproduce patient-like deficits in the behaviour of controls (n = 11), and apply patient-specific compensations that improve reaching accuracy (P < 0.02). Our approach was motivated by the theory that the cerebellum is essential for updating and/or storing an internal dynamic model that relates motor commands to changes in body state (e.g. arm position and velocity). We hypothesized that cerebellar damage causes a mismatch between the brain's modelled dynamics and the actual body dynamics, resulting in ataxia. We used both behavioural and computational approaches to demonstrate that specific cerebellar patient deficits result from biased internal models. Our results strongly support the idea that an intact cerebellum is critical for maintaining accurate internal models of dynamics. Importantly, we demonstrate how subject-specific compensation can improve movement in cerebellar patients, who are notoriously unresponsive to treatment. PMID:24812203

Bhanpuri, Nasir H; Okamura, Allison M; Bastian, Amy J

2014-07-01

397

Early morphological changes of hereditary cerebellar cortical abiotrophy in rabbits.  

PubMed

We previously investigated the hereditary cerebellar cortical abiotrophy in littermates at postnatal day (PD) 25-31 delivered from a pair of rabbits. To estimate the onset time and incipient lesions associated with the cerebellar cortical abiotrophy of the cases, we mated the same pair again and examined early stages of the disease in F1 rabbit showing ataxia (PD 15), finding evidence that the ataxia is passed to subsequent generations via autosomal recessive inheritance. Clinical signs of the affected rabbit showed early-onset dysstasia and ataxia. The affected rabbit showed apoptotic granular cells before and after migration completion, degeneration (swelling) of parallel fiber terminals, abnormal junction (invaginated junction) of the parallel fiber-Purkinje cell synapses and irregular orientation of the Purkinje dendritic arbor in the molecular layer. Additionally, a reduced number of synaptic junctions between parallel fibers and Purkinje cells were detected, as well as at PD 25-31. Secondary changes, such as reduction or degeneration of Purkinje cells and granular cells were not yet observed at early stages. As synapse abnormality preceded the degeneration or reduction of Purkinje and granular cells at early stages, we concluded that the pathogenesis of the present cerebellar lesion was caused by failed synaptogenesis during postnatal cerebellar development. PMID:23182865

Sato, Junko; Sasaki, Satoshi; Yamada, Naoaki; Tsuchitani, Minoru

2013-05-01

398

Tumor-specific killer cells in paraneoplastic cerebellar degeneration  

Microsoft Academic Search

Models for immune-mediated tumor regression in mice have defined an essential role for cytotoxic T lymphocytes (CTLs); however, naturally occurring tumor immunity in humans is poorly understood. Patients with paraneoplastic cerebellar degeneration (PCD) provide an opportunity to explore the mechanisms underlying tumor immunity to breast and ovarian cancer. Although tumor immunity and autoimmune neuronal degeneration in PCD correlates with a

Matthew L. Albert; Jennifer C. Darnell; Armin Bender; Loise M. Francisco; Nina Bhardwaj; Robert B. Darnell

1998-01-01

399

Development of GABA innervation in the cerebral and cerebellar cortices  

Microsoft Academic Search

In many areas of the vertebrate brain, such as the cerebral and cerebellar cortices, neural circuits rely on inhibition mediated by GABA (?-aminobutyric acid) to shape the spatiotemporal patterns of electrical signalling. The richness and subtlety of inhibition are achieved by diverse classes of interneurons that are endowed with distinct physiological properties. In addition, the axons of interneurons display highly

G. Di Cristo; F. Ango; Z. J. Huang

2007-01-01

400

Transcranial magnetic stimulation in patients with cerebellar stroke.  

PubMed

Conduction time of the central motor pathways (CMCT) by transcranial magnetic stimulation (TMS) was performed within the first two weeks in 7 patients with isolated hemicerebellar lesions after stroke. Cerebellar infarcts were small (< 2 cm in diameter) in 5 patients and no brainstem structure was involved in CT studies. The threshold (3 cases) and CMCT (4 cases) were abnormal or asymmetric by stimulation of the motor cortex contralateral to the impaired hemicerebellum. The follow-up study in 2 patients revealed electrophysiological improvement closely related to clinical cerebellar recovery rate. CMCT was significantly longer by cortex stimulation contralateral to the impaired hemicerebellum than by ipsilateral stimulation. Prolonged CMCT was significantly correlated with the rated severity of cerebellar signs. Increased threshold may be due to depressed facilitating action of the deep cerebellar nuclei on contralateral motor cortex. Abnormal CMCT might result in reduced size and increased dispersion of the efferent volleys. Recovery of electrophysiological results could represent in part true potentially reversible functional deficit. Whichever the pathophysiological mechanisms involved, our results demonstrate that the cerebellum dysfunction plays a role in the abnormalities of CMCT elicited by TMS. PMID:9286629

Cruz-Martínez, A; Arpa, J

1997-01-01

401

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

402

Adaptive filters and internal models: multilevel description of cerebellar function.  

PubMed

Cerebellar function is increasingly discussed in terms of engineering schemes for motor control and signal processing that involve internal models. To address the relation between the cerebellum and internal models, we adopt the chip metaphor that has been used to represent the combination of a homogeneous cerebellar cortical microcircuit with individual microzones having unique external connections. This metaphor indicates that identifying the function of a particular cerebellar chip requires knowledge of both the general microcircuit algorithm and the chip's individual connections. Here we use a popular candidate algorithm as embodied in the adaptive filter, which learns to decorrelate its inputs from a reference ('teaching', 'error') signal. This algorithm is computationally powerful enough to be used in a very wide variety of engineering applications. However, the crucial issue is whether the external connectivity required by such applications can be implemented biologically. We argue that some applications appear to be in principle biologically implausible: these include the Smith predictor and Kalman filter (for state estimation), and the feedback-error-learning scheme for adaptive inverse control. However, even for plausible schemes, such as forward models for noise cancellation and novelty-detection, and the recurrent architecture for adaptive inverse control, there is unlikely to be a simple mapping between microzone function and internal model structure. This initial analysis suggests that cerebellar involvement in particular behaviours is therefore unlikely to have a neat classification into categories such as 'forward model'. It is more likely that cerebellar microzones learn a task-specific adaptive-filter operation which combines a number of signal-processing roles. PMID:23391782

Porrill, John; Dean, Paul; Anderson, Sean R

2013-11-01

403

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.

Pong, Milton; Gibson, Alan R.

2010-01-01

404

Cerebellar damage diminishes long-latency responses to multijoint perturbations  

PubMed Central

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.

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

2013-01-01

405

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

406

Sensitivity studies of 4D descent strategies in an advanced metering environment  

NASA Technical Reports Server (NTRS)

An investigation of utilizing various 4D airplane descent strategies in an advanced time-based metering environment was conducted. The three strategies considered were clean-idle Mach/CAS, constant flight path angle (CFPA) Mach/CAS, and fuel-optimal. Traffic inputs consisted of all combinatory pairs of three types of commercial turbojets (B737-300, B747-200, and B767-200) and two weight classes for each airplane type. Sensitivities of traffic throughput and fleet fuel to descent strategies, both among themselves and in combination, for different assigned meter fix times and traffic pairings were studied under controlled initial conditions.

Izumi, K. H.

1986-01-01

407

LaBonte's method revisited: An effective steepest descent method for micromagnetic energy minimization  

NASA Astrophysics Data System (ADS)

We present a steepest descent energy minimization scheme for micromagnetics. The method searches on a curve that lies on the sphere which keeps the magnitude of the magnetization vector constant. The step size is selected according to a modified Barzilai-Borwein method. Standard linear tetrahedral finite elements are used for space discretization. For the computation of quasistatic hysteresis loops, the steepest descent minimizer is faster than a Landau-Lifshitz micromagnetic solver by more than a factor of two. The speed up on a graphic processor is 4.8 as compared to the fastest single-core central processing unit (CPU) implementation.

Exl, Lukas; Bance, Simon; Reichel, Franz; Schrefl, Thomas; Peter Stimming, Hans; Mauser, Norbert J.

2014-05-01

408

Development of Cerebellar Neurons and Glias Revealed by in Utero Electroporation: Golgi-Like Labeling of Cerebellar Neurons and Glias  

PubMed Central

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.

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

2013-01-01

409

Disorders of the cerebellum: ataxia, dysmetria of thought, and the cerebellar cognitive affective syndrome.  

PubMed

Many diseases involve the cerebellum and produce ataxia, which is characterized by incoordination of balance, gait, extremity and eye movements, and dysarthria. Cerebellar lesions do not always manifest with ataxic motor syndromes, however. The cerebellar cognitive affective syndrome (CCAS) includes impairments in executive, visual-spatial, and linguistic abilities, with affective disturbance ranging from emotional blunting and depression, to disinhibition and psychotic features. The cognitive and psychiatric components of the CCAS, together with the ataxic motor disability of cerebellar disorders, are conceptualized within the dysmetria of thought hypothesis. This concept holds that a universal cerebellar transform facilitates automatic modulation of behavior around a homeostatic baseline, and the behavior being modulated is determined by the specificity of anatomic subcircuits, or loops, within the cerebrocerebellar system. Damage to the cerebellar component of the distributed neural circuit subserving sensorimotor, cognitive, and emotional processing disrupts the universal cerebellar transform, leading to the universal cerebellar impairment affecting the lesioned domain. The universal cerebellar impairment manifests as ataxia when the sensorimotor cerebellum is involved and as the CCAS when pathology is in the lateral hemisphere of the posterior cerebellum (involved in cognitive processing) or in the vermis (limbic cerebellum). Cognitive and emotional disorders may accompany cerebellar diseases or be their principal clinical presentation, and this has significance for the diagnosis and management of patients with cerebellar dysfunction. PMID:15377747

Schmahmann, Jeremy D

2004-01-01

410

Determinants of cerebellar and cerebral volume in the general elderly population.  

PubMed

In a population-based study of 3962 community-dwelling nondemented elderly we investigated the relation of age, sex, cardiovascular risk factors, and the presence of infarcts with cerebellar volume, and its interrelationship with cerebral volumes. Cerebellar and cerebral gray and white matter were segmented using Freesurfer version 4.5 (http://surfer.nmr.mgh.harvard.edu/). We used linear regression analyses to model the relationship between age, sex, cardiovascular risk factors, brain infarcts, white matter lesions (WMLs) and cerebellar and cerebral volume. Smaller cerebellar volumes with increasing age were mainly driven by loss of white matter. Diabetes, higher serum glucose and lower cholesterol levels were related to smaller cerebellar volume. No association was found between hypertension, smoking, apolipoprotein E (ApoE) genotype, and cerebellar volume. Supratentorial lacunar infarcts and WMLs were related to smaller cerebellar volume. Infratentorial infarcts were related to smaller cerebellar white matter volume and total cerebral volume. This study suggests that determinants of cerebellar volume do not entirely overlap with those established for cerebral volume. Furthermore, presence of infarcts or WMLs in the cerebrum can affect cerebellar volume. PMID:22405042

Hoogendam, Yoo Young; van der Geest, Jos N; van der Lijn, Fedde; van der Lugt, Aad; Niessen, Wiro J; Krestin, Gabriel P; Hofman, Albert; Vernooij, Meike W; Breteler, Monique M B; Ikram, M Arfan

2012-12-01

411

Justification of the Steepest Descent Method for the Integral Statement of an Inverse Problem for a Hyperbolic Equation  

Microsoft Academic Search

Under consideration is the steepest descent method for solving the problem of determination of a coefficient in a hyperbolic equation in integral statement. The properties of solutions to the direct and inverse problems are studied. Estimates for the objective functional and its gradient are obtained. Convergence in the mean is proved for the steepest descent method for minimizing the residual

S. I. Kabanikhin; K. T. Iskakov

2001-01-01

412

[Experience of 23 cases of cerebellar hemorrhage--indication for evacuation of cerebellar hematoma].  

PubMed

Twenty-three cases of cerebellar hemorrhage diagnosed by CTscan were evaluated. The subject were 13 males and 10 females and the ages of the patients were 58 years in average ranging from 24 to 83 years. Fourteen cases were treated surgically. Evacuation of hematoma by suboccipital craniectomy were performed in 11 patients and suboccipital decompression alone in one case. Two cases were underwent ventricular drainage alone for treatment of hydrocephalus. ADL assessed at discharge of the hospital was as follows: ADL 1 or 2 in 13 patients, ADL 3 or 4 in 5 patients and ADL 5 (dead) in 5 patients. The patients with small hematoma of less than 40 mm in diameter on CTscan were recovered to ADL 1 or 2 regardless of surgical or conservative treatments. The authors concluded that evacuation of hematoma is indicated for the patients with hematoma of more than 40 mm in diameter on CTscan, for the patients whose consciousness level is progressively aggravated regardless of size of hematoma and also for the patients whose CTscan shows deformity or obstruction of ambient and/or prepontine cisterns. PMID:3240922

Ishikawa, T; Nakagawa, Y; Kitaoka, K; Hida, K; Kitagawa, M

1988-09-01

413

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

414

Smart-Divert Powered Descent Guidance to Avoid the Backshell Landing Dispersion Ellipse  

NASA Technical Reports Server (NTRS)

A smart-divert capability has been added into the Powered Descent Guidance (PDG) software originally developed for Mars pinpoint and precision landing. The smart-divert algorithm accounts for the landing dispersions of the entry backshell, which separates from the lander vehicle at the end of the parachute descent phase and prior to powered descent. The smart-divert PDG algorithm utilizes the onboard fuel and vehicle thrust vectoring to mitigate landing error in an intelligent way: ensuring that the lander touches down with minimum- fuel usage at the minimum distance from the desired landing location that also avoids impact by the descending backshell. The smart-divert PDG software implements a computationally efficient, convex formulation of the powered-descent guidance problem to provide pinpoint or precision-landing guidance solutions that are fuel-optimal and satisfy physical thrust bound and pointing constraints, as well as position and speed constraints. The initial smart-divert implementation enforced a lateral-divert corridor parallel to the ground velocity vector; this was based on guidance requirements for MSL (Mars Science Laboratory) landings. This initial method was overly conservative since the divert corridor was infinite in the down-range direction despite the backshell landing inside a calculable dispersion ellipse. Basing the divert constraint instead on a local tangent to the backshell dispersion ellipse in the direction of the desired landing site provides a far less conservative constraint. The resulting enhanced smart-divert PDG algorithm avoids impact with the descending backshell and has reduced conservatism.

Carson, John M.; Acikmese, Behcet

2013-01-01

415

Pattern recognition using a family of design algorithms based upon the generalized probabilistic descent method  

Microsoft Academic Search

This paper provides a comprehensive introduction to a novel approach to pattern recognition which is based on the generalized probabilistic descent method (GPD) and its related design algorithms. The paper contains a survey of recent recognizer design techniques, the formulation of GPD, the concept of minimum classification error learning that is closely related to the GPD formalization, a relational analysis

SHIGERU KATAGIRI; Biing-Hwang Juang; Chin-Hui Lee

1998-01-01

416

Space shuttle descent flight control design requirements and experiments Learned, Pt. 1 p 617-628  

NASA Technical Reports Server (NTRS)

Some of the lessons learned during the development of the Space Shuttle descent flight control system (FCS) are reviewed. Examples confirm the importance for requirements definition, systems level analyses, and testing. In sounding these experiences may have implication for future designs or suggest the discipline required in this engineering art.

Kafer, G.; Wilson, D.

1983-01-01

417

Entry descent, and landing scenario for the Mars Exploration Rover mission  

Microsoft Academic Search

In January 2004, the Mars Exploration Rover (MER) mission will land two landers on the surface of Mars. Both landers will deliver a rover to the surface using an entry, descent, and landing (EDL) scenario based on Mars Pathfinder heritage. However, the entry conditions and environments are different from that of Mars Pathfinder. Unique challenges are present due to the

Prasun N. Desai; Wayne J. Lee

2004-01-01

418

Meteorological Predictions in Support of the Mars Science Laboratory Entry, Descent and Landing  

Microsoft Academic Search

The Mars Science Laboratory (MSL) entry, descent, and landing (EDL) system employs a standard parachute strategy followed by a new sky crane concept where the rover is lowered to the ground via a tether from a hovering entry vehicle. As with previous missions, EDL system performance is sensitive to atmospheric conditions. While some observations characterizing the mean, large-scale atmospheric temperature

A. Rothchild; S. C. Rafkin; R. A. Pielke Sr.

2010-01-01

419

Final STS35 Columbia descent BET products and results for LaRC OEX investigations  

Microsoft Academic Search

Final STS-35 'Columbia' descent Best Estimate Trajectory (BET) products have been developed for Langley Research Center (LaRC) Orbiter Experiments (OEX) investigations. Included are the reconstructed inertial trajectory profile; the Extended BET, which combines the inertial data and, in this instance, the National Weather Service atmospheric information obtained via Johnson Space Center; and the Aerodynamic BET. The inertial BET utilized Inertial

Kevin F. Oakes; John T. Findlay; Rachel A. Jasinski; James S. Wood

1991-01-01

420

Cinco De Mayo, Normative Whiteness, and the Marginalization of Mexican-Descent Students  

ERIC Educational Resources Information Center

This case study is concerned with how institutional practices of normative whiteness can impede the school involvement of Mexican-descent students. It examines how damaging forms of white normativity can operate in school settings where one might least expect to find them: in commemorations of Mexican cultural holidays. The author shows how such…

Hurd, Clayton A.

2008-01-01

421

Perceived Factors Influencing the Academic Underachievement of Talented Students of Puerto Rican Descent.  

ERIC Educational Resources Information Center

A study explored the self and environmental perceptions of six talented high school students of Puerto Rican descent who were underachieving. The absence of early appropriate academic experiences thwarted students' possibilities of developing their high abilities or talents. A model explaining underachievement and suggestions for meeting students'…

Diaz, Eva I.

1998-01-01

422

A concept for the entry, descent, and landing of high-mass payloads at Mars  

Microsoft Academic Search

The architecture concepts and aggressive science objectives for the next phases of Mars exploration will require landed masses an order of magnitude or greater than any Mars mission previously planned or flown. Additional studies have shown the requirements for missions more ambitious than the 2009 Mars Science Laboratory (?900kg payload mass) to extend beyond the capabilities of Viking-heritage entry, descent,

Ashley M. Korzun; Gregory F. Dubos; Curtis K. Iwata; Benjamin A. Stahl; John J. Quicksall

2010-01-01

423

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

424

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

425

Spread of cattle led to the loss of matrilineal descent in Africa: a coevolutionary analysis.  

PubMed Central

Matrilineal descent is rare in human societies that keep large livestock. However, this negative correlation does not provide reliable evidence that livestock and descent rules are functionally related, because human cultures are not statistically independent owing to their historical relationships (Galton's problem). We tested the hypothesis that when matrilineal cultures acquire cattle they become patrilineal using a sample of 68 Bantu- and Bantoid-speaking populations from sub-Saharan Africa. We used a phylogenetic comparative method to control for Galton's problem, and a maximum-parsimony Bantu language tree as a model of population history. We tested for coevolution between cattle and descent. We also tested the direction of cultural evolution--were cattle acquired before matriliny was lost? The results support the hypothesis that acquiring cattle led formerly matrilineal Bantu-speaking cultures to change to patrilineal or mixed descent. We discuss possible reasons for matriliny's association with horticulture and its rarity in pastoralist societies. We outline the daughter-biased parental investment hypothesis for matriliny, which is supported by data on sex, wealth and reproductive success from two African societies, the matrilineal Chewa in Malawi and the patrilineal Gabbra in Kenya.

Holden, Clare Janaki; Mace, Ruth

2003-01-01

426

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

427

The Cyclic Coordinate Descent in Hydrothermal Optimization Problems with Non-Regular Lagrangian  

NASA Astrophysics Data System (ADS)

In this paper we present an algorithm, inspired by the cyclic coordinate descent method, which allows the resolution of hydrothermal optimization problems involving pumped-storage plants. The proof of the convergence of the succession generated by the algorithm was based on the use of an appropriate adaptation of Zangwill's global theorem of convergence.

Bayón, L.; Grau, J. M.; Ruiz, M. M.; Suárez, P. M.

2007-12-01

428

Coherent Beam Combining of Fiber Amplifiers Using Stochastic Parallel Gradient Descent Algorithm and Its Application  

Microsoft Academic Search

We present theoretical and experimental research on coherent beam combining of fiber amplifiers using stochastic parallel gradient descent (SPGD) algorithm. The feasibility of coherent beam combining using SPGD algorithm is detailed analytically. Numerical simulation is accomplished to explore the scaling potential to higher number of laser beams. Experimental investigation on coherent beam combining of two and three W-level fiber amplifiers

Pu Zhou; Zejin Liu; Xiaolin Wang; Yanxing Ma; Haotong Ma; Xiaojun Xu; Shaofeng Guo

2009-01-01

429

Coherent beam combination of fiber lasers based on the stochastic parallel gradient descent algorithm  

Microsoft Academic Search

Coherent beam combination of fiber laser arrays plays an important role in realizing high power, high radiance fiber laser systems. The stochastic parallel gradient descent (SPGD) algorithm is a newly developed optimization method using the technique of parallel perturbation and stochastic approximation and it is expected that this algorithm can reduce the cost and complexity of a high power fiber

Xuejun Long; Yonghui Liang; Xiaojun Xu; Sanhong Wang; Qifeng Yu

2008-01-01

430

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