Stiff baby syndrome er en sjælden årsag til neonatal hypertonicitet

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Rønne, Maria Sode; Nielsen, Preben Berg; Mogensen, Christian Backer

2014-01-01

Stiff baby syndrome (hyperekplexia) is a rare genetic disorder. The condition can easily be misdiagnosed as epilepsy or severe sepsis because of hypertonicity and seizure-like episodes and has an increased risk of severe apnoea and sudden infant death. Tapping of the nasal bridge inducing a start...

The effects of resistance exercise training on arterial stiffness in metabolic syndrome.

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DeVallance, E; Fournier, S; Lemaster, K; Moore, C; Asano, S; Bonner, D; Donley, D; Olfert, I M; Chantler, P D

2016-05-01

Arterial stiffness is a strong independent risk factor for cardiovascular disease and is elevated in individuals with metabolic syndrome (MetS). Resistance training is a popular form of exercise that has beneficial effects on muscle mass, strength, balance and glucose control. However, it is unknown whether resistance exercise training (RT) can lower arterial stiffness in patients with MetS. Thus, the aim of this study was to examine whether a progressive RT program would improve arterial stiffness in MetS. A total of 57 subjects (28 healthy sedentary subjects; 29 MetS) were evaluated for arterial structure and function, including pulse wave velocity (cfPWV: arterial stiffness), before and after an 8-week period of RT or continuation of sedentary lifestyle. We found that 8 weeks of progressive RT increased skeletal muscle strength in both Con and MetS, but did not change arterial stiffness in either MetS (cfPWV; Pre 7.9 ± 0.4 m/s vs. Post 7.7 ± 0.4 m/s) or healthy controls (cfPWV; Pre 6.9 ± 0.3 m/s vs. Post 7.0 ± 0.3 m/s). However, when cfPWV is considered as a continuous variable, high baseline measures of cfPWV tended to show a decrease in cfPWV following RT. Eight weeks of progressive RT did not decrease the group mean values of arterial stiffness in individuals with MetS or healthy controls.

In vivo Evaluation of Patellar Tendon Stiffness in Individuals with Patellofemoral Pain Syndrome

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Hsin-Yi Liu

2008-01-01

Full Text Available The objective of this study was to utilise an ultrasonic technique to assess the effect of patellofemoral pain syndrome (PFPS on the mechanical properties of the patellar tendon. Seven subjects with PFPS and seven matched control subjects volunteered to participate in this study. Subjects were asked to perform isometric maximal voluntary contractions of the knee extensors while their knee extension torque was monitored and the displacement of the patellar tendon was recorded with an ultrasonic system. Our results showed significantly lower tendon stiffness (by ∼30% in the PFPS subjects. Although tendon secant modulus was lower by 34% in the PFPS subjects, the difference was not statistically significant. Therefore, we conclude that the ultrasonic technique was able to detect a decrease in the structural stiffness of the patellar tendon associated with PFPS. The decrease in tendon stiffness was moderately correlated with the length of symptoms in these individuals.

Metabolic risk factors and arterial stiffness in Indian children of parents with metabolic syndrome.

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Khadilkar, Anuradha V; Chiplonkar, Shashi A; Pandit, Deepa S; Kinare, Arun S; Khadilkar, Vaman V

2012-02-01

To investigate the possible association between metabolic syndrome (MS) and arterial stiffness in Indian children with parental MS status. A cross-sectional study was conducted in 140 overweight/obese and 60 normal-weight Indian children (mean age, 11.4 ± 2.8 years) along with one of their parents during 2008-2009. Data on weight, height, blood pressure, serum lipids, zinc, insulin, and glucose were collected. Intima media thickness (CIMT) and stiffness parameters were assessed in the right carotid artery. Physical activity and diet were assessed using structured questionnaires. Body composition was measured using dual-energy x-ray absorptiometry. A gradual increase in the percentage of MS children with an increasing number of MS components in parents was observed. Mean values for arterial stiffness, pulse wave velocity, and elastic modulus were significantly higher in MS children of MS parents than in MS children of normal parents (p parent pairs (p children's CIMT and arterial stiffness were significantly associated (p parental MS-CIMT. Parental MS status and lifestyle factors increase the risk of MS and arterial abnormalities in children.

A 7-year-old with indurated skin and unilateral progressive joint immobility: A case of stiff skin syndrome.

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Ogunmakin, Kehinde; Vangipuram, Ramya; Sturgeon, Ashley; Shimizu, Ikue

2015-09-17

Stiff skin syndrome is a rare sclerotic condition that presents during infancy or early childhood. It has an insidious chronic course and may lead to significant co-morbidity and reduced quality of life. Often, affected individuals experience impaired ambulation and immobilization related to joint involvement. Clinically, it may resemble other sclerotic diseases, so histopathological evaluation is necessary to establish a diagnosis. As it is a condition with limited treatment options, prompt diagnosis and early initiation of physical therapy is crucial to prevent joint restriction and maintain quality of life. We describe a case of a 7-year-old with stiff skin syndrome, and review the literature to discuss the clinical presentation, histological findings, and management of this condition.

Stiffness of the large arteries in individuals with and without Down syndrome

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Nunes Rodrigues A

2011-06-01

Full Text Available Anabel N Rodrigues1,2, Luan Cesar Coelho1, Washington LS Goncalves1,2, Sonia Alves Gouvea2, Maria José Rossi Vasconcellos1, Roberto S Cunha2, Glaucia R Abreu21School of Medicine, University Center of Espírito Santo, Colatina; 2Postgraduate Program in Physiological Sciences, Center for Health Sciences, Federal University of Espirito Santo, Vitória, BrazilBackground: Down syndrome is known to cause premature aging in several organ systems. However, it remains unclear whether this aging effect also affects the structure and function of the large arterial trunks. In this controlled study, the possibility of changes in the large arteries due to aging was evaluated in patients with Down syndrome.Methods: Eighty-two subjects of both genders were selected. The Down syndrome group had 41 active subjects consisting of 19 males and 22 females (mean age 21 ± 1, range 13–42 years without cardiovascular complications and who did not use vasoactive drugs. The control group consisted of 41 healthy individuals without trisomy 21 of the same gender and age as the Down syndrome group and who did not use vasoactive medication. Carotid–femoral pulse wave velocity was obtained as an index of aortic stiffness using an automatic noninvasive method.Results: Individuals with Down syndrome had significantly lower blood pressure than those in the control group. Systolic blood pressure for the Down syndrome group and control group was 106 ± 2 mmHg vs 117 ± 2 mmHg (P < 0.001, respectively; diastolic blood pressure was 66 ± 2 mmHg vs 77 ± 2 mmHg (P <0.001; and mean arterial pressure was 80 ± 1 mmHg vs 90 ± 1 mmHg (P < 0.001. Only age and systolic blood pressure were shown to correlate significantly with pulse wave velocity, but the slopes of the linear regression curves of these two variables showed no significant difference between the two study groups. Pulse wave velocity, which was initially significantly lower in the Down syndrome group (7.51 ± 0.14 m/s vs

Relationships among personality traits, metabolic syndrome, and metabolic syndrome scores: The Kakegawa cohort study.

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Ohseto, Hisashi; Ishikuro, Mami; Kikuya, Masahiro; Obara, Taku; Igarashi, Yuko; Takahashi, Satomi; Kikuchi, Daisuke; Shigihara, Michiko; Yamanaka, Chizuru; Miyashita, Masako; Mizuno, Satoshi; Nagai, Masato; Matsubara, Hiroko; Sato, Yuki; Metoki, Hirohito; Tachibana, Hirofumi; Maeda-Yamamoto, Mari; Kuriyama, Shinichi

2018-04-01

Metabolic syndrome and the presence of metabolic syndrome components are risk factors for cardiovascular disease (CVD). However, the association between personality traits and metabolic syndrome remains controversial, and few studies have been conducted in East Asian populations. We measured personality traits using the Japanese version of the Eysenck Personality Questionnaire (Revised Short Form) and five metabolic syndrome components-elevated waist circumference, elevated triglycerides, reduced high-density lipoprotein cholesterol, elevated blood pressure, and elevated fasting glucose-in 1322 participants aged 51.1±12.7years old from Kakegawa city, Japan. Metabolic syndrome score (MS score) was defined as the number of metabolic syndrome components present, and metabolic syndrome as having the MS score of 3 or higher. We performed multiple logistic regression analyses to examine the relationship between personality traits and metabolic syndrome components and multiple regression analyses to examine the relationship between personality traits and MS scores adjusted for age, sex, education, income, smoking status, alcohol use, and family history of CVD and diabetes mellitus. We also examine the relationship between personality traits and metabolic syndrome presence by multiple logistic regression analyses. "Extraversion" scores were higher in those with metabolic syndrome components (elevated waist circumference: P=0.001; elevated triglycerides: P=0.01; elevated blood pressure: P=0.004; elevated fasting glucose: P=0.002). "Extraversion" was associated with the MS score (coefficient=0.12, P=0.0003). No personality trait was significantly associated with the presence of metabolic syndrome. Higher "extraversion" scores were related to higher MS scores, but no personality trait was significantly associated with the presence of metabolic syndrome. Copyright © 2018 Elsevier Inc. All rights reserved.

Stiff-Person Syndrome

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... awry in the brain and spinal cord. The disorder is often misdiagnosed as Parkinson’s disease, multiple sclerosis, fibromyalgia, psychosomatic illness, or anxiety and phobia. A definitive diagnosis can be made ...

Greater Arterial Stiffness in Polycystic Ovary Syndrome (PCOS) Is an Obesity-But Not a PCOS-Associated Phenomenon

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Ketel, I.J.G.; Stehouwer, C.D.A.; Henry, R.M.; Serné, E.H.; Hompes, P.G.A.; Homburg, R.R.; Smulders, Y.M.; Lambalk, C.B.

2010-01-01

Context: Polycystic ovary syndrome (PCOS) and obesity are associated with cardiovascular disease, but it is unclear to what extent they contribute independently. Arterial stiffness might link obesity and PCOS to cardiovascular diseases. Objective: Our objective was to investigate whether PCOS in the

Distinct effects of losartan and atenolol on vascular stiffness in Marfan syndrome.

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Bhatt, Ami B; Buck, J Stewart; Zuflacht, Jonah P; Milian, Jessica; Kadivar, Samoneh; Gauvreau, Kimberlee; Singh, Michael N; Creager, Mark A

2015-08-01

We conducted a randomized, double-blind trial of losartan (100 mg QD) versus atenolol (50 mg QD) for 6 months in adults with Marfan syndrome. Carotid-femoral pulse wave velocity (PWV), central augmentation index (AIx), aortic diameter and left ventricular (LV) function were assessed with arterial tonometry and echocardiography. Thirty-four subjects (18 female; median age 35 years, IQR 27, 45) were randomized. Central systolic and diastolic blood pressure decreased comparably with atenolol and losartan (p = 0.64 and 0.31, respectively); heart rate decreased with atenolol (p = 0.02), but not with losartan. PWV decreased in patients treated with atenolol (-1.15 ± 1.68 m/s; p = 0.01), but not in those treated with losartan (-0.22 ± 0.59 m/s; p = 0.15; between-group difference p = 0.04). In contrast, AIx decreased in the losartan group (-9.6 ± 8.6%; p Marfan syndrome, 6 months of treatment with atenolol improves PWV, whereas losartan reduces the AIx. By improving vascular stiffness via distinct mechanisms of action, there is physiologic value to considering the use of both medications in individuals with Marfan syndrome. © The Author(s) 2015.

Arterial stiffness and its association with clustering of metabolic syndrome risk factors

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Wanda R. P. Lopes-Vicente

2017-10-01

Full Text Available Abstract Background Metabolic syndrome (MetS is associated with structural and functional vascular abnormalities, which may lead to increased arterial stiffness, more frequent cardiovascular events and higher mortality. However, the role played by clustering of risk factors and the combining pattern of MetS risk factors and their association with the arterial stiffness have yet to be fully understood. Age, hypertension and diabetes mellitus seem to be strongly associated with increased pulse wave velocity (PWV. This study aimed at determining the clustering and combining pattern of MetS risk factors and their association with the arterial stiffness in non-diabetic and non-hypertensive patients. Methods Recently diagnosed and untreated patients with MetS (n = 64, 49 ± 8 year, 32 ± 4 kg/m2 were selected, according to ATP III criteria and compared to a control group (Control, n = 17, 49 ± 6 year, 27 ± 2 kg/m2. Arterial stiffness was evaluated by PWV in the carotid-femoral segment. Patients were categorized and analyzed according MetS risk factors clustering (3, 4 and 5 factors and its combinations. Results Patients with MetS had increased PWV when compared to Control (7.8 ± 1.1 vs. 7.0 ± 0.5 m/s, p < 0.001. In multivariate analysis, the variables that remained as predictors of PWV were age (β = 0.450, p < 0.001, systolic blood pressure (β = 0.211, p = 0.023 and triglycerides (β = 0.212, p = 0.037. The increased number of risk factors reflected in a progressive increase in PWV. When adjusted to systolic blood pressure, PWV was greater in the group with 5 risk factors when compared to the group with 3 risk factors and Control (8.5 ± 0.4 vs. 7.5 ± 0.2, p = 0.011 and 7.2 ± 0.3 m/s, p = 0.012. Similarly, the 4 risk factors group had higher PWV than the Control (7.9 ± 0.2 vs. 7.2 ± 0.3, p = 0.047. Conclusions The number of risk factors seems to increase arterial stiffness. Notably, besides

Borderline personality disorder and polycystic ovary syndrome: A review of the literature.

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Tan, Raelene Ym; Grigg, Jasmin; Kulkarni, Jayashri

2018-02-01

This review examines the existing evidence for the relationship between borderline personality disorder and polycystic ovary syndrome, and to identify commonalities in etiological mechanisms of borderline personality disorder and polycystic ovary syndrome that might explain the relationship between these seemingly disparate disorders. A search of Medline, EMBASE and Cochrane Central was undertaken on 5 December 2016 to identify studies investigating women with borderline personality disorder and polycystic ovary syndrome (or symptoms and markers specific to polycystic ovary syndrome). Nine studies were identified, including three cross-sectional studies investigating symptoms of polycystic ovary syndrome in women with borderline personality disorder, two cross-sectional and one cohort study examining the prevalence of psychiatric diagnoses in women with polycystic ovary syndrome and three case reports of comorbid borderline personality disorder and polycystic ovary syndrome. Overall, the literature shows women with borderline personality disorder to have higher than expected serum androgen levels and incidence of polycystic ovaries, which can be key features of polycystic ovary syndrome. However, this research is still in its infancy, which limits our understanding of this potential comorbid phenomenon. Given the emerging anecdotal and empirical evidence to date, a theoretical discussion of the potential psychoneuroendocrinological mechanism underlying the borderline personality disorder and polycystic ovary syndrome comorbidity is provided. Further rigorous studies using standardized diagnostic criteria for polycystic ovary syndrome are warranted. Specifically, the use of prospective controlled cohort studies may be able to determine the causality and temporality of observed comorbid borderline personality disorder and polycystic ovary syndrome.

Ambulatory (24 h) blood pressure and arterial stiffness measurement in Marfan syndrome patients: a case control feasibility and pilot study.

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Hillebrand, Matthias; Nouri, Ghazaleh; Hametner, Bernhard; Parragh, Stephanie; Köster, Jelena; Mortensen, Kai; Schwarz, Achim; von Kodolitsch, Yskert; Wassertheurer, Siegfried

2016-05-06

The aim of this work is the investigation of measures of ambulatory brachial and aortic blood pressure and indices of arterial stiffness and aortic wave reflection in Marfan patients. A case-control study was conducted including patients with diagnosed Marfan syndrome following Ghent2 nosology and healthy controls matched for sex, age and daytime brachial systolic blood pressure. For each subject a 24 h ambulatory blood pressure and 24 h pulse wave analysis measurement was performed. All parameters showed a circadian pattern whereby pressure dipping was more pronounced in Marfan patients. During daytime only Marfan patients with aortic root surgery showed increased pulse wave velocity. In contrast, various nighttime measurements, wave reflection determinants and circadian patterns showed a significant difference. The findings of our study provide evidence that ambulatory measurement of arterial stiffness parameters is feasible and that these determinants are significantly different in Marfan syndrome patients compared to controls in particular at nighttime. Further investigation is therefore indicated.

Personalized medicine for individuals with Down syndrome.

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McCabe, Linda L; McCabe, Edward R B

2011-01-01

As the cost of whole genome analysis decreases, we have the opportunity to explore the interactions of various gene changes in an individual that lead to their particular phenotype. This will provide the ability to move from the epidemiologic study of groups, in which, the individuals are treated collectively and homogenously, to personalized medicine, and a model in which the individual is recognized and treated as a distinct entity. We will be applying personalized medicine to individuals with Down syndrome in order to understand and develop biomarkers for increased risk of co-morbidities. Personalized medicine will change the "culture of intractability" of Down syndrome. Copyright © 2011 Elsevier Inc. All rights reserved.

Aerobic exercise training reduces arterial stiffness in metabolic syndrome.

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Donley, David A; Fournier, Sara B; Reger, Brian L; DeVallance, Evan; Bonner, Daniel E; Olfert, I Mark; Frisbee, Jefferson C; Chantler, Paul D

2014-06-01

The metabolic syndrome (MetS) is associated with a threefold increase risk of cardiovascular disease (CVD) mortality partly due to increased arterial stiffening. We compared the effects of aerobic exercise training on arterial stiffening/mechanics in MetS subjects without overt CVD or type 2 diabetes. MetS and healthy control (Con) subjects underwent 8 wk of exercise training (ExT; 11 MetS and 11 Con) or remained inactive (11 MetS and 10 Con). The following measures were performed pre- and postintervention: radial pulse wave analysis (applanation tonometry) was used to measure augmentation pressure and index, central pressures, and an estimate of myocardial efficiency; arterial stiffness was assessed from carotid-femoral pulse-wave velocity (cfPWV, applanation tonometry); carotid thickness was assessed from B-mode ultrasound; and peak aerobic capacity (gas exchange) was performed in the seated position. Plasma matrix metalloproteinases (MMP) and CVD risk (Framingham risk score) were also assessed. cfPWV was reduced (P Exercise training reduced (P exercise training, thereby lowering their cardiovascular risk. Copyright © 2014 the American Physiological Society.

Prevalence and Influencing Factors of Metabolic Syndrome Among Persons with Physical Disabilities

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Jeonghee Jeong, RN, PhD

2018-03-01

Full Text Available Purpose: Metabolic syndrome is an important cluster of coronary heart disease risk factors. However, it remains unclear to what extent metabolic syndrome is associated with demographic and potentially modifiable lifestyle factors among Korean persons with physical disabilities. This study aimed to determine the prevalence and influencing factors of metabolic syndrome among persons with physical disabilities using the Korean National Health Insurance Service–National Sample Cohort. Methods: The Adult Treatment Panel III criteria were used to define metabolic syndrome influencing factors and prevalence, which were evaluated in a representative sample from the 2013 Korean National Health Insurance Service–National Sample Cohort database. Characteristics were compared based on frequency using the χ2 test. The associations between metabolic syndrome and its risk factors were estimated using logistic multivariable regression analysis. Results: Metabolic syndrome was detected in 31.5% of the surveyed persons with physical disabilities. Female sex, age of ≥65 years, smoking, greater alcohol consumption, physical inactivity, higher body mass index, and a family history of diabetes were associated with increased risks of metabolic syndrome. Conclusion: The major risk factors for metabolic syndrome among persons with physical disabilities were obesity and older age. Performing physical activity was associated with a lower risk of metabolic syndrome. Therefore, we recommend using a continuous obesity management program and physical activity to prevent metabolic syndrome among persons with physical disabilities. Keywords: disabled persons, metabolic syndrome X, physical activity, obesity

Personality Profile of Male Adolescents With Tourette Syndrome: A Controlled Study.

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Balottin, Laura; Selvini, Claudia; Luoni, Chiara; Mannarini, Stefania; Chiappedi, Matteo; Seri, Stefano; Termine, Cristiano; Cavanna, Andrea E

2016-03-01

Tourette syndrome is a neurodevelopmental disorder characterized by multiple tics and commonly associated with behavioral problems, especially obsessive-compulsive disorder and attention-deficit hyperactivity disorder (ADHD). The presence of specific personality traits has been documented in adult clinical populations with Tourette syndrome but has been underresearched in younger patients. We assessed the personality profiles of 17 male adolescents with Tourette syndrome and 51 age- and gender-matched healthy controls using the Minnesota Multiphasic Personality Inventory-Adolescent version, along with a standardized psychometric battery. All participants scored within the normal range across all Minnesota Multiphasic Personality Inventory-Adolescent version scales. Patients with Tourette syndrome scored significantly higher than healthy controls on the Obsessiveness Content Scale only (P = .046). Our findings indicate that younger male patients with Tourette syndrome do not report abnormal personality traits and have similar personality profiles to healthy peers, with the exception of obsessionality traits, which are likely to be related to the presence of comorbid obsessive compulsive symptoms rather than tics. © The Author(s) 2015.

Sudden death and paroxysmal autonomic dysfunction in stiff-man syndrome.

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Mitsumoto, H; Schwartzman, M J; Estes, M L; Chou, S M; La Franchise, E F; De Camilli, P; Solimena, M

1991-04-01

Two women with typical stiff-man syndrome (SMS) developed increasingly frequent attacks of muscle spasms with severe paroxysmal autonomic dysfunctions such as transient hyperpyrexia, diaphoresis, tachypnea, tachycardia, pupillary dilation, and arterial hypertension. Autoantibodies to GABA-ergic neurons were identified in the serum of both patients and in the cerebrospinal fluid of one. Both died suddenly and unexpectedly. General autopsy did not reveal the cause of death. Neuropathological studies revealed perivascular gliosis in the spinal cord and brain stem of one patient and lymphocytic perivascular infiltration in the spinal cord, brain stem, and basal ganglia of the other. The occurrence of a chronic inflammatory reaction in one of the two patients supports the idea that an autoimmune disease against GABA-ergic neurons may be involved in SMS. A review of the literature indicates that functional impairment in SMS is severe and prognosis is unpredictable because of the potential for sudden and unexpected death. Both muscular abnormalities and autonomic dysfunctions may result from autoimmunity directed against GABA-ergic neurons.

Prevalence and Influencing Factors of Metabolic Syndrome Among Persons with Physical Disabilities.

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Jeong, Jeonghee; Yu, Jungok

2018-03-01

Metabolic syndrome is an important cluster of coronary heart disease risk factors. However, it remains unclear to what extent metabolic syndrome is associated with demographic and potentially modifiable lifestyle factors among Korean persons with physical disabilities. This study aimed to determine the prevalence and influencing factors of metabolic syndrome among persons with physical disabilities using the Korean National Health Insurance Service-National Sample Cohort. The Adult Treatment Panel III criteria were used to define metabolic syndrome influencing factors and prevalence, which were evaluated in a representative sample from the 2013 Korean National Health Insurance Service-National Sample Cohort database. Characteristics were compared based on frequency using the χ 2 test. The associations between metabolic syndrome and its risk factors were estimated using logistic multivariable regression analysis. Metabolic syndrome was detected in 31.5% of the surveyed persons with physical disabilities. Female sex, age of ≥65 years, smoking, greater alcohol consumption, physical inactivity, higher body mass index, and a family history of diabetes were associated with increased risks of metabolic syndrome. The major risk factors for metabolic syndrome among persons with physical disabilities were obesity and older age. Performing physical activity was associated with a lower risk of metabolic syndrome. Therefore, we recommend using a continuous obesity management program and physical activity to prevent metabolic syndrome among persons with physical disabilities. Copyright © 2018. Published by Elsevier B.V.

Dissociation of endothelial function and arterial stiffness in nonobese women with polycystic ovary syndrome (PCOS).

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Cussons, Andrea J; Watts, Gerald F; Stuckey, Bronwyn G A

2009-12-01

Polycystic ovary syndrome (PCOS) is associated with cardiovascular risk but it is not clear if this is independent of obesity and insulin resistance. This study therefore investigates endothelial function and arterial stiffness in nonobese, noninsulin resistant women with PCOS. This is cross-sectional case-control study. A total of 19 young women with PCOS, with body mass index (BMI) PCOS and control subjects when assessing the following clinical and biochemical variables: blood pressure, homeostasis model assessment insulin-resistance index, lipids and oestradiol. Women with PCOS had higher free androgen index scores (5.14 ± 3.47 vs. 3.25 ± 1.42, P = 0.036). The PCOS subjects had significantly lower FMD of the brachial artery compared with the controls (6.5 ± 2.9%vs. 10.5 ± 4.0%, P insulin resistance, have abnormal vascular function, but normal arterial stiffness, when compared with age and weight matched control subjects. Whether this leads to a greater risk of cardiovascular disease requires further investigation. © 2009 Blackwell Publishing Ltd.

Reconceptualizing personality pathology in DSM-5: limitations in evidence for eliminating dependent personality disorder and other DSM-IV syndromes.

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Bornstein, Robert F

2011-04-01

The DSM-5 Personality and Personality Disorders Workgroup proposed that five DSM-IV personality disorders be eliminated as formal diagnostic categories (paranoid, schizoid, histrionic, narcissistic, and dependent), because these syndromes purportedly have low clinical utility and minimal evidence for validity. Scrutiny of studies cited in support of this proposal reveals difficulties in three areas: (1) Inadequate information regarding parameters of the literature search; (2) Mixed empirical support for proposed changes; and (3) Selective attention to certain disorders and not others. Review of validity and clinical utility data related to dependent personality disorder indicates that evidence regarding this syndrome does not differ from that of syndromes proposed for retention in DSM-5. Limitations in the research base cited by the workgroup illuminates gaps in the personality disorder literature, and may serve as a starting point for systematic research on personality pathology so that adequate empirical data are available to decide which syndromes to retain, revise, or remove in future versions of the diagnostic manual.

Muscle stiffness of posterior lower leg in runners with a history of medial tibial stress syndrome.

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Saeki, J; Nakamura, M; Nakao, S; Fujita, K; Yanase, K; Ichihashi, N

2018-01-01

Previous history of medial tibial stress syndrome (MTSS) is a risk factor for MTSS relapse, which suggests that there might be some physical factors that are related to MTSS development in runners with a history of MTSS. The relationship between MTSS and muscle stiffness can be assessed in a cross-sectional study that measures muscle stiffness in subjects with a history of MTSS, who do not have pain at the time of measurement, and in those without a history of MTSS. The purpose of this study was to compare the shear elastic modulus, which is an index of muscle stiffness, of all posterior lower leg muscles of subjects with a history of MTSS and those with no history and investigate which muscles could be related to MTSS. Twenty-four male collegiate runners (age, 20.0±1.7 years; height, 172.7±4.8 cm; weight, 57.3±3.7 kg) participated in this study; 14 had a history of MTSS, and 10 did not. The shear elastic moduli of the lateral gastrocnemius, medial gastrocnemius, soleus, peroneus longus, peroneus brevis, flexor hallucis longus, flexor digitorum longus, and tibialis posterior were measured using shear wave elastography. The shear elastic moduli of the flexor digitorum longus and tibialis posterior were significantly higher in subjects with a history of MTSS than in those with no history. However, there was no significant difference in the shear elastic moduli of other muscles. The results of this study suggest that flexor digitorum longus and tibialis posterior stiffness could be related to MTSS. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

[The correlation between personality characteristics and burnout syndrome in emergency ambulance workers].

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Bergmueller, A; Zavgorodnii, I; Zavgorodnia, N; Kapustnik, W; Boeckelmann, I

The work in Emergency Medical Ambulance Service is one of the professions, which is accompanied by high psychological and emotional stress. The aim was to determine the risk of professional burnout syndrome of Emergency Medical Ambulance Service staff and the relationship between burnout syndrome and personality. Ninety-seven doctors (57 women and 40 men, aged 37.0±12.21) of Emergency Medical Ambulance Service were interviewed using the MBI-GS questionnaire and the Freiburg personality questionnaire (FPI). Correlation and regression analysis were used. Nine (11.5%) of respondents had a risk of burnout syndrome and 28 (35.9%) had some symptoms. In the group, aged 45 years and older, the risk of burnout syndrome was not identified. The staff of Emergency Medical Ambulance Service is characterized by stable personality features. It is necessary to identify the prevalence of burnout syndrome and also to identity the causes for its prevention and development of measures on the increase of personal stress resilience.

Segmental stiff skin syndrome (SSS): A distinct clinical entity.

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Myers, Kathryn L; Mir, Adnan; Schaffer, Julie V; Meehan, Shane A; Orlow, Seth J; Brinster, Nooshin K

2016-07-01

Stiff skin syndrome (SSS) is a noninflammatory, fibrosing condition of the skin, often affecting the limb girdles. We present 4 new patients with SSS with largely unilateral, segmental distribution. To date, reported cases of SSS have been grouped based on generally accepted clinical and histopathologic findings. The purpose of this study was to analyze differences in clinical and histopathologic findings between previously reported SSS cases. This is a retrospective review of 4 new cases and 48 previously published cases of SSS obtained from PubMed search. Of 52 total cases, 18 (35%) were segmentally distributed and 34 (65%) were widespread. The average age of onset was 4.1 years versus 1.6 years for segmental versus widespread SSS, respectively. Limitation in joint mobility affected 44% of patients with segmental SSS and 97% of patients with widespread SSS. Histopathologic findings were common between the 2 groups. This was a retrospective study of previously published cases limited by the completeness and accuracy of the reviewed cases. We propose a distinct clinical entity, segmental SSS, characterized by a segmental distribution, later age of onset, and less severe functional limitation. Both segmental SSS and widespread SSS share common diagnostic histopathologic features. Copyright © 2016 American Academy of Dermatology, Inc. All rights reserved.

Arterial Stiffness in Children: Pediatric Measurement and Considerations

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Savant, Jonathan D.; Furth, Susan L.; Meyers, Kevin E.C.

2014-01-01

Background Arterial stiffness is a natural consequence of aging, accelerated in certain chronic conditions, and predictive of cardiovascular events in adults. Emerging research suggests the importance of arterial stiffness in pediatric populations. Methods There are different indices of arterial stiffness. The present manuscript focuses on carotid-femoral pulse wave velocity and pulse wave analysis, although other methodologies are discussed. Also reviewed are specific measurement considerations for pediatric populations and the literature describing arterial stiffness in children with certain chronic conditions (primary hypertension, obesity, diabetes, chronic kidney disease, hypercholesterolemia, genetic syndromes involving vasculopathy, and solid organ transplant recipients). Conclusions The measurement of arterial stiffness in children is feasible and, under controlled conditions, can give accurate information about the underlying state of the arteries. This potentially adds valuable information about the functionality of the cardiovascular system in children with a variety of chronic diseases well beyond that of the brachial artery blood pressure. PMID:26587447

Functional status of persons with chronic fatigue syndrome in the Wichita, Kansas, population

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Reyes Michele

2003-10-01

Full Text Available Abstract Background Scant research has adequately addressed the impact of chronic fatigue syndrome on patients' daily activities and quality of life. Enumerating specific problems related to quality of life in chronic fatigue syndrome patients can help us to better understand and manage this illness. This study addresses issues of functional status in persons with chronic fatigue syndrome and other fatiguing illnesses in a population based sample, which can be generalized to all persons with chronic fatigue. Methods We conducted a random telephone survey in Wichita, Kansas to identify persons with chronic fatigue syndrome and other fatiguing illnesses. Respondents reporting severe fatigue of at least 1 month's duration and randomly selected non-fatigued respondents were asked to participate in a detailed telephone interview. Participants were asked about symptoms, medical and psychiatric illnesses, and about physical, social, and recreational functioning. Those meeting the 1994 chronic fatigue syndrome case definition, as determined on the basis of their telephone responses, were invited for clinical evaluation to confirm a diagnosis of chronic fatigue syndrome. For this analysis, we evaluated unemployment due to fatigue, number of hours per week spent on work, chores, and other activities (currently and prior to the onset of fatigue, and energy level. Results There was no difference between persons with chronic fatigue syndrome and persons with a chronic fatigue syndrome-like illness that could be explained by a medical or psychiatric condition for any of the outcomes we measured except for unemployment due to fatigue (15% vs. 40%, P Conclusions Persons with chronic fatigue syndrome are as impaired as persons whose fatigue could be explained by a medical or psychiatric condition, and they have less energy than non-fatigued controls.

Savant syndrome in music at persons with mental disability in Slovenia

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Nadler, Irena

2017-01-01

Savant syndrome is a congenital or acquired condition that combines certain inabilities of a person; often a person with intellectual disability, or a person with a cognitive or developmental disorder, but also above-average, outstanding or even brilliant abilities in a particular area are demonstrated. There are three levels of savant syndrome: savants with splinter skills, talented savants and prodigious savants. Even in people with intellectual disability, we can find people with avera...

EFFECT OF OBSTRUCTIVE SLEEP APNEA SYNDROME ON ARTERIAL STIFFNESS IN PATIENTS AT HIGH CARDIOVASCULAR RISK

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V. E. Oleynikov

2016-01-01

Full Text Available Aim. To assess the impact of metabolic abnormalities in combination with obstructive sleep apnea on endothelial function and vascular stiffness parameters in patients with arterial hypertension 1-2 degrees. Material and methods. Patients (n=74 with metabolic syndrome and obstructive sleep apnea were included into the study. All patients underwent cardiorespiratory monitoring of sleep using SomnoCheck2 device (Wiennmann, Germany and were divided into two groups based on its results. Patients with apnea-hypopnea index (AHI <30 episodes per hour were included into group 1 and patients with AHI >30 episodes per hour – into group 2. Monitoring of ambulatory blood pressure (BP and arterial stiffness was performed by the device BPLab ("Peter Telegin", Russia. Endothelial function was assessed in a probe of flow-mediated dilation by the ultrasound device MyLab 90 (Esaote, Italy. Diameter of the common carotid artery (DCCA and the intima-media thickness (IMT were determined. Results. Patients with AHI >30 episodes per hour had higher mean daily and night systolic BP and pulse BP in aorta and brachial artery. Pulse wave velocity in aorta in per day averaged was also higher in these patients (8.2±0.8 vs 9.1±1.1 m/sec; p<0.05. Mean level of flow-mediated dilation was significantly lower in patients with severe sleep apnea> (8.8% (5.6; 13.1 vs 4.5% (2.2; 8.0; p<0.05. Prevalence of negative index of reactivity in group 2 was 2 times higher than this in group 1. An increase in IMT and DCCA in patients with severe obstructive sleep apnea was also revealed. Conclusion. Severe sleep apnea in patients with metabolic syndrome in combination with hypertension aggravates structural changes and endothelial dysfunction of the main arteries, as well as contributes to the progression of atherosclerosis.

Burnout Syndrome Among Health Care Students: The Role of Type D Personality.

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Skodova, Zuzana; Lajciakova, Petra; Banovcinova, Lubica

2016-07-18

The aim of this study was to examine the effect of Type D personality, along with other personality traits (resilience and sense of coherence), on burnout syndrome and its counterpart, engagement, among students of nursing, midwifery, and psychology. A cross-sectional study was conducted on 97 university students (91.9% females; M age = 20.2 ± 1.49 years). A Type D personality subscale, School Burnout Inventory, Utrecht Work Engagement Scale, Sense of Coherence Questionnaire, and Baruth Protective Factor Inventory were used. Linear regression models, Student's t test, and Pearson's correlation analysis were employed. Negative affectivity, a dimension of Type D personality, was a significant personality predictor for burnout syndrome (β = .54; 95% CI = [0.33, 1.01]). The only significant personality predictor of engagement was a sense of coherence. Students who were identified as having Type D personality characteristics scored significantly higher on the burnout syndrome questionnaire (t = -2.58, p burnout. © The Author(s) 2016.

Aortic dilatation in Marfan syndrome: role of arterial stiffness and fibrillin-1 variants.

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Salvi, Paolo; Grillo, Andrea; Marelli, Susan; Gao, Lan; Salvi, Lucia; Viecca, Maurizio; Di Blasio, Anna Maria; Carretta, Renzo; Pini, Alessandro; Parati, Gianfranco

2018-01-01

Marfan syndrome (MFS) is an autosomal dominant genetic disorder characterized by aortic root dilation and dissection and an abnormal fibrillin-1 synthesis. In this observational study, we evaluated aortic stiffness in MFS and its association with ascending aorta diameters and fibrillin-1 genotype. A total of 116 Marfan adult patients without history of cardiovascular surgery, and 144 age, sex, blood pressure and heart rate matched controls were enrolled. All patients underwent arterial stiffness evaluation through carotid-femoral pulse wave velocity (PWV) and central blood pressure waveform analysis (PulsePen tonometer). Fibrillin-1 mutations were classified based on the effect on the protein, into 'dominant negative' and 'haploinsufficient' mutations. PWV and central pulse pressure were significantly higher in MFS patients than in controls [respectively 7.31 (6.81-7.44) vs. 6.69 (6.52-6.86) m/s, P = 0.0008; 41.3 (39.1-43.5) vs. 34.0 (32.7-35.3) mmHg, P < 0.0001], with a higher age-related increase of PWV in MFS (β 0.062 vs. 0.036). Pressure amplification was significantly reduced in MFS [18.2 (15.9-20.5) vs. 33.4 (31.6-35.2)%, P < 0.0001]. Central pressure profile was altered even in MFS patients without aortic dilatation. Multiple linear regression models showed that PWV independently predicted aortic diameters at the sinuses of Valsalva (ß = 0.243, P = 0.002) and at the sinotubular junction (ß = 0.186, P = 0.048). PWV was higher in 'dominant negative' than 'haploinsufficient' fibrillin-1 mutations [7.37 (7.04-7.70) vs. 6.60 (5.97-7.23) m/s, P = 0.035], although this difference was not significant after adjustment. Aortic stiffness is increased in MFS, independently from fibrillin-1 genotype and is associated with diameters of ascending aorta. Alterations in central hemodynamics are present even when aortic diameter is within normal limits. Our findings suggest an accelerated arterial aging in MFS.

BORDERLINE PERSONALITY DISORDER IN THE MEDICAL SETTING: Suggestive Behaviors, Syndromes, and Diagnoses.

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Sansone, Randy A; Sansone, Lori A

2015-01-01

Borderline personality disorder is a personality dysfunction that is characterized by disinhibition and impulsivity, which oftentimes manifest as self-regulation difficulties. Patients with this disorder have always been present in medical settings, but have been described as "difficult patients" rather than patients with borderline personality disorder. According to empirical findings, a number of behaviors and medical syndromes/diagnoses are suggestive of borderline personality disorder. Suggestive behaviors in the medical setting may include aggressive or disruptive behaviors, the intentional sabotage of medical care, and excessive healthcare utilization. Suggestive medical syndromes and diagnoses in the medical setting may include alcohol and substance misuse (including the abuse of prescription medications), multiple somatic complaints, chronic pain, obesity, sexual impulsivity, and hair pulling. While not all-inclusive or diagnostic, these behaviors and syndromes/diagnoses may invite further clinical evaluation of the patient for borderline personality disorder.

Effects of metabolic syndrome on arterial function in different age groups: the Advanced Approach to Arterial Stiffness study.

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Topouchian, Jirar; Labat, Carlos; Gautier, Sylvie; Bäck, Magnus; Achimastos, Apostolos; Blacher, Jacques; Cwynar, Marcin; de la Sierra, Alejandro; Pall, Denes; Fantin, Francesco; Farkas, Katalin; Garcia-Ortiz, Luis; Hakobyan, Zoya; Jankowski, Piotr; Jelakovic, Ana; Kobalava, Zhanna; Konradi, Alexandra; Kotovskaya, Yulia; Kotsani, Marina; Lazareva, Irina; Litvin, Alexander; Milyagin, Viktor; Mintale, Iveta; Persson, Oscar; Ramos, Rafael; Rogoza, Anatoly; Ryliskyte, Ligita; Scuteri, Angelo; Sirenko, Yuriy; Soulis, Georges; Tasic, Nebojsa; Udovychenko, Maryna; Urazalina, Saule; Wohlfahrt, Peter; Zelveian, Parounak; Benetos, Athanase; Asmar, Roland

2018-04-01

The aim of the Advanced Approach to Arterial Stiffness study was to compare arterial stiffness measured simultaneously with two different methods in different age groups of middle-aged and older adults with or without metabolic syndrome (MetS). The specific effects of the different MetS components on arterial stiffness were also studied. This prospective, multicentre, international study included 2224 patients aged 40 years and older, 1664 with and 560 without MetS. Patients were enrolled in 32 centres from 18 European countries affiliated to the International Society of Vascular Health & Aging. Arterial stiffness was evaluated using the cardio-ankle vascular index (CAVI) and the carotid-femoral pulse wave velocity (CF-PWV) in four prespecified age groups: 40-49, 50-59, 60-74, 75-90 years. In this report, we present the baseline data of this study. Both CF-PWV and CAVI increased with age, with a higher correlation coefficient for CAVI (comparison of coefficients P Age-adjusted and sex-adjusted values of CF-PWV and CAVI were weakly intercorrelated (r = 0.06, P Age-adjusted and sex-adjusted values for CF-PWV but not CAVI were higher in presence of MetS (CF-PWV: 9.57 ± 0.06 vs. 8.65 ± 0.10, P age on CAVI and CF-PWV and suggests that age may have a more pronounced effect on CAVI, whereas MetS increases CF-PWV but not CAVI. This important finding may be due to heterogeneous effects of MetS components on CAVI. The clinical significance of these original results will be assessed during the longitudinal phase of the study.

Personality and chronic fatigue syndrome: methodological and conceptual issues.

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van Geelen, Stefan M; Sinnema, Gerben; Hermans, Hubert J M; Kuis, Wietse

2007-12-01

Among clinical psychologists, consulting physicians, scientific researchers and society in general an image has emerged of patients with chronic fatigue syndrome (CFS) as perfectionist, conscientious, hardworking, somewhat neurotic and introverted individuals with high personal standards, a great desire to be socially accepted and with a history of continuously pushing themselves past their limits. The aim of this article is to (a) give a concise review of the main recent studies on personality and CFS, (b) address the major methodological problems in the study of personality in CFS and (c) discuss some of the conceptual assumptions that seem to limit the research on personality and CFS. The results of the reviewed studies range from no evidence of major differences between the personalities of patients with CFS and controls, to evidence of severe psychopathology and personality disorder in patients with CFS. Although personality seems to play a role in CFS, it is difficult to draw general conclusions on the relation between personality and CFS. It is argued that this is partially due to the diversity and heterogeneity in study methods, patient populations, control groups and CFS case definitions. Personality should be regarded as an important factor to be studied in CFS. However, additional studies are needed, not focusing exclusively on personality disorder, or personality considered on a general trait level. In recent developments in personality research, the continually evolving life narrative that makes sense of, and gives direction to, an individual's life is also regarded as an important aspect of personality. New insights into personality and CFS might be gained by systematically studying the self-narratives of patients with the syndrome.

Influence of Passive Joint Stiffness on Proprioceptive Acuity in Individuals With Functional Instability of the Ankle.

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Marinho, Hellen Veloso Rocha; Amaral, Giovanna Mendes; de Souza Moreira, Bruno; Araújo, Vanessa Lara; Souza, Thales Rezende; Ocarino, Juliana Melo; da Fonseca, Sérgio Teixeira

2017-12-01

Study Design Controlled laboratory study, cross-sectional. Background Deficits in ankle proprioceptive acuity have been reported in persons with functional instability of the ankle. Passive stiffness has been proposed as a possible mechanism underlying proprioceptive acuity. Objective To compare proprioceptive acuity and passive ankle stiffness in persons with and without functional ankle instability, and to assess the influence of passive joint stiffness on proprioceptive acuity in persons with functional ankle instability. Methods A sample of 18 subjects with and 18 without complaints of functional ankle instability following lateral ankle sprain participated. An isokinetic dynamometer was used to compare motion perception threshold, passive position sense, and passive ankle stiffness between groups. To evaluate the influence of passive stiffness on proprioceptive acuity, individuals in the lateral functional ankle instability group were divided into 2 subgroups: "high" and "low" passive ankle stiffness. Results The functional ankle instability group exhibited increased motion perception threshold when compared with the corresponding limb of the control group. Between-group differences were not found for passive position sense and passive ankle stiffness. Those in the functional ankle instability group with higher passive ankle stiffness had smaller motion perception thresholds than those with lower passive ankle stiffness. Conclusion Unlike motion perception threshold, passive position sense is not affected by the presence of functional ankle instability. Passive ankle stiffness appears to influence proprioceptive acuity in persons with functional ankle instability. J Orthop Sports Phys Ther 2017;47(12):899-905. Epub 7 Oct 2017. doi:10.2519/jospt.2017.7030.

A diabetic patient presenting with stiff hand following fasciectomy for Dupuytren's contracture: A case report.

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Fournier, Katia; Papanas, Nikolaos; Compson, Jonathan P; Maltezos, Efstratios

2008-10-27

Reported is the case of a 68-year-old male presenting with severe wrist and hand stiffness following surgery for a Dupuytren's contracture. Complications of surgery or rehabilitation and complex regional pain syndrome were excluded as factors explaining this stiffness. Given the patient's diabetes mellitus and the striking similarity with the typical diabetic stiff hand, it is suggested that diabetes may have contributed to the development of the complication.

Incontinence in persons with Down Syndrome.

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Niemczyk, Justine; von Gontard, Alexander; Equit, Monika; Medoff, David; Wagner, Catharina; Curfs, Leopold

2017-08-01

To assess the rates of incontinence and associated psychological problems in children, adolescents and adults with Down Syndrome, a genetic syndrome caused by partial or complete triplication (trisomy) of chromosome 21 and characterized by typical facial features, a physical growth delay and mild or moderate intellectual disability. Three hundred and seventeen persons with Down Syndrome (4-51 years) were recruited through a German parent support group (59.6% male, mean age 19.2 years). The Parental Questionnaire: Enuresis/Urinary Incontinence, the Incontinence Questionnaire-Pediatric Lower Urinary Tract Symptoms, as well as the Developmental Behavior Checklist (DBC) for parents or for adults were filled out by parents or care-givers. 17.2% of the sample had nocturnal enuresis, 15.9% had daytime urinary incontinence, and 14.2% had fecal incontinence. Incontinence was present in 64.0% of young children (4-12 years), 10.3% of teens (13-17 years), 12.8% of young adults (18-30 years) and in 22.4% of older adults (>30 years). 13.6% of children and 8.4% of adults had a DBC score in the clinical range. 19.5% of children and 27.8% of adults with incontinence had behavioral problems. There was a significant association between nocturnal enuresis, daytime urinary incontinence and clinical DBC scores in adults. Incontinence in Down Syndrome is mainly present in young children and increases in older adults. Behavioral comorbidity is associated with incontinence only in adults with Down Syndrome. Screening and treatment of incontinence in individuals with Down Syndrome is recommended. © 2016 Wiley Periodicals, Inc.

Uncommon presentation of a common disorder

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P R Sowmini

2013-01-01

Full Text Available We report about a young male who presented with generalized muscle stiffness, involving the limb, facial, and paraspinal muscles. The stiffness was severe enough to restrict all his daily activities, progressively increased with movements and also produced recurrent falls. This clinical picture resembled one of stiff person syndrome. As he had hypertrophy of calf muscles and generalized muscle tautness he was evaluated for other disorders which can resemble stiff person syndrome. Investigations revealed severe hypothyroidism with thyroid antibodies being elevated. This case is reported to highlight the fact that myopathy as a presenting manifestation of hypothyroidism can simulate stiff person syndrome. It is essential to identify the condition early as it recovers fully with treatment. Our patient responded well to thyroid replacement therapy and was able to lead a normal life.

Urinary incontinence in persons with Prader-Willi Syndrome

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Gontard, A. von; Didden, H.C.M.; Sinnema, M.; Curfs, L.M.G.

2010-01-01

OBJECTIVE To assess and identify the frequency and type of urinary incontinence (UI), as well as associated symptoms in persons with Prader-Willi syndrome (PWS). PWS is characterized by mental retardation, short stature, obesity and hypogonadism. The behavioural phenotype includes eating problems,

Personality Traits and Behavioral Syndromes in Differently Urbanized Populations of House Sparrows (Passer domesticus)

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Bókony, Veronika; Kulcsár, Anna; Tóth, Zoltán; Liker, András

2012-01-01

Urbanization creates novel environments for wild animals where selection pressures may differ drastically from those in natural habitats. Adaptation to urban life involves changes in various traits, including behavior. Behavioral traits often vary consistently among individuals, and these so-called personality traits can be correlated with each other, forming behavioral syndromes. Despite their adaptive significance and potential to act as constraints, little is known about the role of animal personality and behavioral syndromes in animals' adaptation to urban habitats. In this study we tested whether differently urbanized habitats select for different personalities and behavioral syndromes by altering the population mean, inter-individual variability, and correlations of personality traits. We captured house sparrows (Passer domesticus) from four different populations along the gradient of urbanization and assessed their behavior in standardized test situations. We found individual consistency in neophobia, risk taking, and activity, constituting three personality axes. On the one hand, urbanization did not consistently affect the mean and variance of these traits, although there were significant differences between some of the populations in food neophobia and risk taking (both in means and variances). On the other hand, both urban and rural birds exhibited a behavioral syndrome including object neophobia, risk taking and activity, whereas food neophobia was part of the syndrome only in rural birds. These results indicate that there are population differences in certain aspects of personality in house sparrows, some of which may be related to habitat urbanization. Our findings suggest that urbanization and/or other population-level habitat differences may not only influence the expression of personality traits but also alter their inter-individual variability and the relationships among them, changing the structure of behavioral syndromes. PMID:22574204

Intraventricular filling under increasing left ventricular wall stiffness and heart rates

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Samaee, Milad; Lai, Hong Kuan; Schovanec, Joseph; Santhanakrishnan, Arvind; Nagueh, Sherif

2015-11-01

Heart failure with normal ejection fraction (HFNEF) is a clinical syndrome that is prevalent in over 50% of heart failure patients. HFNEF patients show increased left ventricle (LV) wall stiffness and clinical diagnosis is difficult using ejection fraction (EF) measurements. We hypothesized that filling vortex circulation strength would decrease with increasing LV stiffness irrespective of heart rate (HR). 2D PIV and hemodynamic measurements were acquired on LV physical models of varying wall stiffness under resting and exercise HRs. The LV models were comparatively tested in an in vitro flow circuit consisting of a two-element Windkessel model driven by a piston pump. The stiffer LV models were tested in comparison with the least stiff baseline model without changing pump amplitude, circuit compliance and resistance. Increasing stiffness at resting HR resulted in diminishing cardiac output without lowering EF below 50% as in HFNEF. Increasing HR to 110 bpm in addition to stiffness resulted in lowering EF to less than 50%. The circulation strength of the intraventricular filling vortex diminished with increasing stiffness and HR. The results suggest that filling vortex circulation strength could be potentially used as a surrogate measure of LV stiffness. This research was supported by the Oklahoma Center for Advancement of Science and Technology (HR14-022).

Personalizing mechanical ventilation for acute respiratory distress syndrome.

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Berngard, S Clark; Beitler, Jeremy R; Malhotra, Atul

2016-03-01

Lung-protective ventilation with low tidal volumes remains the cornerstone for treating patient with acute respiratory distress syndrome (ARDS). Personalizing such an approach to each patient's unique physiology may improve outcomes further. Many factors should be considered when mechanically ventilating a critically ill patient with ARDS. Estimations of transpulmonary pressures as well as individual's hemodynamics and respiratory mechanics should influence PEEP decisions as well as response to therapy (recruitability). This summary will emphasize the potential role of personalized therapy in mechanical ventilation.

Personal Space Regulation in Williams Syndrome: The Effect of Familiarity

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Lough, Emma; Flynn, Emma; Riby, Deborah M.

2016-01-01

Personal space refers to a protective barrier that we strive to maintain around our body. We examined personal space regulation in young people with Williams syndrome (WS) and their typically developing, chronological age-matched peers using a parent report questionnaire and a stop-distance paradigm. Individuals with WS were reported by their…

Relationship between Static Stiffness and Modal Stiffness of Structures

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Tianjian Ji Tianjian Ji

2010-02-01

Full Text Available This paper derives the relationship between the static stiffness and modal stiffness of a structure. The static stiffness and modal stiffness are two important concepts in both structural statics and dynamics. Although both stiffnesses indicate the capacity of the structure to resist deformation, they are obtained using different methods. The former is calculated by solving the equations of equilibrium and the latter can be obtained by solving an eigenvalue problem. A mathematical relationship between the two stiffnesses was derived based on the definitions of two stiffnesses. This relationship was applicable to a linear system and the derivation of relationships does not reveal any other limitations. Verification of the relationship was given by using several examples. The relationship between the two stiffnesses demonstrated that the modal stiffness of the fundamental mode was always larger than the static stiffness of a structure if the critical point and the maximum mode value are at the same node, i.e. for simply supported beam and seven storeys building are 1.5% and 15% respectively. The relationship could be applied into real structures, where the greater the number of modes being considered, the smaller the difference between the modal stiffness and the static stiffness of a structure.

Cerebellar Cognitive Affective Syndrome Presented as Severe Borderline Personality Disorder

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Danilo Pesic

2014-01-01

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

Hypertension, Diabetes Type II, and Their Association: Role of Arterial Stiffness.

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Smulyan, Harold; Lieber, Ari; Safar, Michel E

2016-01-01

In patients with both hypertension and type II diabetes, the systolic blood pressure (SBP) increases linearly with age, while that of diastolic blood pressure (DBP) declines curvilinearly as early as age 45, all suggesting the development of increased arterial stiffness. Increased stiffness is an important, independent, and significant risk predictor in subjects with hypertension and diabetes. In patients with both diseases, stiffness assessed at the same mean arterial pressure (MAP) was significantly higher in diabetic patients. Arterial stiffness is related to age, heart rate (HR), and MAP, but in diabetic patients, it also related to diabetes duration and insulin treatment (IT). In the metabolic syndrome (MetSyn), diabetes also acts on the small arteries through capillary rarefaction to reduce the effective length of the arterial tree, increases the reflected pulse wave and thus the pulse pressure (PP). These studies indicate that diabetes and hypertension additively contribute to increased pulsatility and suggest that any means to reduce stiffness would be beneficial in these conditions. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Personality Disorders and Clinical Syndromes in ADHD Prisoners

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Gudjonsson, Gisli H.; Wells, June; Young, Susan

2012-01-01

Objective: The main objective of this article is to investigate the type of personality disorders and clinical syndromes (CSs) that were best related to ADHD symptoms among prisoners. Method: The authors screened for childhood and adult ADHD symptoms and administered the Millon Clinical Multiaxial Inventory-III (MCMI-III) to 196 serving prisoners.…

Association of Gastrocnemius Muscle Stiffness With Passive Ankle Joint Stiffness and Sex-Related Difference in the Joint Stiffness.

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Chino, Kintaro; Takashi, Hideyuki

2017-11-15

Passive ankle joint stiffness is affected by all structures located within and over the joint, and is greater in men than in women. Localized muscle stiffness can be assessed by ultrasound shear wave elastography, and muscle architecture such as fascicle length and pennation angle can be measured by B-mode ultrasonography. Thus, we assessed localized muscle stiffness of the medial gastrocnemius (MG) with consideration of individual variability in the muscle architecture, and examined the association of the muscle stiffness with passive ankle joint stiffness and the sex-related difference in the joint stiffness. Localized muscle stiffness of the MG in 16 men and 17 women was assessed at 10° and 20° plantar flexion, neutral anatomical position, 10° and 20° dorsiflexion. Fascicle length and pennation angle of the MG were measured at these joint positions. Passive ankle joint stiffness was determined by the ankle joint angle-torque relationship. Localized MG muscle stiffness was not significantly correlated with passive ankle joint stiffness, and did not show significant sex-related difference, even when considering the muscle architecture. This finding suggest that muscle stiffness of the MG would not be a prominent factor to determine passive ankle joint stiffness and the sex-related difference in the joint stiffness.

Use of an electronic cognitive aid by a person with Korsakoff syndrome.

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de Joode, E A; van Boxtel, M P J; Hartjes, P; Verhey, F R J; van Heugten, C M

2013-11-01

The purpose of the current study was to evaluate the feasibility and the effectiveness of the use of a customized personal digital assistant (PDA) to support cognitive functioning in a person with Korsakoff syndrome. The PDA was compared with no external support and the use of a memory watch in a single case experimental design. Three main personal goal tasks were defined: "arrive at appointments on time", "execute a long-term task successfully", and "remember to ask for medication". No significant differences were found between the use of the memory watch and the use of the customized PDA. PDA use was perceived as feasible and effective and was considered as a more comprehensive aid than the memory watch. This study shows that a person with Korsakoff syndrome is able to use and benefit from a customized PDA. Replication of these findings in a larger effectiveness study is necessary.

Motor, linguistic, personal and social aspects of children with Down syndrome

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Amanda Tragueta FERREIRA-VASQUES

2015-08-01

Full Text Available AbstractA global developmental delay is expected from Down syndrome, affecting motor, cognitive, linguistic and personal-social skills. However, not always these delays are proportional; different conditions occur due to several intrinsic and extrinsic variables that must be controlled to form groups of greater homogeneity.Objective To enhance personal-social, fine motor-adaptive, gross motor and linguistic skills among children with Down syndrome and compare them with typically developing children, matched for gender, socioeconomic status and mental age, while controlling some variables that interfere with the global development.Methods The ethical aspects were fulfilled (Case No. 040/2009. The following inclusion criteria were considered: participants without a history of prematurity, very low birth weight, congenital hypothyroidism, significant hearing and vision problems, and signs of Autism Spectrum Disorder. After the inclusion criteria were considered, 40 children participated in the study, of which 20 had Down syndrome (experimental group - EG, these being of both genders and with chronological ages ranging from 38 to 63 months, and the other 20 being typically developing children (control group - CG, matching the EG in terms of gender, socioeconomic status and mental age, with this age ranging from 13 to 50 months. The evaluation consisted in applying the Denver Developmental Screening Test II, a test that assesses areas such as personal-social, fine motor-adaptive, linguistic and gross motor development. The results were subjected to statistical analysis using Student’s t-test.Results A statistically significant difference was verified between the groups for the language and fine motor-adaptive areas.Conclusion Children with Down syndrome showed lower performance in language and fine motor skills when compared with typically developing children. There was no statistically significant difference in gross motor and personal

Inverse relationship between physical activity and arterial stiffness in adults with hypertension.

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O'Donovan, Cuisle; Lithander, Fiona E; Raftery, Tara; Gormley, John; Mahmud, Azra; Hussey, Juliette

2014-02-01

Physical activity has beneficial effects on arterial stiffness among healthy adults. There is a lack of data on this relationship in adults with hypertension. The majority of studies which have examined physical activity and arterial stiffness have used subjective measures of activity. The aim of this study was to investigate the relationship between objectively measured habitual physical activity and arterial stiffness in individuals with newly diagnosed essential hypertension. Adults attending an outpatient hypertension clinic were recruited into this cross sectional study. Physical activity was measured using a triaxial accelerometer. Pulse wave velocity (PWV) and augmentation index (AIx) were measured using applanation tonometry. Participant's full lipid profile and glucose were determined through the collection of a fasting blood sample. Fifty-three adults [51(14) years, 26 male] participated, 16 of whom had the metabolic syndrome. Inactivity was positively correlated with PWV (r = .53, P arterial stiffness among adults with hypertension.

Personality characteristics and quality of life in patients treated for Cushing's syndrome.

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Sonino, Nicoletta; Bonnini, Stefano; Fallo, Francesco; Boscaro, Marco; Fava, Giovanni A

2006-03-01

Psychological distress does not always disappear upon proper endocrine treatment of Cushing's syndrome, and quality of life may still be compromised. Little is known on the personality correlates that may be involved. The aim of this study was to provide a controlled assessment of personality characteristics and quality of life in patients successfully treated for Cushing's syndrome. A single-centred, controlled, prospective study. Twenty-four consecutive outpatients who were in remission upon proper treatment of Cushing's syndrome for at least 1 year and no more than 3 years (20 with pituitary-dependent Cushing's disease and four with a cortisol-secreting adrenal adenoma; 5 M/19 F; mean age 34.5, SD = 10.6; range 18-57 years) were compared with 24 healthy control subjects matched for sociodemographic variables. Both patients and controls were administered two self-rating scales: (a) tridimensional personality questionnaire (TPQ), a 100-item inventory that yields three scales: novelty seeking, harm avoidance and reward dependence. (b) symptom rating test (SRT), a 46-item scale for assessing psychological distress and quality of life with six subscales (anxiety, depression, somatic symptoms, anger-hostility, cognitive symptoms, psychotic symptoms). There were no significant differences in personality dimensions, as measured by the TPQ, between patients and controls. The results did not change when the four patients with an adrenal adenoma were excluded and only the 20 with pituitary-dependent Cushing's disease were considered. As to the SRT scale, patients with Cushing's syndrome displayed significantly higher scores in anxiety (P= 0.046), depression (P= 0.013), and psychotic symptoms (P= 0.006), with a generalized compromised quality of life (P= 0.02). Again, no differences were found in evaluating the 20 patients with Cushing's disease separately. Even though personality traits other than those explored here may be involved, the results seem to exclude the

Personality profiles of youngsters with Velo-Cardio-Facial Syndrome

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Prinzie, P.; Swillen, A.; Vogels, A.; Kockuyt, V.; Curfs, L.M.G.; Haselager, G.J.T.; Hellinckx, W.; Devriendt, K.; Onghena, P.; Lieshout, C.F.M. van; Fryns, J.P.

2002-01-01

The personality profile of 48 youngsters (24 males and 24 females, mean age 8 years, 5 months) with Velo-Cardio-Facial Syndrome (VCFS) was compared with a group of 240 non VCFS control youngsters (matched on age and gender), and, in addition, with groups of youngsters with Prader-Willi (PWS),

Impairment of Arterial Compliance in Cushing’s Syndrome

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Maria Zedda, Angela; Mercuro, Giuseppe

2014-01-01

Abstract Arterial stiffness may be useful for stratifying cardiovascular risk in individuals suffering from a number of pathologies, such as hypertension, diabetes, obesity, dyslipidaemia and coronary artery disease. Cushing’s syndrome is underpinned by a complex metabolic syndrome, which is potentially implicated in the onset of blood vessel alterations and the increase in arterial wall stiffness. The aim of this paper was to perform a review about the most important studies conducted in order to evaluate the arterial distensibility profile of subjects affected by Cushing’s syndrome. Increased arterial stiffness may persist even after successful cure of this disease. It is therefore of fundamental importance to identify the presence of early vascular alterations in these patients, in order to commence their treatment and thus attempt to prevent the subsequent onset of adverse cardiovascular events.

Personalizing mechanical ventilation for acute respiratory distress syndrome

OpenAIRE

Berngard, S. Clark; Beitler, Jeremy R.; Malhotra, Atul

2016-01-01

Lung-protective ventilation with low tidal volumes remains the cornerstone for treating patient with acute respiratory distress syndrome (ARDS). Personalizing such an approach to each patient's unique physiology may improve outcomes further. Many factors should be considered when mechanically ventilating a critically ill patient with ARDS. Estimations of transpulmonary pressures as well as individual's hemodynamics and respiratory mechanics should influence PEEP decisions as well as response ...

A structured review of spinal stiffness as a kinesiological outcome of manipulation: its measurement and utility in diagnosis, prognosis and treatment decision-making.

Science.gov (United States)

Snodgrass, Suzanne J; Haskins, Robin; Rivett, Darren A

2012-10-01

To review and discuss the methods used for measuring spinal stiffness and factors associated with stiffness, how stiffness is used in diagnosis, prognosis, and treatment decision-making and the effects of manipulative techniques on stiffness. A systematic search of MEDLINE, EMBASE, CINAHL, AMED and ICL databases was conducted. Included studies addressed one of four constructs related to stiffness: measurement, diagnosis, prognosis and/or treatment decision-making, and the effects of manipulation on stiffness. Spinal stiffness was defined as the relationship between force and displacement. One hundred and four studies are discussed in this review, with the majority of studies focused on the measurement of stiffness, most often in asymptomatic persons. Eight studies investigated spinal stiffness in diagnosis, providing limited evidence that practitioner-judged stiffness is associated with radiographic findings of sagittal rotational mobility. Fifteen studies investigated spinal stiffness in prognosis or treatment decision-making, providing limited evidence that spinal stiffness is unlikely to independently predict patient outcomes, though stiffness may influence a practitioner's application of non-thrust manipulative techniques. Nine studies investigating the effects of manipulative techniques on spinal stiffness provide very limited evidence that there is no change in spinal stiffness following thrust or non-thrust manipulation in asymptomatic individuals and non-thrust techniques in symptomatic persons, with only one study supporting an immediate, but not sustained, stiffness decrease following thrust manipulation in symptomatic individuals. The existing limited evidence does not support an association between spinal stiffness and manipulative treatment outcomes. There is a need for additional research investigating the effects of manipulation on spinal stiffness in persons with spinal pain. Copyright © 2012 Elsevier Ltd. All rights reserved.

Distinctive personality profiles of fibromyalgia and chronic fatigue syndrome patients

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Jacob N. Ablin

2016-09-01

Full Text Available Objective The current study is an innovative exploratory investigation, aiming at identifying differences in personality profiles within Fibromyalgia Syndrome (FMS and Chronic Fatigue Syndrome (CFS patients. Method In total, 344 participants (309 female, 35 male reported suffering from FMS and/or CFS and consented to participate in the study. Participants were recruited at an Israeli FM/CFS patient meeting held in May 2013, and through an announcement posted on several social networks. Participants were asked to complete a research questionnaire, which included FMS criteria and severity scales, and measures of personality, emotional functioning, positivity, social support and subjective assessment of general health. In total, 204 participants completed the research questionnaire (40.7% attrition rate. Results A cluster analysis produced two distinct clusters, which differed significantly on psychological variables, but did not differ on demographic variables or illness severity. As compared to cluster number 2 (N = 107, participants classified into cluster number 1 (N = 97 showed a less adaptive pattern, with higher levels of Harm Avoidance and Alexithymia; higher prevalence of Type D personality; and lower levels of Persistence (PS, Reward dependence (RD, Cooperation, Self-directedness (SD, social support and positivity. Conclusion The significant pattern of results indicates at least two distinct personality profiles of FM and CFS patients. Findings from this research may help improve the evaluation and treatment of FM and CFS patients, based on each patient’s unique needs, psychological resources and weaknesses, as proposed by the current trend of personalized medicine.

The bipolar II disorder personality traits, a true syndrome?

Science.gov (United States)

Gudmundsson, Einar

2015-06-01

The author was struck by the similarities and commonality of complaints, aside from mood swings, made by Bipolar II patients and started registrating these complaints. This registrational work eventually led to the development of The Bipolar II Syndome Checklist. The aim of this work was to understand how widely the Bipolar II disorder affects the personality, and what disturbing personality traits are the most common? Deliberately, no attempt was made to diagnose psychiatric comorbidities, in the hope that one would get a clearer view of what symptoms, if any, could be considered a natural part of the Bipolar II Disorder. As far as the author knows this is a novel approach. 105 Bipolar II patients completed the Bipolar II Syndrome Checklist. The answers to the 44 questions on the list are presented in tables. Symptoms like anxiety, low self esteem, paranoia, extreme hurtfulness, migraine, Post Partum Depression, obsessive traits, alcoholism in the family are amongst the findings which will be presented in greater detail. No control group. Bipolar I patients excluded. The Bipolar II Syndrome Checklist has not been systematically validated. The results show that Bipolar II Disorder causes multiple symptoms so commonly that it may be justified to describe it as a syndrome, The Bipolar II Syndrome. Also these disturbances commonly lie in families of Bipolar II patients and are in all likelihood, greatly underdiagnosed. The clinical relevance of this study lies in increasing our knowledge and understanding of the nature of the Bipolar II Disorder, which in all probability will increase the diagnostic and treatment accuracy, since clinicians are more likely to scan for other symptoms needing treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Healthcare transition in persons with intellectual disabilities: general issues, the Maastricht model, and Prader-Willi syndrome.

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Schrander-Stumpel, Constance T R M; Sinnema, Margje; van den Hout, Lieke; Maaskant, Marian A; van Schrojenstein Lantman-de Valk, Henny M J; Wagemans, Annemieke; Schrander, Jaap J P; Curfs, Leopold M G

2007-08-15

In current healthcare, transitional healthcare is a very important and timely issue. Thanks to the major advances made in medical care and technology, many children with childhood onset diseases and/or genetic syndromes survive to adulthood. These children are at risk of not being provided with adequate healthcare as they reach adulthood. Healthcare transition is an essential part of healthcare provision, referred to as the shift from one type of healthcare to another. In Maastricht, we developed a transition/out clinic led by a medical doctor specialized in persons with intellectual disability (ID), together with a clinical geneticist. We aim to coordinate healthcare issues based on guidelines if available. Also questions concerning living, daily activities, relations, sexuality, and sterilization can be discussed. The aging process of persons with ID has been a topic of interest in recent years. Little is known about the aging process of people with specific syndromes, except for persons with Down syndrome. We present some data of a recent questionnaire study in persons with Prader-Willi syndrome. In only 50% in persons with a clinical diagnosis genetic test results could be reported. The majority of persons were obese. Diabetes mellitus, hypertension, skin problems, sleep apnea, and hormonal problems like osteoporosis and hypothyroidism were common. Psychiatric problems were frequent, especially in the persons with uniparental disomy. Osteoporosis and sleep apnoea seem to be underestimated. Further longitudinal research is necessary for a better understanding of the aging process in PWS. (c) 2007 Wiley-Liss, Inc.

Coupling between the Output Force and Stiffness in Different Variable Stiffness Actuators

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Amir Jafari

2014-08-01

Full Text Available The fundamental objective in developing variable stiffness actuators is to enable the actuator to deliberately tune its stiffness. This is done through controlling the energy flow extracted from internal power units, i.e., the motors of a variable stiffness actuator (VSA. However, the stiffness may also be unintentionally affected by the external environment, over which, there is no control. This paper analysis the correlation between the external loads, applied to different variable stiffness actuators, and their resultant output stiffness. Different types of variable stiffness actuators have been studied considering springs with different types of nonlinearity. The results provide some insights into how to design the actuator mechanism and nonlinearity of the springs in order to increase the decoupling between the load and stiffness in these actuators. This would significantly widen the application range of a variable stiffness actuator.

Fitness as a determinant of arterial stiffness in healthy adult men: a cross-sectional study.

Science.gov (United States)

Chung, Jinwook; Kim, Milyang; Jin, Youngsoo; Kim, Yonghwan; Hong, Jeeyoung

2018-01-01

Fitness is known to influence arterial stiffness. This study aimed to assess differences in cardiorespiratory endurance, muscular strength, and flexibility according to arterial stiffness, based on sex and age. We enrolled 1590 healthy adults (men: 1242, women: 348) who were free of metabolic syndrome. We measured cardiorespiratory endurance in an exercise stress test on a treadmill, muscular strength by a grip test, and flexibility by upper body forward-bends from a standing position. The brachial-ankle pulse wave velocity test was performed to measure arterial stiffness before the fitness test. Cluster analysis was performed to divide the patients into groups with low (Cluster 1) and high (Cluster 2) arterial stiffness. According to the k-cluster analysis results, Cluster 1 included 624 men and 180 women, and Cluster 2 included 618 men and 168 women. Men in the middle-aged group with low arterial stiffness demonstrated higher cardiorespiratory endurance, muscular strength, and flexibility than those with high arterial stiffness. Similarly, among men in the old-aged group, the cardiorespiratory endurance and muscular strength, but not flexibility, differed significantly according to arterial stiffness. Women in both clusters showed similar cardiorespiratory endurance, muscular strength, and flexibility regardless of their arterial stiffness. Among healthy adults, arterial stiffness was inversely associated with fitness in men but not in women. Therefore, fitness seems to be a determinant for arterial stiffness in men. Additionally, regular exercise should be recommended for middle-aged men to prevent arterial stiffness.

Marital quality in wives of persons with alcohol dependence syndrome

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Debasree Bora

2017-01-01

Full Text Available Background: Marriage is a strong bond between couples with the promise of lifelong dedication and emotional wellbeing. The effects of alcoholism in husbands may lead to disturbances in marital life. Lack of understanding, unpredictable behaviour of the husbands, and their irresponsibility in family matters can often lead to poor quality of a couple’s relationship. Aim of the study: The study is aimed to understand the marital quality of the wives of persons with alcohol dependence syndrome. Material and methods: Thirty wives of persons with alcohol dependence syndrome according to ICD-10 were taken as the sample, using purposive sample collection. Socio-demographic profile was assessed through semi-structured questionnaire while Marital Quality Scale (MQS-1995 was applied to assess the marital quality after taking their informed consent. Higher scores indicate poorer quality of marital life. Data analysis was done using SPSS for descriptive statistics. Results: The domain mean scores of rejection, understanding, and decision-making, and the total score of marital quality were high. Thus, indicating poorer quality of marital life among the wives of persons with alcohol dependence. Conclusion: Alcohol dependence is highly associated with poor marital quality as the person with alcohol dependence tends to adapt faulty communication patterns and behaviour which in turn leads to poor adjustment, unhappiness, and a high degree of dissatisfaction with relationships. Treatment plan for this group should be planned keeping these factors in consideration, as a priority.

Personality disorders in women with severe premenstrual syndrome.

Science.gov (United States)

Sassoon, Stephanie A; Colrain, Ian M; Baker, Fiona C

2011-06-01

Premenstrual syndrome (PMS) and its more severe form, premenstrual dysphoric disorder, affect up to 18% of women. Both are commonly associated with other mood-related disorders such as major depression, and cause significant life impairment, but their relationship with personality disorders is less clear. After completing the Structured Clinical Interview for DSM-IV-TR disorders, 33 women with severe PMS and 26 asymptomatic women, counterbalanced for menstrual cycle phase, were administered the Structured Interview for DSM-IV Personality Disorders, a diagnostic interview with low transparency, strong inter-rater reliability, and good diagnostic clarity. Women with severe PMS had a higher prevalence of personality disorders (p = 0.003) than asymptomatic women (27% versus 0%), and were more likely to have odd-eccentric, dramatic-erratic, and anxious-fearful personality disorder traits (p OCPD) was the most common character pathology in the PMS group (n = 6, 18%). OCPD, although not necessarily associated with greater severity of premenstrual symptoms, was related to poorer life functioning in women with PMS. The comorbidity of a personality disorder and severe PMS places an additive burden on general life functioning and may have implications for psychiatric treatment or medication given to those with severe premenstrual symptoms.

OroSTIFF: Face-referenced measurement of perioral stiffness in health and disease.

Science.gov (United States)

Chu, Shin-Ying; Barlow, Steven M; Kieweg, Douglas; Lee, Jaehoon

2010-05-28

A new device and automated measurement technology known as OroSTIFF is described to characterize non-participatory perioral stiffness in healthy adults for eventual application to patients with orofacial movement disorders associated with neuromotor disease, traumatic injury, or congenital clefts of the upper lip. Previous studies of perioral biomechanics required head stabilization for extended periods of time during measurement, which precluded sampling patients with involuntary body/head movements (dyskinesias), or pediatric subjects. The OroSTIFF device is face-referenced and avoids the complications associated with head-restraint. Supporting data of non-participatory perioral tissue stiffness using OroSTIFF are included from 10 male and 10 female healthy subjects. The OroSTIFF device incorporates a pneumatic glass air cylinder actuator instrumented for pressure, and an integrated subminiature displacement sensor to encode lip aperture. Perioral electromyograms were simultaneously sampled to confirm passive muscle state for the superior and inferior divisions of the orbicularis oris muscles. Perioral stiffness, derived as a quotient from resultant force (DeltaF) and interangle span (DeltaX), was modeled with multilevel regression techniques. Real-time calculation of the perioral stiffness function demonstrated a significant quadratic relation between imposed interangle stretch and resultant force. This stiffness growth function also differed significantly between males and females. This study demonstrates the OroSTIFF 'proof-of-concept' for cost-effective non-invasive stimulus generation and derivation of perioral stiffness in a group of healthy unrestrained adults, and a case study to illustrate the dose-dependent effects of Levodopa on perioral stiffness in an individual with advanced Parkinson's disease who exhibited marked dyskinesia and rigidity. Copyright 2010 Elsevier Ltd. All rights reserved.

Coexistence of Ankylosing Spondylitis and Klinefelter's Syndrome.

Science.gov (United States)

Kobak, Senol; Yalçin, Murat; Karadeniz, Muamer; Oncel, Guray

2013-01-01

Ankylosing spondylitis is a chronic inflammatory disease characterized by inflammatory lower back pain and morning stiffness and accompanied by spine and sacroiliac joint involvement. Klinefelter's syndrome is a genetic condition that only affects males. Affected males have an extra X chromosome. This paper reports a 30-years-old male on followup with the diagnosis of Klinefelters syndrome. The patient admitted with complaints of inflammatory lower back, and neck pain and morning stiffness and was diagnosed with ankylosing spondylitis. Nonsteroidal anti-inflammatory drug and salazopyrine treatment resulted in significant regression in his complaints.

Coexistence of Ankylosing Spondylitis and Klinefelter's Syndrome

Directory of Open Access Journals (Sweden)

Şenol Kobak

2013-01-01

Full Text Available Ankylosing spondylitis is a chronic inflammatory disease characterized by inflammatory lower back pain and morning stiffness and accompanied by spine and sacroiliac joint involvement. Klinefelter's syndrome is a genetic condition that only affects males. Affected males have an extra X chromosome. This paper reports a 30-years-old male on followup with the diagnosis of Klinefelters syndrome. The patient admitted with complaints of inflammatory lower back, and neck pain and morning stiffness and was diagnosed with ankylosing spondylitis. Nonsteroidal anti-inflammatory drug and salazopyrine treatment resulted in significant regression in his complaints.

Down syndrome and personalized medicine: changing paradigms from genotype to phenotype to treatment.

Science.gov (United States)

McCabe, Linda L; McCabe, Edward R B

2013-03-01

Personalized Medicine represents a paradigm shift in the conceptual framework of research and clinical care. This shift argues that Down syndrome is a treatable condition, and therefore we must invest in research to improve outcomes. Individuals with Down syndrome have varying levels of increased risk for a number of co-morbidities, including infantile spasms and early onset Alzheimer's disease. We will review research in these associated conditions to show how investigators are attempting to identify biomarkers, including genomic, epigenomic, proteomic and metabolomic "signatures" that will predict who may be at risk to develop a specific co-morbidity prior to onset and will provide novel targets for therapeutic development. This Personalized Medicine approach will permit predictive and preventive approaches for individuals at increased risk for co-morbidities. The support for clinical trials among individuals with Down syndrome is beginning to overcome the "culture of intractability" that has surrounded this disorder. © 2012 The Authors. Congenital Anomalies © 2012 Japanese Teratology Society.

Potential Relationship between Passive Plantar Flexor Stiffness and Running Performance.

Science.gov (United States)

Ueno, Hiromasa; Suga, Tadashi; Takao, Kenji; Tanaka, Takahiro; Misaki, Jun; Miyake, Yuto; Nagano, Akinori; Isaka, Tadao

2018-02-01

The present study aimed to determine the relationship between passive stiffness of the plantar flexors and running performance in endurance runners. Forty-eight well-trained male endurance runners and 24 untrained male control subjects participated in this study. Plantar flexor stiffness during passive dorsiflexion was calculated from the slope of the linear portion of the torque-angle curve. Of the endurance runners included in the present study, running economy in 28 endurance runners was evaluated by measuring energy cost during three 4-min trials (14, 16, and 18 km/h) of submaximal treadmill running. Passive stiffness of the plantar flexors was significantly higher in endurance runners than in untrained subjects. Moreover, passive plantar flexor stiffness in endurance runners was significantly correlated with a personal best 5000-m race time. Furthermore, passive plantar flexor stiffness in endurance runners was significantly correlated with energy cost during submaximal running at 16 km/h and 18 km/h, and a trend towards such significance was observed at 14 km/h. The present findings suggest that stiffer plantar flexors may help achieve better running performance, with greater running economy, in endurance runners. Therefore, in the clinical setting, passive stiffness of the plantar flexors may be a potential parameter for assessing running performance. © Georg Thieme Verlag KG Stuttgart · New York.

Type D personality is associated with increased metabolic syndrome prevalence and an unhealthy lifestyle in a cross-sectional Dutch community sample

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Denollet Johan

2010-11-01

Full Text Available Abstract Background People with Type D-Distressed-personality have a general tendency towards increased negative affectivity (NA, while at the same time inhibiting these emotions in social situations (SI. Type D personality is associated with an increased risk of adverse outcomes in patients with cardiovascular disease. Whether Type D personality is a cardiovascular risk factor in healthy populations remains to be investigated. In the present study, the relations between Type D personality and classical cardiovascular risk factors, i.e. metabolic syndrome and lifestyle were investigated in a Dutch community sample. Methods In a cross-sectional study 1592 participants were included, aged 20-80 years. Metabolic syndrome was defined by self-report, following the International Diabetes Federation-IDF-guidelines including an increased waist circumference, dyslipidemia, hypertension, and diabetes. In addition lifestyle factors smoking, alcohol use, exercise and dietary habits were examined. Metabolic syndrome prevalence was stratified by Type D personality (a high score on both NA and SI, lifestyle and confounders age, gender, having a partner, higher education level, cardiac history, family history of cardiovascular disease. Results Metabolic syndrome was more prevalent in persons with a Type D personality (13% vs. 6%. Persons with Type D personality made poorer lifestyle choices, adhered less to the physical activity norm (OR = 1.5, 95%CI = 1.1-2.0, p = .02, had a less varied diet (OR = 0.50, 95%CI = 0.40-0.70, p p = .01. Type D personality was related to a twofold increased risk of metabolic syndrome (OR = 2.2, 95%CI = 1.2-4.0, p = .011, independent of lifestyle factors and confounders. Conclusions Type D personality is related to an increased prevalence of metabolic syndrome and unhealthy lifestyle, which suggests both behavioral and biological vulnerability for development of cardiovascular disorders and diabetes.

Clinical study of the relation of borderline personality disorder to Briquet's syndrome (hysteria), somatization disorder, antisocial personality disorder, and substance abuse disorders.

Science.gov (United States)

Hudziak, J J; Boffeli, T J; Kreisman, J J; Battaglia, M M; Stanger, C; Guze, S B; Kriesman, J J

1996-12-01

The criteria for borderline personality disorder seem to select patients with very high rates of Briquet's syndrome (hysteria), somatization disorder, antisocial personality disorder, and substance abuse disorders. This study was undertaken to determine whether systematic assessment of patients with borderline personality disorder would reveal characteristic features of that condition which would distinguish it from these other disorders. Eighty-seven white female patients (75 in St. Louis and 12 in Milan, Italy) who had borderline personality disorder according to both the DSM-III-R criteria and the Revised Diagnostic Interview for Borderlines were further examined with the DSM-III-R Checklist and the Perley-Guze Hysteria Checklist to determine their patterns of psychiatric comorbidity. Every patient had at least one additional DSM diagnosis. Patients in St. Louis and Milan averaged five and four additional diagnoses, respectively. Eighty-four percent of the patients in St. Louis met criteria for either somatization disorder, Briquet's syndrome, antisocial personality disorder, or substance abuse disorders. Patterns of comorbidity for panic (51%), generalized anxiety disorder (55%), and major depression (87%) in St. Louis were consistent with those in other studies. The data indicate that the boundaries for the borderline condition are not specific and identify a high percentage of patients with these other disorders. Furthermore, the comorbidity profiles closely resemble the psychiatric profiles of patients with these disorders. If the borderline syndrome is meant to include all of these disorders, its usefulness as a diagnosis is limited. Until the fundamental features of borderline personality disorder that distinguish it from the others are identified, it is recommended that clinicians carefully assess patients for these other diagnoses. Efforts should be made to change the borderline personality disorder criteria by shifting away from overlap with the

Type D personality is associated with increased metabolic syndrome prevalence and an unhealthy lifestyle in a cross-sectional Dutch community sample.

Science.gov (United States)

Mommersteeg, Paula M C; Kupper, Nina; Denollet, Johan

2010-11-19

People with Type D-Distressed-personality have a general tendency towards increased negative affectivity (NA), while at the same time inhibiting these emotions in social situations (SI). Type D personality is associated with an increased risk of adverse outcomes in patients with cardiovascular disease. Whether Type D personality is a cardiovascular risk factor in healthy populations remains to be investigated. In the present study, the relations between Type D personality and classical cardiovascular risk factors, i.e. metabolic syndrome and lifestyle were investigated in a Dutch community sample. In a cross-sectional study 1592 participants were included, aged 20-80 years. Metabolic syndrome was defined by self-report, following the International Diabetes Federation-IDF-guidelines including an increased waist circumference, dyslipidemia, hypertension, and diabetes. In addition lifestyle factors smoking, alcohol use, exercise and dietary habits were examined. Metabolic syndrome prevalence was stratified by Type D personality (a high score on both NA and SI), lifestyle and confounders age, gender, having a partner, higher education level, cardiac history, family history of cardiovascular disease. Metabolic syndrome was more prevalent in persons with a Type D personality (13% vs. 6%). Persons with Type D personality made poorer lifestyle choices, adhered less to the physical activity norm (OR = 1.5, 95%CI = 1.1-2.0, p = .02), had a less varied diet (OR = 0.50, 95%CI = 0.40-0.70, p lifestyle factors and confounders. Type D personality is related to an increased prevalence of metabolic syndrome and unhealthy lifestyle, which suggests both behavioral and biological vulnerability for development of cardiovascular disorders and diabetes.

Patients with Gilles de la Tourette syndrome have widespread personality differences.

Science.gov (United States)

Trillini, Morounke O; Müller-Vahl, Kirsten R

2015-08-30

Only little is known about pathological personality traits in patients with Gilles de la Tourette syndrome (GTS). The aim of this study was to further investigate the prevalence of personality traits in adults with GTS. We used a variety of rating scales to assess not only personality traits, but also severity of tics, quality of life, and comorbidities (obsessive-compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), depression), in a large group (n=50) of patients. Our major finding was that pathological personality traits are very common in patients with GTS encompassing a wide range of different personality traits, but most typically personality traits related to cluster C. Demand-anxious was the most common personality trait, while histrionic personality trait was absent. Patients' quality of life was more impaired by personality traits than comorbidities. Personality traits were more common in patients with comorbid OCD and depression, while comorbid ADHD had no influence. Our findings, therefore, corroborate the hypothesis that GTS plus OCD represents a more severe subtype of GTS, and support the assumption that OCD and depression, but not ADHD, are part of the GTS spectrum. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Psychoneurological character of persons who had acute radiation syndrome

International Nuclear Information System (INIS)

Nyagu, A.I.; Khalyavka, I.G.; Loganovskij, K.N.; Plachinda, Yu.I.; Yur'ev, K.L.; Loganovskaya, T.K.

1996-01-01

Survivors of the Chernobyl accident who had an acute radiation syndrome (ARS,110 persons) were observed for 8 years after Chernobyl accident. It has been found that the cerebrovascular pathology and vertebral osteochondrosis rate increase as well as abnormal psychoorganic changes in personality and endogenic-like psychoorganic process, their rate being in proportion to the ARS heaviness. The EEG and evoked potentials have confirmed the dyscirculatory and toxic-metabolic organic disorders of the central nervous system as a result of irradiation in the remote period of the ARS consequences. It is necessary for early and differential diagnostic of the psychoneurological disorders after ARS to carry out the neuro- and psychophysiological examination as well as computer tomography, nucleic magnetic resonance and positron emission tomography of the brain

Association of Metabolic Syndrome with the Cardioankle Vascular Index in Asymptomatic Korean Population

Science.gov (United States)

Nam, Su-Hyun; Lee, Yun-Ah; Rho, Jun-Seung

2015-01-01

Aim. Metabolic syndrome is characterized by a cluster of atherosclerotic cardiovascular risk factors. The cardioankle vascular index (CAVI) reflects arterial stiffness and may be used as an indicator of atherosclerotic cardiovascular disease. In this study, we investigated the association of CAVI with metabolic syndrome. Methods. A total of 1,144 adults were included in this study. We measured CAVIs and examined blood samples to identify metabolic syndrome according to WHO Asia Pacific criteria and NCEP-ATPIII criteria. AST, ALT, r-GTP, BUN, creatinine, high sensitivity C-reactive protein, and uric acid were also measured. Results. CAVI values were significantly higher in subjects with metabolic syndrome than those without metabolic syndrome and increased according to the number of metabolic syndrome components present. Subjects with high fasting blood sugar levels or high blood pressure showed high CAVI values. Multiple regression analysis showed that age, sex, diastolic blood pressure, and uric acid were independent predictors of CAVI. Conclusion. Subjects with metabolic syndrome had high CAVIs, which indicated arterial stiffness, and were closely associated with an increase in the number of metabolic risk factors. The individual risk factors for metabolic syndrome have the synergistic effect of elevating arterial stiffness in asymptomatic Korean population. PMID:26273666

Limit cycles and stiffness control with variable stiffness actuators

NARCIS (Netherlands)

Carloni, Raffaella; Marconi, L.

2012-01-01

Variable stiffness actuators realize highly dynamic systems, whose inherent mechanical compliance can be properly exploited to obtain a robust and energy-efficient behavior. The paper presents a control strategy for variable stiffness actuators with the primarily goal of tracking a limit cycle

Personality traits and emotional patterns in irritable bowel syndrome.

Science.gov (United States)

Muscatello, Maria Rosaria A; Bruno, Antonio; Mento, Carmela; Pandolfo, Gianluca; Zoccali, Rocco A

2016-07-28

The review focuses on those personality traits (neuroticism, extraversion, openness to experience, agreeableness, and conscientiousness), constructs (alexithymia and distressed - Type D personality) and emotional patterns (negative and positive) that are of particular concern in health psychology, with the aim to highlight their potential role on the pathogenesis, onset, symptom clusters, clinical course, and outcome of irritable bowel syndrome (IBS). Personality traits and emotional patterns play key roles in affecting autonomic, immune, inflammatory, and endocrine functions, thus contributing not only to IBS clinical expression and symptomatic burden, but also to disease physiopathology. In this sense, psychological treatments should address those personality traits and emotional features that are constitutive of, and integral to IBS. The biopsychosocial model of illness applied to IBS acknowledges the interaction between biological, psychological, environmental, and social factors in relation to pain and functional disability. A holistic approach to IBS should take into account the heterogeneous nature of the disorder, and differentiate treatments for different types of IBS, also considering the marked individual differences in prevalent personality traits and emotional patterns. Beyond medications, and lifestyle/dietary interventions, psychological and educational treatments may provide the optimal chance of addressing clinical symptoms, comorbid conditions, and quality of life in IBS patients.

Development of a stiffness-angle law for simplifying the measurement of human hair stiffness.

Science.gov (United States)

Jung, I K; Park, S C; Lee, Y R; Bin, S A; Hong, Y D; Eun, D; Lee, J H; Roh, Y S; Kim, B M

2018-04-01

This research examines the benefits of caffeine absorption on hair stiffness. To test hair stiffness, we have developed an evaluation method that is not only accurate, but also inexpensive. Our evaluation method for measuring hair stiffness culminated in a model, called the Stiffness-Angle Law, which describes the elastic properties of hair and can be widely applied to the development of hair care products. Small molecules (≤500 g mol -1 ) such as caffeine can be absorbed into hair. A common shampoo containing 4% caffeine was formulated and applied to hair 10 times, after which the hair stiffness was measured. The caffeine absorption of the treated hair was observed using Fourier-transform infrared spectroscopy (FTIR) with a focal plane array (FPA) detector. Our evaluation method for measuring hair stiffness consists of a regular camera and a support for single strands of hair. After attaching the hair to the support, the bending angle of the hair was observed with a camera and measured. Then, the hair strand was weighed. The stiffness of the hair was calculated based on our proposed Stiffness-Angle Law using three variables: angle, weight of hair and the distance the hair was pulled across the support. The caffeine absorption was confirmed by FTIR analysis. The concentration of amide bond in the hair certainly increased due to caffeine absorption. After caffeine was absorbed into the hair, the bending angle and weight of the hair changed. Applying these measured changes to the Stiffness-Angle Law, it was confirmed that the hair stiffness increased by 13.2% due to caffeine absorption. The theoretical results using the Stiffness-Angle Law agree with the visual examinations of hair exposed to caffeine and also the known results of hair stiffness from a previous report. Our evaluation method combined with our proposed Stiffness-Angle Law effectively provides an accurate and inexpensive evaluation technique for measuring bending stiffness of human hair. © 2018

Arterial stiffness and peripheral vascular resistance in offspring of hypertensive parents

DEFF Research Database (Denmark)

Buus, Niels Henrik; Carlsen, Rasmus K; Khatir, Dinah S

2018-01-01

AIM: Established essential hypertension is associated with increased arterial stiffness and peripheral resistance, but the extent of vascular changes in persons genetically predisposed for essential hypertension is uncertain. METHODS: Participants from the Danish Hypertension Prevention Project...... (DHyPP) (both parents hypertensive) (n = 95, 41 ± 1 years, 53% men) were compared with available spouses (n = 45, 41 ± 1 years) using measurements of ambulatory blood pressure (BP), left ventricular mass index (LVMI), pulse wave velocity, central BP and augmentation index (AIx) in addition to forearm...... than men (P hypertension display increased AIx and LVMI, although vascular stiffness...

Posttraumatic stiff elbow

Directory of Open Access Journals (Sweden)

Ravi Mittal

2017-01-01

Full Text Available Posttraumatic stiff elbow is a frequent and disabling complication and poses serious challenges for its management. In this review forty studies were included to know about the magnitude of the problem, causes, pathology, prevention, and treatment of posttraumatic stiff elbow. These studies show that simple measures such as internal fixation, immobilization in extension, and early motion of elbow joint are the most important steps that can prevent elbow stiffness. It also supports conservative treatment in selected cases. There are no clear guidelines about the choice between the numerous procedures described in literature. However, this review article disproves two major beliefs-heterotopic ossification is a bad prognostic feature, and passive mobilization of elbow causes elbow stiffness.

Relationship between occupational exposure to lead and local arterial stiffness and left ventricular diastolic function in individuals with arterial hypertension

International Nuclear Information System (INIS)

Poreba, Rafal; Gac, Pawel; Poreba, Malgorzata; Antonowicz-Juchniewicz, Jolanta; Andrzejak, Ryszard

2011-01-01

Relationship between occupational exposure to lead and frequency of complications in persons with arterial hypertension has been poorly investigated. This study aimed at evaluation of the relationship between occupational exposure to lead and manifestation of an increased local arterial stiffness and left ventricular diastolic dysfunction. The studies included 105 men (mean age: 44.47 ± 9.12 years) with arterial hypertension, treated with hypotensive drugs: group I - men occupationally exposed to lead (n = 53), and group II - men not exposed to lead (n = 52). In echocardiographic examination, the left ventricular diastolic dysfunction was diagnosed significantly more frequently in group I than in group II. In eTracking examination mean values of stiffness parameter (β), augmentation index (AI) and one-point pulse wave velocity (PWV-β) were significantly higher and mean values of arterial compliance (AC) were significantly lower in group I than in group II. The logistic regression showed that in the group of persons with arterial hypertension occupationally exposed to lead a more advanced age, higher blood lead concentration and higher mean values of augmentation index represent independent risk factors of left ventricular diastolic dysfunction. The multifactorial regression showed that amongst persons with arterial hypertension occupationally exposed to lead higher blood zinc protoporphyrin concentration, a more advanced age and higher value of body mass index (BMI) represent independent risk factors of an increased local arterial stiffness. In summary, we should note that in the group of persons with arterial hypertension occupationally exposed to lead the study has demonstrated a significantly more frequent manifestation of left ventricular diastolic dysfunction and an increase in local arterial stiffness. - Highlights: → Amongst persons with AH exposed to Pb higher ZnPP represent independent risk factor of increased local arterial stiffness. → Higher Pb

Cardiovascular profile in postural orthostatic tachycardia syndrome and Ehlers-Danlos syndrome type III.

Science.gov (United States)

Cheng, Jem L; Au, Jason S; Guzman, Juan C; Morillo, Carlos A; MacDonald, Maureen J

2017-04-01

The cardiovascular profile of postural orthostatic tachycardia syndrome + Ehlers-Danlos syndrome hypermobility type (POTS + EDSIII) has not been described, despite suggestions that it plays a role in orthostatic intolerance. We studied nine individuals diagnosed with POTS + EDSIII and found that the arterial stiffness and cardiac profiles of patients with POTS + EDSIII were comparable to those of age- and sex-matched controls, suggesting an alternate explanation for orthostatic intolerance.

The Effect of Acetyl-L-Carnitine Administration on Persons with Down Syndrome

Science.gov (United States)

Pueschel, Siegfried M.

2006-01-01

Since previous investigations reported improvements in cognition of patients with dementia after acetyl-L-carnitine therapy and since there is an increased risk for persons with Down syndrome to develop Alzheimer disease, this study was designed to investigate the effect of acetyl-L-carnitine administration on neurological, intellectual, and…

[Chronic Pelvic Pain Syndrome and Personality--Association of Somatic Symptoms and Psychic Structure].

Science.gov (United States)

Albrecht, Rebecca; Löwe, Bernd; A Brünahl, Christian; Riegel, Björn

2015-11-01

Despite its high prevalence, little is known about the aetiology and maintenance of Chronic Pelvic Pain Syndrome (CPPS). CPPS is is considered to be a multi-causal syndrome with discomfort and pain in the pelvis. Recent literature suggests that psychosocial factors are important for understanding CPPS. For example, CPPS has been associated with deficits in mentalization and bonding experiences. Our study aims to characterize features of personality disorders according to DSM-IV and psychic structure according to OPD-2 in CPPS patients. Furthermore, we examine the association of personality aspects with urological symptoms (NIH Questionnaire) and pain perception (MPQ Questionnaire). Personality aspects were assessed in a total of 109 patients from our CPPS outpatient clinic using standardized questionnaires. To characterize CPPS patients, we compared the sample's scores with reference groups, mostly the general population. In addition, the associations between personality aspects and both the urologic symptoms and pain perception were assessed using correlations. Missing data were replaced using multiple imputation methods. Compared to reference values, we found 'experiencing emotions' and 'creating relationships' as specific deficits in CPPS patients. Furthermore, patients' self-image (more dominant, higher depressive mood) differs from the general population. A higher pain perception was correlated with deficits in most personality aspects we measured. However, this was not the case for the severity of urological symptoms. Compared to the reference values, only a few personality aspects differed in CPPS patients but there was a correlational association between different personality traits and pain perception. Despite the extend of symptoms, pain perception is associated with difficulty (emotional ability) in dealing with emotions, self-management and relationships. These personality aspects should be taken into account when planning therapy. © Georg Thieme

Arterial stiffness and cognitive impairment.

Science.gov (United States)

Li, Xiaoxuan; Lyu, Peiyuan; Ren, Yanyan; An, Jin; Dong, Yanhong

2017-09-15

Arterial stiffness is one of the earliest indicators of changes in vascular wall structure and function and may be assessed using various indicators, such as pulse-wave velocity (PWV), the cardio-ankle vascular index (CAVI), the ankle-brachial index (ABI), pulse pressure (PP), the augmentation index (AI), flow-mediated dilation (FMD), carotid intima media thickness (IMT) and arterial stiffness index-β. Arterial stiffness is generally considered an independent predictor of cardiovascular and cerebrovascular diseases. To date, a significant number of studies have focused on the relationship between arterial stiffness and cognitive impairment. To investigate the relationships between specific arterial stiffness parameters and cognitive impairment, elucidate the pathophysiological mechanisms underlying the relationship between arterial stiffness and cognitive impairment and determine how to interfere with arterial stiffness to prevent cognitive impairment, we searched PUBMED for studies regarding the relationship between arterial stiffness and cognitive impairment that were published from 2000 to 2017. We used the following key words in our search: "arterial stiffness and cognitive impairment" and "arterial stiffness and cognitive impairment mechanism". Studies involving human subjects older than 30years were included in the review, while irrelevant studies (i.e., studies involving subjects with comorbid kidney disease, diabetes and cardiac disease) were excluded from the review. We determined that arterial stiffness severity was positively correlated with cognitive impairment. Of the markers used to assess arterial stiffness, a higher PWV, CAVI, AI, IMT and index-β and a lower ABI and FMD were related to cognitive impairment. However, the relationship between PP and cognitive impairment remained controversial. The potential mechanisms linking arterial stiffness and cognitive impairment may be associated with arterial pulsatility, as greater arterial pulsatility

Antibodies against severe fever with Thrombocytopenia syndrome Virus in healthy persons, China, 2013

NARCIS (Netherlands)

Zhang Lei, Lei; Sun, J.; Yan, J.; Huakun, L.; Chai, C.Y.; Sun, Y.; Shao, B.; Jiang, J.D.; Chen, Z.; Kortekaas, J.A.; Zhang, Y.

2014-01-01

In June 2013, a subclinical infection with severe fever with thrombocytopenia syndrome virus (SFTSV) was detected in Zhejiang Province, China, prompting seroprevalence studies in 6 districts within the province. Of 986 healthy persons tested, 71 had IgG antibodies against SFTSV. This finding

Relationship between uric acid and arterial stiffness in the elderly with metabolic syndrome components.

Science.gov (United States)

Sun, Ning; Zhang, Yun; Tian, Jian-li; Wang, Hui

2013-08-01

High uric acid (UA) levels and metabolic syndrome (MS) are risk factors for atherosclerotic diseases. Brachial-ankle pulse wave velocity (baPWV) is a valid and reproducible measurement by which to assess arterial stiffness and a surrogate marker of atherosclerosis. However, little is known about the relationship between them, especially in elderly Chinese with MS components who are at high risk for atherosclerotic diseases. One thousand and twenty Chinese subjects (159 women) older than 60 years of age (mean age (70.6 ± 5.7) years) with at least one MS component underwent routine laboratory tests, and baPWV measurements were analyzed. Participants were divided into four groups by MS components. The mean age did not significantly differ among the MS component groups. We found that not only the diagnostic factors (blood pressure, body mass index (BMI), lipids, glucose) of MS but also baPWV, UA, insulin, homeostasis model of assessment for insulin resistence index (HOMAIR) levels increased, and high density lipoprotein (HDL)-C decreased with an increased number of MS components (test for trend P insulin resistance (r = 0.186, P insulin or HOMA-IR, there were no significant differences in the multivariate odds ratios among the number of MS components for UA. The UA level is positively associated with baPWV and MS, but the association between UA and MS is dependent on insulin resistance. Furthermore, baPWV is independently associated with MS in our study population.

Estimating Gear Teeth Stiffness

DEFF Research Database (Denmark)

Pedersen, Niels Leergaard

2013-01-01

The estimation of gear stiffness is important for determining the load distribution between the gear teeth when two sets of teeth are in contact. Two factors have a major influence on the stiffness; firstly the boundary condition through the gear rim size included in the stiffness calculation...... and secondly the size of the contact. In the FE calculation the true gear tooth root profile is applied. The meshing stiffness’s of gears are highly non-linear, it is however found that the stiffness of an individual tooth can be expressed in a linear form assuming that the contact length is constant....

A personal 35 year perspective on Gilles de la Tourette syndrome: prevalence, phenomenology, comorbidities, and coexistent psychopathologies.

Science.gov (United States)

Robertson, Mary M

2015-01-01

This Series is a personal narrative of my experience with patients with Gilles de la Tourette syndrome and covers its definition and history since the first description in 1825. Controversy entered the prevalence debate early. Although originally considered very rare, in the 1980s, Tourette's syndrome was reported to be common. However, Tourette's syndrome has been shown to occur at a prevalence of about 0·85% to 1%. Tourette's syndrome is more common in the male population, more prominent during childhood, and usually improves, but does not disappear with age. Tourette's syndrome is considered less common in people of sub-Saharan black African, African-American, and American Hispanic ethnic origin. The phenomenology is similar worldwide, indicating a biological basis. The hallmark characteristics are multiple motor and one or more vocal/phonic tics. Other associated features include premonitory urges, a waxing and waning course, and to a much lesser degree, coprolalia. Comorbid disorders are common and are suggested to include obsessive-compulsive disorder and behaviours, attention deficit hyperactivity disorder, and autistic spectrum disorder. Coexistent psychopathologies are suggested to include depression and conduct and personality disorders. Importantly, I argue that Tourette's syndrome is not a unitary condition. Finally, I offer suggestions for future research. Copyright © 2015 Elsevier Ltd. All rights reserved.

Low tendon stiffness and abnormal ultrastructure distinguish classic Ehlers-Danlos syndrome from benign joint hypermobility syndrome in patients

DEFF Research Database (Denmark)

Nielsen, Rie Harboe; Couppé, Christian; Jensen, Jacob Kildevang

2014-01-01

There is a clinical overlap between classic Ehlers-Danlos syndrome (cEDS) and benign joint hypermobility syndrome (BJHS), with hypermobility as the main symptom. The purpose of this study was to investigate the role of type V collagen mutations and tendon pathology in these 2 syndromes. In patients...... and abnormal ultrastructure distinguish classic Ehlers-Danlos syndrome from benign joint hypermobility syndrome in patients....

Correlations among measures of knee stiffness, gait performance and complaints in individuals with knee osteoarthritis.

Science.gov (United States)

Oatis, Carol A; Wolff, Edward F; Lockard, Margery A; Michener, Lori A; Robbins, Steven J

2013-03-01

Stiffness is a common complaint in individuals with knee osteoarthritis and is a component of the osteoarthritis diagnosis. Yet the relationship between stiffness and function is poorly understood and methods to quantify stiffness are limited. Using a cross-sectional observational design with 66 subjects with knee osteoarthritis, stiffness and damping coefficients were calculated from a relaxed knee oscillation procedure. Gait parameters were measured using an electronic walkway. Self-reported pain, stiffness, and function were measured with the Western Ontario and McMaster Osteoarthritis Index. Correlation and Alexander's normalized-t approximation analyses were used to assess associations among the variables. Subset analysis was performed on subjects with and without tibiofemoral joint crepitus. Slight to moderate correlations existed between stiffness and damping coefficients and most gait parameters ((| r |=0.30-0.56; PMcMaster Osteoarthritis Index scores and all gait parameters (| r |=0.35-0.62; Pcoefficient was only slightly associated with patient-rated Western Ontario and McMaster Osteoarthritis Index stiffness subscale scores. Subset analysis revealed significant correlations that differed between those with and without crepitus. These findings suggest that laboratory measured stiffness and damping coefficients, Western Ontario and McMaster Osteoarthritis Index scores and gait-related measurements assess different aspects related to movement in individuals with knee osteoarthritis. Stiffness and damping coefficients may offer the ability to explain gait changes in the knee that are independent of a person's perceptions particularly in the early stages of the disease. Copyright © 2013 Elsevier Ltd. All rights reserved.

Trabecular meshwork stiffness in glaucoma.

Science.gov (United States)

Wang, Ke; Read, A Thomas; Sulchek, Todd; Ethier, C Ross

2017-05-01

Alterations in stiffness of the trabecular meshwork (TM) may play an important role in primary open-angle glaucoma (POAG), the second leading cause of blindness. Specifically, certain data suggest an association between elevated intraocular pressure (IOP) and increased TM stiffness; however, the underlying link between TM stiffness and IOP remains unclear and requires further study. We here first review the literature on TM stiffness measurements, encompassing various species and based on a number of measurement techniques, including direct approaches such as atomic force microscopy (AFM) and uniaxial tension tests, and indirect methods based on a beam deflection model. We also briefly review the effects of several factors that affect TM stiffness, including lysophospholipids, rho-kinase inhibitors, cytoskeletal disrupting agents, dexamethasone (DEX), transforming growth factor-β 2 (TGF-β 2 ), nitric oxide (NO) and cellular senescence. We then describe a method we have developed for determining TM stiffness measurement in mice using a cryosection/AFM-based approach, and present preliminary data on TM stiffness in C57BL/6J and CBA/J mouse strains. Finally, we investigate the relationship between TM stiffness and outflow facility between these two strains. The method we have developed shows promise for further direct measurements of mouse TM stiffness, which may be of value in understanding mechanistic relations between outflow facility and TM biomechanical properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Artificial muscles with adjustable stiffness

International Nuclear Information System (INIS)

Mutlu, Rahim; Alici, Gursel

2010-01-01

This paper reports on a stiffness enhancement methodology based on using a suitably designed contact surface with which cantilevered-type conducting polymer bending actuators are in contact during operation. The contact surface constrains the bending behaviour of the actuators. Depending on the topology of the contact surface, the resistance of the polymer actuators to deformation, i.e. stiffness, is varied. As opposed to their predecessors, these polymer actuators operate in air. Finite element analysis and modelling are used to quantify the effect of the contact surface on the effective stiffness of a trilayer cantilevered beam, which represents a one-end-free, the-other-end-fixed polypyrrole (PPy) conducting polymer actuator under a uniformly distributed load. After demonstrating the feasibility of the adjustable stiffness concept, experiments were conducted to determine the stiffness of bending-type conducting polymer actuators in contact with a range (20–40 mm in radius) of circular contact surfaces. The numerical and experimental results presented demonstrate that the stiffness of the actuators can be varied using a suitably profiled contact surface. The larger the radius of the contact surface is, the higher is the stiffness of the polymer actuators. The outcomes of this study suggest that, although the stiffness of the artificial muscles considered in this study is constant for a given geometric size, and electrical and chemical operation conditions, it can be changed in a nonlinear fashion to suit the stiffness requirement of a considered application. The stiffness enhancement methodology can be extended to other ionic-type conducting polymer actuators

A variable stiffness joint with electrospun P(VDF-TrFE-CTFE) variable stiffness springs

NARCIS (Netherlands)

Carloni, Raffaella; Lapp, Valerie I.; Cremonese, Andrea; Belcari, Juri; Zucchelli, Andrea

This letter presents a novel rotational variable stiffness joint that relies on one motor and a set of variable stiffness springs. The variable stiffness springs are leaf springs with a layered design, i.e., an electro-active layer of electrospun aligned nanofibers of poly(vinylidene

Pharmacological modulation of arterial stiffness.

LENUS (Irish Health Repository)

Boutouyrie, Pierre

2011-09-10

Arterial stiffness has emerged as an important marker of cardiovascular risk in various populations and reflects the cumulative effect of cardiovascular risk factors on large arteries, which in turn is modulated by genetic background. Arterial stiffness is determined by the composition of the arterial wall and the arrangement of these components, and can be studied in humans non-invasively. Age and distending pressure are two major factors influencing large artery stiffness. Change in arterial stiffness with drugs is an important endpoint in clinical trials, although evidence for arterial stiffness as a therapeutic target still needs to be confirmed. Drugs that independently affect arterial stiffness include antihypertensive drugs, mostly blockers of the renin-angiotensin-aldosterone system, hormone replacement therapy and some antidiabetic drugs such as glitazones. While the quest continues for \\'de-stiffening drugs\\

Measurement of passive ankle stiffness in subjects with chronic hemiparesis using a novel ankle robot

Science.gov (United States)

Roy, Anindo; Bever, Christopher T.; Forrester, Larry W.; Macko, Richard F.; Hogan, Neville

2011-01-01

Our objective in this study was to assess passive mechanical stiffness in the ankle of chronic hemiparetic stroke survivors and to compare it with those of healthy young and older (age-matched) individuals. Given the importance of the ankle during locomotion, an accurate estimate of passive ankle stiffness would be valuable for locomotor rehabilitation, potentially providing a measure of recovery and a quantitative basis to design treatment protocols. Using a novel ankle robot, we characterized passive ankle stiffness both in sagittal and in frontal planes by applying perturbations to the ankle joint over the entire range of motion with subjects in a relaxed state. We found that passive stiffness of the affected ankle joint was significantly higher in chronic stroke survivors than in healthy adults of a similar cohort, both in the sagittal as well as frontal plane of movement, in three out of four directions tested with indistinguishable stiffness values in plantarflexion direction. Our findings are comparable to the literature, thus indicating its plausibility, and, to our knowledge, report for the first time passive stiffness in the frontal plane for persons with chronic stroke and older healthy adults. PMID:21346215

Psychological underpinning of personalized approaches in modern medicine: syndrome analysis of mitral valve prolapsed patients

Directory of Open Access Journals (Sweden)

Zinchenko, Yury P.

2013-06-01

Full Text Available The article aims to demonstrate a high efficiency of the methodological means suggested by psychological syndrome analysis approach (Vygotsky-Luria school for solving theoretical and applied issues in contemporary person-centered medicine. This is achieved through an example of empirical study meant to construct a psychosomatic syndrome for 290 patients with mitral valve prolapse (MVP. Analysis of all collected data was based on psychological syndrome analysis concept (Vygotsky–Luria school and A.R. Luria’s principles for psychological factors (causes selection, which determine the logic and structure of a neuropsychological syndrome. It demonstrated the association between characteristics of emotional experiences and clinical symptoms manifested in MVP patients. This correlation was statistically verified. The results proved that the most important syndrome-establishment factor (radical is a specific emotionality and dysfunction of emotion regulation and emotional control in MVP patients (excessive emotional repression with insufficient reflection of emotional experiences. Features of the motivation sphere of MVP patients appear as a second psychological syndrome-establishment factor: these are domination of the motive of failure avoidance and unsatisfied self-approval need. We argue that psychological syndrome analysis can be used as a means to approach not only diagnostic but also prognostic tasks both in clinical psychology and medicine, as well as for the development and implementation of the person-centered integrative diagnosis model. We maintained that this approach, applied in theoretical and practical fields of clinical psychology and mental health care is highly efficient at the current stage of the science evolution due to prospects revealed by s new methodological context of postnonclassical model of rationality and a comprehensive character of the cultural-historical concept regarding an individual and his mind as a self

Personality assessment of patients with complex regional pain syndrome type I.

Science.gov (United States)

Monti, D A; Herring, C L; Schwartzman, R J; Marchese, M

1998-12-01

There is controversy regarding the importance of psychological/psychiatric factors in the development of the Complex Regional Pain Syndrome (CRPS). Our objective was to determine whether CRPS type I patients were psychiatrically different from other chronic pain patients, with particular attention to personality pathology. A standardized clinical assessment of all major psychiatric categories, including personality disorders, was performed on 25 CRPS type I patients and a control group of 25 patients with chronic low back pain from disc-related radiculopathy. Both sections of the Structured Clinical Interview for the Diagnostic and Statistical Manual (3rd ed., rev.) and the visual analog scale. Both groups were similar in terms of pain intensity and duration. Statistical analysis showed both groups to have a significant amount of major psychiatric comorbidity, in particular major depressive disorder, and a high incidence of personality disorders. Therefore, intense chronic pain was associated with significant psychiatric comorbidity in both groups and in similar proportions. The high incidence of personality pathology in both groups may represent an exaggeration of maladaptive personality traits and coping styles as a result of a chronic, intense, state of pain.

Measurement and Treatment of Passive Muscle Stiffness

DEFF Research Database (Denmark)

Kirk, Henrik

, which aimed to investigate: 1) The development of a clinical method to evaluate and distinguish neural (reflex mediated stiffness) and non-neural (passive muscle stiffness) components of muscle stiffness in adults with CP by objective and reliable measurements. 2) The association between increased...... and reliability of the method, and argue for the use of the method in the clinical practice. The device is able to distinguish between passive muscle stiffness and reflex-mediated stiffness in subjects with CP. It shows good high intrarater and interrater reliability in evaluation of passive muscle stiffness...... to measure muscle stiffness, and distinguish between passive muscle stiffness and reflex-mediated stiffness. Furthermore, it is a reliable device to measure changes in passive ROM. Treatment of passive muscle stiffness should be directed towards intense training, comprising many repetitions with a functional...

Central arterial stiffness and diastolic dysfunction are associated with insulin resistance and abdominal obesity in young women but polycystic ovary syndrome does not confer additional risk.

Science.gov (United States)

Rees, E; Coulson, R; Dunstan, F; Evans, W D; Blundell, H L; Luzio, S D; Dunseath, G; Halcox, J P; Fraser, A G; Rees, D A

2014-09-01

Are arterial stiffness, carotid intima-media thickness and diastolic dysfunction increased in young women with polycystic ovary syndrome (PCOS) independently of the effects of obesity? Insulin resistance and central obesity are associated with subclinical cardiovascular dysfunction in young women, but a diagnosis of PCOS does not appear to confer additional risk at this age. Some studies have shown that young women with PCOS may have increased measures of cardiovascular risk, including arterial stiffness, carotid intima-media thickness and myocardial dysfunction. However, it is difficult to establish how much of this risk is due to PCOS per se and how much is due to obesity and insulin resistance, which are common in PCOS and themselves associated with greater vascular risk. This cross-sectional study comprised 84 women with PCOS and 95 healthy volunteers, aged 16-45 years. The study was conducted in a university hospital. Subjects underwent a comprehensive assessment of body composition (including computed tomography (CT) assessment of visceral fat; VF), measurements of arterial stiffness (aortic pulse wave velocity; aPWV), common carotid intima-media thickness (ccIMT), diastolic function (longitudinal tissue velocity; e':a') and endocrinological measures. A sample size of 80 in each group gave 80% power for detecting a difference of 0.45 m/s in aPWV or a difference of 0.25 in e':a'. After adjustment for age and body mass index (BMI), PCOS subjects had a greater insulin response (insulin area under the curve-IAUC) following glucose challenge (adjusted difference [AD] 35 900 pmol min/l, P insulin resistance were only partly attenuated by adjusting for logVF. There was no significant relationship between aPWV or e':a' and either testosterone or adiponectin. The study recruited young women meeting the Rotterdam criteria for PCOS diagnosis; hence our findings may not be generalizable to older patients or those meeting other definitions of the syndrome. Biochemical

Physical and Psychological Health in Persons with Deafblindness that Is due to Usher Syndrome Type II

Science.gov (United States)

Wahlqvist, Moa; Moller, Claes; Moller, Kerstin; Danermark, Berth

2013-01-01

Introduction: The objectives of the study reported here were to describe the physical and psychological health of persons with Usher syndrome Type II (USH2) and to explore any differences in terms of gender. Methods: The participants were recruited from the Swedish Usher database. In the first step, 122 persons received the questionnaire by mail,…

Correlation of liver stiffness measured by FibroScan with sex and age in healthy adults undergoing physical examination

Directory of Open Access Journals (Sweden)

ZHAO Chongshan

2016-04-01

Full Text Available ObjectiveTo determine the reference range of liver stiffness in healthy population, and to investigate the influence of age and sex on liver stiffness. MethodsA total of 1794 healthy subjects who underwent physical examination in China National Petroleum Corporation Central Hospital from October 1, 2012 to October 31, 2014 were enrolled, and FibroScan was used to perform liver stiffness measurement (LSM. Since LSM value was not normally distributed, the Wilcoxon rank sum test was used to compare LSM value between male and female patients, the Kruskal-Wallis test was used to compare LSM value between different age groups, and the Spearman's rank correlation analysis was used to analyze the correlation between LSM value and age. The one-sided percentile method was used to determine the range of normal reference values in male and female subjects or in different age groups. ResultsLSM was successfully performed in 1590 patients, and the rate of successful measurement was 88.63%. A total of 107 patients were excluded due to abnormal liver enzymes. The analysis showed that LSM value showed a significant difference between male and female subjects (Z=-4.980, P＜0.001, as well as between different age groups (χ2=16.983, P=0.001. Age was positively correlated with LSM value (r=0.087, P=0.001. The reference range was estimated to be ≤7.1 kPa in adults, ≤7.0 kPa in females, and ≤7.2 kPa in males. From the perspective of age, the reference range was estimated to be ≤6.8 kPa in persons aged 20-29 years, ≤6.7 kPa in persons aged 30-44 years, ≤7.8 kPa in persons aged 45-59 years, and ≤8.8 kPa in persons aged 60-74 years. ConclusionLiver stiffness value is influenced by sex and age. Sex and age should be taken into account while performing liver stiffness measurement in healthy subjects.

A prospective 20-year longitudinal follow-up of dementia in persons with Down syndrome.

Science.gov (United States)

McCarron, M; McCallion, P; Reilly, E; Dunne, P; Carroll, R; Mulryan, N

2017-09-01

To examine dementia characteristics, age at onset and associated co-morbidities in persons with Down syndrome. A total of 77 people with Down syndrome aged 35 years and older were followed up from 1996 to 2015. The diagnosis of dementia was established using the modified ICD 10 Criteria and a combination of objective and informant-based tests. Cognitive tests included the Test for Severe Impairment and the Down Syndrome Mental Status Examination; adaptive behaviour was measured using the Daily Living Skills Questionnaire, and data from the Dementia Questionnaire for People with Intellectual Disabilities have been available since 2005. Over the 20-year period, 97.4% (75 of 77) persons developed dementia with a mean age of dementia diagnosis of 55 years (SD = 7.1, median = 56 years). Clinical dementia was associated with cognitive and function decline and seizure activity. Risk for dementia increased from 23% in those aged 50 years to 80% in those aged 65 years and above. There were no differences by level of ID. The previously reported high risk levels for dementia among people with Down syndrome were confirmed in this data as was the relationship with late onset epilepsy. The value of the instruments utilised in tracking decline and helping to confirm diagnosis is further highlighted. © 2017 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Neural activity in relation to clinically derived personality syndromes in depression using a psychodynamic fMRI paradigm

Directory of Open Access Journals (Sweden)

Svenja eTaubner

2013-12-01

Full Text Available Objective: The heterogeneity between patients with depression cannot be captured adequately with existing descriptive systems of diagnosis and neurobiological models of depression. Furthermore, considering the highly individual nature of depression, the application of general stimuli in past research efforts may not capture the essence of the disorder. This study aims to identify subtypes of depression by using empirically-derived personality-syndromes, and to explore neural correlates of the derived personality syndromes.Method: In the present exploratory study an individually tailored and psychodynamically based fMRI paradigm using dysfunctional relationship patterns was presented to 20 chronically depressed patients. Results from the Shedler-Westen-Assessment-Procedure (SWAP-200 were analyzed by Q-factor analysis to identify clinically relevant subgroups of depression and related brain activation.Results: The principle component analysis of SWAP-200 items from all 20 patients lead to a 2-factor solution: Depressive Personality and Emotional-Hostile-Externalizing Personality. Both factors were used in a whole-brain correlational analysis but only the second factor yielded significant positive correlations in four regions: A large cluster in the right orbitofrontal cortex (OFC, the left ventral striatum, a small cluster in the left temporal pole and another small cluster in the right middle frontal gyrus. Discussion: The degree to which patients with depression score high on the factor Emotional-Hostile-Externalizing Personality correlated with relatively higher activity in three key areas involved in emotion processing, evaluation of reward/punishment, negative cognitions, depressive pathology and social knowledge (OFC, ventral striatum, temporal pole. Results may contribute to an alternative description of neural correlates of depression showing differential brain activation dependent on the extent of specific personality syndromes in

On gear tooth stiffness evaluation

DEFF Research Database (Denmark)

Pedersen, Niels Leergaard; Jørgensen, Martin Felix

2014-01-01

The estimation of gear stiffness is important for determining the load distribution between the gear teeth when two sets of teeth are in contact. Two factors have a major influence on the stiffness; firstly the boundary condition through the gear rim size included in the stiffness calculation...

Dynamic stiffness of suction caissons

DEFF Research Database (Denmark)

Ibsen, Lars Bo; Liingaard, Morten; Andersen, Lars

The purpose of this report is to evaluate the dynamic soil-structure interaction of suction caissons for offshore wind turbines. The investigation is limited to a determination of the vertical dynamic stiffness of suction caissons. The soil surrounding the foundation is homogenous with linear...... viscoelastic properties. The dynamic stiffness of the suction caisson is expressed by dimensionless frequency-dependent dynamic stiffness coefficients corresponding to the vertical degree of freedom. The dynamic stiffness coefficients for the foundations are evaluated by means of a dynamic three...

Personal risk factors for carpal tunnel syndrome in female visual display unit workers

Directory of Open Access Journals (Sweden)

Matteo Riccò

2016-12-01

Full Text Available Objectives: Carpal tunnel syndrome (CTS is the most common nerve entrapment syndrome, which since the beginning of the seventies has been linked to the keyboard and visual display unit (VDU. The objective of this study was to investigate the prevalence and personal factors associated with CTS in female VDU workers in Italy. Material and Methods: Participants in this study were female adult subjects, working ≥ 20 h/week (N = 631, mean age 38.14±7.81 years, mean working age 12.9±7.24 years. Signs and symptoms were collected during compulsory occupational medical surveillance. The binary logistic regression was used to estimate adjusted odds ratios for the factors of interest. Results: Diagnosis of CTS was reported in 48 cases (7.6%, 11 of them or 1.7% after a surgical correction for the incidence of 5.94/1000 person-years. In general, signs and symptoms of CTS were associated with the following demographic factors: previous trauma of upper limb (adjusted odds ratio (ORa = 8.093, 95% confidence interval (CI: 2.347–27.904, history (> 5 years of oral contraceptives therapy/hormone replacement therapy (ORa = 3.77, 95% CI: 1.701–8.354 and cervical spine signs/symptoms (ORa = 4.565, 95% CI: 2.281–9.136. Conclusions: The prevalence of CTS was similar to the estimates for the general population of Italy. Among personal risk factors, hormone therapy, previous trauma of the upper limb and signs/symptoms of the cervical spine appeared to be associated with a higher risk of CTS syndrome. Eventually, the results reinforce interpretation of CTS in VDU workers as a work-related musculoskeletal disorder rather than a classical occupational disease. Int J Occup Med Environ Health 2016;29(6:927–936

Personal risk factors for carpal tunnel syndrome in female visual display unit workers.

Science.gov (United States)

Riccò, Matteo; Cattani, Silvia; Signorelli, Carlo

2016-11-18

Carpal tunnel syndrome (CTS) is the most common nerve entrapment syndrome, which since the beginning of the seventies has been linked to the keyboard and visual display unit (VDU). The objective of this study was to investigate the prevalence and personal factors associated with CTS in female VDU workers in Italy. Participants in this study were female adult subjects, working ≥ 20 h/week (N = 631, mean age 38.14±7.81 years, mean working age 12.9±7.24 years). Signs and symptoms were collected during compulsory occupational medical surveillance. The binary logistic regression was used to estimate adjusted odds ratios for the factors of interest. Diagnosis of CTS was reported in 48 cases (7.6%, 11 of them or 1.7% after a surgical correction) for the incidence of 5.94/1000 person-years. In general, signs and symptoms of CTS were associated with the following demographic factors: previous trauma of upper limb (adjusted odds ratio (ORa) = 8.093, 95% confidence interval (CI): 2.347-27.904), history (> 5 years) of oral contraceptives therapy/hormone replacement therapy (ORa = 3.77, 95% CI: 1.701-8.354) and cervical spine signs/symptoms (ORa = 4.565, 95% CI: 2.281-9.136). The prevalence of CTS was similar to the estimates for the general population of Italy. Among personal risk factors, hormone therapy, previous trauma of the upper limb and signs/symptoms of the cervical spine appeared to be associated with a higher risk of CTS syndrome. Eventually, the results reinforce interpretation of CTS in VDU workers as a work-related musculoskeletal disorder rather than a classical occupational disease. Int J Occup Med Environ Health 2016;29(6):927-936. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Associations between bicycling and carotid arterial stiffness in adolescents

DEFF Research Database (Denmark)

Ried-Larsen, M; Grøntved, A; Østergaard, Lars

2015-01-01

Youth Heart Study. Total frequency of bicycle usage was assessed by self-report, and carotid arterial stiffness was assessed using B-mode ultrasound. After adjusting for pubertal status, body height, and objectively measured physical activity and other personal lifestyle and demographic factors, boys......The aim of the study was to investigate the associations between bicycling and carotid arterial stiffness, independent of objectively measured moderate-and-vigorous physical activity. This cross-sectional study included 375 adolescents (age 15.7 ± 0.4 years) from the Danish site of the European...... using their bicycle every day of the week displayed a higher carotid arterial compliance {standard beta 0.47 [95% confidence interval (CI) 0.07-0.87]} and distension [standard beta 0.38 (95% CI -0.04 to 0.81)]. Boys using their bicycle every day of the week furthermore displayed a lower Young's elastic...

Coexistence of Reverse Capgras Syndrome, Subjective Double and Cotard Syndrome

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Azadeh Mashayekhi

2016-01-01

Full Text Available Misidentification syndrome is a condition in which the person thinks that familiar persons have been replaced with other one. Coexistence of some types of this syndrome has been reported with other psychiatric syndromes. In this report, we present a 47-year-old married man with coexistence of reverse Capgras and subjective double syndromes with Cotard syndrome. There is no previous report of coexistence of these three forms of delusions in a single case.

Inflammatory potential of the diet and colorectal tumor risk in persons with Lynch syndrome

NARCIS (Netherlands)

Brouwer, Jesca G.M.; Makama, Maureen; Woudenbergh, Van Geertruida J.; Vasen, Hans F.A.; Nagengast, Fokko M.; Kleibeuker, Jan H.; Kampman, Ellen; Duijnhoven, Van Fränzel J.B.

2017-01-01

Background: Persons with Lynch syndrome (LS) have high lifetime risk of developing colorectal tumors (CRTs) because of a germline mutation in one of their mismatch repair (MMR) genes. An important process in the development of CRTs is inflammation, which has been shown to be modulated by diet.

LSODE, 1. Order Stiff or Non-Stiff Ordinary Differential Equations System Initial Value Problems

International Nuclear Information System (INIS)

Hindmarsh, A.C.; Petzold, L.R.

2005-01-01

1 - Description of program or function: LSODE (Livermore Solver for Ordinary Differential Equations) solves stiff and non-stiff systems of the form dy/dt = f. In the stiff case, it treats the Jacobian matrix df/dy as either a dense (full) or a banded matrix, and as either user-supplied or internally approximated by difference quotients. It uses Adams methods (predictor-corrector) in the non-stiff case, and Backward Differentiation Formula (BDF) methods (the Gear methods) in the stiff case. The linear systems that arise are solved by direct methods (LU factor/solve). The LSODE source is commented extensively to facilitate modification. Both a single-precision version and a double-precision version are available. 2 - Methods: It is assumed that the ODEs are given explicitly, so that the system can be written in the form dy/dt = f(t,y), where y is the vector of dependent variables, and t is the independent variable. LSODE contains two variable-order, variable- step (with interpolatory step-changing) integration methods. The first is the implicit Adams or non-stiff method, of orders one through twelve. The second is the backward differentiation or stiff method (or BDF method, or Gear's method), of orders one through five. 3 - Restrictions on the complexity of the problem: The differential equations must be given in explicit form, i.e., dy/dt = f(y,t). Problems with intermittent high-speed transients may cause inefficient or unstable performance

Personality and psychiatric disorders in women affected by polycystic ovary syndrome.

Science.gov (United States)

Scaruffi, Elisabetta; Gambineri, Alessandra; Cattaneo, Stefania; Turra, Jenni; Vettor, Roberto; Mioni, Roberto

2014-01-01

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine disorder among fertile women. Studies show reduced quality of life, anxiety, depression, body dissatisfaction, eating disorder, and sexual dysfunction, but the etiology of these disturbs remains still debated. The aim of our study is to verify whether this hyperandrogenic syndrome characterizes a strong psycho(patho)logical personality. Sixty PCOS subjects (mean age 25.8 ± 4.7 years) were evaluated by anthropometric, metabolic, hormonal, clinical, and psychological parameters. After the certainty of the diagnosis of PCOS, the Rorschach test, according to Exner's comprehensive system (CS) and the Millon Clinical Multiaxial Inventory-III (MCMI-III) were administered to each patient. The control group, on which the comparison was carried out, was composed by 40 healthy and aged compared women who were exclusively administered the Rorschach test according to CS. MCMI-III evidenced axis II DSM-IV personality disorders [4.1% schizoid, depressive, sadistic, negativistic (passive-aggressive), and masochistic, 6.1% avoiding, 12.2% dependent, 20.4% histrionic, 16.3% narcissistic, 2.0% obsessive-compulsive], and axis I DSM-IV psychiatric disorders: 10.2% anxiety, 2.0% somatoform disorder and bipolar disorder, 16.3% major depressive disorder. Finally, we found 44.9% delusional disorder and 4.1% thought disorder. Rorschach test's results show 53.1% reduced coping abilities and social skills, 55.1% depression, 30.6% perceptual distortion and cognitive slippage, 24.5% constantly alert and worry, 8.1% at risk for suicide, and finally about 50% of our patients had chronic stress. PCOS women have relevant personality and psychiatric disorders, when compared with normal subjects.

Antibodies against Severe Fever with Thrombocytopenia Syndrome Virus in Healthy Persons, China, 2013

Science.gov (United States)

Zhang, Lei; Sun, Jimin; Yan, Jie; Lv, Huakun; Chai, Chengliang; Sun, Yi; Shao, Bin; Jiang, Jianmin; Chen, Zhiping

2014-01-01

In June 2013, a subclinical infection with severe fever with thrombocytopenia syndrome virus (SFTSV) was detected in Zhejiang Province, China, prompting seroprevalence studies in 6 districts within the province. Of 986 healthy persons tested, 71 had IgG antibodies against SFTSV. This finding suggests that most natural infections with SFTSV are mild or subclinical. PMID:25061813

Properties and determination of the interface stiffness

International Nuclear Information System (INIS)

Du Danxu; Zhang Hao; Srolovitz, David J.

2007-01-01

The chemical potential of a curved interface contains a term that is proportional to the product of the interface curvature and the interface stiffness. In crystalline materials, the interface stiffness is a tensor. This paper examines several basic issues related to the properties of the interface stiffness, especially the determination of the interface stiffness in particular directions (i.e. the commonly used scalar form of the interface stiffness). Of the five parameters that describe an arbitrary grain boundary, only those describing the inclination are crucial for the scalar stiffness. We also examine the influence of crystal symmetry on the stiffness tensor for both free surfaces and grain boundaries. This results in substantial simplifications for cases in which interfaces possess mirror or rotational symmetries. An efficient method for determining the interface stiffness tensor using atomistic simulations is proposed

Metacarpophalangeal joint stiffness. Still a challenge for the hand surgeon?

Science.gov (United States)

Jiménez, I; Muratore-Moreno, G; Marcos-García, A; Medina, J

2016-01-01

The aim of this study is to analyse the outcomes of the surgical treatment of metacarpophalangeal stiffness by dorsal teno-arthrolysis in our centre, and present a review the literature. This is a retrospective study of 21 cases of metacarpophalangeal stiffness treated surgically. Dorsal teno-arthrolysis was carried out on all patients. A rehabilitation programme was started ten days after surgery. An evaluation was performed on the aetiology, variation in pre- and post-operative active mobility, complications, DASH questionnaire, and a subjective satisfaction questionnaire. The mean age of the patients was 36.5 years and the mean follow-up was 6.5 years. Of the 21 cases, the most common cause was a metacarpal fracture (52.4%), followed by complex trauma of the forearm (19%). Improvement in active mobility was 30.5°, despite obtaining an intra-operative mobility 0-90° in 80% of cases. Mean DASH questionnaire score was 36.9 points. The outcome was described as excellent in 10% of our patients, good in 30%, poor in 40%, and bad in the remaining 20%. There was a complex regional pain syndrome in 9.5% of cases, and intrinsic muscle injury in 14.3%. Because of its difficult management and poor outcomes, surgical treatment of metacarpophalangeal stiffness in extension is highly complex, with dorsal teno-arthrolysis being a reproducible technique according to our results, and the results reported in the literature. Copyright © 2016 SECOT. Published by Elsevier Espana. All rights reserved.

Personality, immune response and reproductive success: an appraisal of the pace-of-life syndrome hypothesis.

Science.gov (United States)

Monceau, Karine; Dechaume-Moncharmont, François-Xavier; Moreau, Jérôme; Lucas, Camille; Capoduro, Rémi; Motreuil, Sébastien; Moret, Yannick

2017-07-01

The pace-of-life syndrome (POLS) hypothesis is an extended concept of the life-history theory that includes behavioural traits. The studies challenging the POLS hypothesis often focus on the relationships between a single personality trait and a physiological and/or life-history trait. While pathogens represent a major selective pressure, few studies have been interested in testing relationships between behavioural syndrome, and several fitness components including immunity. The aim of this study was to address this question in the mealworm beetle, Tenebrio molitor, a model species in immunity studies. The personality score was estimated from a multidimensional syndrome based of four repeatable behavioural traits. In a first experiment, we investigated its relationship with two measures of fitness (reproduction and survival) and three components of the innate immunity (haemocyte concentration, and levels of activity of the phenoloxidase including the total proenzyme and the naturally activated one) to challenge the POLS hypothesis in T. molitor. Overall, we found a relationship between behavioural syndrome and reproductive success in this species, thus supporting the POLS hypothesis. We also showed a sex-specific relationship between behavioural syndrome and basal immune parameters. In a second experiment, we tested whether this observed relationship with innate immunity could be confirmed in term of differential survival after challenging by entomopathogenic bacteria, Bacillus thuringiensis. In this case, no significant relationship was evidenced. We recommend that future researchers on the POLS should control for differences in evolutionary trajectory between sexes and to pay attention to the choice of the proxy used, especially when looking at immune traits. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

A Novel Variable Stiffness Mechanism Capable of an Infinite Stiffness Range and Unlimited Decoupled Output Motion

Directory of Open Access Journals (Sweden)

Stefan Groothuis

2014-06-01

Full Text Available In this paper, a novel variable stiffness mechanism is presented, which is capable of achieving an output stiffness with infinite range and an unlimited output motion, i.e., the mechanism output is completely decoupled from the rotor motion, in the zero stiffness configuration. The mechanism makes use of leaf springs, which are engaged at different positions by means of two movable supports, to realize the variable output stiffness. The Euler–Bernoulli leaf spring model is derived and validated through experimental data. By shaping the leaf springs, it is shown that the stiffness characteristic of the mechanism can be changed to fulfill different application requirements. Alternative designs can achieve the same behavior with only one leaf spring and one movable support pin.

Stiffness of desiccating insect wings

International Nuclear Information System (INIS)

Mengesha, T E; Vallance, R R; Mittal, R

2011-01-01

The stiffness of insect wings is typically determined through experimental measurements. Such experiments are performed on wings removed from insects. However, the wings are subject to desiccation which typically leads to an increase in their stiffness. Although this effect of desiccation is well known, a comprehensive study of the rate of change in stiffness of desiccating insect wings would be a significant aid in planning experiments as well as interpreting data from such experiments. This communication presents a comprehensive experimental analysis of the change in mass and stiffness of gradually desiccating forewings of Painted Lady butterflies (Vanessa cardui). Mass and stiffness of the forewings of five butterflies were simultaneously measured every 10 min over a 24 h period. The averaged results show that wing mass declined exponentially by 21.1% over this time period with a time constant of 9.8 h, while wing stiffness increased linearly by 46.2% at a rate of 23.4 μN mm -1 h -1 . For the forewings of a single butterfly, the experiment was performed over a period of 1 week, and the results show that wing mass declined exponentially by 52.2% with a time constant of 30.2 h until it reached a steady-state level of 2.00 mg, while wing stiffness increased exponentially by 90.7% until it reached a steady-state level of 1.70 mN mm -1 . (communication)

Stiffness of desiccating insect wings

Energy Technology Data Exchange (ETDEWEB)

Mengesha, T E; Vallance, R R [Department of Mechanical Engineering, The George Washington University, 738 Phillips Hall, 801 22nd St NW, Washington, DC 20052 (United States); Mittal, R, E-mail: vallance@gwu.edu [Department of Mechanical Engineering, Johns Hopkins University, 126 Latrobe Hall, 3400 N Charles Street, Baltimore, MD 21218 (United States)

2011-03-15

The stiffness of insect wings is typically determined through experimental measurements. Such experiments are performed on wings removed from insects. However, the wings are subject to desiccation which typically leads to an increase in their stiffness. Although this effect of desiccation is well known, a comprehensive study of the rate of change in stiffness of desiccating insect wings would be a significant aid in planning experiments as well as interpreting data from such experiments. This communication presents a comprehensive experimental analysis of the change in mass and stiffness of gradually desiccating forewings of Painted Lady butterflies (Vanessa cardui). Mass and stiffness of the forewings of five butterflies were simultaneously measured every 10 min over a 24 h period. The averaged results show that wing mass declined exponentially by 21.1% over this time period with a time constant of 9.8 h, while wing stiffness increased linearly by 46.2% at a rate of 23.4 {mu}N mm{sup -1} h{sup -1}. For the forewings of a single butterfly, the experiment was performed over a period of 1 week, and the results show that wing mass declined exponentially by 52.2% with a time constant of 30.2 h until it reached a steady-state level of 2.00 mg, while wing stiffness increased exponentially by 90.7% until it reached a steady-state level of 1.70 mN mm{sup -1}. (communication)

Stiff person syndrome (SPS): Literature review and case report

African Journals Online (AJOL)

options include immunomodulatory agents and plasmapheresis.[51-54] ... She was put on baclofen, a derivative of GABA, to which she showed ..... Dalakas M. IVIg in other autoimmune neurological disorders: Current status and future.

Laron syndrome (primary growth hormone resistance or insensitivity): the personal experience 1958-2003.

Science.gov (United States)

Laron, Zvi

2004-03-01

Clinical and laboratory investigations starting in 1958 of a group of dwarfed children resembling isolated GH deficiency but who had very high serum levels of GH led to the description of the syndrome of primary GH resistance or insensitivity (Laron syndrome) and subsequently to the discovery of its molecular defects residing in the GH receptor and leading to an inability of IGF-I generation. With the biosynthesis of IGF-I in 1986, therapeutic trials started. Continuously more and more patients are being diagnosed in many parts of the world with a variety of molecular defects. This syndrome proved to be a unique model that enables the study of the consequences of GH receptor defects, the physiopathology of GH-IGF-I disruption, and comparison of the GH-independent IGF-I effects. This review presents the personal experience gained from the study follow-up and treatment of the 60 patients followed up for many years in the Israeli cohort.

Arterial stiffness is increased in asymptomatic nondiabetic postmenopausal women with a polycystic ovary syndrome phenotype.

Science.gov (United States)

Armeni, Eleni; Stamatelopoulos, Kimon; Rizos, Demetrios; Georgiopoulos, George; Kazani, Maria; Kazani, Aikaterini; Kolyviras, Athanasios; Stellos, Konstantinos; Panoulis, Konstantinos; Alexandrou, Andreas; Creatsa, Maria; Papamichael, Christos; Lambrinoudaki, Irene

2013-10-01

The metabolic dysfunction accompanying the polycystic ovary syndrome (PCOS) may increase the risk of hypertension and cardiovascular disease (CVD). Although menopause per se may be an additional risk factor of CVD, the association between PCOS in postmenopausal women and cardiovascular risk has not been adequately investigated. We aimed to evaluate the effect of PCOS on markers of subclinical atherosclerosis in nondiabetic postmenopausal women. This cross-sectional study included 286 postmenopausal women with intact ovaries. PCOS phenotype was defined if three of the following were present: insulin resistance, current hyperandrogenism or history of clinical androgen excess, history of infertility, central obesity and history of irregular menses. Traditional CVD risk factors, as well as indices of arterial structure (intima-media thickness, atheromatous plaques presence) and function [flow-mediated dilation, pulse wave velocity (PWV), augmentation index] were compared between women with a PCOS phenotype and the rest of the sample, who served as controls. Women with the PCOS phenotype (N=43) had higher SBP and triglycerides and lower high-density lipoprotein (HDL)-cholesterol than controls. Mean values of PWV differed significantly between PCOS cases and controls (9.46±1.74 vs. 8.60±1.51 m/s, P=0.001, univariate). Multivariate regression analysis showed that the PCOS phenotype, age and SBP were the only independent predictors of PWV. Arterial stiffness is increased in asymptomatic, nondiabetic women with a putative PCOS phenotype, independently of age, BMI or blood pressure. This might present one mechanism through which PCOS increases the risk of CVD and hypertension later in life.

Soft Robotic Haptic Interface with Variable Stiffness for Rehabilitation of Neurologically Impaired Hand Function

Directory of Open Access Journals (Sweden)

Frederick Sebastian

2017-12-01

Full Text Available The human hand comprises complex sensorimotor functions that can be impaired by neurological diseases and traumatic injuries. Effective rehabilitation can bring the impaired hand back to a functional state because of the plasticity of the central nervous system to relearn and remodel the lost synapses in the brain. Current rehabilitation therapies focus on strengthening motor skills, such as grasping, employ multiple objects of varying stiffness so that affected persons can experience a wide range of strength training. These devices have limited range of stiffness due to the rigid mechanisms employed in their variable stiffness actuators. This paper presents a novel soft robotic haptic device for neuromuscular rehabilitation of the hand, which is designed to offer adjustable stiffness and can be utilized in both clinical and home settings. The device eliminates the need for multiple objects by employing a pneumatic soft structure made with highly compliant materials that act as the actuator of the haptic interface. It is made with interchangeable sleeves that can be customized to include materials of varying stiffness to increase the upper limit of the stiffness range. The device is fabricated using existing 3D printing technologies, and polymer molding and casting techniques, thus keeping the cost low and throughput high. The haptic interface is linked to either an open-loop system that allows for an increased pressure during usage or closed-loop system that provides pressure regulation in accordance to the stiffness the user specifies. Preliminary evaluation is performed to characterize the effective controllable region of variance in stiffness. It was found that the region of controllable stiffness was between points 3 and 7, where the stiffness appeared to plateau with each increase in pressure. The two control systems are tested to derive relationships between internal pressure, grasping force exertion on the surface, and displacement using

Are personality patterns and clinical syndromes associated with patients' motives and perceived outcome of orthognathic surgery?

DEFF Research Database (Denmark)

Petersen, Jesper Øland; Jensen, John; Melsen, Birte

2010-01-01

A study of surgical-orthodontic patients was performed to assess whether signs of personality patterns and psychologically defined clinical syndromes influenced patients' motives for treatment, perceived oral function, self-concept, social interaction, and overall satisfaction with treatment....

Marfan syndrome (image)

Science.gov (United States)

Marfan syndrome is a disorder of connective tissue which causes skeletal defects typically recognized in a tall, lanky person. A person with Marfan syndrome may exhibit long limbs and spider-like fingers, ...

Shoulder Stiffness : Current Concepts and Concerns

NARCIS (Netherlands)

Itoi, Eiji; Arce, Guillermo; Bain, Gregory I.; Diercks, Ronald L.; Guttmann, Dan; Imhoff, Andreas B.; Mazzocca, Augustus D.; Sugaya, Hiroyuki; Yoo, Yon-Sik

Shoulder stiffness can be caused by various etiologies such as immobilization, trauma, or surgical interventions. The Upper Extremity Committee of ISAKOS defined the term "frozen shoulder" as idiopathic stiff shoulder, that is, without a known cause. Secondary stiff shoulder is a term that should be

The link between exercise and titin passive stiffness.

Science.gov (United States)

Lalande, Sophie; Mueller, Patrick J; Chung, Charles S

2017-09-01

What is the topic of this review? This review focuses on how in vivo and molecular measurements of cardiac passive stiffness can predict exercise tolerance and how exercise training can reduce cardiac passive stiffness. What advances does it highlight? This review highlights advances in understanding the relationship between molecular (titin-based) and in vivo (left ventricular) passive stiffness, how passive stiffness modifies exercise tolerance, and how exercise training may be therapeutic for cardiac diseases with increased passive stiffness. Exercise can help alleviate the negative effects of cardiovascular disease and cardiovascular co-morbidities associated with sedentary behaviour; this may be especially true in diseases that are associated with increased left ventricular passive stiffness. In this review, we discuss the inverse relationship between exercise tolerance and cardiac passive stiffness. Passive stiffness is the physical property of cardiac muscle to produce a resistive force when stretched, which, in vivo, is measured using the left ventricular end diastolic pressure-volume relationship or is estimated using echocardiography. The giant elastic protein titin is the major contributor to passive stiffness at physiological muscle (sarcomere) lengths. Passive stiffness can be modified by altering titin isoform size or by post-translational modifications. In both human and animal models, increased left ventricular passive stiffness is associated with reduced exercise tolerance due to impaired diastolic filling, suggesting that increased passive stiffness predicts reduced exercise tolerance. At the same time, exercise training itself may induce both short- and long-term changes in titin-based passive stiffness, suggesting that exercise may be a treatment for diseases associated with increased passive stiffness. Direct modification of passive stiffness to improve exercise tolerance is a potential therapeutic approach. Titin passive stiffness itself may

Associations between lower extremity muscle mass and multiplanar knee laxity and stiffness: a potential explanation for sex differences in frontal and transverse plane knee laxity.

Science.gov (United States)

Shultz, Sandra J; Pye, Michele L; Montgomery, Melissa M; Schmitz, Randy J

2012-12-01

Compared with men, women have disproportionally greater frontal (varus-valgus) and transverse (internal-external) plane laxity and lower stiffness, despite having similar sagittal (anterior-posterior) plane laxity and stiffness. While the underlying cause is unclear, the amount of lower extremity lean mass (LELM) may be a contributing factor. Lower extremity lean mass would be a stronger predictor of frontal and transverse plane laxity and incremental stiffness than the sagittal plane. Associations between LELM and stiffness would be stronger at lower force increments. Descriptive laboratory study. Sixty-three women and 30 men with no history of ligament injury were measured for knee laxity and incremental stiffness in the sagittal (-90- to 130-N posterior-to-anterior directed loads), frontal (±10-N·m varus-valgus torques), and transverse (±5-N·m internal-external rotation torques) planes and underwent dual-energy X-ray absorptiometry scans to measure LELM. Linear regressions examined the extent to which LELM predicted each laxity and stiffness value, while also accounting for a person's sex. Females (vs males) had greater laxity and less stiffness in the frontal and transverse planes but not the sagittal plane. Lower extremity lean mass was a poor predictor of sagittal laxity and stiffness (R (2) range = .021-.081; P > .06) but was a stronger predictor of frontal (R (2) range = .215-.567; P plane laxity and stiffness. Associations were stronger for low (R (2) = .495-.504) versus high (R (2) = .215-.435) frontal plane stiffness but were similar for low (R (2) = .233-.293) versus high (R (2) = .224-.356) transverse plane stiffness. Once we accounted for a person's LELM, sex had little effect on laxity and stiffness (change in R (2) after removal = .01-.08; P = .027-.797). Less LELM was associated with greater laxity and less stiffness in frontal and transverse planes, which may contribute to the disproportionally higher laxities and reduced stiffnesses observed

Efficient Method for Calculating the Composite Stiffness of Parabolic Leaf Springs with Variable Stiffness for Vehicle Rear Suspension

Directory of Open Access Journals (Sweden)

Wen-ku Shi

2016-01-01

Full Text Available The composite stiffness of parabolic leaf springs with variable stiffness is difficult to calculate using traditional integral equations. Numerical integration or FEA may be used but will require computer-aided software and long calculation times. An efficient method for calculating the composite stiffness of parabolic leaf springs with variable stiffness is developed and evaluated to reduce the complexity of calculation and shorten the calculation time. A simplified model for double-leaf springs with variable stiffness is built, and a composite stiffness calculation method for the model is derived using displacement superposition and material deformation continuity. The proposed method can be applied on triple-leaf and multileaf springs. The accuracy of the calculation method is verified by the rig test and FEA analysis. Finally, several parameters that should be considered during the design process of springs are discussed. The rig test and FEA analytical results indicate that the calculated results are acceptable. The proposed method can provide guidance for the design and production of parabolic leaf springs with variable stiffness. The composite stiffness of the leaf spring can be calculated quickly and accurately when the basic parameters of the leaf spring are known.

Hydration Status Is Associated with Aortic Stiffness, but Not with Peripheral Arterial Stiffness, in Chronically Hemodialysed Patients

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Daniel Bia

2015-01-01

Full Text Available Background. Adequate fluid management could be essential to minimize high arterial stiffness observed in chronically hemodialyzed patients (CHP. Aim. To determine the association between body fluid status and central and peripheral arterial stiffness levels. Methods. Arterial stiffness was assessed in 65 CHP by measuring the pulse wave velocity (PWV in a central arterial pathway (carotid-femoral and in a peripheral pathway (carotid-brachial. A blood pressure-independent regional arterial stiffness index was calculated using PWV. Volume status was assessed by whole-body multiple-frequency bioimpedance. Patients were first observed as an entire group and then divided into three different fluid status-related groups: normal, overhydration, and dehydration groups. Results. Only carotid-femoral stiffness was positively associated (P<0.05 with the hydration status evaluated through extracellular/intracellular fluid, extracellular/Total Body Fluid, and absolute and relative overhydration. Conclusion. Volume status and overload are associated with central, but not peripheral, arterial stiffness levels with independence of the blood pressure level, in CHP.

Comparison of the Effect of Aliskiren Versus Negative Controls on Aortic Stiffness in Patients With Marfan Syndrome Under Treatment With Atenolol.

Science.gov (United States)

Hwang, Ji-Won; Kim, Eun Kyoung; Jang, Shin Yi; Chung, Tae-Young; Ki, Chang-Seok; Sung, Kiick; Kim, Sung Mok; Ahn, Joonghyun; Carriere, Keumhee; Choe, Yeon Hyeon; Chang, Sung-A; Kim, Duk-Kyung

2017-11-29

The aim of this study was to evaluate the effect of aliskiren on aortic stiffness in patients with Marfan syndrome (MS). Twenty-eight MS patients (mean age ± standard deviation: 32.6 ± 10.6 years) were recruited from November 2009 to October 2014. All patients were receiving atenolol as standard beta-blocker therapy. A prospective randomization process was performed to assign participants to either aliskiren treatment (150-300mg orally per day) or no aliskiren treatment (negative control) in an open-label design. Central aortic distensibility and central pulsed wave velocity (PWV) by magnetic resonance imaging (MRI), peripheral PWV, central aortic blood pressure and augmentation index by peripheral tonometry, and aortic dilatation by echocardiography were examined initially and after 24 weeks. The primary endpoint was central aortic distensibility by MRI. In analyses of differences between baseline and 24 weeks for the aliskiren treatment group vs the negative control group, central distensibility (overall; P = .26) and central PWV (0.2 ± 0.9 vs 0.03 ± 0.7 [m/s]; P = .79) by MRI were not significantly different. Central systolic aortic blood pressure tended to be lower by 14mmHg in patients in the aliskiren treatment group than in the control group (P = .09). A significant decrease in peripheral PWV (brachial-ankle PWV) in the aliskiren treatment group (-1.6 m/s) compared with the control group (+0.28 m/s) was noted (P = .005). Among patients with MS, the addition of aliskiren to beta-blocker treatment did not significantly improve central aortic stiffness during a 24-week period. Copyright © 2017 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

PERSONALITY AND PSYCHIATRIC DISORDERS IN WOMEN AFFECTED BY POLYCYSTIC OVARY SYNDROME (PCOS

Directory of Open Access Journals (Sweden)

Elisabetta eScaruffi

2014-11-01

Full Text Available AbstractBackground: Polycystic ovary syndrome (PCOS is the most prevalent endocrine disorder among fertile women. Studies show reduced quality of life, anxiety, depression, body dissatisfaction, eating disorder and sexual dysfunction, but the etiology of these disturbs remains still debated. The aim of our study is to verify whether this hyperandrogenic syndrome characterizes a strong psycho(pathological personality. Method: Sixty PCOS subjects (mean age 25.8 ± 4.7 yrs were evaluated by antropometric, metabolic, hormonal, clinical and psychological parameters. After the certainty of the diagnosis of PCOS, the Rorschach test, according to Exner's Comprehensive System (CS and the Millon Clinical Multiaxial Inventory-III (MCMI-III were administered to each patient. The control group, on which the comparison was carried out, was composed by 40 healthy and aged compared women who were exclusively administered the Rorschach test according to C.S. Results: MCMI-III evidenced axis II DSM-IV personality disorders (4.1% schizoid, depressive, sadistic, negativistic (passive-aggressive and masochistic, 6.1% avoiding, 12.2% dependent, 20.4% histrionic, 16.3% narcissistic, 2.0% obsessive-compulsive and axis I DSM-IV psychiatric disorders: 10.2% anxiety, 2.0%, somatoform disorder and bipolar disorder, 16.3% major depressive disorder. Finally we found 44.9% delusional disorder and 4.1% thought disorder. Rorschach test’s results show 53.1% reduced coping abilities and social skills, 55.1% depression, 30.6% perceptual distortion and cognitive slippage, 24.5% constantly alert and worry, 8.1% at risk for suicide and finally about 50% of our patients had chronic stress.Conclusion: PCOS women have relevant personality and psychiatric disorders, when compared with normal subjects.

Renal physiology in elderly persons with severe immobility syndrome.

Science.gov (United States)

Musso, Carlos; Liakopoulos, Vassilios; Pangre, Norma; DiTrolio, Julio; Jauregui, Ricardo; De Miguel, Raul; Stefanidis, Ioanis; Imperiali, Nora; Algranati, Luis

2009-01-01

The immobility syndrome (IS) is a common condition in the elderly and consists of a reduction in the capacity to perform daily activities because of motor function deterioration. This syndrome leads to characteristic structural and physiological changes in the body, but renal physiology studies have not been conducted on this population. For this reason, we decided to study prospectively changes in renal function in these individuals. We enrolled into this study 17 volunteers over 64 years of age, all of whom lived in the same nursing home. The patients were divided into two groups: nine healthy mobile persons and eight others who suffered from severe IS. Exclusion criteria were the presence of any disease or use of any drug that could induce water and electrolytes alteration. Blood and urine samples were drawn to measure sodium, potassium, creatinine, urea, calcium, phosphorus, magnesium, and uric acid in order to obtain their fractional excretion. Plasma osmolality and vasopressin were also measured. Total body water and lean body mass were obtained by bioelectrical impedance analysis. Statistical analysis was performed applying Student's t-test (P = 0.01) and Pearson's correlation test. A significant difference in body water composition was found between the groups. Thus in the IS group plasma sodium level was slightly lower and total water content was significantly higher than in the mobile subjects: 140 +/- 5 vs. 143 +/- 1 mmol/l (P = 0.01); 61 +/- 8% vs. 50 +/- 10% (P immobility syndrome than in healthy mobile elderly. In contrast with the mobile group, for which there was a good positive correlation between plasma osmolality and plasma vasopressin, for individuals with IS there was no correlation between plasma osmolality and plasma vasopressin.

VCODE, Ordinary Differential Equation Solver for Stiff and Non-Stiff Problems

International Nuclear Information System (INIS)

Cohen, Scott D.; Hindmarsh, Alan C.

2001-01-01

1 - Description of program or function: CVODE is a package written in ANSI standard C for solving initial value problems for ordinary differential equations. It solves both stiff and non stiff systems. In the stiff case, it includes a variety of options for treating the Jacobian of the system, including dense and band matrix solvers, and a preconditioned Krylov (iterative) solver. 2 - Method of solution: Integration is by Adams or BDF (Backward Differentiation Formula) methods, at user option. Corrector iteration is by functional iteration or Newton iteration. For the solution of linear systems within Newton iteration, users can select a dense solver, a band solver, a diagonal approximation, or a preconditioned Generalized Minimal Residual (GMRES) solver. In the dense and band cases, the user can supply a Jacobian approximation or let CVODE generate it internally. In the GMRES case, the pre-conditioner is user-supplied

Executive functions in persons with metabolic syndrome

Directory of Open Access Journals (Sweden)

Subotić Tatjana

2016-01-01

Full Text Available Modern man lyfestyle contributes to the increasing incidence of metabolic syndrome in the developed world. Prevalence of the metabolic syndrome in adults ranges from 20 to 25%, and it tends to increase. Each year, 3.2 million people around the world die from complications associated with this syndrome. Treatment involves cooperation of medical doctors of various specialties, but the decisive factor is patient motivation, given that the treatment requires significant lifestyle changes. Our hypothesis is that metabolic syndrome patients have reduced ability to plan, convert plan into action and effectively implement planned activities, showing signs of dysexecutive syndrome. The term executive functions comes from the English word 'executive', which also means the controlling, in neuropsychology reserved for high-level abilities that influence more basic abilities such as attention, perception, memory, thinking and speaking. The main objective of this study was to determine characteristics of executive functioning in patients with metabolic syndrome. The sample consisted of 61 subjects of both sexes, aged 20 to 60 years, divided into two groups - those with a diagnosis of metabolic syndrome and those without this diagnosis. The results suggest that people with metabolic syndrome showed significantly poorer performance in almost all indicators of executive functions, represented by Wisconsin Card Sorting Test (Wisconsin Card Sorting Test variables.

The Evaluation of a Personal Narrative Language Intervention for School-Age Children with Down Syndrome

Science.gov (United States)

Finestack, Lizbeth; O'Brien, Katy H.; Hyppa-Martin, Jolene; Lyrek, Kristen A.

2017-01-01

The purpose of this study was to evaluate the feasibility of an intervention focused on improving personal narrative skills of school-age children with Down syndrome (DS) using an approach involving visual supports. Four females with DS, ages 10 through 15 years, participated in this multiple baseline across participants single-subject…

Stiffness and thickness of fascia do not explain chronic exertional compartment syndrome

DEFF Research Database (Denmark)

Dahl, Morten; Hansen, Philip; Stål, Per

2011-01-01

Chronic exertional compartment syndrome is diagnosed based on symptoms and elevated intramuscular pressure and often is treated with fasciotomy. However, what contributes to the increased intramuscular pressure remains unknown.......Chronic exertional compartment syndrome is diagnosed based on symptoms and elevated intramuscular pressure and often is treated with fasciotomy. However, what contributes to the increased intramuscular pressure remains unknown....

Real-Time Vision-Based Stiffness Mapping †.

Science.gov (United States)

Faragasso, Angela; Bimbo, João; Stilli, Agostino; Wurdemann, Helge Arne; Althoefer, Kaspar; Asama, Hajime

2018-04-26

This paper presents new findings concerning a hand-held stiffness probe for the medical diagnosis of abnormalities during palpation of soft-tissue. Palpation is recognized by the medical community as an essential and low-cost method to detect and diagnose disease in soft-tissue. However, differences are often subtle and clinicians need to train for many years before they can conduct a reliable diagnosis. The probe presented here fills this gap providing a means to easily obtain stiffness values of soft tissue during a palpation procedure. Our stiffness sensor is equipped with a multi degree of freedom (DoF) Aurora magnetic tracker, allowing us to track and record the 3D position of the probe whilst examining a tissue area, and generate a 3D stiffness map in real-time. The stiffness probe was integrated in a robotic arm and tested in an artificial environment representing a good model of soft tissue organs; the results show that the sensor can accurately measure and map the stiffness of a silicon phantom embedded with areas of varying stiffness.

Real-Time Vision-Based Stiffness Mapping †

Directory of Open Access Journals (Sweden)

Angela Faragasso

2018-04-01

Full Text Available This paper presents new findings concerning a hand-held stiffness probe for the medical diagnosis of abnormalities during palpation of soft-tissue. Palpation is recognized by the medical community as an essential and low-cost method to detect and diagnose disease in soft-tissue. However, differences are often subtle and clinicians need to train for many years before they can conduct a reliable diagnosis. The probe presented here fills this gap providing a means to easily obtain stiffness values of soft tissue during a palpation procedure. Our stiffness sensor is equipped with a multi degree of freedom (DoF Aurora magnetic tracker, allowing us to track and record the 3D position of the probe whilst examining a tissue area, and generate a 3D stiffness map in real-time. The stiffness probe was integrated in a robotic arm and tested in an artificial environment representing a good model of soft tissue organs; the results show that the sensor can accurately measure and map the stiffness of a silicon phantom embedded with areas of varying stiffness.

Dynamic stiffness of suction caissons - vertical vibrations

Energy Technology Data Exchange (ETDEWEB)

Ibsen, Lars Bo; Liingaard, M.; Andersen, Lars

2006-12-15

The dynamic response of offshore wind turbines are affected by the properties of the foundation and the subsoil. The purpose of this report is to evaluate the dynamic soil-structure interaction of suction caissons for offshore wind turbines. The investigation is limited to a determination of the vertical dynamic stiffness of suction caissons. The soil surrounding the foundation is homogenous with linear viscoelastic properties. The dynamic stiffness of the suction caisson is expressed by dimensionless frequency-dependent dynamic stiffness coefficients corresponding to the vertical degree of freedom. The dynamic stiffness coefficients for the foundations are evaluated by means of a dynamic three-dimensional coupled Boundary Element/Finite Element model. Comparisons are made with known analytical and numerical solutions in order to evaluate the static and dynamic behaviour of the Boundary Element/Finite Element model. The vertical frequency dependent stiffness has been determined for different combinations of the skirt length, Poisson's ratio and the ratio between soil stiffness and skirt stiffness. Finally the dynamic behaviour at high frequencies is investigated. (au)

Observer-Based Human Knee Stiffness Estimation.

Science.gov (United States)

Misgeld, Berno J E; Luken, Markus; Riener, Robert; Leonhardt, Steffen

2017-05-01

We consider the problem of stiffness estimation for the human knee joint during motion in the sagittal plane. The new stiffness estimator uses a nonlinear reduced-order biomechanical model and a body sensor network (BSN). The developed model is based on a two-dimensional knee kinematics approach to calculate the angle-dependent lever arms and the torques of the muscle-tendon-complex. To minimize errors in the knee stiffness estimation procedure that result from model uncertainties, a nonlinear observer is developed. The observer uses the electromyogram (EMG) of involved muscles as input signals and the segmental orientation as the output signal to correct the observer-internal states. Because of dominating model nonlinearities and nonsmoothness of the corresponding nonlinear functions, an unscented Kalman filter is designed to compute and update the observer feedback (Kalman) gain matrix. The observer-based stiffness estimation algorithm is subsequently evaluated in simulations and in a test bench, specifically designed to provide robotic movement support for the human knee joint. In silico and experimental validation underline the good performance of the knee stiffness estimation even in the cases of a knee stiffening due to antagonistic coactivation. We have shown the principle function of an observer-based approach to knee stiffness estimation that employs EMG signals and segmental orientation provided by our own IPANEMA BSN. The presented approach makes realtime, model-based estimation of knee stiffness with minimal instrumentation possible.

The cardiometabolic syndrome in persons of the African diaspora: challenges and opportunities.

Science.gov (United States)

Schuster, Dara P; Gaillard, Trudy; Osei, Kwame

2007-01-01

Unique genetic traits appear to play a role in the increased rates of hypertension (HTN), glucose dysregulation/diabetes (T2DM), and obesity in persons of African descent. Indeed, with increasing rates of westernization/urbanization and concomitant increases in obesity and T2DM, a similar predisposition to the cardiometabolic syndrome and cardiovascular disease (CVD) can be seen in Africans compared with persons of African descent, with CVD reaching epidemic proportions in many areas of Africa. In addition, the complex relationships of metabolic abnormalities that are unique to individuals of African descent have also been demonstrated in Africans. These include: (1) a dissociation of HTN to insulin resistance; (2) relative favorable lipid profile in the setting of increasing rates of CVD; (3) low levels of visceral adiposity in the setting of obesity and insulin resistance; and (4) a dissociation of insulin sensitivity and adiponectin when compared with Caucasians. Although not well understood, these unique relationships suggest that conventional parameters for CVD do not apply to Africans of persons of African descent.

Peculiarities of family doctors' medical assistance for persons with 'Chernobyl syndrome'

International Nuclear Information System (INIS)

Margine, Le.; Tintiuc, D.; Grejdeanu, T.; Margine, Lu.; Badan, V.

2012-01-01

Medical and social protection and rehabilitation of patients with 'Chernobyl syndrome' is provided by legislation of the Republic of Moldova, which is reflected in a comprehensive action plan for rehabilitation and protection of this category of citizens. This plan includes such medical activities as detailed medical ambulatory and stationary examination, purchase prescription drugs, annual sanatorium treatment, annual compensation recovery in the value of 2 average monthly salaries for health improvement. The role of family doctors' medical assistance for persons suffered due to the accident at the Chernobyl Nuclear Power Plant is very important in this plan implementation.

Optimization of a quasi-zero-stiffness isolator

International Nuclear Information System (INIS)

Carrella, A.; Brennan, M. J.; Waters, T. P.

2007-01-01

The frequency range over which a mount can isolate a mass from a vibrating base (or vice versa) is often limited by the mount stiffness required to support the weight of the mass. This compromise can be made more favourable by employing non-linear mounts with a softening spring characteristic such that small excursions about the static equilibrium position result in small dynamic spring forces and a correspondingly low natural frequency. This paper concerns the force-displacement characteristic of a so-called quasi-zero-stiffness (QZS) mechanism which is characterised by an appreciable static stiffness but very small (theoretically zero) dynamic stiffness. The mechanism studied comprises a vertical spring acting in parallel with two further springs which, when inclined at an appropriate angle to the vertical, produce a cancelling negative stiffness effect. Analysis of the system shows that a QZS characteristic can be obtained if the systems parameters (angle of inclination and ratio of spring stiffness) are opportunely chosen. By introducing the additional criterion that the displacement of the system be largest without exceeding a desired (low) value of stiffness an optimal set of parameter values is derived. Under sufficiently large displacements the stiffness of the QZS mechanism can eventually exceed that of the simple mass-spring system and criteria for this detrimental scenario to arise are presented

Intraindividual variability in cognitive performance in persons with chronic fatigue syndrome.

Science.gov (United States)

Fuentes, K; Hunter, M A; Strauss, E; Hultsch, D F

2001-05-01

Studies of cognitive performance among persons with chronic fatigue syndrome (CFS) have yielded inconsistent results. We sought to contribute to findings in this area by examining intraindividual variability as well as level of performance in cognitive functioning. A battery of cognitive measures was administered to 14 CFS patients and 16 healthy individuals on 10 weekly occasions. Analyses comparing the two groups in terms of level of performance defined by latency and accuracy scores revealed that the CFS patients were slower but not less accurate than healthy persons. The CFS group showed greater intraindividual variability (as measured by intraindividual standard deviations and coefficients of variation) than the healthy group, although the results varied by task and time frame. Intraindividual variability was found to be stable across time and correlated across tasks at each testing occasion. Intraindividual variability also uniquely differentiated the groups. The present findings support the proposition that intraindividual variability is a meaningful indicator of cognitive functioning in CFS patients.

Personal factors of burnout syndrome in teachers in the framework of self-determination theory

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Ranđelović Kristina

2013-01-01

Full Text Available Teachers perform numerous professional roles that can serve as the source of prolonged stress and lead to the occurrence of burnout syndrome. This research was aimed at studying the personal factors of burnout, using self-determination theory as a starting point. We used a sample of 200 teachers to study the following: the level of satisfaction of basic psychological needs at work, the prominence of self-orientations and the presence of burnout syndrome. We also studied whether these variables were significant burnout predictors, as well as whether there was a difference in the pattern of personal burnout predictors in primary school and university teachers. The following instruments were used: the scale of satisfaction of basic psychological needs at work, the ego function questionnaire, the scale of burnout syndrome in teachers. The results point to a relatively moderate satisfaction of all psychological needs, a higher level of integrated self-regulation as well as the medium presence of ego-invested and impersonal orientations. On the whole, teachers showed low burnout. Significant burnout predictors include an integrated self and the need for autonomy (university teachers and an impersonal self (primary school teachers. This implies that teachers whose psychological needs are satisfied and who have an integrated self are less susceptible to burnout. The findings are discussed from the viewpoint of the self-determination theory, their educational implications and the possibility of preventing work burnout in education workers. [Projekat Ministarstva nauke Republike Srbije, br. 179002: Indikatori i modeli usklađivanja porodičnih i poslovnih uloga

A Case with Cramp-Fasciculation Syndrome

Directory of Open Access Journals (Sweden)

Pinar Yalinay Dikmen

2014-12-01

Full Text Available Cramp-fasciculation syndrome is one of the peripheral nerve hyperexcitability disorders and presents muscle aching, cramps, stiffness and exercise intolerance. Fasciculation and cramps can be seen both in healthy individuals and in those with fatal diseases, such as Amyotrophic Lateral Sclerosis. We present a 27-year-old male patient, professional soccer player with fasciculations and cramps in  bilateral gastrocnemius-soleus complex. The patient complained about having to stop playing soccer because of muscle cramps and twitches in both calves, which had started 3 years earlier. After completing all laboratory and electrophysiological examinations, the patient was diagnosed as cramp-fasciculation syndrome. The aim of this paper was to present a rare case of cramp-fasiculation syndrome and discuss if the syndrome is benign or pioneer of a severe pathological process.

Personality factors and profiles in variants of irritable bowel syndrome

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

AIM: To study the association between irritable bowel syndrome (IBS) variants (constipation, diarrhea, or both)and personality traits in non-psychiatric patients.METHODS: IBS was diagnosed using the Rome Ⅱ diagnostic criteria after exclusion of organic bowel pathology. The entry of each patient was confirmed following a psychiatric interview. Personality traits and the score of each factor were evaluated using the NEO Five Factor Inventory.RESULTS: One hundred and fifty patients were studied.The mean age (±SD) was 33.4 (±11.0) year (62% female). Subjects scored higher in neuroticism (26.25±7.80 vs 22.92±9.54, P ＜ 0.0005), openness (26.25±5.22 vs 27.94±4.87, P ＜ 0.0005) and conscientiousness (32.90 ±7.80 vs 31.62±5.64, P ＜ 0.01) compared to our general population derived from universities of Iran. Our studied population consisted of 71 patients with Diarrhea dominant-IBS, 33 with Constipation dominant-IBS and 46 with Altering type-IBS. Scores of conscientiousness and neuroticism were significantly higher in C-IBS compared to D-IBS and A-IBS (35.79±5.65 vs 31.95±6.80,P = 0.035 and 31.97±9.87, P = 0.043, respectively).Conscientiousness was the highest dimension of personality in each of the variants. Patients with C-IBS had almost similar personality profiles, composed of higher scores for neuroticism and conscientiousness, with low levels of agreeableness, openness and extraversion that were close to those of the general population.CONCLUSION: Differences were observed between IBS patients and the general population, as well as between IBS subtypes, in terms of personality factors.Patients with constipation-predominant IBS showed similar personality profiles. Patients with each subtype of IBS may benefit from psychological interventions, which can be focused considering the characteristics of each subtype.

Constitutive Modelling of Resins in the Stiffness Domain

Science.gov (United States)

Klasztorny, M.

2004-09-01

An analytic method for inverting the constitutive compliance equations of viscoelasticity for resins is developed. These equations describe the HWKK/H rheological model, which makes it possible to simulate, with a good accuracy, short-, medium- and long-term viscoelastic processes in epoxy and polyester resins. These processes are of first-rank reversible isothermal type. The time histories of deviatoric stresses are simulated with three independent strain history functions of fractional and normal exponential types. The stiffness equations are described by two elastic and six viscoelastic constants having a clear physic meaning (three long-term relaxation coefficients and three relaxation times). The time histories of axiatoric stresses are simulated as perfectly elastic. The inversion method utilizes approximate constitutive stiffness equations of viscoelasticity for the HWKK/H model. The constitutive compliance equations for the model are a basis for determining the exact complex shear stiffness, whereas the approximate constitutive stiffness equations are used for determining the approximate complex shear stiffness. The viscoelastic constants in the stiffness domain are derived by equating the exact and approximate complex shear stiffnesses. The viscoelastic constants are obtained for Epidian 53 epoxy and Polimal 109 polyester resins. The accuracy of the approximate constitutive stiffness equations are assessed by comparing the approximate and exact complex shear stiffnesses. The constitutive stiffness equations for the HWKK/H model are presented in uncoupled (shear/bulk) and coupled forms. Formulae for converting the constants of shear viscoelasticity into the constants of coupled viscoelasticity are given as well.

The stiffness change and the increase in the ultimate capacity for a stiff pile resulting from a cyclic loading

DEFF Research Database (Denmark)

Lada, Aleksandra; Ibsen, Lars Bo; Nicolai, Giulio

In the paper the experimental results of small-scale tests on a stiff monopile are presented to outline the change in stiffness during the cyclic loading and the change in the ultimate pile capacity. The results confirm the increase of stiffness and the increase in bearing capacity resulting from...

The Borderline Syndrome Index: a validation study using the personality assessment schedule.

Science.gov (United States)

Marlowe, M J; O'Neill-Byrne, K; Lowe-Ponsford, F; Watson, J P

1996-01-01

This study examines the validity and screening properties of the Borderline Syndrome Index--BSI (developed in the USA) for categories of the Personality Assessment Schedule--PAS (developed in the UK). Patients were recruited by case control sampling. Chance corrected agreement between instruments and screening properties of the BSI were calculated. The BSI proved a moderately sensitive but non-specific screen. Questionnaire scores were highly correlated with symptom measures. The results do not support the validity of the BSI or its use as a screening instrument. BSI scores may be distorted by current symptoms.

[Systemic and local stiffness of the arteries in young patients with arterial hypertension].

Science.gov (United States)

Chernova, I M; Zairova, A R; Luk'ianov, M M; Serdiuk, S E; Boĭtsov, S A

2014-01-01

The aim of the work was to study characteristics of systemic and local arterial stiffness in young patients with arterial hypertension (AH) suffering this condition in the childhood or adulthood and to relate them to risk factors of cardiovascular complications. Materials and methods. 54 patients aged 18-35 (mean 25.3 +/- 3.4) years with AH. 37 of them had AH since 18 year and 27 ones starting from the childhood or adulthood Control group included 26 healthy volunteers aged 25.8 +/- 3.7 year. The carotid-femoral pulse wave propagation rate (PWPR) was measured by applanation tonometry with a SphygmoCor apparatus. Parameters of carotid stiffness of CCA were studied by the echo-tracking method using Aloka ProSound a7 device. Results. Patients with AH and without it in the childhood or adulthood showed higher PWPR values than controls (7.1 +/- 1.2 and 7.5 +/- 1.4 vs. 6.3 +/- 1.0 m/s respectively) Ep and AC values were higher in patients who did not have AH in the childhood or adulthood: right Ep 89 +/- 24.4 and 68.7 +/- 18.4 kPa, AC 0.9 +/- 0.2 and 1.1 +/- 0.1 mm2/kPa respectively; left Ep 86.1 +/- 20.3 and 71/4 +/- 16 kP AC 0.9 +/- 0.2 and 1.1 +/- 0.1 mm2/kPA (p < 0.05). In the patients with AH since the childhood or adulthood with concomitant metabolic syndrome (MS) the PWPR values and carotid artery stiffness were higher than in the absence of MS (p < 0.05). Young patients with AH showed carotid-femoral PWPR compared with control regardless of AH in the childhood or adulthood Parameters of local carotid stiffness were increased only in patients having no AH in the childhood or adulthood Patients with AH since the childhood or adulthood with concomitant MS had higher carotid stiffness and carotid-femoral PWPR than in the absence of MS

Analytical study of a quasi-zero stiffness coupling using a torsion magnetic spring with negative stiffness

Science.gov (United States)

Zheng, Yisheng; Zhang, Xinong; Luo, Yajun; Zhang, Yahong; Xie, Shilin

2018-02-01

By now, many translation quasi-zero stiffness (QZS) mechanisms have been proposed to overcome the restriction between the isolation frequency range and the load bearing capacity of linear isolators. The couplings of rotor systems undertake the functions of transmitting static driving torque and isolating disturbing torque simultaneously, which creates the demand of torsion QZS mechanisms. Hence a QZS coupling is presented in this paper, where a torsion magnetic spring (TMS) composed of two coaxial ring magnet arrangements in repulsive configuration is employed to produce negative torsion stiffness to counteract the positive stiffness of a rubber spring. In this paper, the expressions of magnetic torque and stiffness are given firstly and verified by finite element simulations; and the effect of geometric parameters of the TMS on its stiffness characteristic is analyzed in detail, which contributes to the optimal design of the TMS. Then dynamic analysis of the QZS coupling is performed and the analytical expression of the torque transmissibility is achieved based on the Harmonic Balance Method. Finally, simulation of the torque transmissibility is carried out to reveal how geometric parameters of the TMS affect the isolation performance.

Stiffness of Railway Soil-Steel Structures

Directory of Open Access Journals (Sweden)

Machelski Czesław

2015-12-01

Full Text Available The considerable influence of the soil backfill properties and that of the method of compacting it on the stiffness of soil-steel structures is characteristic of the latter. The above factors (exhibiting randomness become apparent in shell deformation measurements conducted during construction and proof test loading. A definition of soil-shell structure stiffness, calculated on the basis of shell deflection under the service load, is proposed in the paper. It is demonstrated that the stiffness is the inverse of the deflection influence function used in structural mechanics. The moving load methodology is shown to be useful for testing, since it makes it possible to map the shell deflection influence line also in the case of group loads (concentrated forces, as in bridges. The analyzed cases show that the shell’s span, geometry (static scheme and the height of earth fill influence the stiffness of the structure. The soil-steel structure’s characteristic parameter in the form of stiffness k is more suitable for assessing the quality of construction works than the proposed in code geometric index ω applied to beam structures. As shown in the given examples, parameter k is more effective than stiffness parameter λ used to estimate the deformation of soil-steel structures under construction. Although the examples concern railway structures, the methodology proposed in the paper is suitable also for road bridges.

Stiffness of Railway Soil-Steel Structures

Science.gov (United States)

Machelski, Czesław

2015-12-01

The considerable influence of the soil backfill properties and that of the method of compacting it on the stiffness of soil-steel structures is characteristic of the latter. The above factors (exhibiting randomness) become apparent in shell deformation measurements conducted during construction and proof test loading. A definition of soil-shell structure stiffness, calculated on the basis of shell deflection under the service load, is proposed in the paper. It is demonstrated that the stiffness is the inverse of the deflection influence function used in structural mechanics. The moving load methodology is shown to be useful for testing, since it makes it possible to map the shell deflection influence line also in the case of group loads (concentrated forces), as in bridges. The analyzed cases show that the shell's span, geometry (static scheme) and the height of earth fill influence the stiffness of the structure. The soil-steel structure's characteristic parameter in the form of stiffness k is more suitable for assessing the quality of construction works than the proposed in code geometric index ω applied to beam structures. As shown in the given examples, parameter k is more effective than stiffness parameter λ used to estimate the deformation of soil-steel structures under construction. Although the examples concern railway structures, the methodology proposed in the paper is suitable also for road bridges.

Single motor–variable stiffness actuator using bistable switching mechanisms for independent motion and stiffness control

NARCIS (Netherlands)

Groothuis, Stefan; Carloni, Raffaella; Stramigioli, Stefano

This paper presents a proof of concept of a variable stiffness actuator (VSA) that uses only one (high power) input motor. In general, VSAs use two (high power) motors to be able to control both the output position and the output stiffness, which possibly results in a heavy, and bulky system. In

Efficient improvement of virtual crack extension method by a derivative of the finite element stiffness matrix

International Nuclear Information System (INIS)

Ishikawa, H.; Nakano, S.; Yuuki, R.; Chung, N.Y.

1991-01-01

In the virtual crack extension method, the stress intensity factor, K, is obtained from the converged value of the energy release rate by the difference of the finite element stiffness matrix when some crack extension are taken. Instead of the numerical difference of the finite element stiffness, a new method to use a direct dirivative of the finite element stiffness matrix with respect to crack length is proposed. By the present method, the results of some example problems, such as uniform tension problems of a square plate with a center crack and a rectangular plate with an internal slant crack, are obtained with high accuracy and good efficiency. Comparing with analytical results, the present values of the stress intensity factors of the problems are obtained with the error that is less than 0.6%. This shows the numerical assurance of the usefulness of the present method. A personal computer program for the analysis is developed

Big bang nucleosynthesis with a stiff fluid

International Nuclear Information System (INIS)

Dutta, Sourish; Scherrer, Robert J.

2010-01-01

Models that lead to a cosmological stiff fluid component, with a density ρ S that scales as a -6 , where a is the scale factor, have been proposed recently in a variety of contexts. We calculate numerically the effect of such a stiff fluid on the primordial element abundances. Because the stiff fluid energy density decreases with the scale factor more rapidly than radiation, it produces a relatively larger change in the primordial helium-4 abundance than in the other element abundances, relative to the changes produced by an additional radiation component. We show that the helium-4 abundance varies linearly with the density of the stiff fluid at a fixed fiducial temperature. Taking ρ S10 and ρ R10 to be the stiff fluid energy density and the standard density in relativistic particles, respectively, at T=10 MeV, we find that the change in the primordial helium abundance is well-fit by ΔY p =0.00024(ρ S10 /ρ R10 ). The changes in the helium-4 abundance produced by additional radiation or by a stiff fluid are identical when these two components have equal density at a 'pivot temperature', T * , where we find T * =0.55 MeV. Current estimates of the primordial 4 He abundance give the constraint on a stiff fluid energy density of ρ S10 /ρ R10 <30.

Direct measurement of the intrinsic ankle stiffness during standing.

Science.gov (United States)

Vlutters, M; Boonstra, T A; Schouten, A C; van der Kooij, H

2015-05-01

Ankle stiffness contributes to standing balance, counteracting the destabilizing effect of gravity. The ankle stiffness together with the compliance between the foot and the support surface make up the ankle-foot stiffness, which is relevant to quiet standing. The contribution of the intrinsic ankle-foot stiffness to balance, and the ankle-foot stiffness amplitude dependency remain a topic of debate in the literature. We therefore developed an experimental protocol to directly measure the bilateral intrinsic ankle-foot stiffness during standing balance, and determine its amplitude dependency. By applying fast (40 ms) ramp-and-hold support surface rotations (0.005-0.08 rad) during standing, reflexive contributions could be excluded, and the amplitude dependency of the intrinsic ankle-foot stiffness was investigated. Results showed that reflexive activity could not have biased the torque used for estimating the intrinsic stiffness. Furthermore, subjects required less recovery action to restore balance after bilateral rotations in opposite directions compared to rotations in the same direction. The intrinsic ankle-foot stiffness appears insufficient to ensure balance, ranging from 0.93±0.09 to 0.44±0.06 (normalized to critical stiffness 'mgh'). This implies that changes in muscle activation are required to maintain balance. The non-linear stiffness decrease with increasing rotation amplitude supports the previous published research. With the proposed method reflexive effects can be ruled out from the measured torque without any model assumptions, allowing direct estimation of intrinsic stiffness during standing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Observed variations of monopile foundation stiffness

DEFF Research Database (Denmark)

Kallehave, Dan; Thilsted, C.L.; Diaz, Alberto Troya

2015-01-01

full-scale measurements obtained from one offshore wind turbine structure located within Horns Reef II offshore wind farm. Data are presented for a 2.5 years period and covers normal operating conditions and one larger storm event. A reduction of the pile-soil stiffness was observed during the storm...... events, followed by a complete regain to a pre-storm level when the storm subsided. In additional, no long term variations of the pile-soil stiffness was observed. The wind turbine is located in dense to very dense sand deposits.......The soil-structure stiffness of monopile foundations for offshore wind turbines has a high impact on the fatigue loading during normal operating conditions. Thus, a robust design must consider the evolution of pile-soil stiffness over the lifetime of the wind farm. This paper present and discuss...

Stiff Hands

Science.gov (United States)

... All Topics A-Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is a Hand Therapist? Media Find a Hand Surgeon Home Anatomy Stiff Hands Email to a friend * required fields ...

A Stewart isolator with high-static-low-dynamic stiffness struts based on negative stiffness magnetic springs

Science.gov (United States)

Zheng, Yisheng; Li, Qingpin; Yan, Bo; Luo, Yajun; Zhang, Xinong

2018-05-01

In order to improve the isolation performance of passive Stewart platforms, the negative stiffness magnetic spring (NSMS) is employed to construct high static low dynamic stiffness (HSLDS) struts. With the NSMS, the resonance frequencies of the platform can be reduced effectively without deteriorating its load bearing capacity. The model of the Stewart isolation platform with HSLDS struts is presented and the stiffness characteristic of its struts is studied firstly. Then the nonlinear dynamic model of the platform including both geometry nonlinearity and stiffness nonlinearity is established; and its simplified dynamic model is derived under the condition of small vibration. The effect of nonlinearity on the isolation performance is also evaluated. Finally, a prototype is built and the isolation performance is tested. Both simulated and experimental results demonstrate that, by using the NSMS, the resonance frequencies of the Stewart isolator are reduced and the isolation performance in all six directions is improved: the isolation frequency band is increased and extended to a lower-frequency level.

Fractal dynamics of heartbeat time series of young persons with metabolic syndrome

Science.gov (United States)

Muñoz-Diosdado, A.; Alonso-Martínez, A.; Ramírez-Hernández, L.; Martínez-Hernández, G.

2012-10-01

Many physiological systems have been in recent years quantitatively characterized using fractal analysis. We applied it to study heart variability of young subjects with metabolic syndrome (MS); we examined the RR time series (time between two R waves in ECG) with the detrended fluctuation analysis (DFA) method, the Higuchi's fractal dimension method and the multifractal analysis to detect the possible presence of heart problems. The results show that although the young persons have MS, the majority do not present alterations in the heart dynamics. However, there were cases where the fractal parameter values differed significantly from the healthy people values.

Presence of non-fibrillar amyloid beta protein in skin biopsies of Alzheimer's disease (AD), Down's syndrome and non-AD normal persons

DEFF Research Database (Denmark)

Wen, G Y; Wisniewski, H M; Blondal, H

1994-01-01

A total of 66 skin biopsies from persons with Alzheimer's disease (AD) or Down's syndrome (DS) and from persons without AD were used in this study. The age range was from 7 to 89 years. Positive immunoreactivity of skin biopsies to monoclonal antibody 4G8, which is reactive to amino acid residue 17...

A novel energy-efficient rotational variable stiffness actuator

NARCIS (Netherlands)

Rao, S.; Carloni, Raffaella; Stramigioli, Stefano

This paper presents the working principle, the design and realization of a novel rotational variable stiffness actuator, whose stiffness can be varied independently of its output angular position. This actuator is energy-efficient, meaning that the stiffness of the actuator can be varied by keeping

Subclinical dysphagia in persons with Prader-Willi syndrome.

Science.gov (United States)

Gross, Roxann Diez; Gisser, Ronit; Cherpes, Gregory; Hartman, Katie; Maheshwary, Rishi

2017-02-01

Prader-Willi Syndrome (PWS) is caused by a genetic imprinting abnormality resulting from the lack of expression of the paternal genes at 15q11-q13. Intellectual disability, low muscle tone, and life-threatening hyperphagia are hallmarks of the phenotype. The need for the Heimlich maneuver, death from choking, and pulmonary infection occur in a disproportionally high number of persons with PWS. The widely held belief is that eating behaviors are responsible for choking and aspiration; yet, no investigation had sought to determine if swallowing impairments were present in persons with PWS. To address this research and clinical gap, simultaneous videofluoroscopy and nasal respiratory signals were used to record swallowing function and breathing/swallowing coordination in 30 participants with PWS. Subjects consumed thin liquid and barium cookies under two randomized conditions as follows: (i) controlled (cues to swallow and standardized bolus sizes); (ii) spontaneous (no cues or bolus size control). Under videofluoroscopy, the cohort showed disordered pharyngeal and esophageal swallowing in both conditions with disturbances in timing, clearance, and coordination of swallowing with the respiratory cycle. No participant showed a sensory response such as attempting to clear residue or coughing; thereby supporting the lack of overt symptoms. We conclude that the high death rate from choking and pulmonary infection in children and adults with PWS may be related, in part, to underlying, asymptomatic dysphagia. The combination of rapid eating and dysphagia would increase the risk of aspiration-related morbidity and mortality. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Stiffness and the automatic selection of ODE codes

International Nuclear Information System (INIS)

Shampine, L.F.

1984-01-01

The author describes the basic ideas behind the most popular methods for the numerical solution of ordinary differential equations (ODEs). He takes up the qualitative behavior of solutions of ODEs and its relation ot the propagation of numerical error. Codes for ODEs are intended either for stiff problems or for non-stiff problems. The difference is explained. Users of codes do not have the information needed to recognize stiffness. A code, DEASY, which automatically recognizes stiffness and selects a suitable method is described

Feasibility, test-retest reliability, and interrater reliability of the Modified Ashworth Scale and Modified Tardieu Scale in persons with profound intellectual and multiple disabilities

NARCIS (Netherlands)

Waninge, A.; Rook, R.A.; Dijkhuizen, A.; Gielen, E.; van der Schans, C.P.

2011-01-01

Caregivers of persons with profound intellectual and multiple disabilities (PIMD) often describe the quality of the daily movements of these persons in terms of flexibility or stiffness. Objective outcome measures for flexibility and stiffness are muscle tone or level of spasticity. Two instruments

Multi-fingered haptic palpation utilizing granular jamming stiffness feedback actuators

International Nuclear Information System (INIS)

Li, Min; Sareh, Sina; Seneviratne, Lakmal D; Wurdemann, Helge A; Althoefer, Kaspar; Ranzani, Tommaso; Dasgupta, Prokar

2014-01-01

This paper describes a multi-fingered haptic palpation method using stiffness feedback actuators for simulating tissue palpation procedures in traditional and in robot-assisted minimally invasive surgery. Soft tissue stiffness is simulated by changing the stiffness property of the actuator during palpation. For the first time, granular jamming and pneumatic air actuation are combined to realize stiffness modulation. The stiffness feedback actuator is validated by stiffness measurements in indentation tests and through stiffness discrimination based on a user study. According to the indentation test results, the introduction of a pneumatic chamber to granular jamming can amplify the stiffness variation range and reduce hysteresis of the actuator. The advantage of multi-fingered palpation using the proposed actuators is proven by the comparison of the results of the stiffness discrimination performance using two-fingered (sensitivity: 82.2%, specificity: 88.9%, positive predicative value: 80.0%, accuracy: 85.4%, time: 4.84 s) and single-fingered (sensitivity: 76.4%, specificity: 85.7%, positive predicative value: 75.3%, accuracy: 81.8%, time: 7.48 s) stiffness feedback. (paper)

A novel variable stiffness mechanism for dielectric elastomer actuators

Science.gov (United States)

Li, Wen-Bo; Zhang, Wen-Ming; Zou, Hong-Xiang; Peng, Zhi-Ke; Meng, Guang

2017-08-01

In this paper, a novel variable stiffness mechanism is proposed for the design of a variable stiffness dielectric elastomer actuator (VSDEA) which combines a flexible strip with a DEA in a dielectric elastomer minimum energy structure. The DEA induces an analog tuning of the transverse curvature of the strip, thus conveniently providing a voltage-controllable flexural rigidity. The VSDEA tends to be a fully flexible and compact structure with the advantages of simplicity and fast response. Both experimental and theoretical investigations are carried out to reveal the variable stiffness performances of the VSDEA. The effect of the clamped location on the bending stiffness of the VSDEA is analyzed, and then effects of the lengths, the loading points and the applied voltages on the bending stiffness are experimentally investigated. An analytical model is developed to verify the availability of this variable stiffness mechanism, and the theoretical results demonstrate that the bending stiffness of the VSDEA decreases as the applied voltage increases, which agree well with the experimental data. Moreover, the experimental results show that the maximum change of the relative stiffness can reach about 88.80%. It can be useful for the design and optimization of active variable stiffness structures and DEAs for soft robots, vibration control, and morphing applications.

Stability of generalized Runge-Kutta methods for stiff kinetics coupled differential equations

International Nuclear Information System (INIS)

Aboanber, A E

2006-01-01

A stability and efficiency improved class of generalized Runge-Kutta methods of order 4 are developed for the numerical solution of stiff system kinetics equations for linear and/or nonlinear coupled differential equations. The determination of the coefficients required by the method is precisely obtained from the so-called equations of condition which in turn are derived by an approach based on Butcher series. Since the equations of condition are fewer in number, free parameters can be chosen for optimizing any desired feature of the process. A further related coefficient set with different values of these parameters and the region of absolute stability of the method have been introduced. In addition, the A(α) stability properties of the method are investigated. Implementing the method in a personal computer estimated the accuracy and speed of calculations and verified the good performances of the proposed new schemes for several sample problems of the stiff system point kinetics equations with reactivity feedback

Lower Body Stiffness Modulation Strategies in Well Trained Female Athletes.

Science.gov (United States)

Millett, Emma L; Moresi, Mark P; Watsford, Mark L; Taylor, Paul G; Greene, David A

2016-10-01

Millett, EL, Moresi, MP, Watsford, ML, Taylor, PG, and Greene, DA. Lower body stiffness modulation strategies in well trained female athletes. J Strength Cond Res 30(10): 2845-2856, 2016-Lower extremity stiffness quantifies the relationship between the amount of leg compression and the external load to which the limb are subjected. This study aimed to assess differences in leg and joint stiffness and the subsequent kinematic and kinetic control mechanisms between athletes from various training backgrounds. Forty-seven female participants (20 nationally identified netballers, 13 high level endurance athletes and 14 age and gender matched controls) completed a maximal unilateral countermovement jump, drop jump and horizontal jump to assess stiffness. Leg stiffness, joint stiffness and associated mechanical parameters were assessed with a 10 camera motion analysis system and force plate. No significant differences were evident for leg stiffness measures between athletic groups for any of the tasks (p = 0.321-0.849). However, differences in joint stiffness and its contribution to leg stiffness, jump performance outcome measures and stiffness control mechanisms were evident between all groups. Practitioners should consider the appropriateness of the task utilised in leg stiffness screening. Inclusion of mechanistic and/or more sports specific tasks may be more appropriate for athletic groups.

Imaging evidence for anatomical disturbances and neuroplastic compensation in persons with Tourette syndrome

DEFF Research Database (Denmark)

Plessen, Kerstin J; Bansal, Ravi; Peterson, Bradley S

2009-01-01

BACKGROUND: Tourette syndrome (TS) is a disorder of chronic motor and vocal tics that begins in childhood. METHODS: A systematic Medline search was conducted to identify existing anatomical imaging studies in persons with TS. RESULTS: Thirty studies were identified, and their methods and findings......, and methods of image analysis, the preponderance of evidence suggests that disturbances in the development of the motor portions of cortical-subcortical circuits likely predispose to the development TS and that neuroplastic changes in control systems of the brain help to modulate the severity of symptom...

Stiffness Evolution in Frozen Sands Subjected to Stress Changes

KAUST Repository

Dai, Sheng; Santamarina, Carlos

2017-01-01

Sampling affects all soils, including frozen soils and hydrate-bearing sediments. The authors monitor the stiffness evolution of frozen sands subjected to various temperature and stress conditions using an oedometer cell instrumented with P-wave transducers. Experimental results show the stress-dependent stiffness of freshly remolded sands, the dominant stiffening effect of ice, creep after unloading, and the associated exponential decrease in stiffness with time. The characteristic time for stiffness loss during creep is of the order of tens of minutes; therefore it is inevitable that frozen soils experience sampling disturbances attributable to unloading. Slow unloading minimizes stiffness loss; conversely, fast unloading causes a pronounced reduction in stiffness probably attributable to the brittle failure of ice or ice-mineral bonding.

Stiffness Evolution in Frozen Sands Subjected to Stress Changes

KAUST Repository

Dai, Sheng

2017-04-21

Sampling affects all soils, including frozen soils and hydrate-bearing sediments. The authors monitor the stiffness evolution of frozen sands subjected to various temperature and stress conditions using an oedometer cell instrumented with P-wave transducers. Experimental results show the stress-dependent stiffness of freshly remolded sands, the dominant stiffening effect of ice, creep after unloading, and the associated exponential decrease in stiffness with time. The characteristic time for stiffness loss during creep is of the order of tens of minutes; therefore it is inevitable that frozen soils experience sampling disturbances attributable to unloading. Slow unloading minimizes stiffness loss; conversely, fast unloading causes a pronounced reduction in stiffness probably attributable to the brittle failure of ice or ice-mineral bonding.

Experimental Challenges to Stiffness as a Transport Paradigm

Science.gov (United States)

Luce, T. C.

2017-10-01

Transport in plasmas is treated experimentally as a relationship between gradients and fluxes in analogy to the random-walk problem. Gyrokinetic models often predict strong increases in local flux for small increases in local gradient when above a threshold, holding all other parameters fixed. This has been named `stiffness'. The radial scalelength is then expected to vary little with source strength as a result of high stiffness. To probe the role of ExB shearing on stiffness in the DIII-D tokamak, two neutral beam injection power scans in H-mode plasmas were specially crafted-one with constant, low torque and one with increasing torque. The ion heat, electron heat, and ion toroidal momentum transport do not show expected signatures of stiffness, while the ion particle transport does. The ion heat transport shows the clearest discrepancy; the normalized heat flux drops with increasing inverse ion temperature scalelength. ExB shearing affects the transport magnitude, but not the scalelength dependence. Linear gyrofluid (TGLF) and nonlinear gyrokinetic (GYRO) predictions show stiff ion heat transport around the experimental profiles. The ion temperature gradient required to match the ion heat flux with increasing auxiliary power is not correctly described by TGLF, even when parameters are varied within the experimental uncertainties. TGLF also underpredicts transport at smaller radii, but overpredicts transport at larger radii. Independent of the theory/experiment comparison, it is not clear that the theoretical definition of stiffness yields any prediction about parameter scans such as the power scans here, because the quantities that must be held fixed to quantify stiffness are varied. A survey of recent literature indicated that profile resilience is routinely attributed to stiffness, but simple model calculations show profile resilience does not imply stiffness. Taken together, these observations challenge the use of local stiffness as a paradigm for explaining

Unmasking diogenes syndrome

Directory of Open Access Journals (Sweden)

Kashinath Nayak

2015-01-01

Full Text Available Diogenes syndrome is characterized by extreme self-neglect, social withdrawal, and poor personal and domestic hygiene. We report a case of Diogenes syndrome presenting with dermatitis passivata. An unusual "mask" of dirt resembling a carapace, onset of neglect after awareness of a breast lump and resumption of personal grooming and social activities after removal of the lump and counseling were seen.

Stiffness Evaluation of High Temperature Superconductor Bearing Stiffness for 10 kWh Superconductor Flywheel Energy Storage System

International Nuclear Information System (INIS)

Park, B. J.; Jung, S. Y.; Lee, J. P.; Park, B. C.; Kim, C. H.; Han, S. C.; Du, S. G.; Han, Y. H.; Sung, T. H.

2009-01-01

A superconductor flywheel energy storage(SFES) system is mainly act an electro-mechanical battery which transfers mechanical energy into electrical form and vice versa. SFES system consists of a pair of non-contacting High Temperature Superconductor (HTS) bearings with a very low frictional loss. But it is essential to design an efficient HTS bearing considering with rotor dynamic properties through correct calculation of stiffness in order to support a huge composite flywheel rotor with high energy storage density. Static properties of HTS bearings provide data to solve problems which may occur easily in a running system. Since stiffness to counter vibration is the main parameter in designing an HTS bearing system, we investigate HTS bearing magnetic force through static properties between the Permanent Magnet(PM) and HTS. We measured axial / radial stiffness and found bearing stiffness can be easily changed by activated vibration direction between PM and HTS bulk. These results are used to determine the optimal design for a 10 kWh SFES.

Elastic properties of the aorta and factors affecting aortic stiffness in patients with

Directory of Open Access Journals (Sweden)

Derya Tok

2012-09-01

Full Text Available Objectives: In this study, we evaluated aortic stiffnessand echocardiographic and laboratory factors affectingaortic stiffness in patients with metabolic syndrome(MetS.Materials and methods: Forty-six patients (25 male,mean age 47.3±6.5 years with the diagnosis of MetS accordingto the Adult Treatment Panel III Final Report criteriawere included. Forty-four age and gender matchedhealthy subjects (18 male, mean age 46.0±6.1 yearswere recruited as the control group. Aortic strain, distensibilityand stiffness index were calculated by M-modeechocardiography and diastolic parameters were measured.Results: Left ventricular mass index (LVMI, decelerationtime (DT, isovolumic relaxation time (IVRT wereincreased and mitral E/A ratio was decreased in patientswith MetS compared to controls. In the MetS patients,aortic distensibility was significantly decreased (10.4±3.5cm2.dyn-1.10-6 vs. 12.7±3.4 cm2.dyn-1.10-6, p=0.002,and ASI was significantly increased (6.5±2.0 vs. 3.2±0.8,p<0.001. ASI was positively correlated with triglycerides,fasting glucose, uric acid, hsCRP, LVMI, DT, IVRT andsystolic blood pressure level, and was negatively correlatedwith HDL-cholesterol and mitral E/A ratio. In regressionanalysis, hsCRP (p=0.05 and systolic blood pressurelevel (p<0.001 were independent predictors of ASI.Conclusions: ASI is increased in patients with MetS. Inthese patients; decrease in aortic elasticity properties wasassociated with left ventricular diastolic dysfunction. Highsystolic pressure and hsCRP levels were found to be independentpredictors of ASI.Key words: Metabolic syndrome, Echocardiography,elastic properties of aorta, hsCRP

Age-related changes of adaptive and neuropsychological features in persons with Down Syndrome.

Directory of Open Access Journals (Sweden)

Alessandro Ghezzo

Full Text Available Down Syndrome (DS is characterised by premature aging and an accelerated decline of cognitive functions in the vast majority of cases. As the life expectancy of DS persons is rapidly increasing, this decline is becoming a dramatic health problem. The aim of this study was to thoroughly evaluate a group of 67 non-demented persons with DS of different ages (11 to 66 years, from a neuropsychological, neuropsychiatric and psychomotor point of view in order to evaluate in a cross-sectional study the age-related adaptive and neuropsychological features, and to possibly identify early signs predictive of cognitive decline. The main finding of this study is that both neuropsychological functions and adaptive skills are lower in adult DS persons over 40 years old, compared to younger ones. In particular, language and short memory skills, frontal lobe functions, visuo-spatial abilities and adaptive behaviour appear to be the more affected domains. A growing deficit in verbal comprehension, along with social isolation, loss of interest and greater fatigue in daily tasks, are the main features found in older, non demented DS persons evaluated in our study. It is proposed that these signs can be alarm bells for incipient dementia, and that neuro-cognitive rehabilitation and psycho-pharmacological interventions must start as soon as the fourth decade (or even earlier in DS persons, i.e. at an age where interventions can have the greatest efficacy.

Stiffness and damping in mechanical design

National Research Council Canada - National Science Library

Rivin, Eugene I

1999-01-01

... important conceptual issues are stiffness of mechanical structures and their components and damping in mechanical systems sensitive to and/or generating vibrations. Stiffness and strength are the most important criteria for many mechanical designs. However, although there are hundreds of books on various aspects of strength, and strength issues ar...

MR Elastography Can Be Used to Measure Brain Stiffness Changes as a Result of Altered Cranial Venous Drainage During Jugular Compression.

Science.gov (United States)

Hatt, A; Cheng, S; Tan, K; Sinkus, R; Bilston, L E

2015-10-01

Compressing the internal jugular veins can reverse ventriculomegaly in the syndrome of inappropriately low pressure acute hydrocephalus, and it has been suggested that this works by "stiffening" the brain tissue. Jugular compression may also alter blood and CSF flow in other conditions. We aimed to understand the effect of jugular compression on brain tissue stiffness and CSF flow. The head and neck of 9 healthy volunteers were studied with and without jugular compression. Brain stiffness (shear modulus) was measured by using MR elastography. Phase-contrast MR imaging was used to measure CSF flow in the cerebral aqueduct and blood flow in the neck. The shear moduli of the brain tissue increased with the percentage of blood draining through the internal jugular veins during venous compression. Peak velocity of caudally directed CSF in the aqueduct increased significantly with jugular compression (P drainage through the internal jugular veins during jugular compression have stiffer brains than those who divert venous blood through alternative pathways. These methods may be useful for studying this phenomenon in patients with the syndrome of inappropriately low-pressure acute hydrocephalus and other conditions. © 2015 by American Journal of Neuroradiology.

The Effect of Shoe Insole Stiffness on Leg Stiffness during Stance Phase of Running in Two Different Speeds ‎among Active Men

Directory of Open Access Journals (Sweden)

Zeinab Tazike-Lemeski

2016-08-01

Full Text Available Introduction: The effect of shoe insoles with different characteristics and in different running speeds on lower-limb stiffness is still ‎controversial. The aim of this study was to investigate the effect of two types of insoles (soft and semi-rigid in two ‎different running speeds on leg stiffness during stance phase of running among active men.‎ Materials and Methods: ‎15 male students without any background of lower extremity injury were selected. Subjects were asked to run with ‎two controlled velocities of 3.0 ± 0.2 and 5.0 ± 0.1 m/s in control and insole conditions (soft and semi-rigid on a ‎force plate, placed on the middle of 15-meter runway. The cinematics and cinetics of motion were measured and ‎calculated using 5 video cameras and one force plate. The leg stiffness was achieved via dividing the vertical ‎ground reaction force by leg compression. Two-factor repeated measures ANOVA was used to test the hypothesis at ‎the significance level of P £ 0.050.‎ Results: There was a significant difference between the two types of insoles on leg stiffness. In fact, semi-rigid insole significantly increased leg stiffness (P < 0.001. However, this discrepancy was not related to the running speed (P = 0.999. In addition, there was no significant difference between the two different speeds on leg stiffness (P = 0.632. Conclusion: It seems that the increase in shoe insole stiffness may increase the leg stiffness. Furthermore, the effect of insole ‎stiffness is not related to the running speed, and leg stiffness will remains constant in low to medium running speeds.‎

Personality and Affect When the Central Nervous System is Sensitized: An Analysis of Central Sensitization Syndromes in a Substance Use Disorder Population.

Science.gov (United States)

McKernan, Lindsey C; Finn, Michael T M; Carr, Erika R

2017-01-01

Functional somatic syndromes, or more recently termed central sensitivity syndromes (CSS), comprise a significant portion of the chronic pain population. Although it is evident that personality is intricately related to the pain experience, it has not been widely studied. This article examines the impact of CSS on the clinical presentation of individuals presenting to treatment for a substance use disorder (SUD), with an emphasis on personality and emotional functioning. We examined personality profiles of individuals presenting to treatment with SUD between three groups: those with a CSS (n = 30), non-CSS chronic pain (n = 79), and no pain (n = 232). Based on previous research and a psychodynamic conceptualization of CSS, we hypothesized that predictors of the presence of a CSS in this sample would be higher rates of overall anxiety, traumatic stress, perfectionistic traits, and a need for interpersonal closeness. Logistic regression analyses did not support our hypothesis. Exploratory analyses indicated which personality traits most strongly predicted the presence of CSS. We discuss these findings using descriptive psychopathology literature, with recommendations for future research.

The stable stiffness triangle - drained sand during deformation cycles

DEFF Research Database (Denmark)

Sabaliauskas, Tomas; Ibsen, Lars Bo

2017-01-01

Cyclic, drained sand stiffness was observed using the Danish triaxial appa- ratus. New, deformation dependant soil property (the stable stiffness triangle) was detected. Using the the stable stiffness triangle, secant stiffness of drained sand was plausible to predict (and control) even during ir...... findings can find application in off-shore, seismic and other engi- neering practice, or inspire new branches of research and modelling wherever dynamic, cyclic or transient loaded sand is encountered....

Is change bad? Personality change is associated with poorer psychological health and greater metabolic syndrome in midlife

Science.gov (United States)

Human, Lauren J.; Biesanz, Jeremy C.; Miller, Gregory E.; Chen, Edith; Lachman, Margie E.; Seeman, Teresa E.

2013-01-01

Objective Personality change is emerging as an important predictor of health and well-being. Extending previous research, we examined whether two types of personality change, directional and absolute, are associated with both subjective and objective indicators of health. Method Utilizing the longitudinal Midlife in the United States Survey (MIDUS) data, we examined whether both types of change over 10 years were associated with psychological well-being, self-reported global health, and the presence of metabolic syndrome (MetS) components and diagnosis. Results Socially undesirable personality change (e.g., becoming less conscientious and more neurotic) and absolute personality change were independently associated with worse perceived health and well-being at Time 2. Notably, absolute personality change, regardless of the direction, was also associated with having a greater number of MetS components and a greater probability of diagnosis at Time 2. Conclusions In sum, too much personality change may be bad for one’s health: socially undesirable and absolute personality change were both associated with worse psychological health and worse metabolic profiles over 10 years. These findings suggest that personality change may contribute to psychological and physical health, and provide initial insight into potential intermediate links between personality change and distal outcomes such as mortality. PMID:22924900

Is change bad? Personality change is associated with poorer psychological health and greater metabolic syndrome in midlife.

Science.gov (United States)

Human, Lauren J; Biesanz, Jeremy C; Miller, Gregory E; Chen, Edith; Lachman, Margie E; Seeman, Teresa E

2013-06-01

Personality change is emerging as an important predictor of health and well-being. Extending previous research, we examined whether two types of personality change, directional and absolute, are associated with both subjective and objective indicators of health. Utilizing the longitudinal Midlife in the United States survey (MIDUS) data, we examined whether both types of change over 10 years were associated with psychological well-being, self-reported global health, and the presence of metabolic syndrome (MetS) components and diagnosis. Socially undesirable personality change (e.g., becoming less conscientious and more neurotic) and absolute personality change were independently associated with worse perceived health and well-being at Time 2. Notably, absolute personality change, regardless of the direction, was also associated with having a greater number of MetS components and a greater probability of diagnosis at Time 2. In sum, too much personality change may be bad for one's health: Socially undesirable and absolute personality change were both associated with worse psychological health and worse metabolic profiles over 10 years. These findings suggest that personality change may contribute to psychological and physical health, and provide initial insight into potential intermediate links between personality change and distal outcomes such as mortality. © 2012 Wiley Periodicals, Inc.

Pipe elbow stiffness coefficients including shear and bend flexibility factors for use in direct stiffness codes

International Nuclear Information System (INIS)

Perry, R.F.

1977-01-01

Historically, developments of computer codes used for piping analysis were based upon the flexibility method of structural analysis. Because of the specialized techniques employed in this method, the codes handled systems composed of only piping elements. Over the past ten years, the direct stiffness method has gained great popularity because of its systematic solution procedure regardless of the type of structural elements composing the system. A great advantage is realized with a direct stiffness code that combines piping elements along with other structural elements such as beams, plates, and shells, in a single model. One common problem, however, has been the lack of an accurate pipe elbow element that would adequately represent the effects of transverse shear and bend flexibility factors. The purpose of the present paper is to present a systematic derivation of the required 12x12 stiffness matrix and load vectors for a three dimensional pipe elbow element which includes the effects of transverse shear and pipe bend flexibility according to the ASME Boiler and Pressure Vessel Code, Section III. The results are presented analytically and as FORTRAN subroutines to be directly incorporated into existing direct stiffness codes. (Auth.)

The role of genes, intelligence, personality, and social engagement in cognitive performance in Klinefelter syndrome

DEFF Research Database (Denmark)

Skakkebæk, Anne; Moore, Philip J.; Pedersen, Anders Degn

2017-01-01

of controls matched for age and years of education. Methods: Sixty-nine patients with KS and 69 controls were assessed in terms of IQ, NEO personality inventory, the Autism Spectrum Quotient (AQ) scale, and measures of cognitive performance reflecting working memory and executive function. Results: Patients......Introduction: The determinants of cognitive deficits among individuals with Klinefelter syndrome (KS) are not well understood. This study was conducted to assess the impact of general intelligence, personality, and social engagement on cognitive performance among patients with KS and a group...... with KS performed more poorly on memory and executive-function tasks. Patients with KS also exhibited greater neuroticism and less extraversion, openness, and conscientiousness than controls. Memory deficits among patients with KS were associated with lower intelligence, while diminished executive...

Direct measurement of the intrinsic ankle stiffness during standing

NARCIS (Netherlands)

Vlutters, Mark; Vlutters, M.; Boonstra, Tjitske; Schouten, Alfred Christiaan; van der Kooij, Herman

2015-01-01

Ankle stiffness contributes to standing balance, counteracting the destabilizing effect of gravity. The ankle stiffness together with the compliance between the foot and the support surface make up the ankle-foot stiffness, which is relevant to quiet standing. The contribution of the intrinsic

Operator-Based Preconditioning of Stiff Hyperbolic Systems

International Nuclear Information System (INIS)

Reynolds, Daniel R.; Samtaney, Ravi; Woodward, Carol S.

2009-01-01

We introduce an operator-based scheme for preconditioning stiff components encountered in implicit methods for hyperbolic systems of partial differential equations posed on regular grids. The method is based on a directional splitting of the implicit operator, followed by a characteristic decomposition of the resulting directional parts. This approach allows for solution to any number of characteristic components, from the entire system to only the fastest, stiffness-inducing waves. We apply the preconditioning method to stiff hyperbolic systems arising in magnetohydro- dynamics and gas dynamics. We then present numerical results showing that this preconditioning scheme works well on problems where the underlying stiffness results from the interaction of fast transient waves with slowly-evolving dynamics, scales well to large problem sizes and numbers of processors, and allows for additional customization based on the specific problems under study

[Sudeck syndrome (CRPS) caused by unique personality traits: myth and fiction].

Science.gov (United States)

Lesky, J

2010-12-01

In analogy to the thesis of "pain-proneness", conceptualised by G. Engel more than 50 years ago, the idea of a unique structure in personality emerged, which was given a causal meaning in the development of Sudeck's Disease (now known as complex regional pain syndrome - CRPS), of which the pathogenesis is particularly unknown until today. It was supposed that certain psychological traits predispose one to develop CRPS. Predisposition in this context was apprehended as a personal susceptibility to produce and maintain an excessive reaction to nociceptive stimulations. This model has been maintained for a long time and was the subject of scientific examination just in the last two decades. Some publications reporting sporadic correlations between CRPS and certain personality traits, for example anxiety, neuroticism and depressive mood, are presented as are also 15 current empirical studies and five reviews, which deal in a more differentiated manner with the formulated question and lead to sobering results. The relevant state of research as well as the fundamental and methodical difficulties in regard to verifying a CRPS personality or pain-prone personality are discussed critically. In general, there is a lack of high-quality relevant studies. Some retrospective/cross-sectional studies yield contradictory results regarding psychological problems in patients with CRPS but the majority shows no association, and studies with higher methodological quality tend to the conclusion of no relationship between psychological factors like depression, anxiety, neuroticism, or anger and CRPS. Especially, the few prospective studies do not report such a relationship, psychological factors are not associated with CRPS onset. Compared to other patients with chronic pain there is no unique disturbed psychological profile and no higher degree of psychosocial disturbance in CRPS patients. In all, the results of research cannot confirm the hypothesis of correlations between

Biomechanical constraints on the feedforward regulation of endpoint stiffness.

Science.gov (United States)

Hu, Xiao; Murray, Wendy M; Perreault, Eric J

2012-10-01

Although many daily tasks tend to destabilize arm posture, it is still possible to have stable interactions with the environment by regulating the multijoint mechanics of the arm in a task-appropriate manner. For postural tasks, this regulation involves the appropriate control of endpoint stiffness, which represents the stiffness of the arm at the hand. Although experimental studies have been used to evaluate endpoint stiffness control, including the orientation of maximal stiffness, the underlying neural strategies remain unknown. Specifically, the relative importance of feedforward and feedback mechanisms has yet to be determined due to the difficulty separately identifying the contributions of these mechanisms in human experiments. This study used a previously validated three-dimensional musculoskeletal model of the arm to quantify the degree to which the orientation of maximal endpoint stiffness could be changed using only steady-state muscle activations, used to represent feedforward motor commands. Our hypothesis was that the feedforward control of endpoint stiffness orientation would be significantly constrained by the biomechanical properties of the musculoskeletal system. Our results supported this hypothesis, demonstrating substantial biomechanical constraints on the ability to regulate endpoint stiffness throughout the workspace. The ability to regulate stiffness orientation was further constrained by additional task requirements, such as the need to support the arm against gravity or exert forces on the environment. Together, these results bound the degree to which slowly varying feedforward motor commands can be used to regulate the orientation of maximum arm stiffness and provide a context for better understanding conditions in which feedback control may be needed.

The study of stiffness modulus values for AC-WC pavement

Science.gov (United States)

Lubis, AS; Muis, Z. A.; Iskandar, T. D.

2018-02-01

One of the parameters of the asphalt mixture in order for the strength and durability to be achieved as required is the stress-and-strain showing the stiffness of a material. Stiffness modulus is a very necessary factor that will affect the performance of asphalt pavements. If the stiffness modulus value decreases there will be a cause of aging asphalt pavement crack easily when receiving a heavy load. The high stiffness modulus asphalt concrete causes more stiff and resistant to bending. The stiffness modulus value of an asphalt mixture material can be obtained from the theoretical (indirect methods) and laboratory test results (direct methods). For the indirect methods used Brown & Brunton method, and Shell Bitumen method; while for the direct methods used the UMATTA tool. This study aims to determine stiffness modulus values for AC-WC pavement. The tests were conducted in laboratory that used 3 methods, i.e. Brown & Brunton Method, Shell Bitumen Method and Marshall Test as a substitute tool for the UMATTA tool. Hotmix asphalt made from type AC-WC with pen 60/70 using a mixture of optimum bitumen content was 5.84% with a standard temperature variation was 60°C and several variations of temperature that were 30, 40, 50, 70 and 80°C. The stiffness modulus value results obtained from Brown & Brunton Method, Shell Bitumen Method and Marshall Test which were 1374,93 Mpa, 235,45 Mpa dan 254,96 Mpa. The stiffness modulus value decreases with increasing temperature of the concrete asphalt. The stiffness modulus value from the Bitumen Shell method and the Marshall Test has a relatively similar value.The stiffness modulus value from the Brown & Brunton method is greater than the Bitumen Shell method and the Marshall Test, but can not measure the stiffness modulus value at temperature above 80°C.

Stiffness and thickness of fascia do not explain chronic exertional compartment syndrome

DEFF Research Database (Denmark)

Dahl, Morten; Hansen, Philip; Stål, Per

2011-01-01

Chronic exertional compartment syndrome is diagnosed based on symptoms and elevated intramuscular pressure and often is treated with fasciotomy. However, what contributes to the increased intramuscular pressure remains unknown....

Person-centred care after acute coronary syndrome, from hospital to primary care - A randomised controlled trial.

Science.gov (United States)

Fors, Andreas; Ekman, Inger; Taft, Charles; Björkelund, Cecilia; Frid, Kerstin; Larsson, Maria Eh; Thorn, Jörgen; Ulin, Kerstin; Wolf, Axel; Swedberg, Karl

2015-01-01

To evaluate if person-centred care can improve self-efficacy and facilitate return to work or prior activity level in patients after an event of acute coronary syndrome. 199 patients with acute coronary syndrome < 75 years were randomly assigned to person-centred care intervention or treatment as usual and followed for 6 months. In the intervention group a person-centred care process was added to treatment as usual, emphasising the patient as a partner in care. Care was co-created in collaboration between patients, physicians, registered nurses and other health care professionals and documented in a health plan. A team-based partnership across three health care levels included transparent knowledge about the disease and medical state to achieve agreed goals during recovery. Main outcome measure was a composite score of changes in general self-efficacy ≥ 5 units, return to work or prior activity level and re-hospitalisation or death. The composite score showed that more patients (22.3%, n=21) improved in the intervention group at 6 months compared to the control group (9.5%, n=10) (odds ratio, 2.7; 95% confidence interval: 1.2-6.2; P=0.015). The effect was driven by improved self-efficacy ≥ 5 units in the intervention group. Overall general self-efficacy improved significantly more in the intervention group compared with the control group (P=0.026). There was no difference between groups on re-hospitalisation or death, return to work or prior activity level. A person-centred care approach emphasising the partnership between patients and health care professionals throughout the care chain improves general self-efficacy without causing worsening clinical events. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Simvastatin Ameliorates Matrix Stiffness-Mediated Endothelial Monolayer Disruption.

Directory of Open Access Journals (Sweden)

Marsha C Lampi

Full Text Available Arterial stiffening accompanies both aging and atherosclerosis, and age-related stiffening of the arterial intima increases RhoA activity and cell contractility contributing to increased endothelium permeability. Notably, statins are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA reductase inhibitors whose pleiotropic effects include disrupting small GTPase activity; therefore, we hypothesized the statin simvastatin could be used to attenuate RhoA activity and inhibit the deleterious effects of increased age-related matrix stiffness on endothelial barrier function. Using polyacrylamide gels with stiffnesses of 2.5, 5, and 10 kPa to mimic the physiological stiffness of young and aged arteries, endothelial cells were grown to confluence and treated with simvastatin. Our data indicate that RhoA and phosphorylated myosin light chain activity increase with matrix stiffness but are attenuated when treated with the statin. Increases in cell contractility, cell-cell junction size, and indirect measurements of intercellular tension that increase with matrix stiffness, and are correlated with matrix stiffness-dependent increases in monolayer permeability, also decrease with statin treatment. Furthermore, we report that simvastatin increases activated Rac1 levels that contribute to endothelial barrier enhancing cytoskeletal reorganization. Simvastatin, which is prescribed clinically due to its ability to lower cholesterol, alters the endothelial cell response to increased matrix stiffness to restore endothelial monolayer barrier function, and therefore, presents a possible therapeutic intervention to prevent atherogenesis initiated by age-related arterial stiffening.

Feasibility, Test-Retest Reliability, and Interrater Reliability of the Modified Ashworth Scale and Modified Tardieu Scale in Persons with Profound Intellectual and Multiple Disabilities

Science.gov (United States)

Waninge, A.; Rook, R. A.; Dijkhuizen, A.; Gielen, E.; van der Schans, C. P.

2011-01-01

Caregivers of persons with profound intellectual and multiple disabilities (PIMD) often describe the quality of the daily movements of these persons in terms of flexibility or stiffness. Objective outcome measures for flexibility and stiffness are muscle tone or level of spasticity. Two instruments used to grade muscle tone and spasticity are the…

Analysis of Dynamic Stiffness of Bridge Cap-Pile System

Directory of Open Access Journals (Sweden)

Jinhui Chu

2018-01-01

Full Text Available In order to investigate the applicability of dynamic stiffness for bridge cap-pile system, a laboratory test was performed. A numerical model was also built for this type of system. The impact load was applied on the cap top and the dynamic stiffness was analysed. Then, the effect of the effective friction area between pile and soil was also considered. Finally, the dynamic stiffness relationship between the single pile and the cap-pile system was also compared. The results show that the dynamic stiffness is a sensitive index and can well reflect the static characteristics of the pile at the elastic stage. There is a significant positive correlation between the vertical dynamic stiffness index and bearing capacity of the cap-pile system in the similar formation environment. For the cap-pile system with four piles, the dynamic stiffness is about four times as large as the single pile between 10 and 20 Hz.

Stiff quantum polymers

OpenAIRE

Kleinert, H.

2009-01-01

At ultralow temperatures, polymers exhibit quantum behavior, which is calculated here for the second and fourth moments of the end-to-end distribution in the large-stiffness regime. The result should be measurable for polymers in wide optical traps.

Echocardiographic evaluation of the arterial stiffness in healthy subjects and hypertensive patients under 60 years

International Nuclear Information System (INIS)

Valiente Mustelier, Juan; Suarez Vazquez, Leisy; Cabrera Rego, Julio Oscar; Gandarilla Sarmientos, Julio Cesar

2011-01-01

We conducted a cross-sectional study that included 83 patients (healthy, n=43; hypertensive, n=40) assisted in the external consultation of the National Cardiology and Cardiovascular Surgery Institute, from April to October, 2009. We included clinical (age, sex, personal antecedents of smoking habit, obesity, hypercholesterolemia, arterial hypertension) and echocardiographic (diastolic function, arterial stiffness index [β], pressure strain elastic modulus [Ep], arterial compliance, local pulse wave velocity [LPWV]) variables

Technology of wellness aerobics in the structure of personality-oriented program of physical rehabilitation of women with postmastectomy syndrome

Directory of Open Access Journals (Sweden)

Tatiana Odynets

2015-10-01

Full Text Available Purpose: to develop and substantiate technology of wellness aerobics in the structure of personality-oriented program of physical rehabilitation of women with postmastectomy syndrome on the dispensary stage of rehabilitation. Material and Methods: theoretical analysis and compilation of scientific and methodical literature and internet providers; induction and comparison. The study involved 115 women with postmastectomy syndrome on the dispensary stage of rehabilitation. Results: the developed program of wellness aerobics includes elements of basic aerobics, fitball aerobics, step-aerobics, strength training and stretching and their rational combination, which was implemented in accordance with the adaptation and training period of follow steps. Customization means of wellness aerobics depended on cardiorespiratory disorders, autonomic systems, limiting range of motion of the shoulder joint, degree of lymphostasis of women with postmastectomy syndrome

Controlled Evaluation of an Educational Intervention Used to Modify Peer Attitudes and Behavior toward Persons with Tourette's Syndrome

Science.gov (United States)

Woods, Douglas; Marcks, Brook

2005-01-01

Individuals who exhibit motor and vocal tics are viewed as less socially acceptable than persons who do not exhibit tics. Efforts have been made to alter the negative perceptions through the use of education. However, the effectiveness of peer education and whether it need be Tourette syndrome (TS) specific remains unclear. One hundred and seventy…

The Basic Nature of Ethical Problems Experienced by Persons with Acquired Immunodeficiency Syndrome: Implications for Nursing Ethics Education and Practice.

Science.gov (United States)

Cameron, Miriam E.; And Others

1993-01-01

Twenty-five persons with acquired immunodeficiency syndrome (AIDS) described and validated 100 ethical problems that are experienced by people with AIDS from 3 levels of ethical inquiry: descriptive ethics, normative ethics, and metaethics. Findings suggest strategies for improving nursing ethics education. (JOW)

Ball Bearing Stiffnesses- A New Approach Offering Analytical Expressions

Science.gov (United States)

Guay, Pascal; Frikha, Ahmed

2015-09-01

Space mechanisms use preloaded ball bearings in order to withstand the severe vibrations during launch.The launch strength requires the calculation of the bearing stiffness, but this calculation is complex. Nowadays, there is no analytical expression that gives the stiffness of a bearing. Stiffness is computed using an iterative algorithm such as Newton-Raphson, to solve the nonlinear system of equations.This paper aims at offering a simplified analytical approach, based on the assumption that the contact angle is constant. This approach gives analytical formulas of the stiffness of preloaded ball bearing.

Assessment of activity limitations and participation restrictions with persons with chronic fatigue syndrome: a systematic review.

Science.gov (United States)

Vergauwen, Kuni; Huijnen, Ivan P J; Kos, Daphne; Van de Velde, Dominique; van Eupen, Inge; Meeus, Mira

2015-01-01

To summarize measurement instruments used to evaluate activity limitations and participation restrictions in patients with chronic fatigue syndrome (CFS) and review the psychometric properties of these instruments. General information of all included measurement instruments was extracted. The methodological quality was evaluated using the COSMIN checklist. Results of the measurement properties were rated based on the quality criteria of Terwee et al. Finally, overall quality was defined per psychometric property and measurement instrument by use of the quality criteria by Schellingerhout et al. A total of 68 articles were identified of which eight evaluated the psychometric properties of a measurement instrument assessing activity limitations and participation restrictions. One disease-specific and 37 generic measurement instruments were found. Limited evidence was found for the psychometric properties and clinical usability of these instruments. However, the CFS-activities and participation questionnaire (APQ) is a disease-specific instrument with moderate content and construct validity. The psychometric properties of the reviewed measurement instruments to evaluate activity limitations and participation restrictions are not sufficiently evaluated. Future research is needed to evaluate the psychometric properties of the measurement instruments, including the other properties of the CFS-APQ. If it is necessary to use a measurement instrument, the CFS-APQ is recommended. Chronic fatigue syndrome (CFS). Chronic fatigue syndrome causes activity limitations and participation restrictions in one or more areas of life. Standardized, reliable and valid measurement instruments are necessary to identify these limitations and restrictions. Currently, no measurement instrument is sufficiently evaluated with persons with CFS. If a measurement instrument is needed to identify activity limitations and participation restrictions with persons with CFS, it is recommended to use

Plant fibre composites - porosity and stiffness

DEFF Research Database (Denmark)

Madsen, Bo; Thygesen, Anders; Lilholt, Hans

2009-01-01

Plant fibre composites contain typically a relatively large amount of porosity which influences their performance. A model, based on a modified rule of mixtures, is presented to include the influence of porosity on the composite stiffness. The model integrates the volumetric composition...... of the composites with their mechanical properties. The fibre weight fraction is used as an independent parameter to calculate the complete volumetric composition. A maximum obtainable stiffness of the composites is calculated at a certain transition fibre weight fraction, which is characterised by a best possible...... combination of high fibre volume fraction and low porosity. The model is validated with experimental data from the literature on several types of composites. A stiffness diagram is presented to demonstrate that the calculations can be used for tailoring and design of composites with a given profile...

Molecular Cues Guiding Matrix Stiffness in Liver Fibrosis

Directory of Open Access Journals (Sweden)

Takaoki Saneyasu

2016-01-01

Full Text Available Tissue and matrix stiffness affect cell properties during morphogenesis, cell growth, differentiation, and migration and are altered in the tissue remodeling following injury and the pathological progression. However, detailed molecular mechanisms underlying alterations of stiffness in vivo are still poorly understood. Recent engineering technologies have developed powerful techniques to characterize the mechanical properties of cell and matrix at nanoscale levels. Extracellular matrix (ECM influences mechanical tension and activation of pathogenic signaling during the development of chronic fibrotic diseases. In this short review, we will focus on the present knowledge of the mechanisms of how ECM stiffness is regulated during the development of liver fibrosis and the molecules involved in ECM stiffness as a potential therapeutic target for liver fibrosis.

The savant syndrome and autistic disorder.

Science.gov (United States)

Treffert, D A

1999-12-01

Savant syndrome, characterized by remarkable islands of mental ability in otherwise mentally handicapped persons, may occur in autistic as well as nonautistic individuals. Overall, approximately 10% of autistic persons exhibit savant abilities; roughly 50% of those with savant syndrome have autism, and the remaining 50% have other forms of developmental disability. Most commonly, savant syndrome takes the form of extraordinary musical abilities, but may also include calendar-calculation, artistic, mathematical, spatial, mechanical, and memory skills. While savant syndrome was first described more than a century ago, only recently have researchers begun to employ a more uniform nomenclature and more standardized testing in an effort to compare the abilities of savants with those of normal persons. Males show signs of savant syndrome approximately four times more often than females. Along with imaging study findings, this fact suggests the presence of a developmental disorder involving left-brain damage with right-brain compensation.

Is chronic obstructive pulmonary disease associated with increased arterial stiffness?

DEFF Research Database (Denmark)

Janner, Julie H; McAllister, David A; Godtfredsen, Nina S

2012-01-01

We hypothesize that airflow limitation is associated with increasing arterial stiffness and that having COPD increases a non-invasive measure of arterial stiffness - the aortic augmentation index (AIx) - independently of other CVD risk factors.......We hypothesize that airflow limitation is associated with increasing arterial stiffness and that having COPD increases a non-invasive measure of arterial stiffness - the aortic augmentation index (AIx) - independently of other CVD risk factors....

A Rapid Aeroelasticity Optimization Method Based on the Stiffness characteristics

OpenAIRE

Yuan, Zhe; Huo, Shihui; Ren, Jianting

2018-01-01

A rapid aeroelasticity optimization method based on the stiffness characteristics was proposed in the present study. Large time expense in static aeroelasticity analysis based on traditional time domain aeroelasticity method is solved. Elastic axis location and torsional stiffness are discussed firstly. Both torsional stiffness and the distance between stiffness center and aerodynamic center have a direct impact on divergent velocity. The divergent velocity can be adjusted by changing the cor...

Damper modules with adapted stiffness ratio

Energy Technology Data Exchange (ETDEWEB)

Sonnenburg, R.; Stretz, A. [ZF Sachs AG, Entwicklungszentrum, Schweinfurt (Germany)

2011-07-15

A mechanism for the excitation of piston rod vibrations in automotive damper modules is discussed by a simple model. An improved nonlinear model based on elasticity effects leads to good simulation results. It is shown theoretically and experimentally that the adaptation of the stiffness of the piston rod bushing to the ''stiffness'' of the damper force characteristic can eliminate the piston rod oscillations completely. (orig.)

Rotational and peak torque stiffness of rugby shoes.

Science.gov (United States)

Ballal, Moez S; Usuelli, Federico Giuseppe; Montrasio, Umberto Alfieri; Molloy, Andy; La Barbera, Luigi; Villa, Tomaso; Banfi, Giuseppe

2014-09-01

Sports people always strive to avoid injury. Sports shoe designs in many sports have been shown to affect traction and injury rates. The aim of this study is to demonstrate the differing stiffness and torque in rugby boots that are designed for the same effect. Five different types of rugby shoes commonly worn by scrum forwards were laboratory tested for rotational stiffness and peak torque on a natural playing surface generating force patterns that would be consistent with a rugby scrum. The overall internal rotation peak torque was 57.75±6.26 Nm while that of external rotation was 56.55±4.36 Nm. The Peak internal and external rotational stiffness were 0.696±0.1 and 0.708±0.06 Nm/deg respectively. Our results, when compared to rotational stiffness and peak torques of football shoes published in the literature, show that shoes worn by rugby players exert higher rotational and peak torque stiffness compared to football shoes when tested on the same natural surfaces. There was significant difference between the tested rugby shoes brands. In our opinion, to maximize potential performance and lower the potential of non-contact injury, care should be taken in choosing boots with stiffness appropriate to the players main playing role. Copyright © 2014 Elsevier Ltd. All rights reserved.

Static stiffness modeling of a novel hybrid redundant robot machine

International Nuclear Information System (INIS)

Li Ming; Wu Huapeng; Handroos, Heikki

2011-01-01

This paper presents a modeling method to study the stiffness of a hybrid serial-parallel robot IWR (Intersector Welding Robot) for the assembly of ITER vacuum vessel. The stiffness matrix of the basic element in the robot is evaluated using matrix structural analysis (MSA); the stiffness of the parallel mechanism is investigated by taking account of the deformations of both hydraulic limbs and joints; the stiffness of the whole integrated robot is evaluated by employing the virtual joint method and the principle of virtual work. The obtained stiffness model of the hybrid robot is analytical and the deformation results of the robot workspace under certain external load are presented.

Stiffness requirement of flexible skin for variable trailing-edge camber wing

Institute of Scientific and Technical Information of China (English)

无

2010-01-01

The method for analyzing the deformation of flexible skin under the air loads was developed based on the panel method and finite element method.The deformation of flexible skin under air pressures and effects of the local deformation on the aerodynamic characteristics were discussed.Numerical results show that the flexible skin on the upper surface of trailing-edge will bubble under the air loads and the bubble has a powerful effect on the aerodynamic pressure near the surface of local deforma-tion.Then the stiffness requirements for flexible skin of variable trailing-edge were given by using the Jacobs rule,i.e.,the maximum displacement of skin is not greater than 0.1% of wing chord.Results show that the in-plane stiffness can be reduced by increasing the ratio of bending stiffness to in-plane stiffness.Although the deformation of flexible skin increases with the in-plane stiffness decreasing,it depends on the bending stiffness.When the bending stiffness exceeds critical value,the deformation of flexible skin only depends on the bending stiffness and has nothing to do with the in-plane stiffness.The conclusions can be used for the structural design of flexible skin.

RASopathies are associated with a distinct personality profile.

Science.gov (United States)

Bizaoui, Varoona; Gage, Jessica; Brar, Rita; Rauen, Katherine A; Weiss, Lauren A

2018-06-01

Personality is a complex, yet partially heritable, trait. Although some Mendelian diseases like Williams-Beuren syndrome are associated with a particular personality profile, studies have failed to assign the personality features to a single gene or pathway. As a family of monogenic disorders caused by mutations in the Ras/MAPK pathway known to influence social behavior, RASopathies are likely to provide insight into the genetic basis of personality. Eighty subjects diagnosed with cardiofaciocutaneous syndrome, Costello syndrome, neurofibromatosis type 1, and Noonan syndrome were assessed using a parent-report BFQ-C (Big Five Questionnaire for Children) evaluating agreeableness, extraversion, conscientiousness, intellect/openness, and neuroticism, along with 55 unaffected sibling controls. A short questionnaire was added to assess sense of humor. RASopathy subjects and sibling controls were compared for individual components of personality, multidimensional personality profiles, and individual questions using Student tests, analysis of variance, and principal component analysis. RASopathy subjects were given lower scores on average compared to sibling controls in agreeableness, extraversion, conscientiousness, openness, and sense of humor, and similar scores in neuroticism. When comparing the multidimensional personality profile between groups, RASopathies showed a distinct profile from unaffected siblings, but no difference in this global profile was found within RASopathies, revealing a common profile for the Ras/MAPK-related disorders. In addition, several syndrome-specific strengths or weaknesses were observed in individual domains. We describe for the first time an association between a single pathway and a specific personality profile, providing a better understanding of the genetics underlying personality, and new tools for tailoring educational and behavioral approaches for individuals with RASopathies. © 2018 Wiley Periodicals, Inc.

Subspace methods for identification of human ankle joint stiffness.

Science.gov (United States)

Zhao, Y; Westwick, D T; Kearney, R E

2011-11-01

Joint stiffness, the dynamic relationship between the angular position of a joint and the torque acting about it, describes the dynamic, mechanical behavior of a joint during posture and movement. Joint stiffness arises from both intrinsic and reflex mechanisms, but the torques due to these mechanisms cannot be measured separately experimentally, since they appear and change together. Therefore, the direct estimation of the intrinsic and reflex stiffnesses is difficult. In this paper, we present a new, two-step procedure to estimate the intrinsic and reflex components of ankle stiffness. In the first step, a discrete-time, subspace-based method is used to estimate a state-space model for overall stiffness from the measured overall torque and then predict the intrinsic and reflex torques. In the second step, continuous-time models for the intrinsic and reflex stiffnesses are estimated from the predicted intrinsic and reflex torques. Simulations and experimental results demonstrate that the algorithm estimates the intrinsic and reflex stiffnesses accurately. The new subspace-based algorithm has three advantages over previous algorithms: 1) It does not require iteration, and therefore, will always converge to an optimal solution; 2) it provides better estimates for data with high noise or short sample lengths; and 3) it provides much more accurate results for data acquired under the closed-loop conditions, that prevail when subjects interact with compliant loads.

[The Capgras syndrome].

Science.gov (United States)

Anikina, M A; Levin, O S

2013-01-01

The Capgras syndrome is one of delusional-like misidentification syndrome in which a person holds a delusion that one or several his/her friends or relatives have been replaced by an identical-looking impostor. As any other delusional disorder, the Capgras syndrome is characterized by stability despite the indisputable arguments against fault views. Initially, this syndrome was considered as a presentation of schizophrenia but later it has been described in brain organic disorders, primarily in elderly patients with dementia.

Violations of Personal Space in Young People with Autism Spectrum Disorders and Williams Syndrome: Insights from the Social Responsiveness Scale

Science.gov (United States)

Lough, Emma; Hanley, Mary; Rodgers, Jacqui; South, Mikle; Kirk, Hannah; Kennedy, Daniel P.; Riby, Deborah M.

2015-01-01

Interpersonal distance regulation is crucial for successful social interactions. We investigated personal space awareness in Williams syndrome (WS) and autism spectrum disorder (ASD) compared to typical development. Parents reported that individuals with WS and ASD were significantly more likely than those developing typically to invade the…

Pulling a polymer with anisotropic stiffness near a sticky wall

International Nuclear Information System (INIS)

Tabbara, R; Owczarek, A L

2012-01-01

We solve exactly a two-dimensional partially directed walk model of a semi-flexible polymer that has one end tethered to a sticky wall, while a pulling force away from the adsorbing surface acts on the free end of the walk. This model generalizes a number of previously considered adsorption models by incorporating individual horizontal and vertical stiffness effects, in competition with a variable pulling angle. A solution to the corresponding generating function is found by means of the kernel method. While the phases and related phase transitions are similar in nature to those found previously the analysis of the model in terms of its physical variables highlights various novel structures in the shapes of the phase diagrams and related behaviour of the polymer. We review the results of previously considered sub-cases, augmenting these findings to include analysis with respect to the model’s physical variables—namely, temperature, pulling force, pulling angle away from the surface, stiffness strength and the ratio of vertical to horizontal stiffness potentials, with our subsequent analysis for the general model focusing on the effect that stiffness has on this pulling angle range. In analysing the model with stiffness we also pay special attention to the case where only vertical stiffness is included. The physical analysis of this case reveals behaviour more closely resembling that of an upward pulling force acting on a polymer than it does of a model where horizontal stiffness acts. The stiffness–temperature phase diagram exhibits re-entrance for low temperatures, previously only seen for three-dimensional or co-polymer models. For the most general model we delineate the shift in the physical behaviour as we change the ratio of vertical to horizontal stiffness between the horizontal-only and the vertical-only stiffness regimes. We find that a number of distinct physical characteristics will only be observed for a model where the vertical stiffness dominates

Influence of stiffness on CHF for horizontal tubes under LPLF conditions

Energy Technology Data Exchange (ETDEWEB)

Baburajan, P.K. [Nuclear Safety Analysis Division, AERB, Niyamak Bhavan, 400094 (India); Bisht, Govind Singh [Department of Mechanical Engineering, IIT Bombay, 400076 (India); Gaikwad, Avinash J. [Nuclear Safety Analysis Division, AERB, Niyamak Bhavan, 400094 (India); Prabhu, S.V., E-mail: svprabhu@iitb.ac.in [Department of Mechanical Engineering, IIT Bombay, 400076 (India)

2014-10-01

Highlights: • Effect of stiffness on the CHF in horizontal tube under LPLF conditions is studied. • CHF increases with the increase in stiffness. • Correlation for the prediction of CHF as a function of stiffness is developed. • Correlation for mass flux at CHF in terms of stiffness and initial mass flux is given. • RELAP5 is capable of predicting the effect of stiffness on CHF. - Abstract: Studies reported in the past on critical heat flux (CHF) are mostly limited to vertical flow, large channel diameter, high pressure and high mass flux. Since horizontal flow is commonly encountered in boiler tubes, refrigerating equipments and nuclear reactor fuel channels (PHWR), there is a need to understand horizontal flow CHF, generate sufficient experimental database and to develop reliable predictive method. Few studies are reported on the effect of upstream flow restrictions on flow instabilities and CHF. The present work investigates the effect of upstream flow restriction on CHF in horizontal flow at near atmospheric pressure conditions. In the present study, stiffness is defined as the ratio of upstream flow restriction pressure drop to the test section pressure drop. The classification of a flow boiling system as soft or stiff on the basis of quantification of the stiffness is attempted. Experimental data shows an increase in the CHF with the increase in the stiffness for a given initial mass flux. A correlation for the prediction of CHF under various stiffness conditions is developed. A correlation is suggested to predict the mass flux at CHF as a function of stiffness and initial mass flux. Modeling and transient analysis of the stiffness effect on CHF is carried out using the thermal hydraulic system code RELAP5. The predicted phenomena are in agreement with the experimental observations.

Fatigue crack paths under the influence of changes in stiffness

Directory of Open Access Journals (Sweden)

G. Kullmer

2016-02-01

Full Text Available An important topic of the Collaborative Research Centre TRR 30 of the Deutsche Forschungsgemeinschaft (DFG is the crack growth behaviour in graded materials. In addition, the growth of cracks in the neighbourhood of regions and through regions with different material properties belongs under this topic. Due to the different material properties, regions with differing stiffness compared to the base material may arise. Regions with differing stiffness also arise from ribs, grooves or boreholes. Since secure findings on the propagation behaviour of fatigue cracks are essential for the evaluation of the safety of components and structures, the growth of cracks near changes in stiffness has to be considered, too. Depending on the way a crack penetrates the zone of influence of such a change in stiffness and depending on whether this region is more compliant or stiffer than the surrounding area the crack may grow towards or away from this region. Both cases result in curved crack paths that cannot be explained only by the global loading situation. To evaluate the influence of regions with differing stiffness on the path of fatigue cracks the paths and the stress intensity factors of cracks growing near and through regions with differing stiffness are numerically determined with the program system ADAPCRACK3D. Therefore, arrangements of changes in stiffness modelled as material inclusions with stiffness properties different from the base material or modelled as ribs and grooves are systematically varied to develop basic conclusions about the crack growth behaviour near and through changes in stiffness.

On prestress stiffness analysis of bolt-plate contact assemblies

DEFF Research Database (Denmark)

Pedersen, Niels Leergaard; Pedersen, Pauli

2008-01-01

, but with finite element (FE) and contact analysis, it is possible to find the stiffness of the member. In the case of many connections and for practical applications, it is not suitable to make a full FE analysis. The purpose of the present paper is to find simplified expressions for the stiffness of the member......, including the case when the width of the member is limited. The calculation of the stiffness is based on the FE, including the solution to the contact problem, and we express the stiffness as a function of the elastic energy in the structure, whereby the definition of the displacements related...

Low frequency noise reduction using stiff light composite panels

Institute of Scientific and Technical Information of China (English)

DENG Yongchang; LIN Weizheng

2003-01-01

The experiment presented in this paper is to investigate and analyze the noise reduction at low frequency using stiff light composite panels. Since these composite panels are made of lightweight and stiff materials, this actuation strategy will enable the creation of composite panels for duct noise control without using traditional heavy structural mass. The results suggest that the mass-spring resonance absorption in the case of a comparatively stiff thick panel with a thin flexible plate is more efficient with minimum weight, when subjected to low-frequency (<500 Hz). The efficiency of the panel absorber depends on the mass of the thin flexible plate and the stiffness of the panel.

Elastin in large artery stiffness and hypertension

Science.gov (United States)

Wagenseil, Jessica E.; Mecham, Robert P.

2012-01-01

Large artery stiffness, as measured by pulse wave velocity (PWV), is correlated with high blood pressure and may be a causative factor in essential hypertension. The extracellular matrix components, specifically the mix of elastin and collagen in the vessel wall, determine the passive mechanical properties of the large arteries. Elastin is organized into elastic fibers in the wall during arterial development in a complex process that requires spatial and temporal coordination of numerous proteins. The elastic fibers last the lifetime of the organism, but are subject to proteolytic degradation and chemical alterations that change their mechanical properties. This review discusses how alterations in the amount, assembly, organization or chemical properties of the elastic fibers affect arterial stiffness and blood pressure. Strategies for encouraging or reversing alterations to the elastic fibers are addressed. Methods for determining the efficacy of these strategies, by measuring elastin amounts and arterial stiffness, are summarized. Therapies that have a direct effect on arterial stiffness through alterations to the elastic fibers in the wall may be an effective treatment for essential hypertension. PMID:22290157

Advanced damper with negative structural stiffness elements

International Nuclear Information System (INIS)

Dong, Liang; Lakes, Roderic S

2012-01-01

Negative stiffness is understood as the occurrence of a force in the same direction as the imposed deformation. Structures and composites with negative stiffness elements enable a large amplification in damping. It is shown in this work, using an experimental approach, that when a flexible flat-ends column is aligned in a post-buckled condition, a negative structural stiffness and large hysteresis (i.e., high damping) can be achieved provided the ends of the column undergo tilting from flat to edge contact. Stable axial dampers with initial modulus equivalent to that of the parent material and with enhanced damping were designed and built using constrained negative stiffness effects entailed by post-buckled press-fit flat-ends columns. Effective damping of approximately 1 and an effective stiffness–damping product of approximately 1.3 GPa were achieved in such stable axial dampers consisting of PMMA columns. This is a considerable improvement for this figure of merit (i.e., the stiffness–damping product), which generally cannot exceed 0.6 GPa for currently used damping layers. (paper)

Systematic profiling of spatiotemporal tissue and cellular stiffness in the developing brain.

Science.gov (United States)

Iwashita, Misato; Kataoka, Noriyuki; Toida, Kazunori; Kosodo, Yoichi

2014-10-01

Accumulating evidence implicates the significance of the physical properties of the niche in influencing the behavior, growth and differentiation of stem cells. Among the physical properties, extracellular stiffness has been shown to have direct effects on fate determination in several cell types in vitro. However, little evidence exists concerning whether shifts in stiffness occur in vivo during tissue development. To address this question, we present a systematic strategy to evaluate the shift in stiffness in a developing tissue using the mouse embryonic cerebral cortex as an experimental model. We combined atomic force microscopy measurements of tissue and cellular stiffness with immunostaining of specific markers of neural differentiation to correlate the value of stiffness with the characteristic features of tissues and cells in the developing brain. We found that the stiffness of the ventricular and subventricular zones increases gradually during development. Furthermore, a peak in tissue stiffness appeared in the intermediate zone at E16.5. The stiffness of the cortical plate showed an initial increase but decreased at E18.5, although the cellular stiffness of neurons monotonically increased in association with the maturation of the microtubule cytoskeleton. These results indicate that tissue stiffness cannot be solely determined by the stiffness of the cells that constitute the tissue. Taken together, our method profiles the stiffness of living tissue and cells with defined characteristics and can therefore be utilized to further understand the role of stiffness as a physical factor that determines cell fate during the formation of the cerebral cortex and other tissues. © 2014. Published by The Company of Biologists Ltd.

Evaluating pulp stiffness from fibre bundles by ultrasound

Science.gov (United States)

Karppinen, Timo; Montonen, Risto; Määttänen, Marjo; Ekman, Axel; Myllys, Markko; Timonen, Jussi; Hæggström, Edward

2012-06-01

A non-destructive ultrasonic tester was developed to measure the stiffness of pulp bundles. The mechanical properties of pulp are important when estimating the behaviour of paper under stress. Currently available pulp tests are tedious and alter the fibres structurally and mechanically. The developed tester employs (933 ± 15) kHz tweezer-like ultrasonic transducers and time-of-flight measurement through (9.0 ± 2.5) mm long and (0.8 ± 0.1) mm thick fibre bundles kept at (19.1 ± 0.4) °C and (62 ± 1)% RH. We determined the stiffness of soft wood pulps produced by three kraft pulping modifications: standard kraft pulp, (5.2 ± 0.4) GPa, prehydrolysis kraft pulp, (4.3 ± 0.4) GPa, and alkali extracted prehydrolysis kraft pulp, (3.3 ± 0.4) GPa. Prehydrolysis and alkali extraction processes mainly lowered the hemicellulose content of the pulps, which essentially decreased the fibre-wall stiffness hence impairing the stiffness of the fibre networks. Our results indicate that the method allows ranking of pulps according to their stiffness determined from bundle-like samples taken at an early phase of the papermaking process.

Health, work, social trust, and financial situation in persons with Usher syndrome type 1.

Science.gov (United States)

Ehn, Mattias; Wahlqvist, Moa; Danermark, Berth; Dahlström, Örjan; Möller, Claes

2018-05-28

Research has demonstrated that persons with Usher syndrome type 1 (USH1) have significantly poorer physical and psychological health compared to a reference group. To explore the relation between work, health, social trust, and financial situation in USH1 compared to a reference group. Sixty-six persons (18-65 y) from the Swedish Usher database received a questionnaire and 47 were included, 23 working and 24 non-working. The reference group comprised 3,049 working and 198 non-working persons. The Swedish Health on Equal Terms questionnaire was used and statistical analysis with multiple logistic regression was conducted. The USH1 non-work group had a higher Odds ratio (95% CI) in poor psychological and physical health, social trust, and financial situation compared to the USH1 work group and reference groups. Age, gender, hearing, and vision impairment did not explain the differences. The relation between the USH1 work and non-work groups showed the same pattern as the reference groups, but the magnitude of problems was significantly higher. Both disability and unemployment increased the risk of poor health, social trust and financial situation in persons with USH1, but having an employment seemed to counteract the risks related to disability.

A new variable stiffness suspension system: passive case

Directory of Open Access Journals (Sweden)

O. M. Anubi

2013-02-01

Full Text Available This paper presents the design, analysis, and experimental validation of the passive case of a variable stiffness suspension system. The central concept is based on a recently designed variable stiffness mechanism. It consists of a horizontal control strut and a vertical strut. The main idea is to vary the load transfer ratio by moving the location of the point of attachment of the vertical strut to the car body. This movement is controlled passively using the horizontal strut. The system is analyzed using an L2-gain analysis based on the concept of energy dissipation. The analyses, simulation, and experimental results show that the variable stiffness suspension achieves better performance than the constant stiffness counterpart. The performance criteria used are; ride comfort, characterized by the car body acceleration, suspension deflection, and road holding, characterized by tire deflection.

Association of Parental Hypertension With Arterial Stiffness in Nonhypertensive Offspring

DEFF Research Database (Denmark)

Andersson, Charlotte; Quiroz, Rene; Enserro, Danielle

2016-01-01

High arterial stiffness seems to be causally involved in the pathogenesis of hypertension. We tested the hypothesis that offspring of parents with hypertension may display higher arterial stiffness before clinically manifest hypertension, given that hypertension is a heritable condition. We compa......, in this community-based sample of young, nonhypertensive adults, we observed greater arterial stiffness in offspring of parents with hypertension. These observations are consistent with higher vascular stiffness at an early stage in the pathogenesis of hypertension.......High arterial stiffness seems to be causally involved in the pathogenesis of hypertension. We tested the hypothesis that offspring of parents with hypertension may display higher arterial stiffness before clinically manifest hypertension, given that hypertension is a heritable condition. We...... compared arterial tonometry measures in a sample of 1564 nonhypertensive Framingham Heart Study third-generation cohort participants (mean age: 38 years; 55% women) whose parents were enrolled in the Framingham Offspring Study. A total of 468, 715, and 381 participants had 0 (referent), 1, and 2 parents...

28 CFR 41.31 - Handicapped person.

Science.gov (United States)

2010-07-01

... Persons § 41.31 Handicapped person. (a) Handicapped person means any person who has a physical or mental...: (1) Physical or mental impairment means: (i) Any physiological disorder or condition, cosmetic... disorder, such as mental retardation, organic brain syndrome, emotional or mental illness, and specific...

VARIABLE STIFFNESS HAND PROSTHESIS: A SYSTEMATIC REVIEW

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S. Cecilia Tapia-Siles

2017-06-01

Full Text Available Prosthetics is an important field in engineering due to the large number of amputees worldwide and the associated problems such as limited functionality of the state of the art. An important functionality of the human hand is its capability of adjusting the stiffness of the joints depending on the currently performed task. For the development of new technology it is important to understand the limitations of existing resources. As part of our efforts to develop a variable stiffness grasper for developing countries a systematic review was performed covering technology of body powered and myoelectric hand prosthesis. Focus of the review is readiness of prosthetic hands regarding their capability of controlling the stiffness of the end effector. Publications sourced through three different digital libraries were systematically reviewed on the basis of the PRISMA standard. We present a search strategy as well as the PRISMA assessment of the resulting records which covered 321 publications. The records were assessed and the results are presented for the ability of devices to control their joint stiffness. The review indicates that body powered prosthesis are preferred to myoelectric hands due to the reduced cost, the simplicity of use and because of their inherent ability to provide feedback to the user. Stiffness control was identified but has not been fully covered in the current state of the art. In addition we summarise the identified requirements on prosthetic hands as well as related information which can support the development of new prosthetics.

Effect of long-term isometric training on core/torso stiffness.

Science.gov (United States)

Lee, Benjamin C Y; McGill, Stuart M

2015-06-01

Although core stiffness enhances athletic performance traits, controversy exists regarding the effectiveness of isometric vs. dynamic core training methods. This study aimed to determine whether long-term changes in stiffness can be trained, and if so, what is the most effective method. Twenty-four healthy male subjects (23 ± 3 years; 1.8 ± 0.06 m; 77.5 ± 10.8 kg) were recruited for passive and active stiffness measurements before and after a 6-week core training intervention. Twelve subjects (22 ± 2 years; 1.8 ± 0.08 m; 78.3 ± 12.3 kg) were considered naive to physical and core exercise. The other 12 subjects (24 ± 3 years; 1.8 ± 0.05 m; 76.8 ± 9.7 kg) were Muay Thai athletes (savvy). A repeated-measures design compared core training methods (isometric vs. dynamic, with a control group) and subject training experience (naive vs. savvy) before and after a 6-week training period. Passive stiffness was assessed on a "frictionless" bending apparatus and active stiffness assessed through a quick release mechanism. Passive stiffness increased after the isometric training protocol. Dynamic training produced a smaller effect, and as expected, there was no change in the control group. Active stiffness did not change in any group. Comparisons between subject and training groups did not reveal any interactions. Thus, an isometric training approach was superior in terms of enhancing core stiffness. This is important since increased core stiffness enhances load bearing ability, arrests painful vertebral micromovements, and enhances ballistic distal limb movement. This may explain the efficacy reported for back and knee injury reduction.

An Empirically Derived Taxonomy for Personality Diagnosis: Bridging Science and Practice in Conceptualizing Personality

Science.gov (United States)

Westen, Drew; Shedler, Jonathan; Bradley, Bekh; DeFife, Jared A.

2013-01-01

Objective The authors describe a system for diagnosing personality pathology that is empirically derived, clinically relevant, and practical for day-to-day use. Method A random national sample of psychiatrists and clinical psychologists (N=1,201) described a randomly selected current patient with any degree of personality dysfunction (from minimal to severe) using the descriptors in the Shedler-Westen Assessment Procedure–II and completed additional research forms. Results The authors applied factor analysis to identify naturally occurring diagnostic groupings within the patient sample. The analysis yielded 10 clinically coherent personality diagnoses organized into three higher-order clusters: internalizing, externalizing, and borderline-dysregulated. The authors selected the most highly rated descriptors to construct a diagnostic prototype for each personality syndrome. In a second, independent sample, research interviewers and patients’ treating clinicians were able to diagnose the personality syndromes with high agreement and minimal comorbidity among diagnoses. Conclusions The empirically derived personality prototypes described here provide a framework for personality diagnosis that is both empirically based and clinically relevant. PMID:22193534

Sway‐dependent changes in standing ankle stiffness caused by muscle thixotropy

Science.gov (United States)

Sakanaka, Tania E.; Lakie, Martin

2016-01-01

Key points The passive stiffness of the calf muscles contributes to standing balance, although the properties of muscle tissue are highly labile.We investigated the effect of sway history upon intrinsic ankle stiffness and demonstrated reductions in stiffness of up to 43% during conditions of increased baseline sway.This sway dependence was most apparent when using low amplitude stiffness‐measuring perturbations, and the short‐range stiffness component was smaller during periods of high sway.These characteristics are consistent with the thixotropic properties of the calf muscles causing the observed changes in ankle stiffness.Periods of increased sway impair the passive stabilization of standing, demanding more active neural control of balance. Abstract Quiet standing is achieved through a combination of active and passive mechanisms, consisting of neural control and intrinsic mechanical stiffness of the ankle joint, respectively. The mechanical stiffness is partly determined by the calf muscles. However, the viscoelastic properties of muscle are highly labile, exhibiting a strong dependence on movement history. By measuring the effect of sway history upon ankle stiffness, the present study determines whether this lability has consequences for the passive stabilization of human standing. Ten subjects stood quietly on a rotating platform whose axis was collinear with the ankle joint. Ankle sway was increased by slowly tilting this platform in a random fashion, or decreased by fixing the body to a board. Ankle stiffness was measured by using the same platform to simultaneously apply small, brief perturbations (ankle stiffness by up to 43% compared to the body‐fixed condition. Normal quiet stance was associated with intermediate values. The effect was most apparent when using smaller perturbation amplitudes to measure stiffness (0.1 vs. 0.6 deg). Furthermore, torque responses exhibited a biphasic pattern, consisting of an initial steep rise followed by a

Determination of Ankle and Metatarsophalangeal Stiffness During Walking and Jogging.

Science.gov (United States)

Mager, Fabian; Richards, Jim; Hennies, Malika; Dötzel, Eugen; Chohan, Ambreen; Mbuli, Alex; Capanni, Felix

2018-05-29

Forefoot stiffness has been shown to influence joint biomechanics. However, little or no data exists on metatarsophalangeal stiffness. Twenty-four healthy rearfoot strike runners were recruited from a staff and student population at the University of Central Lancashire. Five repetitions of shod, self-selected speed level walking and jogging were performed. Kinetic and kinematic data were collected using retro-reflective markers placed on the lower limb and foot, to create a three-segment foot model using the Calibrated Anatomical System Technique. Ankle and metatarsophalangeal moments and angles were calculated. Stiffness values were calculated using a linear best fit line of moment versus of angle plots. Paired t-tests were used to compare values between walking and jogging conditions. Significant differences were seen in ankle range of motion (ROM), but not in metatarsophalangeal ROM. Maximum moments were significantly greater in the ankle during jogging, but these were not significantly different at the metatarsophalangeal joint. Average ankle joint stiffness exhibited significantly lower stiffness when walking compared to jogging. However, the metatarsophalangeal joint exhibited significantly greater stiffness when walking compared to jogging. A greater understanding of forefoot stiffness may inform the development of footwear, prosthetic feet and orthotic devices, such as ankle-foot orthoses for walking and sporting activities.

Personality Traits of Suicidality Are Associated with Premenstrual Syndrome and Premenstrual Dysphoric Disorder in a Suicidal Women Sample

OpenAIRE

Ducasse, D?borah; Jaussent, Isabelle; Oli?, Emilie; Guillaume, S?bastien; Lopez-Castroman, Jorge; Courtet, Philippe

2016-01-01

Objective Both Premenstrual Syndrome (PMS) and Premenstrual Dysphoric Disorder (PMDD) might increase the risk of suicidal behavior. The aim of this study was to assess the relationship between personality dimensions specifically involved in suicidal vulnerability and PMS/PMDD. Method We collected data from 232 women consecutively hospitalized after a suicide attempt. We examined the relationship between impulsivity, aggressiveness/hostility, hopelessness, trait anger, affect intensity, emotio...

Dynamically tuned magnetostrictive spring with electrically controlled stiffness

Science.gov (United States)

Scheidler, Justin J.; Asnani, Vivake M.; Dapino, Marcelo J.

2016-03-01

This paper presents the design and testing of an electrically controllable magnetostrictive spring that has a dynamically tunable stiffness (i.e., a magnetostrictive Varispring). The device enables in situ stiffness tuning or stiffness switching for vibration control applications. Using a nonlinear electromechanical transducer model and an analytical solution of linear, mechanically induced magnetic diffusion, Terfenol-D is shown to have a faster rise time to stepped voltage inputs and a significantly higher magnetic diffusion cut-off frequency relative to Galfenol. A Varispring is manufactured using a laminated Terfenol-D rod. Further rise time reductions are achieved by minimizing the rod’s diameter and winding the electromagnet with larger wire. Dynamic tuning of the Varispring’s stiffness is investigated by measuring the Terfenol-D rod’s strain response to dynamic, compressive, axial forces in the presence of sinusoidal or square wave control currents. The Varispring’s rise time is \\lt 1 ms for 1 A current switches. Continuous modulus changes up to 21.9 GPa and 500 Hz and square wave modulus changes (dynamic {{Δ }}E effect) up to 12.3 GPa and 100 Hz are observed. Stiffness tunability and tuning bandwidth can be considerably increased by operating about a more optimal bias stress and improving the control of the electrical input.

Demens hos personer med Downs syndrom

DEFF Research Database (Denmark)

Salem, Lise Cronberg; Jørgensen, Kasper

2014-01-01

In developed countries the population of elderly people with Down syndrome expands resulting in an increasing incidence of age-related diseases, including dementia. The assessment of dementia in individuals with intellectual disability is often complicated due to large intra-individual variability...

Disease-specific monoclonal antibodies targeting glutamate decarboxylase impair GABAergic neurotransmission and affect motor learning and behavioral functions

Directory of Open Access Journals (Sweden)

Mario U Manto

2015-03-01

Full Text Available Autoantibodies to the smaller isoform of glutamate decarboxylase can be found in patients with type 1 diabetes and a number of neurological disorders, including stiff-person syndrome, cerebellar ataxia and limbic encephalitis. The detection of disease-specific autoantibody epitopes led to the hypothesis that distinct glutamate decarboxylase autoantibodies may elicit specific neurological phenotypes. We explored the in vitro/in vivo effects of well-characterized monoclonal glutamate decarboxylase antibodies. We found that glutamate decarboxylase autoantibodies present in patients with stiff person syndrome (n = 7 and cerebellar ataxia (n = 15 recognized an epitope distinct from that recognized by glutamate decarboxylase autoantibodies present in patients with type 1 diabetes mellitus (n = 10 or limbic encephalitis (n = 4. We demonstrated that the administration of a monoclonal glutamate decarboxylase antibody representing this epitope specificity (1 disrupted in vitro the association of glutamate decarboxylase with γ-Aminobutyric acid containing synaptic vesicles, (2 depressed the inhibitory synaptic transmission in cerebellar slices with a gradual time course and a lasting suppressive effect, (3 significantly decreased conditioned eyelid responses evoked in mice, with no modification of learning curves in the classical eyeblink-conditioning task, (4 markedly impaired the facilitatory effect exerted by the premotor cortex over the motor cortex in a paired-pulse stimulation paradigm, and (5 induced decreased exploratory behavior and impaired locomotor function in rats. These findings support the specific targeting of glutamate decarboxylase by its autoantibodies in the pathogenesis of stiff-person syndrome and cerebellar ataxia. Therapies of these disorders based on selective removal of such glutamate decarboxylase antibodies could be envisioned.

Effects of mechanical properties and geometric conditions on stiffness of Hyperboloid Shallow Shell

Directory of Open Access Journals (Sweden)

Zhao Lihong

2015-01-01

Full Text Available The experiment models based on the hyperboloid shallow shells that represent automobile panel's surface features are established. The effects of material properties and geometric conditions condition on the stiffness of hyperboloid shallow shell are investigated experimentally. The influences of panel thickness and geometric conditions on stiffness are very obvious. Stiffness increases with increasing of the panel thickness, and stiffness doubled as increasing in thickness with 0.1 mm. The effect of thickness on stiffness is far greater than that of blank holding force. The greater the arc height of punch, the greater the stiffness. And stiffness increases nearly by five times with arc height of punch is from 3mm to 9mm. The effect of arc height of punch on stiffness is far greater than that of materials mechanical properties. The stiffness is varied with different panel material properties by the same forming and stiffness test conditions. The decrease of yield strength is beneficial to the panel stiffness. The appropriate choice of materials and forming process condition is important in meeting necessary requirements for the energy-saving, lightweight and reducing wind resistance design in automotive industry.

The effect of short-term isometric training on core/torso stiffness.

Science.gov (United States)

Lee, Benjamin; McGill, Stuart

2017-09-01

"Core" exercise is a basic part of many physical training regimens with goals ranging from rehabilitation of spine and knee injuries to improving athletic performance. Core stiffness has been proposed to perform several functions including reducing pain by minimising joint micro-movements, and enhancing strength and speed performance. This study probes the links between a training approach and immediate but temporary changes in stiffness. Passive and active stiffness was measured on 24 participants; 12 having little to no experience in core training (inexperienced), and the other 12 being athletes experienced to core training methods; before and after a 15 min bout of isometric core exercises. Passive stiffness was assessed on a "frictionless" bending apparatus and active stiffness assessed via a quick release mechanism. Short-term isometric core training increased passive and active stiffness in most directions for both inexperienced and experienced participants, passive left lateral bend among experienced participants being the exception (P core stiffness, in this case following a single session. This may influence performance and injury resilience for a brief period.

Dynamic Stiffness Transfer Function of an Electromechanical Actuator Using System Identification

Science.gov (United States)

Kim, Sang Hwa; Tahk, Min-Jea

2018-04-01

In the aeroelastic analysis of flight vehicles with electromechanical actuators (EMAs), an accurate prediction of flutter requires dynamic stiffness characteristics of the EMA. The dynamic stiffness transfer function of the EMA with brushless direct current (BLDC) motor can be obtained by conducting complicated mathematical calculations of control algorithms and mechanical/electrical nonlinearities using linearization techniques. Thus, system identification approaches using experimental data, as an alternative, have considerable advantages. However, the test setup for system identification is expensive and complex, and experimental procedures for data collection are time-consuming tasks. To obtain the dynamic stiffness transfer function, this paper proposes a linear system identification method that uses information obtained from a reliable dynamic stiffness model with a control algorithm and nonlinearities. The results of this study show that the system identification procedure is compact, and the transfer function is able to describe the dynamic stiffness characteristics of the EMA. In addition, to verify the validity of the system identification method, the simulation results of the dynamic stiffness transfer function and the dynamic stiffness model were compared with the experimental data for various external loads.

Early Impairment of Lung Mechanics in a Murine Model of Marfan Syndrome

Science.gov (United States)

Uriarte, Juan J.; Meirelles, Thayna; Gorbenko del Blanco, Darya; Nonaka, Paula N.; Campillo, Noelia; Sarri, Elisabet; Navajas, Daniel; Egea, Gustavo; Farré, Ramon

2016-01-01

Early morbidity and mortality in patients with Marfan syndrome (MFS) -a connective tissue disease caused by mutations in fibrillin-1 gene- are mainly caused by aorta aneurysm and rupture. However, the increase in the life expectancy of MFS patients recently achieved by reparatory surgery promotes clinical manifestations in other organs. Although some studies have reported respiratory alterations in MFS, our knowledge of how this connective tissue disease modifies lung mechanics is scarce. Hence, we assessed whether the stiffness of the whole lung and of its extracellular matrix (ECM) is affected in a well-characterized MFS mouse model (FBN1C1039G/+). The stiffness of the whole lung and of its ECM were measured by conventional mechanical ventilation and atomic force microscopy, respectively. We studied 5-week and 9-month old mice, whose ages are representative of early and late stages of the disease. At both ages, the lungs of MFS mice were significantly more compliant than in wild type (WT) mice. By contrast, no significant differences were found in local lung ECM stiffness. Moreover, histopathological lung evaluation showed a clear emphysematous-like pattern in MFS mice since alveolar space enlargement was significantly increased compared with WT mice. These data suggest that the mechanism explaining the increased lung compliance in MFS is not a direct consequence of reduced ECM stiffness, but an emphysema-like alteration in the 3D structural organization of the lung. Since lung alterations in MFS are almost fully manifested at an early age, it is suggested that respiratory monitoring could provide early biomarkers for diagnosis and/or follow-up of patients with the Marfan syndrome. PMID:27003297

Martial arts training attenuates arterial stiffness in middle aged adults.

Science.gov (United States)

Douris, Peter C; Ingenito, Teresa; Piccirillo, Barbara; Herbst, Meredith; Petrizzo, John; Cherian, Vincen; McCutchan, Christopher; Burke, Caitlin; Stamatinos, George; Jung, Min-Kyung

2013-09-01

Arterial stiffness increases with age and is related to an increased risk of coronary artery disease. Poor trunk flexibility has been shown to be associated with arterial stiffness in middle-aged subjects. The purpose of our research study was to measure arterial stiffness and flexibility in healthy middle-aged martial artists compared to age and gender matched healthy sedentary controls. Ten martial artists (54.0 ± 2.0 years), who practice Soo Bahk Do (SBD), a Korean martial art, and ten sedentary subjects (54.7 ± 1.8 years) for a total of twenty subjects took part in this cross-sectional study. Arterial stiffness was assessed in all subjects using pulse wave velocity (PWV), a recognized index of arterial stiffness. Flexibility of the trunk and hamstring were also measured. The independent variables were the martial artists and matched sedentary controls. The dependent variables were PWV and flexibility. There were significant differences, between the SBD practitioners and sedentary controls, in PWV (P = 0.004), in trunk flexibility (P= 0.002), and in hamstring length (P= 0.003). The middle-aged martial artists were more flexible in their trunk and hamstrings and had less arterial stiffness compared to the healthy sedentary controls. The flexibility component of martial art training or flexibility exercises in general may be considered as a possible intervention to reduce the effects of aging on arterial stiffness.

Stiffness Coefficients of Mortise and Tenon Joints used on Wooden Window Profiles

Directory of Open Access Journals (Sweden)

Milan Podlena

2016-04-01

Full Text Available Samples of corner joints of wooden rectangular windows, with widths of 78 and 92 mm, were used to determine the stiffness of tenon and mortise joints. Two series of samples were loaded statically in the angular plane of compression and tension, so that the bending moment could be derived. The objective of the experiment was to determine the existing correlations between the stiffness in maximum strength and the stiffness in the elastic area for both types of tests. After strength tests were carried out, the annual ring width of the samples was measured to determine whether this factor affects the stiffness of the joints. The results showed that there was a relatively strong correlation between the stiffness in the elastic area and the maximum load. A two-factor analysis of variance confirmed that the type of load did not affect the stiffness of the joint, but the type of joint (width does significantly affect the stiffness. Therefore, the width of annual rings was positively correlated with the stiffness of the joints.

Variable stiffness and damping MR isolator

Energy Technology Data Exchange (ETDEWEB)

Zhang, X Z; Wang, X Y; Li, W H; Kostidis, K [University of Wollongong, School of Mechanical, Materials and Mechatronic Engineering, NSW 2522 (Australia)], E-mail: weihuali@uow.edu.au

2009-02-01

This paper presents the development of a magnetorheological (MR) fluid-based variable stiffness and damping isolator for vibration suppressions. The MR fluid isolator used a sole MR control unit to achieve the variable stiffness and damping in stepless and relative large scope. A mathematical model of the isolator was derived, and a prototype of the MR fluid isolator was fabricated and its dynamic behavior was measured in vibration under various applied magnetic fields. The parameters of the model under various magnetic fields were identified and the dynamic performances of isolator were evaluated.

Evidence for an agitated-aggressive syndrome in early-onset psychosis correlated with antisocial personality disorder, forensic history, and substance use disorder.

Science.gov (United States)

Huber, Christian G; Hochstrasser, Lisa; Meister, Klara; Schimmelmann, Benno G; Lambert, Martin

2016-08-01

Agitation, aggression, and violence are increased in psychotic disorders. Additionally, an earlier age at onset may be associated with aggressive behavior. However, the relationship of age at onset, an agitated-aggressive syndrome as measured with the Positive And Negative Syndrome Scale for Schizophrenia - Excited Component (PANSS-EC), and its potential correlates in first-episode psychosis (FEP) has not been studied. This study assessed the association between age at onset, an agitated-aggressive syndrome, and its potential correlates in a prospective sample of 52 FEP patients with early-onset and adult-onset followed up for 12months. Twenty-six patients conformed to the criteria of early-onset psychosis. Early age at onset was associated with antisocial personality disorder (p=0.004; φc=0.39), a history of legal involvement (p=0.005; φc=0.39), and higher rates of lifetime substance use disorder (SUD; p=0.002; φc=0.42). Early-onset patients had significantly higher PANSS-EC scores over the course of observation (F(1,44.4)=5.39; p=0.025; d=0.656), but no significant group differences emerged for the remaining PANSS subscores. PANSS-EC scores were correlated positively with antisocial personality disorder and forensic history at 6weeks, 3months, 6months, and 12months, and with lifetime substance use disorder at 3months and 6months. Patients with early onset psychosis may have increased levels of agitation/aggressiveness, and, more likely, antisocial personality disorder, forensic history, and lifetime substance use disorder. These variables were linked to suicidality, aggressiveness, and involuntary treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of lumped mass and support stiffness on pipe seismic response

International Nuclear Information System (INIS)

Chang, P.S.Y.

1986-01-01

In performing pipe stress analysis, generic support stiffness values are typically used to predict the response of the piping systems. Consistent design of every support to match the generic stiffness value is difficult. The difference between the actual and generic stiffness may affect the results of pipe stresses and support reactions. The objective of this study is to develop an acceptance criteria for the actual support stiffness and to avoid unnecessary reanalysis. The support mass in the restraint direction and mass within the pipe span can also affect the piping system behavior and this study will discuss this mass effect as well. Added mass and change in support stiffness will cause the piping system to shift frequency

Optimization of a variable-stiffness skin for morphing high-lift devices

International Nuclear Information System (INIS)

Thuwis, G A A; Abdalla, M M; Gürdal, Z

2010-01-01

One of the possibilities for the next generation of smart high-lift devices is to use a seamless morphing structure. A passive composite variable-stiffness skin as a solution to the dilemma of designing the structure to have high enough stiffness to withstand aerodynamic loading and low stiffness to enable morphing is proposed. The variable-stiffness skin is achieved by allowing for a spatial fibre angle and skin thickness variation on a morphing high-lift system. The stiffness distribution is tailored to influence the deformation of the structure beneficially. To design a realistic stiffness distribution, it is important to take aerodynamic and actuation loads into account during the optimization. A two-dimensional aero-servo-elastic framework is created for this purpose. Skin optimization is performed using a gradient-based optimizer, where sensitivity information is found through application of the adjoint method. The implementation of the aero-servo-elastic environment is addressed and initial optimization results presented. The results indicate that a variable-stiffness skin increases the design space. Moreover, the importance of taking the change in aerodynamic loads due to morphing skin deformation into account during optimization is demonstrated

Adult antisocial syndrome co-morbid with borderline personality disorder is associated with severe conduct disorder, substance dependence and violent antisociality.

Science.gov (United States)

Freestone, Mark; Howard, Rick; Coid, Jeremy W; Ullrich, Simone

2013-01-01

This study tested the hypothesis that syndromal adult antisocial behaviour (AABS) co-morbid with borderline personality disorder (BPD) is a syndrome that emerges from severe conduct disorder (CD) in childhood and adolescence and is strongly associated, in adulthood, with both violence and substance dependence. In a sample of 8 580 community-resident adults screened for the presence of personality disorders, the following predictions arising from this hypothesis were tested: first, that those with AABS co-morbid with BPD would, in comparison with those showing AABS or BPD only, show a high level of antisocial outcomes, including violence; second, that adjusting for co-morbid alcohol dependence would attenuate group differences in many of the antisocial outcomes, and violence in particular; and third, that the AABS/BPD group would show both a high prevalence and a high severity of CD, and that adjusting for co-morbid CD would attenuate any association found between AABS/BPD co-morbidity and violence. Results confirmed these predictions, suggesting that AABS/BPD co-morbidity mediates the relationship between childhood CD and a predisposition to adult violence. The triad of AABS/BPD co-morbidity, alcohol dependence and severe CD is likely associated with the risk of criminal recidivism in offenders with personality disorder following release into the community. Copyright © 2012 John Wiley & Sons, Ltd.

Accurate spring constant calibration for very stiff atomic force microscopy cantilevers

Energy Technology Data Exchange (ETDEWEB)

Grutzik, Scott J.; Zehnder, Alan T. [Field of Theoretical and Applied Mechanics, Cornell University, Ithaca, New York 14853 (United States); Gates, Richard S.; Gerbig, Yvonne B.; Smith, Douglas T.; Cook, Robert F. [Nanomechanical Properties Group, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

2013-11-15

There are many atomic force microscopy (AFM) applications that rely on quantifying the force between the AFM cantilever tip and the sample. The AFM does not explicitly measure force, however, so in such cases knowledge of the cantilever stiffness is required. In most cases, the forces of interest are very small, thus compliant cantilevers are used. A number of methods have been developed that are well suited to measuring low stiffness values. However, in some cases a cantilever with much greater stiffness is required. Thus, a direct, traceable method for calibrating very stiff (approximately 200 N/m) cantilevers is presented here. The method uses an instrumented and calibrated nanoindenter to determine the stiffness of a reference cantilever. This reference cantilever is then used to measure the stiffness of a number of AFM test cantilevers. This method is shown to have much smaller uncertainty than previously proposed methods. An example application to fracture testing of nanoscale silicon beam specimens is included.

Accurate spring constant calibration for very stiff atomic force microscopy cantilevers

International Nuclear Information System (INIS)

Grutzik, Scott J.; Zehnder, Alan T.; Gates, Richard S.; Gerbig, Yvonne B.; Smith, Douglas T.; Cook, Robert F.

2013-01-01

There are many atomic force microscopy (AFM) applications that rely on quantifying the force between the AFM cantilever tip and the sample. The AFM does not explicitly measure force, however, so in such cases knowledge of the cantilever stiffness is required. In most cases, the forces of interest are very small, thus compliant cantilevers are used. A number of methods have been developed that are well suited to measuring low stiffness values. However, in some cases a cantilever with much greater stiffness is required. Thus, a direct, traceable method for calibrating very stiff (approximately 200 N/m) cantilevers is presented here. The method uses an instrumented and calibrated nanoindenter to determine the stiffness of a reference cantilever. This reference cantilever is then used to measure the stiffness of a number of AFM test cantilevers. This method is shown to have much smaller uncertainty than previously proposed methods. An example application to fracture testing of nanoscale silicon beam specimens is included

Exchange stiffness of Ca-doped YIG

Science.gov (United States)

Avgin, I.; Huber, D. L.

1994-05-01

An effective medium theory for the zero-temperature exchange stiffness of uncompensated Ca-doped YIG is presented. The theory is based on the assumption that the effect of the Ca impurities is to produce strong, random ferromagnetic interactions between spins on the a and d sublattices. In the simplest version of the theory, a fraction, x, of the ad exchange integrals are large and positive, x being related to the Ca concentration. The stiffness is calculated as function of x for arbitrary perturbed ad exchange integral, Jxad. For Jxad≳(1/5)‖8Jaa+3Jdd‖, with Jaa and Jdd denoting the aa and dd exchange integrals, respectively, there is a critical concentration, Xc, such that when x≳Xc, the stiffness is complex. It is suggested that Xc delineates the region where there are significant departures from colinearity in the ground state of the Fe spins. Extension of the theory to a model where the Ca doping is assumed to generate Fe4+ ions on the tetrahedral sites is discussed. Possible experimental tests of the theory are mentioned.

A multiwell platform for studying stiffness-dependent cell biology.

Science.gov (United States)

Mih, Justin D; Sharif, Asma S; Liu, Fei; Marinkovic, Aleksandar; Symer, Matthew M; Tschumperlin, Daniel J

2011-01-01

Adherent cells are typically cultured on rigid substrates that are orders of magnitude stiffer than their tissue of origin. Here, we describe a method to rapidly fabricate 96 and 384 well platforms for routine screening of cells in tissue-relevant stiffness contexts. Briefly, polyacrylamide (PA) hydrogels are cast in glass-bottom plates, functionalized with collagen, and sterilized for cell culture. The Young's modulus of each substrate can be specified from 0.3 to 55 kPa, with collagen surface density held constant over the stiffness range. Using automated fluorescence microscopy, we captured the morphological variations of 7 cell types cultured across a physiological range of stiffness within a 384 well plate. We performed assays of cell number, proliferation, and apoptosis in 96 wells and resolved distinct profiles of cell growth as a function of stiffness among primary and immortalized cell lines. We found that the stiffness-dependent growth of normal human lung fibroblasts is largely invariant with collagen density, and that differences in their accumulation are amplified by increasing serum concentration. Further, we performed a screen of 18 bioactive small molecules and identified compounds with enhanced or reduced effects on soft versus rigid substrates, including blebbistatin, which abolished the suppression of lung fibroblast growth at 1 kPa. The ability to deploy PA gels in multiwell plates for high throughput analysis of cells in tissue-relevant environments opens new opportunities for the discovery of cellular responses that operate in specific stiffness regimes.

A multiwell platform for studying stiffness-dependent cell biology.

Directory of Open Access Journals (Sweden)

Justin D Mih

Full Text Available Adherent cells are typically cultured on rigid substrates that are orders of magnitude stiffer than their tissue of origin. Here, we describe a method to rapidly fabricate 96 and 384 well platforms for routine screening of cells in tissue-relevant stiffness contexts. Briefly, polyacrylamide (PA hydrogels are cast in glass-bottom plates, functionalized with collagen, and sterilized for cell culture. The Young's modulus of each substrate can be specified from 0.3 to 55 kPa, with collagen surface density held constant over the stiffness range. Using automated fluorescence microscopy, we captured the morphological variations of 7 cell types cultured across a physiological range of stiffness within a 384 well plate. We performed assays of cell number, proliferation, and apoptosis in 96 wells and resolved distinct profiles of cell growth as a function of stiffness among primary and immortalized cell lines. We found that the stiffness-dependent growth of normal human lung fibroblasts is largely invariant with collagen density, and that differences in their accumulation are amplified by increasing serum concentration. Further, we performed a screen of 18 bioactive small molecules and identified compounds with enhanced or reduced effects on soft versus rigid substrates, including blebbistatin, which abolished the suppression of lung fibroblast growth at 1 kPa. The ability to deploy PA gels in multiwell plates for high throughput analysis of cells in tissue-relevant environments opens new opportunities for the discovery of cellular responses that operate in specific stiffness regimes.

Generating random walks and polygons with stiffness in confinement

International Nuclear Information System (INIS)

Diao, Y; Ernst, C; Saarinen, S; Ziegler, U

2015-01-01

The purpose of this paper is to explore ways to generate random walks and polygons in confinement with a bias toward stiffness. Here the stiffness refers to the curvature angle between two consecutive edges along the random walk or polygon. The stiffer the walk (polygon), the smaller this angle on average. Thus random walks and polygons with an elevated stiffness have lower than expected curvatures. The authors introduced and studied several generation algorithms with a stiffness parameter s>0 that regulates the expected curvature angle at a given vertex in which the random walks and polygons are generated one edge at a time using conditional probability density functions. Our generating algorithms also allow the generation of unconfined random walks and polygons with any desired mean curvature angle. In the case of random walks and polygons confined in a sphere of fixed radius, we observe that, as expected, stiff random walks or polygons are more likely to be close to the confinement boundary. The methods developed here require that the random walks and random polygons be rooted at the center of the confinement sphere. (paper)

Wide-range stiffness gradient PVA/HA hydrogel to investigate stem cell differentiation behavior.

Science.gov (United States)

Oh, Se Heang; An, Dan Bi; Kim, Tae Ho; Lee, Jin Ho

2016-04-15

Although stiffness-controllable substrates have been developed to investigate the effect of stiffness on cell behavior and function, the use of separate substrates with different degrees of stiffness, substrates with a narrow range stiffness gradient, toxicity of residues, different surface composition, complex fabrication procedures/devices, and low cell adhesion are still considered as hurdles of conventional techniques. In this study, a cylindrical polyvinyl alcohol (PVA)/hyaluronic acid (HA) hydrogel with a wide-range stiffness gradient (between ∼20kPa and ∼200kPa) and cell adhesiveness was prepared by a liquid nitrogen (LN2)-contacting gradual freezing-thawing method that does not use any additives or specific devices to produce the stiffness gradient hydrogel. From an in vitro cell culture using the stiffness gradient PVA/HA hydrogel, it was observed that human bone marrow mesenchymal stem cells have favorable stiffness ranges for induction of differentiation into specific cell types (∼20kPa for nerve cell, ∼40kPa for muscle cell, ∼80kPa for chondrocyte, and ∼190kPa for osteoblast). The PVA/HA hydrogel with a wide range of stiffness spectrum can be a useful tool for basic studies related with the stem cell differentiation, cell reprogramming, cell migration, and tissue regeneration in terms of substrate stiffness. It is postulated that the stiffness of the extracellular matrix influences cell behavior. To prove this concept, various techniques to prepare substrates with a stiffness gradient have been developed. However, the narrow ranges of stiffness gradient and complex fabrication procedures/devices are still remained as limitations. Herein, we develop a substrate (hydrogel) with a wide-range stiffness gradient using a gradual freezing-thawing method which does not need specific devices to produce a stiffness gradient hydrogel. From cell culture experiments using the hydrogel, it is observed that human bone marrow mesenchymal stem cells have

Optimization of a variable-stiffness skin for morphing high-lift devices

NARCIS (Netherlands)

Thuwis, G.A.A.; Abdalla, M.M.; Gürdal, Z.

2010-01-01

One of the possibilities for the next generation of smart high-lift devices is to use a seamless morphing structure. A passive composite variable-stiffness skin as a solution to the dilemma of designing the structure to have high enough stiffness to withstand aerodynamic loading and low stiffness to

Design of a Variable Stiffness Soft Dexterous Gripper

Science.gov (United States)

Nefti-Meziani, Samia; Davis, Steve

2017-01-01

Abstract This article presents the design of a variable stiffness, soft, three-fingered dexterous gripper. The gripper uses two designs of McKibben muscles. Extensor muscles that increase in length when pressurized are used to form the fingers of the gripper. Contractor muscles that decrease in length when pressurized are then used to apply forces to the fingers through tendons, which cause flexion and extension of the fingers. The two types of muscles are arranged to act antagonistically and this means that by raising the pressure in all of the pneumatic muscles, the stiffness of the system can be increased without a resulting change in finger position. The article presents the design of the gripper, some basic kinematics to describe its function, and then experimental results demonstrating the ability to adjust the bending stiffness of the gripper's fingers. It has been demonstrated that the fingers' bending stiffness can be increased by more than 150%. The article concludes by demonstrating that the fingers can be closed loop position controlled and are able to track step and sinusoidal inputs. PMID:29062630

Bone metabolism and arterial stiffness after renal transplantation.

Science.gov (United States)

Cseprekál, Orsolya; Kis, Eva; Dégi, Arianna A; Kerti, Andrea; Szabó, Attila J; Reusz, György S

2014-01-01

To assess the relationship between bone and vascular disease and its changes over time after renal transplantation. Metabolic bone disease (MBD) is common in chronic kidney disease (CKD) and is associated with cardiovascular (CV) disease. Following transplantation (Tx), improvement in CV disease has been reported; however, data regarding changes in bone disease remain controversial. Bone turnover and arterial stiffness (pulse wave velocity (PWV)) were assessed in 47 Tx patients (38 (3-191) months after Tx). Bone alkaline phosphatase (BALP), osteocalcin (OC) and beta-crosslaps were significantly higher in Tx patients, and decreased significantly after one year. There was a negative correlation between BALP, OC and steroid administered (r = -0.35; r = -0.36 respectively). PWV increased in the Tx group (1.15 SD). In patients with a follow up of bone turnover and arterial stiffness are present following kidney transplantation. While bone turnover decreases with time, arterial stiffness correlates initially with bone turnover, after which the influence of cholesterol becomes significant. Non-invasive estimation of bone metabolism and arterial stiffness may help to assess CKD-MBD following renal transplantation.

Identification of a parametric, discrete-time model of ankle stiffness.

Science.gov (United States)

Guarin, Diego L; Jalaleddini, Kian; Kearney, Robert E

2013-01-01

Dynamic ankle joint stiffness defines the relationship between the position of the ankle and the torque acting about it and can be separated into intrinsic and reflex components. Under stationary conditions, intrinsic stiffness can described by a linear second order system while reflex stiffness is described by Hammerstein system whose input is delayed velocity. Given that reflex and intrinsic torque cannot be measured separately, there has been much interest in the development of system identification techniques to separate them analytically. To date, most methods have been nonparametric and as a result there is no direct link between the estimated parameters and those of the stiffness model. This paper presents a novel algorithm for identification of a discrete-time model of ankle stiffness. Through simulations we show that the algorithm gives unbiased results even in the presence of large, non-white noise. Application of the method to experimental data demonstrates that it produces results consistent with previous findings.

Extension of elastic stiffness formula for leaf type holddown spring assembly

Energy Technology Data Exchange (ETDEWEB)

Song, Kee Nam; Kang, Heung Seok; Yoon, Kyung Ho; Kim, Hyung Kyu [Korea Atomic Energy Research Institute, Taejon (Korea)

1998-09-01

Based on the Euler beam theory and the strain energy method, an elastic stiffness formula of the holddown spring assembly consisting of several leaves was previously derived. The formula was known to be useful to estimate the elastic stiffness of the holddown spring assembly only with the geometric data and the material properties of the leaf. Recently, it was reported that the elastic stiffness from the formula deviated much from the test results as the number of leaves was increased. In this study, in order to resolve such an increasing deviation as the increasing number of leaves, the formula has been extended to be able to consider normal forces and friction forces acting on interfaces between the leaves. The elastic stiffness analysis on specimens of leaf type holddown springs has been carried out using the extended formula and the analysis results are compared with the test results. As a result of comparisons, it is found that the extended formula is able to evaluate the elastic stiffness of the holddown spring assembly within an error range of 10%, irrespective of the number of leaves. In addition, it is found that the effect of shear forces and axial forces on the elastic stiffness of the holddown spring assembly is only below 0.2% of the elastic stiffness, and therefore the greatest portion of the elastic stiffness of the holddown spring assembly is attributed to the bending moment. (author). 13 refs., 10 figs., 12 tabs.

Dynamic Functional Stiffness Index of the Ankle Joint During Daily Living.

Science.gov (United States)

Argunsah Bayram, Hande; Bayram, Mehmed B

2018-03-30

Exploring ankle joint physiologic functional stiffness is crucial for improving the design of prosthetic feet that aim to mimic normal gait. We hypothesized that ankle joint stiffness would vary among the different activities of daily living and that the magnitude of the stiffness would indicate the degree of energy storage element sufficiency in terms of harvesting and returning energy. We examined sagittal plane ankle moment versus flexion angle curves from 12 healthy subjects during the daily activities. The slopes of these curves were assessed to find the calculated stiffness during the peak energy return and harvest phases. For the energy return and harvest phases, stiffness varied from 0.016 to 0.283 Nm/kg° and 0.025 and 0.858 Nm/kg°, respectively. The optimum stiffness during the energy return phase was 0.111 ± 0.117 Nm/kg° and during the energy harvest phase was 0.234 ± 0.327 Nm/kg°. Ankle joint stiffness varied significantly during the activities of daily living, indicating that an energy storage unit with a constant stiffness would not be sufficient in providing energy regenerative gait during all activities. The present study was directed toward the development of a complete data set to determine the torque-angle properties of the ankle joint to facilitate a better design process. Copyright © 2017 The American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Association of morning blood pressure surge with carotid intima-media thickness and cardiac dysfunction in patients with cardiac syndrome-X.

Science.gov (United States)

Mahfouz, Ragab A; Goda, Mohammad; Galal, Islam; Ghareb, Mohamed S

2018-05-23

Background & hypothesis: We hypothesized that exaggerated morning blood pressure surge, may contribute in cardiac dysfunction and arterial stiffness in patients with cardiac syndrome X. Thus we investigated the impact of morning blood pressure surge on cardiac function and carotid intima-media thickness in subjects with cardiac syndrome X. We studied patients with cardiac syndrome X using ambulatory blood pressure monitoring and investigated the association of morning blood pressure surge with carotid intima thickness, left atrial volume index and left ventricular filling (E/e'). Seventy patients with cardiac syndrome X were enrolled for the study and compared with 70 age and sex matched controls. Patients with cardiac syndrome X were stratified based on the systolic morning blood pressure surge value of control subjects to patients with exaggerated blood pressure surge (n = 42) and those with normal morning blood pressure surge (n = 28). Basal heart rate (p blood pressure surge group than those with morning blood pressure surge group. Morning blood pressure surge was significantly correlated with carotid intima-media thickness, high sensitive C-reactive protein, left atrial volume index and E/e' ratio in patients with cardiac syndrome X. In multivariate analysis, exaggerated morning blood pressure surge was the only independent predictor of increased carotid intima-media thickness (OR = 2.379; p blood pressure surge is an independent predictor for arterial stiffness and diastolic dysfunction in patients with cardiac syndrome X.

Depression and Anorexia Nervosa of Persons with Down Syndrome.

Science.gov (United States)

Szymanski, Ludwik S.; Biederman, Joseph

1984-01-01

Manifestations of depression in three adults wth Down syndrome, one of whom also exhibited anorexia nervosa, are described. Overall findings indicate that major depression in Down syndrome may be more frequent than previously assumed and that it can be diagnosed with standard diagnostic criteria, modified according to the patient's developmental…

Parametric study of roof diaphragm stiffness requirements

International Nuclear Information System (INIS)

Jones, W.D.; Tenbus, M.A.

1991-01-01

A common assumption made in performing a dynamic seismic analysis for a building is that the roof/floor system is open-quotes rigidclose quotes. This assumption would appear to be reasonable for many of the structures found in nuclear power plants, since many of these structures are constructed of heavily reinforced concrete having floor/roof slabs at least two feet in thickness, and meet the code requirements for structural detailing for seismic design. The roofs of many Department of Energy (DOE) buildings at the Oak Ridge Y-12 Plant in Oak Ridge, Tennessee, have roofs constructed of either metal, precast concrete or gypsum plank deck overlaid with rigid insulation, tar and gravel. In performing natural phenomena hazard assessments for one such facility, it was assumed that the existing roof performed first as a flexible diaphragm (zero stiffness) and then, rigid (infinitely stiff). For the flexible diaphragm model it was determined that the building began to experience significant damage around 0.09 g's. For the rigid diaphragm model it was determined that no significant damage was observed below 0.20 g's. A Conceptual Design Report has been prepared for upgrading/replacing the roof of this building. The question that needed to be answered here was, open-quotes How stiff should the new roof diaphragm be in order to satisfy the rigid diaphragm assumption and, yet, be cost effective?close quotes. This paper presents a parametric study of a very simple structural system to show that the design of roof diaphragms needs to consider both strength and stiffness (frequency) requirements. This paper shows how the stiffness of a roof system affects the seismically induced loads in the lateral, vertical load resisting elements of a building and provides guidance in determining how open-quotes rigidclose quotes a roof system should be in order to accomplish a cost effective design

Two divergent paths: compression vs. non-compression in deep venous thrombosis and post thrombotic syndrome

Directory of Open Access Journals (Sweden)

Eduardo Simões Da Matta

Full Text Available Abstract Use of compression therapy to reduce the incidence of postthrombotic syndrome among patients with deep venous thrombosis is a controversial subject and there is no consensus on use of elastic versus inelastic compression, or on the levels and duration of compression. Inelastic devices with a higher static stiffness index, combine relatively small and comfortable pressure at rest with pressure while standing strong enough to restore the “valve mechanism” generated by plantar flexion and dorsiflexion of the foot. Since the static stiffness index is dependent on the rigidity of the compression system and the muscle strength within the bandaged area, improvement of muscle mass with muscle-strengthening programs and endurance training should be encouraged. Therefore, in the acute phase of deep venous thrombosis events, anticoagulation combined with inelastic compression therapy can reduce the extension of the thrombus. Notwithstanding, prospective studies evaluating the effectiveness of inelastic therapy in deep venous thrombosis and post-thrombotic syndrome are needed.

Elevated estimated arterial age is associated with metabolic syndrome and low-grade inflammation

DEFF Research Database (Denmark)

Greve, Sara V; Blicher, Marie K; Kruger, Ruan

2016-01-01

BACKGROUND: Arterial age can be estimated from equations relating arterial stiffness to age and blood pressure in large cohorts. We investigated whether estimated arterial age (eAA) was elevated in patients with the metabolic syndrome and/or known cardiovascular disease (CVD), which factors were...... of metabolic syndrome, Systematic COronary Risk Evaluation, or Framingham risk score. From age, mean blood pressure, and cfPWV, eAA and estimated cfPWV (ePWV) were calculated. In 2006, the combined cardiovascular endpoint (CEP) of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke...

Comparative study of diastolic filling under varying left ventricular wall stiffness

Science.gov (United States)

Mekala, Pritam; Santhanakrishnan, Arvind

2014-11-01

Pathological remodeling of the human cardiac left ventricle (LV) is observed in hypertensive heart failure as a result of pressure overload. Myocardial stiffening occurs in these patients prior to chronic maladaptive changes, resulting in increased LV wall stiffness. The goal of this study was to investigate the change in intraventricular filling fluid dynamics inside a physical model of the LV as a function of wall stiffness. Three LV models of varying wall stiffness were incorporated into an in vitro flow circuit driven by a programmable piston pump. Windkessel elements were used to tune the inflow and systemic pressure in the model with least stiffness to match healthy conditions. Models with stiffer walls were comparatively tested maintaining circuit compliance, resistance and pump amplitude constant. 2D phase-locked PIV measurements along the central plane showed that with increase in wall stiffness, the peak velocity and cardiac output inside the LV decreased. Further, inflow vortex ring propagation toward the LV apex was reduced with increasing stiffness. The above findings indicate the importance of considering LV wall relaxation characteristics in pathological studies of filling fluid dynamics.

Home-care treatment of swimmer syndrome in a miniature schnauzer dog.

Science.gov (United States)

Kim, Sun-A; Na, Ki-Jeong; Cho, Jong-Ki; Shin, Nam-Shik

2013-09-01

A 50-day-old, female miniature schnauzer dog was presented for astasia, dorsoventral flattening of the thorax, hypoplasia of hind-limb muscles, stiffness of hind-limb joints, paddling leg motion, and panting. The dog was diagnosed with swimmers syndrome. The dog recovered completely following 40 days of home-care treatment that involved environmental and nutritional management along with intensive physiotherapy.

Leg stiffness during phases of countermovement and take-off in vertical jump.

Science.gov (United States)

Struzik, Artur; Zawadzki, Jerzy

2013-01-01

With respect to cyclic movements such as human gait, running or hopping, leg stiffness is a little variable parameter. The aim of this study was to investigate changes in leg stiffness during the phase of countermovement and take-off when performing a single maximum counter-movement jump. Kistler force plates and a BTS SMART system for comprehensive motion analysis were employed in the study. The study covered a group of 12 athletes from university basketball teams. Leg stiffness was calculated in those parts of countermovement and take-off phases where its level is relatively constant and the relationship F(Δl) is similar to linear one. Mean total stiffness (±SD) in both legs in the countermovement phase amounted to 6.5 ± 1.5 kN/m, whereas during the take-off phase this value was 6.9 ± 1 kN/m. No statistically significant differences were found between leg stiffness during the countermovement phase and takeoff phase in the study group at the level of significance set at α = 0.05. This suggests that the leg stiffness in phase of countermovement and phase of take-off are much similar to each other, despite different function of both phases. Similar to cyclic movements, leg stiffness turned out relatively constant when performing a single vertical jump. There are also reported statistically significant correlations between body mass, body height, length of lower limbs and leg stiffness. The stiffness analysed by the authors should be understood as quasi-stiffness because the measurements of ΔF(Δl) were made during transient states where inertia and dumping forces are likely to affect the final result.

Critical appraisal of the differential effects of antihypertensive agents on arterial stiffness

Directory of Open Access Journals (Sweden)

Francesca Kum

2010-06-01

Full Text Available Francesca Kum, Janaka KarallieddeUnit for Metabolic Medicine, Cardiovascular Division, Kings College-Waterloo Campus, King’s College London, United KingdomAbstract: Increased central arterial stiffness, involving accelerated vascular ageing of the aorta, is a powerful and independent risk factor for early mortality and provides prognostic information above and beyond traditional risk factors for cardiovascular disease (CVD. Central arterial stiffness is an important determinant of pulse pressure; therefore, any pathological increase may result in left ventricular hypertrophy and impaired coronary perfusion. Central artery stiffness can be assessed noninvasively by measurement of aortic pulse wave velocity, which is the gold standard for measurement of arterial stiffness. Earlier, it was believed that changes in arterial stiffness, which are primarily influenced by long-term pressure-dependent structural changes, may be slowed but not reversed by pharmacotherapy. Recent studies with drugs that inhibit the renin–angiotensin–aldosterone system, advanced glycation end products crosslink breakers, and endothelin antagonists suggest that blood pressure (BP-independent reduction and reversal of arterial stiffness are feasible. We review the recent literature on the differential effect of antihypertensive agents either as monotherapy or combination therapy on arterial stiffness. Arterial stiffness is an emerging therapeutic target for CVD risk reduction; however, further clinical trials are required to confirm whether BP-independent changes in arterial stiffness directly translate to a reduction in CVD events.Keywords: aortic pulse wave velocity, augmentation index, blood pressure, renin–angiotensin–aldosterone system

Flexural Stiffness of Myosin Va Subdomains as Measured from Tethered Particle Motion

Science.gov (United States)

Michalek, Arthur J.; Kennedy, Guy G.; Warshaw, David M.; Ali, M. Yusuf

2015-01-01

Myosin Va (MyoVa) is a processive molecular motor involved in intracellular cargo transport on the actin cytoskeleton. The motor's processivity and ability to navigate actin intersections are believed to be governed by the stiffness of various parts of the motor's structure. Specifically, changes in calcium may regulate motor processivity by altering the motor's lever arm stiffness and thus its interhead communication. In order to measure the flexural stiffness of MyoVa subdomains, we use tethered particle microscopy, which relates the Brownian motion of fluorescent quantum dots, which are attached to various single- and double-headed MyoVa constructs bound to actin in rigor, to the motor's flexural stiffness. Based on these measurements, the MyoVa lever arm and coiled-coil rod domain have comparable flexural stiffness (0.034 pN/nm). Upon addition of calcium, the lever arm stiffness is reduced 40% as a result of calmodulins potentially dissociating from the lever arm. In addition, the flexural stiffness of the full-length MyoVa construct is an order of magnitude less stiff than both a single lever arm and the coiled-coil rod. This suggests that the MyoVa lever arm-rod junction provides a flexible hinge that would allow the motor to maneuver cargo through the complex intracellular actin network. PMID:26770194

Technical Validation of ARTSENS–An Image Free Device for Evaluation of Vascular Stiffness

Science.gov (United States)

Radhakrishnan, Ravikumar; Kusmakar, Shitanshu; Thrivikraman, Arya Sree; Sivaprakasam, Mohanasankar

2015-01-01

Vascular stiffness is an indicator of cardiovascular health, with carotid artery stiffness having established correlation to coronary heart disease and utility in cardiovascular diagnosis and screening. State of art equipment for stiffness evaluation are expensive, require expertise to operate and not amenable for field deployment. In this context, we developed ARTerial Stiffness Evaluation for Noninvasive Screening (ARTSENS), a device for image free, noninvasive, automated evaluation of vascular stiffness amenable for field use. ARTSENS has a frugal hardware design, utilizing a single ultrasound transducer to interrogate the carotid artery, integrated with robust algorithms that extract arterial dimensions and compute clinically accepted measures of arterial stiffness. The ability of ARTSENS to measure vascular stiffness in vivo was validated by performing measurements on 125 subjects. The accuracy of results was verified with the state-of-the-art ultrasound imaging-based echo-tracking system. The relation between arterial stiffness measurements performed in sitting posture for ARTSENS measurement and sitting/supine postures for imaging system was also investigated to examine feasibility of performing ARTSENS measurements in the sitting posture for field deployment. This paper verified the feasibility of the novel ARTSENS device in performing accurate in vivo measurements of arterial stiffness. As a portable device that performs automated measurement of carotid artery stiffness with minimal operator input, ARTSENS has strong potential for use in large-scale screening. PMID:27170892

Superfluid phase stiffness in electron doped superconducting Gd-123

Science.gov (United States)

Das, P.; Ghosh, Ajay Kumar

2018-05-01

Current-voltage characteristics of Ce substituted Gd-123 superconductor exhibits nonlinearity below a certain temperature below the critical temperature. An exponent is extracted using the nonlinearity of current-voltage relation. Superfluid phase stiffness has been studied as a function of temperature following the Ambegaokar-Halperin-Nelson-Siggia (AHNS) theory. Phase stiffness of the superfluid below the superconducting transition is found to be sensitive to the change in the carrier concentration in superconducting system. There may be a crucial electron density which affects superfluid stiffness strongly. Electron doping is found to be effective even if the coupling of the superconducting planes is changed.

Alagille Syndrome

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... Legacy Society Make Gifts of Stock Donate Your Car Personal Fundraising Partnership & Support Share Your Story Spread the Word Give While You Shop Contact Us Donate Now Alagille Syndrome Back Alagille ...

Variable stiffness corrugated composite structure with shape memory polymer for morphing skin applications

Science.gov (United States)

Gong, Xiaobo; Liu, Liwu; Scarpa, Fabrizio; Leng, Jinsong; Liu, Yanju

2017-03-01

This work presents a variable stiffness corrugated structure based on a shape memory polymer (SMP) composite with corrugated laminates as reinforcement that shows smooth aerodynamic surface, extreme mechanical anisotropy and variable stiffness for potential morphing skin applications. The smart composite corrugated structure shows a low in-plane stiffness to minimize the actuation energy, but also possess high out-of-plane stiffness to transfer the aerodynamic pressure load. The skin provides an external smooth aerodynamic surface because of the one-sided filling with the SMP. Due to variable stiffness of the shape memory polymer the morphing skin exhibits a variable stiffness with a change of temperature, which can help the skin adjust its stiffness according different service environments and also lock the temporary shape without external force. Analytical models related to the transverse and bending stiffness are derived and validated using finite element techniques. The stiffness of the morphing skin is further investigated by performing a parametric analysis against the geometry of the corrugation and various sets of SMP fillers. The theoretical and numerical models show a good agreement and demonstrate the potential of this morphing skin concept for morphing aircraft applications. We also perform a feasibility study of the use of this morphing skin in a variable camber morphing wing baseline. The results show that the morphing skin concept exhibits sufficient bending stiffness to withstand the aerodynamic load at low speed (less than 0.3 Ma), while demonstrating a large transverse stiffness variation (up to 191 times) that helps to create a maximum mechanical efficiency of the structure under varying external conditions.

Aortic stiffness and diameter predict progressive aortic dilatation in patients with Marfan syndrome

NARCIS (Netherlands)

Nollen, Gijs J.; Groenink, Maarten; Tijssen, Jan G. P.; van der Wall, Ernst E.; Mulder, Barbara J. M.

2004-01-01

Aim Patients with Marfan syndrome may develop dissection due to progressive dilatation in the entire aorta, which is not always predictable by mere anatomic assessment of the aortic diameter, especially of the descending aorta. The aim of this study was to identify the predictive value of aortic

Imaging evidence for anatomical disturbances and neuroplastic compensation in persons with Tourette syndrome

DEFF Research Database (Denmark)

Plessen, Kerstin J; Bansal, Ravi; Peterson, Bradley S

2009-01-01

BACKGROUND: Tourette syndrome (TS) is a disorder of chronic motor and vocal tics that begins in childhood. METHODS: A systematic Medline search was conducted to identify existing anatomical imaging studies in persons with TS. RESULTS: Thirty studies were identified, and their methods and findings...... were reviewed. Findings of reduced caudate volumes across the life span and thinning of sensorimotor cortices that is proportional with tic severity in children with TS implicate these regions in the genesis of tics. Hypertrophy of limbic and prefrontal cortices and a smaller corpus callosum accompany...... fewer symptoms in children with TS, likely representing an activity-dependent plasticity within these regions that help to modulate tic severity. CONCLUSION: Although existing studies differ with respect to sample size, gender composition, quality of clinical characterization, pulse sequences...

The Capgras syndrome in paranoid schizophrenia.

Science.gov (United States)

Silva, J A; Leong, G B

1992-01-01

Capgras syndrome is characterized by a delusion of impostors who are thought to be physically similar but psychologically distinct from the misidentified person. This syndrome is generally thought to be relatively rare. Most of our knowledge about Capgras syndrome derives from single case studies and small series of cases usually from diagnostically heterogeneous groups. In this article, a series of 31 patients suffering from both paranoid schizophrenia and Capgras syndrome is described. Issues pertaining to the phenomenology of Capgras syndrome, the possible relation between Capgras syndrome and other delusional misidentification syndromes, and a neurobiological hypothesis aimed at explaining Capgras syndrome are discussed.

Water retention properties of stiff silt

Directory of Open Access Journals (Sweden)

Barbara Likar

2017-06-01

Full Text Available Recent research into the behaviour of soils has shown that it is in fact much more complex than can be described by the mechanics of saturated soils. Nowadays the trend of investigations has shifted towards the unsaturated state. Despite the signifiant progress that has been made so far, there are still a lot of unanswered questions related to the behaviour of unsaturated soils. For this reason, in the fild of geotechnics some new concepts are developed, which include the study of soil suction. Most research into soil suction has involved clayey and silty material, whereas up until recently no data have been available about measurements in very stiff preconsolidated sandy silt. Very stiff preconsolidated sandy silt is typical of the Krško Basin, where it is planned that some very important geotechnical structures will be built, so that knowledge about the behaviour of such soils at increased or decreased water content is essential. Several different methods can be used for soil suction measurements. In the paper the results of measurements carried out on very stiff preconsolidated sandy silt in a Bishop - Wesley double-walled triaxial cell are presented and compared with the results of soil suction measurements performed by means of a potentiometer (WP4C. All the measurement results were evaluated taking into account already known results given in the literature, using the three most commonly used mathematical models. Until now a lot of papers dealing with suction measurements in normal consolidated and preconsolidated clay have been published. Measurements on very stiff preconsolidated sandy silt, as presented in this paper were not supported before.

Modelling, simulation and experiment of the spherical flexible joint stiffness

Directory of Open Access Journals (Sweden)

S. Li

2018-02-01

Full Text Available The spherical flexible joint is extensively used in engineering. It is designed to provide flexibility in rotation while bearing vertical compression load. The linear rotational stiffness of the flexible joint is formulated. The rotational stiffness of the bonded rubber layer is related to inner radius, thickness and two edge angles. FEM is used to verify the analytical solution and analyze the stiffness. The Mooney–Rivlin, Neo Hooke and Yeoh constitutive models are used in the simulation. The experiment is taken to obtain the material coefficient and validate the analytical and FEM results. The Yeoh model can reflect the deformation trend more accurately, but the error in the nearly linear district is bigger than the Mooney–Rivlin model. The Mooney–Rivlin model can fit the test result very well and the analytical solution can also be used when the rubber deformation in the flexible joint is small. The increase of Poisson's ratio of the rubber layers will enhance the vertical compression stiffness but barely have effect on the rotational stiffness.

A METHOD OF DETERMINING THE COORDINATES OF THE STIFFNESS CENTER AND THE STIFFNESS PRINCIPAL AXIS OF THE VIBRATING SYSTEM WITH DAMPING

OpenAIRE

Dang Xuan Truong; Tran Duc Chinh

2014-01-01

The report presents a methodology to determine the directions of the stiffness principal axis (in this case subject to the linear displacement and forced rotation angle) of a solid object interact with the surrounding environment by resilient bearing supports. The results also show that determining the coordinates of the stiffness center in the vibrating system with damping factors is necessary in our research.

Dynamic stiffness of suction caissons

DEFF Research Database (Denmark)

Ibsen, Lars Bo; Liingaard, Morten; Andersen, Lars

This report concerns the dynamic soil-structure interaction of steel suction caissons applied as foundations for offshore wind turbines. An emphasis is put on torsional vibrations and coupled sliding/rocking motion, and the influence of the foundation geometry and the properties of the surrounding...... soil is examined. The soil is simplified as a homogenous linear viscoelastic material and the dynamic stiffness of the suction caisson is expressed in terms of dimensionless frequency-dependent coefficients corresponding to the different degrees of freedom. The dynamic stiffness coefficients...... for the skirted foundation are evaluated by means of a three-dimensional coupled boundary element/finite element model. Comparisons with known analytical and numerical solutions indicate that the static and dynamic behaviour of the foundation are predicted accurately with the applied model. The analysis has been...

Substrate stiffness affects skeletal myoblast differentiation in vitro

Directory of Open Access Journals (Sweden)

Sara Romanazzo, Giancarlo Forte, Mitsuhiro Ebara, Koichiro Uto, Stefania Pagliari, Takao Aoyagi, Enrico Traversa and Akiyoshi Taniguchi

2012-01-01

Full Text Available To maximize the therapeutic efficacy of cardiac muscle constructs produced by stem cells and tissue engineering protocols, suitable scaffolds should be designed to recapitulate all the characteristics of native muscle and mimic the microenvironment encountered by cells in vivo. Moreover, so not to interfere with cardiac contractility, the scaffold should be deformable enough to withstand muscle contraction. Recently, it was suggested that the mechanical properties of scaffolds can interfere with stem/progenitor cell functions, and thus careful consideration is required when choosing polymers for targeted applications. In this study, cross-linked poly-ε-caprolactone membranes having similar chemical composition and controlled stiffness in a supra-physiological range were challenged with two sources of myoblasts to evaluate the suitability of substrates with different stiffness for cell adhesion, proliferation and differentiation. Furthermore, muscle-specific and non-related feeder layers were prepared on stiff surfaces to reveal the contribution of biological and mechanical cues to skeletal muscle progenitor differentiation. We demonstrated that substrate stiffness does affect myogenic differentiation, meaning that softer substrates can promote differentiation and that a muscle-specific feeder layer can improve the degree of maturation in skeletal muscle stem cells.

Finding trap stiffness of optical tweezers using digital filters.

Science.gov (United States)

Almendarez-Rangel, Pedro; Morales-Cruzado, Beatriz; Sarmiento-Gómez, Erick; Pérez-Gutiérrez, Francisco G

2018-02-01

Obtaining trap stiffness and calibration of the position detection system is the basis of a force measurement using optical tweezers. Both calibration quantities can be calculated using several experimental methods available in the literature. In most cases, stiffness determination and detection system calibration are performed separately, often requiring procedures in very different conditions, and thus confidence of calibration methods is not assured due to possible changes in the environment. In this work, a new method to simultaneously obtain both the detection system calibration and trap stiffness is presented. The method is based on the calculation of the power spectral density of positions through digital filters to obtain the harmonic contributions of the position signal. This method has the advantage of calculating both trap stiffness and photodetector calibration factor from the same dataset in situ. It also provides a direct method to avoid unwanted frequencies that could greatly affect calibration procedure, such as electric noise, for example.

Reye Syndrome

Science.gov (United States)

... Legacy Society Make Gifts of Stock Donate Your Car Personal Fundraising Partnership & Support Share Your Story Spread the Word Give While You Shop Contact Us Donate Now What Is Reye’s Syndrome? ...

The role of personality in the development and perpetuation of chronic fatigue syndrome.

Science.gov (United States)

White, C; Schweitzer, R

2000-06-01

Qualitative evidence suggests that personality may have special relevance to the predisposition, precipitation and perpetuation of chronic fatigue syndrome (CFS). This study compares three dimensions of personality - perfectionism, self-esteem, and emotional control in the personality profiles of CFS patients (N=44) and a control group (N=44) without a history of CFS, matched for age and gender. Participants were assessed on the MPS [Frost RO, Marten P, Lahart C, Rosenblate R. The dimensions of perfectionism. Cognit Ther Res 1990;14:449-468.]; the Rosenberg Self-Esteem Scale [Rosenberg M. Society and the Adolescent Self-image. Princeton, NJ: Princeton Univ Press, 1965.]; the Courtauld Emotional Scale [Watson M, Greer S. Development of a questionnaire measure of emotional control. J Psychosom Res 1983;27:299-305.] and the Marlowe-Crowne Social Desirability Scale [Crowne DP, Marlowe D. A new scale of social desirability independent of psychopathology. J Consult Psychol 1960;24:349-354.]. Analyses revealed that the CFS group reported higher levels than the control group on the Total Perfectionism score and Doubts about Actions and the Concern over Mistakes subscales. Furthermore, the CFS group also reported lower self-esteem than the control group. No difference between the two groups was found on the dimensions of emotional control and social desirability response bias. A developmental model of CFS, which considers the predisposing, precipitating, and perpetuating factors that may account for the course of the disorder irrespective of etiology, is proposed. In the context of the results, recommendations for practice and future research are discussed.

A Variable Stiffness Analysis Model for Large Complex Thin-Walled Guide Rail

Directory of Open Access Journals (Sweden)

Wang Xiaolong

2016-01-01

Full Text Available Large complex thin-walled guide rail has complicated structure and no uniform low rigidity. The traditional cutting simulations are time consuming due to huge computation especially in large workpiece. To solve these problems, a more efficient variable stiffness analysis model has been propose, which can obtain quantitative stiffness value of the machining surface. Applying simulate cutting force in sampling points using finite element analysis software ABAQUS, the single direction variable stiffness rule can be obtained. The variable stiffness matrix has been propose by analyzing multi-directions coupling variable stiffness rule. Combining with the three direction cutting force value, the reasonability of existing processing parameters can be verified and the optimized cutting parameters can be designed.

Assessment of the Personal Losses Suffered by Correctional Officers due to Burnout Syndrome.

Science.gov (United States)

Stoyanova, R G; Harizanova, S N

2016-01-01

Professional burnout is defined as a state of depletion and loss of motivation accompanied by different mental and physical symptoms. To assess personal losses suffered by correctional officers due to burnout. This cross-sectional study conducted between June and December 2012 included 201 correctional officers in two Bulgarian prisons. The mean age of the whole group was 41.2 (SD 8.0) years. The respondents was mostly male (56.7%), married (72.6%), had a secondary educational level (61.7%), and 76.1% of them had been in current prison work over 5 years. The demographic characteristics had no influence on the occurrence of burnout but there was a correlation between level of burnout and the number of sick-leaves, the need for medical help, and the expenses spent on medications. Officers affected by burnout took more sick-leaves and this affected adversely their remuneration as they lost 3.1% of their annual wages. Their expenses spent on user fees for medical services were 3 times higher. Their monthly expenses spent on medications were 3.14 times higher than those of people without the burnout syndrome. The high level of burnout has a negative personal economic effect on the prison employees.

Assessment of the Personal Losses Suffered by Correctional Officers due to Burnout Syndrome

Directory of Open Access Journals (Sweden)

RG Stoyanova

2016-01-01

Full Text Available Background: Professional burnout is defined as a state of depletion and loss of motivation accompanied by different mental and physical symptoms. Objective: To assess personal losses suffered by correctional officers due to burnout. Methods: This cross-sectional study conducted between June and December 2012 included 201 correctional officers in two Bulgarian prisons. The mean age of the whole group was 41.2 (SD 8.0 years. The respondents was mostly male (56.7%, married (72.6%, had a secondary educational level (61.7%, and 76.1% of them had been in current prison work over 5 years. Results: The demographic characteristics had no influence on the occurrence of burnout but there was a correlation between level of burnout and the number of sick-leaves, the need for medical help, and the expenses spent on medications. Officers affected by burnout took more sick-leaves and this affected adversely their remuneration as they lost 3.1% of their annual wages. Their expenses spent on user fees for medical services were 3 times higher. Their monthly expenses spent on medications were 3.14 times higher than those of people without the burnout syndrome. Conclusion: The high level of burnout has a negative personal economic effect on the prison employees.

Arterial stiffness in normotensive and hypertensive subjects: Frequency in community pharmacies.

Science.gov (United States)

Rodilla Sala, Enrique; Adell Alegre, Manuel; Giner Galvañ, Vicente; Perseguer Torregrosa, Zeneida; Pascual Izuel, Jose Maria; Climent Catalá, María Teresa

2017-12-07

Arterial stiffness (AS) is a well-recognized target organ lesion. This study aims to determine: 1) the frequency of AS in community pharmacies; 2) if stiffened subjects identified by brachial oscillometry have more CV risk factors than normal subjects, and 3) the dependence of stiffness on using either age-adjusted values or a fixed threshold. Observational, cross-sectional study in 32 community pharmacies of the Valencia Community, between November/2015 and April/2016. Stiffness was as pulse wave velocity (PWV) measured with a semi-automatic, validated device (Mobil-O-Graph ® , IEM), followed by a 10-item questionnaire. Mean age of the 1,427 consecutive recruited patients was 56.6 years. Overall proportion of patients with AS was 17.4% with age-adjusted PWV (9.4% in normotensives, 28.3% in hypertensives). Multivariate logistic regression showed independent association of stiffness in normotensives with male gender, obesity, higher pulse pressure and heart rate, in hypertensives, with higher pulse pressure and lower age. AS was globally found in 20.5% of subjects, defining stiffness by PWV>10m/s (6.2% in normotensives, 40.2% in hypertensives). It was associated with higher age and pulse pressure in both groups. Concordance in classifying stiffness was 74.6%. Frequency of AS varied between 17.4-20.5%. Age-adjusted stiffness is associated in normotensives with male gender, pulse pressure, obesity and heart rate, in hypertensives with pulse pressure and inversely to age. Stiffness by 10m/s is determined by higher pulse pressure and higher age. Both definitions of PWV are not interchangeable. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Experimental study on vertical static stiffnesses of polycal wire rope isolators

Science.gov (United States)

Balaji, P. S.; Moussa, Leblouba; Khandoker, Noman; Yuk Shyh, Ting; Rahman, M. E.; Hieng Ho, Lau

2017-07-01

Wire rope isolator is one of the most effective isolation system that can be used to attenuate the vibration disturbances and shocks during the operation of machineries. This paper presents the results of investigation on static elastic stiffnesses (both in tension and in compression) of Polycal Wire Rope Isolator (PWRI) under quasi-static monotonic loading conditions. It also studied effect of variations in height and width of PWRI on its static stiffnesses. Suitable experimental setup was designed and manufactured to meet the test conditions. The results show that their elastic stiffnesses for both tension and compression loading conditions are highly influenced by their geometric dimensions. It is found that their compressive stiffness reduced by 55% for an increment of 20% in their height to width ratio. Therefore, the stiffness of PWRI can be fine-tuned by controlling their dimensions according to the requirements of the application.

A METHOD OF DETERMINING THE COORDINATES OF THE STIFFNESS CENTER AND THE STIFFNESS PRINCIPAL AXIS OF THE VIBRATING SYSTEM WITH DAMPING

Directory of Open Access Journals (Sweden)

Dang Xuan Truong

2014-12-01

Full Text Available The report presents a methodology to determine the directions of the stiffness principal axis (in this case subject to the linear displacement and forced rotation angle of a solid object interact with the surrounding environment by resilient bearing supports. The results also show that determining the coordinates of the stiffness center in the vibrating system with damping factors is necessary in our research.

Spatially varying small-strain stiffness in soils subjected to K0 loading

KAUST Repository

Kim, Hyun-Ki; Santamarina, Carlos

2017-01-01

Grain-scale characteristics and formation history determine spatial variability in granular masses. We investigate the effect of spatially varying stiffness on the load-deformation response under zero-lateral strain conditions using numerical simulations of correlated random fields, where the granular medium is represented by a non-linear stress-dependent meso-scale model. Results show that stiffness heterogeneity results in higher global compressibility as compared to the homogeneous medium with the same arithmetic mean stiffness. Furthermore, the non-homogeneous stress field that develops inside the granular mass is characterized by focused load transfer along columnar regions, higher stress anisotropy and lower horizontal-to-vertical stress ratio K0 than in a granular medium of homogenous stiffness. As the applied stress increases, the inherent stress-dependent response of the granular material leads to a more homogenous stress field. While greater variance in stiffness causes lower global stiffness, a longer correlation length results in greater variance in global mechanical response among multiple realizations.

Spatially varying small-strain stiffness in soils subjected to K0 loading

KAUST Repository

Kim, Hyun-Ki

2017-08-08

Grain-scale characteristics and formation history determine spatial variability in granular masses. We investigate the effect of spatially varying stiffness on the load-deformation response under zero-lateral strain conditions using numerical simulations of correlated random fields, where the granular medium is represented by a non-linear stress-dependent meso-scale model. Results show that stiffness heterogeneity results in higher global compressibility as compared to the homogeneous medium with the same arithmetic mean stiffness. Furthermore, the non-homogeneous stress field that develops inside the granular mass is characterized by focused load transfer along columnar regions, higher stress anisotropy and lower horizontal-to-vertical stress ratio K0 than in a granular medium of homogenous stiffness. As the applied stress increases, the inherent stress-dependent response of the granular material leads to a more homogenous stress field. While greater variance in stiffness causes lower global stiffness, a longer correlation length results in greater variance in global mechanical response among multiple realizations.

Parametric instability of spinning elastic rings excited by fluctuating space-fixed stiffnesses

Science.gov (United States)

Liu, Chunguang; Cooley, Christopher G.; Parker, Robert G.

2017-07-01

This study investigates the vibration of rotating elastic rings that are dynamically excited by an arbitrary number of space-fixed discrete stiffnesses with periodically fluctuating stiffnesses. The rotating, elastic ring is modeled using thin-ring theory with radial and tangential deformations. Primary and combination instability regions are determined in closed-form using the method of multiple scales. The ratio of peak-to-peak fluctuation to average discrete stiffness is used as the perturbation parameter, so the resulting perturbation analysis is not limited to small mean values of discrete stiffnesses. The natural frequencies and vibration modes are determined by discretizing the governing equations using Galerkin's method. Results are demonstrated for compliant gear applications. The perturbation results are validated by direct numerical integration of the equations of motion and Floquet theory. The bandwidths of the instability regions correlate with the fractional strain energy stored in the discrete stiffnesses. For rings with multiple discrete stiffnesses, the phase differences between them can eliminate large amplitude response under certain conditions.

Arterial stiffness

Directory of Open Access Journals (Sweden)

Ursula Quinn

2012-09-01

Full Text Available Measurements of biomechanical properties of arteries have become an important surrogate outcome used in epidemiological and interventional cardiovascular research. Structural and functional differences of vessels in the arterial tree result in a dampening of pulsatility and smoothing of blood flow as it progresses to capillary level. A loss of arterial elastic properties results a range of linked pathophysiological changes within the circulation including increased pulse pressure, left ventricular hypertrophy, subendocardial ischaemia, vessel endothelial dysfunction and cardiac fibrosis. With increased arterial stiffness, the microvasculature of brain and kidneys are exposed to wider pressure fluctuations and may lead to increased risk of stroke and renal failure. Stiffening of the aorta, as measured by the gold-standard technique of aortic Pulse Wave Velocity (aPWV, is independently associated with adverse cardiovascular outcomes across many different patient groups and in the general population. Therefore, use of aPWV has been proposed for early detection of vascular damage and individual cardiovascular risk evaluation and it seems certain that measurement of arterial stiffness will become increasingly important in future clinical care. In this review we will consider some of the pathophysiological processes that result from arterial stiffening, how it is measured and factors that may drive it as well as potential avenues for therapy. In the face of an ageing population where mortality from atheromatous cardiovascular disease is falling, pathology associated with arterial stiffening will assume ever greater importance. Therefore, understanding these concepts for all clinicians involved in care of patients with cardiovascular disease will become vital.

Mixed, Nonsplit, Extended Stability, Stiff Integration of Reaction Diffusion Equations

KAUST Repository

Alzahrani, Hasnaa H.

2016-01-01

A tailored integration scheme is developed to treat stiff reaction-diffusion prob- lems. The construction adapts a stiff solver, namely VODE, to treat reaction im- plicitly together with explicit treatment of diffusion. The second-order Runge

Increase in Leg Stiffness Reduces Joint Work During Backpack Carriage Running at Slow Velocities.

Science.gov (United States)

Liew, Bernard; Netto, Kevin; Morris, Susan

2017-10-01

Optimal tuning of leg stiffness has been associated with better running economy. Running with a load is energetically expensive, which could have a significant impact on athletic performance where backpack carriage is involved. The purpose of this study was to investigate the impact of load magnitude and velocity on leg stiffness. We also explored the relationship between leg stiffness and running joint work. Thirty-one healthy participants ran overground at 3 velocities (3.0, 4.0, 5.0 m·s -1 ), whilst carrying 3 load magnitudes (0%, 10%, 20% weight). Leg stiffness was derived using the direct kinetic-kinematic method. Joint work data was previously reported in a separate study. Linear models were used to establish relationships between leg stiffness and load magnitude, velocity, and joint work. Our results found that leg stiffness did not increase with load magnitude. Increased leg stiffness was associated with reduced total joint work at 3.0 m·s -1 , but not at faster velocities. The association between leg stiffness and joint work at slower velocities could be due to an optimal covariation between skeletal and muscular components of leg stiffness, and limb attack angle. When running at a relatively comfortable velocity, greater leg stiffness may reflect a more energy efficient running pattern.

Tailoring the mechanical properties by molecular integration of flexible and stiff polymer networks.

Science.gov (United States)

Wan, Haixiao; Shen, Jianxiang; Gao, Naishen; Liu, Jun; Gao, Yangyang; Zhang, Liqun

2018-03-28

Designing a multiple-network structure at the molecular level to tailor the mechanical properties of polymeric materials is of great scientific and technological importance. Through the coarse-grained molecular dynamics simulation, we successfully construct an interpenetrating polymer network (IPN) composed of a flexible polymer network and a stiff polymer network. First, we find that there is an optimal chain stiffness for a single network (SN) to achieve the best stress-strain behavior. Then we turn to study the mechanical behaviors of IPNs. The result shows that the stress-strain behaviors of the IPNs appreciably exceed the sum of that of the corresponding single flexible and stiff network, which highlights the advantage of the IPN structure. By systematically varying the stiffness of the stiff polymer network of the IPNs, optimal stiffness also exists to achieve the best performance. We attribute this to a much larger contribution of the non-bonded interaction energy. Last, the effect of the component concentration ratio is probed. With the increase of the concentration of the flexible network, the stress-strain behavior of the IPNs is gradually enhanced, while an optimized concentration (around 60% molar ration) of the stiff network occurs, which could result from the dominant role of the enthalpy rather than the entropy. In general, our work is expected to provide some guidelines to better tailor the mechanical properties of the IPNs made of a flexible network and a stiff network, by manipulating the stiffness of the stiff polymer network and the component concentration ratio.

Triceps-surae musculotendinous stiffness: relative differences between obese and non-obese postmenopausal women.

Science.gov (United States)

Faria, Aurélio; Gabriel, Ronaldo; Abrantes, João; Brás, Rui; Moreira, Helena

2009-12-01

There is a lack of research into the relationship between obesity and muscle-tendon unit stiffness in postmenopausal women. Muscle-tendon unit stiffness appears to affect human motion performance and excessive and insufficient stiffness can increase the risk of bone and soft tissue injuries, respectively. The aim of this study was to investigate the relationship between muscle-tendon unit stiffness and obesity in postmenopausal women. 105 postmenopausal women (58 [SD 5.5] years) participated. Four groups (normal weight, pre-obese, obesity class I and obesity class II) were defined according World Health Organization classification of body mass index. The ankle muscle-tendon unit stiffness was assessed in vivo with a free oscillation technique using a load of 30% of maximal voluntary isometric contraction. ANOVA shows significant difference in muscle-tendon unit stiffness among the groups defined (Pnormal weight-pre-obese; normal weight-obesity class I and normal weight-obesity class II. The normal weight group had stiffness of 15789 (SD 2969) N/m, pre-obese of 19971 (SD 3678) N/m, obesity class I of 21435 (SD 4295) N/m, and obesity class II of 23497 (SD 1776) N/m. Obese subjects may have increased muscle-tendon unit stiffness because of fat infiltration in leg skeletal muscles, range of motion restrictions and stability/posture reasons and might be more predisposed to develop musculoskeletal injuries. Normal weight group had identical stiffness values to those reported in studies where subjects were not yet menopausal, suggesting that stiffness might not be influenced by menopause.

The effect of personality traits and psychosocial training on burnout syndrome among healthcare students.

Science.gov (United States)

Skodova, Zuzana; Lajciakova, Petra

2013-11-01

The aims of this paper were to explore the influence of personality factors on student burnout syndrome and to explore the effect of psychosocial training on burnout and personality predictors among university students in health care professions. A quasi-experimental pre-test/post-test design was used to evaluate the effect of psychosocial training. A sample of 111 university students were divided into experimental and control groups (average age 20.7 years, SD=2.8 years; 86.1% females). The School Burnout Inventory (SBI), Sense of Coherence (SOC) questionnaire, and Rosenberg's Self-esteem scale were employed. Linear regression and analysis of variance were applied for statistical analysis. The results show that socio-psychological training had a positive impact on the level of burnout and on personality factors that are related to burnout. After completing the training, the level of burnout in the experimental group significantly decreased (95% confidence interval: 0.93, 9.25), and no significant change was observed in the control group. Furthermore, respondents' sense of coherence increased in the experimental group (95% confidence interval: -9.11, 2.64), but there were no significant changes in respondents' self-esteem levels in either group. Psychosocial training positively influenced burnout among students in health care professions. Because the coping strategies that were used during the study are similar to effective work coping strategies, psychosocial training can be considered to be an effective tool to prevent burnout in the helping professions. Copyright © 2013. Published by Elsevier Ltd.

CARDIOVASCULAR DISORDERS AMONG PERSONS WITH DOWN SYNDROME

NARCIS (Netherlands)

Vis, Jeroen C.; van Engelen, Klaartje; Bouma, Berto J.; Bilardo, Catia M.; Blom, Nico A.; Mulder, Barbara J. M.

2010-01-01

Down syndrome is the most common chromosomal abnormality among liveborn infants and is the most frequent chromosomal cause of intellectual disability (Frid, Drott, Lundell, Rasmussen, & Anneren, 1999). It is a multisystem disorder, characterized by various congenital defects, organic disorders,

Betel nut chewing associated with increased risk of arterial stiffness.

Science.gov (United States)

Wei, Yu-Ting; Chou, Yu-Tsung; Yang, Yi-Ching; Chou, Chieh-Ying; Lu, Feng-Hwa; Chang, Chih-Jen; Wu, Jin-Shang

2017-11-01

Betel nut chewing is associated with certain cardiovascular outcomes. Subclinical atherosclerosis may be one link between betel nut chewing and cardiovascular risk. Few studies have examined the association between chewing betel nut and arterial stiffness. The aim of this study was thus to determine the relationship between betel nut chewing and arterial stiffness in a Taiwanese population. We enrolled 7540 eligible subjects in National Cheng Kung University Hospital from October 2006 to August 2009. The exclusion criteria included history of cerebrovascular events, coronary artery disease, and taking lipid-lowering drugs, antihypertensives, and hypoglycemic agents. Increased arterial stiffness was defined as brachial-ankle pulse wave velocity (baPWV) ≥1400cm/s. According to their habit of betel nut use, the subjects were categorized into non-, ex-, and current chewers. The prevalence of increased arterial stiffness was 32.7, 43.3, and 43.2% in non-, ex- and current chewers, respectively (p=0.011). Multiple logistic regression analysis revealed that ex-chewers (odds ratio [OR] 1.69, 95% confidence interval (CI)=1.08-2.65) and current chewers (OR 2.29, 95% CI=1.05-4.99) had elevated risks of increased arterial stiffness after adjustment for co-variables. Both ex- and current betel nut chewing were associated with a higher risk of increased arterial stiffness. Stopping betel nut chewing may thus potentially be beneficial to reduce cardiovascular risk, based on the principals of preventive medicine. Copyright © 2017 Elsevier B.V. All rights reserved.

Sex Differences in Limb and Joint Stiffness in Recreational Runners

Directory of Open Access Journals (Sweden)

Sinclair Jonathan

2015-09-01

Full Text Available Purpose. Female runners are known to be at greater risk from chronic running injuries than age-matched males, although the exact mechanisms are often poorly understood. The aim of the current investigation was to determine if female recreational runners exhibit distinct limb and joint stiffness characteristics in relation to their male counterparts. Methods. Fourteen male and fourteen female runners ran over a force platform at 4.0 m · s-1. Lower limb kinematics were collected using an eight-camera optoelectric motion capture system operating at 250 Hz. Measures of limb and joint stiffness were calculated as a function of limb length and joint moments divided by the extent of limb and joint excursion. All stiffness and joint moment parameters were normalized to body mass. Sex differences in normalized limb and knee and ankle joint stiffness were examined statistically using independent samples t tests. Results. The results indicate that normalized limb (male = 0.18 ± 0.07, female = 0.37 ± 0.10 kN · kg · m-1 and knee stiffness (male = 5.59 ± 2.02, female = 7.34 ± 1.78 Nm · kg · rad-1 were significantly greater in female runners. Conclusions. On the basis that normalized knee and limb stiffness were shown to be significantly greater in female runners, the findings from the current investigation may provide further insight into the aetiology of the distinct injury patterns observed between sexes.

Nephrotic Syndrome

Science.gov (United States)

... your blood — typically with an artificial kidney machine (dialyzer). Chronic kidney disease. Nephrotic syndrome may cause your ... opportunities Reprint Permissions A single copy of these materials may be reprinted for noncommercial personal use only. " ...

An L-stable method for solving stiff hydrodynamics

Science.gov (United States)

Li, Shengtai

2017-07-01

We develop a new method for simulating the coupled dynamics of gas and multi-species dust grains. The dust grains are treated as pressure-less fluids and their coupling with gas is through stiff drag terms. If an explicit method is used, the numerical time step is subject to the stopping time of the dust particles, which can become extremely small for small grains. The previous semi-implicit method [1] uses second-order trapezoidal rule (TR) on the stiff drag terms and it works only for moderately small size of the dust particles. This is because TR method is only A-stable not L-stable. In this work, we use TR-BDF2 method [2] for the stiff terms in the coupled hydrodynamic equations. The L-stability of TR-BDF2 proves essential in treating a number of dust species. The combination of TR-BDF2 method with the explicit discretization of other hydro terms can solve a wide variety of stiff hydrodynamics equations accurately and efficiently. We have implemented our method in our LA-COMPASS (Los Alamos Computational Astrophysics Suite) package. We have applied the code to simulate some dusty proto-planetary disks and obtained very good match with astronomical observations.

Hormones and arterial stiffness in patients with chronic kidney disease.

Science.gov (United States)

Gungor, Ozkan; Kircelli, Fatih; Voroneanu, Luminita; Covic, Adrian; Ok, Ercan

2013-01-01

Cardiovascular disease constitutes the major cause of mortality in patients with chronic kidney disease. Arterial stiffness is an important contributor to the occurrence and progression of cardiovascular disease. Various risk factors, including altered hormone levels, have been suggested to be associated with arterial stiffness. Based on the background that chronic kidney disease predisposes individuals to a wide range of hormonal changes, we herein review the available data on the association between arterial stiffness and hormones in patients with chronic kidney disease and summarize the data for the general population.

Cellular shear stiffness reflects progression of arsenic-induced transformation during G1

DEFF Research Database (Denmark)

Muñoz, Alexandra; Eldridge, Will J; Jakobsen, Nina Munkholt

2017-01-01

epithelial cells were exposed to sodium arsenite to initiate early stages of transformation. Exposed cells were cultured in soft agar to further transformation and select for clonal populations exhibiting anchorage independent growth. Shear stiffness of various cell populations in G1 was assessed using...... reduced stiffness relative to control clonal lines, which were cultured in soft agar but did not receive arsenic treatment. The relative standard deviation of the stiffness of Arsenic clones was reduced compared to control clones, as well as to the arsenic exposed cell population. Cell stiffness...

Research on a novel high stiffness axial passive magnetic bearing for DGMSCMG

International Nuclear Information System (INIS)

Sun, Jinji; Wang, Chun'e; Le, Yun

2016-01-01

To increase the displacement stiffness and decrease power loss of double gimbals magnetically suspended control momentum gyro (DGMSCMG), this paper researches a new structure of axial passive magnetic bearing (APMB). Different from the existing APMB, the proposed APMB is composed of segmented permanent magnets and magnetic rings. The displacement stiffness and angular stiffness expressions are derived by equivalent magnetic circuit method and infinitesimal method based on the end magnetic flux. The relationships are analyzed between stiffness and structure parameters such as length of air gap, length of permanent magnet, height of permanent magnet and end length of magnetic ring. Besides, the axial displacement stiffness measurement method of the APMB is proposed, and it verified the correctness of proposed theoretical method. The DGMSCMG prototype is manufactured and the slow-down characteristic experiment is carried out, and the experimental result reflects the low power loss feature of the APMB. - Highlights: • A novel high stiffness axial passive magnetic bearing for DGMSCMG. • The proposed APMB is composed of segmented permanent magnets and magnetic rings. • The APMB is analyzed by EMCM and infinitesimal method based on the end magnetic flux. • The axial displacement stiffness measurement method of the APMB is proposed. • The DGMSCMG is manufactured and proved the correctness of theoretical analysis.

Theoretical and experimental studies on in-plane stiffness of integrated container structure

Directory of Open Access Journals (Sweden)

Xiaoxiong Zha

2016-03-01

Full Text Available This article presents analytical, numerical, and experimental studies on the in-plane stiffness of container buildings. First, based on diaphragm theory, parallel corrugated direction stiffness of corrugated sheet has been deduced, and based on energy method, shear modulus of two elastic principal directions of orthotropic plate has been deduced, and through stiffness conversion method, the stiffness relationship between parallel corrugated direction and vertical corrugated direction has been obtained. Combined with container frame, the container stiffness of loading end and non-loading end, as bottom side beam fixed, has been obtained. Second, through the software Abaqus, full-scale container model has been established. The loading–displacement curve of finite element model has been compared with theoretical analysis and has a good agreement. Third, through 20 and 40 ft container, corresponding experimental verification has been done, and by comparison of container stiffness, the theoretical analysis and finite element simulation have been verified. Finally, based on verified finite element model, parametric analysis of corrugated sheet size, corrugated sheeting cross section, elasticity modulus of top side beam, and every plate action for container stiffness have been given. Research result has made feasible in design and construction of container buildings and can provide some references to corresponding specification preparation.

Usher's Syndrome: A 1986 Update.

Science.gov (United States)

Baechle, Cathy L.; Rittenhouse, Robert K.

The authors describe personal experiences with Usher's Syndrome, a condition involving visual impairment (due to Retinitis Pigmentosa) and deafness. Prevalence and onset of Usher's Syndrome are described along with characteristics of two different types. Problems connected with diagnosis are reviewed, including genetic aspects and the progressive…

Human arm stiffness and equilibrium-point trajectory during multi-joint movement.

Science.gov (United States)

Gomi, H; Kawato, M

1997-03-01

By using a newly designed high-performance manipulandum and a new estimation algorithm, we measured human multi-joint arm stiffness parameters during multi-joint point-to-point movements on a horizontal plane. This manipulandum allows us to apply a sufficient perturbation to subject's arm within a brief period during movement. Arm stiffness parameters were reliably estimated using a new algorithm, in which all unknown structural parameters could be estimated independent of arm posture (i.e., constant values under any arm posture). Arm stiffness during transverse movement was considerably greater than that during corresponding posture, but not during a longitudinal movement. Although the ratios of elbow, shoulder, and double-joint stiffness were varied in time, the orientation of stiffness ellipses during the movement did not change much. Equilibrium-point trajectories that were predicted from measured stiffness parameters and actual trajectories were slightly sinusoidally curved in Cartesian space and their velocity profiles were quite different from the velocity profiles of actual hand trajectories. This result contradicts the hypothesis that the brain does not take the dynamics into account in movement control depending on the neuromuscular servo mechanism; rather, it implies that the brain needs to acquire some internal models of controlled objects.

Sabot Front Borerider Stiffness vs. Dispersion: Finding the Knee in the Curve

Directory of Open Access Journals (Sweden)

Alan F. Hathaway

2001-01-01

Full Text Available In the design of armor piercing, fin-stabilized, discarding sabot projectiles, the radial stiffness of the sabot front borerider has a significant impact on the projectile's dispersion and is, therefore, an important design consideration. Whether designing a new projectile or trying to improve an existing design, projectile designers can achieve front borerider stiffness without understanding its affect on dispersion characteristics. There is a knee in the stiffness vs. dispersion curve at which a change in the sabot front borerider stiffness will have a significant impact on dispersion or no impact at all depending on whether the stiffness is increased or decreased. The subject of this paper is an analytical approach to quantitatively determine the knee in the curve. Results from using this approach on the M865 APFSDS projectile are also presented.

Knee joint stiffness in individuals with and without knee osteoarthritis: a preliminary study.

Science.gov (United States)

Oatis, Carol A; Wolff, Edward F; Lennon, Sandra K

2006-12-01

Descriptive, case-matched comparison. To compare the knee joint stiffness and damping coefficients of individuals with knee osteoarthritis (KOA) to those of age- and gender-matched individuals without KOA. A secondary purpose was to investigate relationships between these coefficients and complaints of stiffness in individuals with KOA. KOA is a leading cause of disability, and stiffness is a common complaint in individuals with KOA. Yet the most common method of assessing knee joint stiffness is through a self-report questionnaire. Stiffness and damping coefficients at the knee were calculated in 10 volunteers (mean age +/- SD, 64.1+/-15.5 years) with KOA and compared to coefficients from age-and gender-matched individuals without KOA, collected in a previous study (mean age +/- SD, 62.1+/-13.9 years). Stiffness and damping coefficients were calculated from the angular motion of the knee during a relaxed oscillation. Spearman correlation coefficients were calculated between stiffness and damping coefficients and WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) scores for subjects with KOA. Independent 2-tailed t tests revealed significantly larger damping coefficients (P = .035) among those with KOA (95% CI, 0.10-2.32 Nm s/rad). Spearman rank correlations revealed a significant positive relationship (r = .85, P = .003) between the damping coefficient and the stiffness subscore of the WOMAC. This study offers preliminary data demonstrating the feasibility of measuring stiffness and damping coefficients in individuals with KOA. Additionally, the damping coefficient is increased in people with KOA when compared to age- and gender-matched individuals without KOA. The damping coefficient appears to be associated with the complaints of stiffness reported by the WOMAC.

Evaluation of stiffness feedback for hard nodule identification on a phantom silicone model.

Science.gov (United States)

Li, Min; Konstantinova, Jelizaveta; Xu, Guanghua; He, Bo; Aminzadeh, Vahid; Xie, Jun; Wurdemann, Helge; Althoefer, Kaspar

2017-01-01

Haptic information in robotic surgery can significantly improve clinical outcomes and help detect hard soft-tissue inclusions that indicate potential abnormalities. Visual representation of tissue stiffness information is a cost-effective technique. Meanwhile, direct force feedback, although considerably more expensive than visual representation, is an intuitive method of conveying information regarding tissue stiffness to surgeons. In this study, real-time visual stiffness feedback by sliding indentation palpation is proposed, validated, and compared with force feedback involving human subjects. In an experimental tele-manipulation environment, a dynamically updated color map depicting the stiffness of probed soft tissue is presented via a graphical interface. The force feedback is provided, aided by a master haptic device. The haptic device uses data acquired from an F/T sensor attached to the end-effector of a tele-manipulated robot. Hard nodule detection performance is evaluated for 2 modes (force feedback and visual stiffness feedback) of stiffness feedback on an artificial organ containing buried stiff nodules. From this artificial organ, a virtual-environment tissue model is generated based on sliding indentation measurements. Employing this virtual-environment tissue model, we compare the performance of human participants in distinguishing differently sized hard nodules by force feedback and visual stiffness feedback. Results indicate that the proposed distributed visual representation of tissue stiffness can be used effectively for hard nodule identification. The representation can also be used as a sufficient substitute for force feedback in tissue palpation.

Evaluation of stiffness feedback for hard nodule identification on a phantom silicone model.

Directory of Open Access Journals (Sweden)

Min Li

Full Text Available Haptic information in robotic surgery can significantly improve clinical outcomes and help detect hard soft-tissue inclusions that indicate potential abnormalities. Visual representation of tissue stiffness information is a cost-effective technique. Meanwhile, direct force feedback, although considerably more expensive than visual representation, is an intuitive method of conveying information regarding tissue stiffness to surgeons. In this study, real-time visual stiffness feedback by sliding indentation palpation is proposed, validated, and compared with force feedback involving human subjects. In an experimental tele-manipulation environment, a dynamically updated color map depicting the stiffness of probed soft tissue is presented via a graphical interface. The force feedback is provided, aided by a master haptic device. The haptic device uses data acquired from an F/T sensor attached to the end-effector of a tele-manipulated robot. Hard nodule detection performance is evaluated for 2 modes (force feedback and visual stiffness feedback of stiffness feedback on an artificial organ containing buried stiff nodules. From this artificial organ, a virtual-environment tissue model is generated based on sliding indentation measurements. Employing this virtual-environment tissue model, we compare the performance of human participants in distinguishing differently sized hard nodules by force feedback and visual stiffness feedback. Results indicate that the proposed distributed visual representation of tissue stiffness can be used effectively for hard nodule identification. The representation can also be used as a sufficient substitute for force feedback in tissue palpation.

Cryotherapy induces an increase in muscle stiffness.

Science.gov (United States)

Point, M; Guilhem, G; Hug, F; Nordez, A; Frey, A; Lacourpaille, L

2018-01-01

Although cold application (ie, cryotherapy) may be useful to treat sports injuries and to prevent muscle damage, it is unclear whether it has adverse effects on muscle mechanical properties. This study aimed to determine the effect of air-pulsed cryotherapy on muscle stiffness estimated using ultrasound shear wave elastography. Myoelectrical activity, ankle passive torque, shear modulus (an index of stiffness), and muscle temperature of the gastrocnemius medialis were measured before, during an air-pulsed cryotherapy (-30°C) treatment of four sets of 4 minutes with 1-minute recovery in between and during a 40 minutes postcryotherapy period. Muscle temperature significantly decreased after the second set of treatment (10 minutes: 32.3±2.5°C; Pcryotherapy induces an increase in muscle stiffness. This acute change in muscle mechanical properties may lower the amount of stretch that the muscle tissue is able to sustain without subsequent injury. This should be considered when using cryotherapy in athletic practice. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The relationship between passive stiffness and evoked twitch properties: the influence of muscle CSA normalization

International Nuclear Information System (INIS)

Ryan, E D; Thompson, B J; Sobolewski, E J; Herda, T J; Costa, P B; Walter, A A; Cramer, J T

2011-01-01

Passive stiffness measurements are often used as a clinical tool to examine a muscle's passive lengthening characteristics. The purpose of this study was to examine the relationship between passive stiffness and evoked twitch properties prior to and following normalization of passive stiffness to muscle cross-sectional area (CSA). Ten healthy volunteers (mean ± SD age = 23 ± 3 year) performed passive range of motion, evoked twitch, and muscle CSA assessments of the plantar flexor muscles. Passive stiffness was determined from the slope of the final 5° of the angle–torque curve. Peak twitch torque (PTT) and rate of torque development (RTD) were determined via transcutaneous electrical stimulation, and muscle CSA was assessed using a peripheral quantitative computed tomography scanner. Pearson product moment correlation coefficients (r) were used to assess the relationships between passive stiffness and PTT and RTD and normalized passive stiffness (passive stiffness . muscle CSA −1 ) and PTT and RTD. Significant positive relationships were observed between passive stiffness and PTT (P = 0.003, r = 0.828) and RTD (P = 0.003, r = 0.825). There were no significant relationships between normalized passive stiffness and PTT (P = 0.290, r = 0.372) or RTD (P = 0.353, r = 0.329) demonstrating that stiffness did not account for a significant portion of the variance in twitch properties. Passive stiffness was largely influenced by the amount of muscle tissue in this study. Future studies that examine muscle stiffness and its relationship with performance measures, among different populations, and following various interventions may consider normalizing stiffness measurements to muscle CSA

Cushing's Syndrome

Science.gov (United States)

... person cured of Cushing’s syndrome might have some memory loss and slight mental decline. But the change is ... Categories: Family Health, Infants and Toddlers, Kids and Teens, Men, Seniors, WomenTags: acth, adenomas, hormone, sickness September ...

Stiffness Analysis and Comparison of 3-PPR Planar Parallel Manipulators with Actuation Compliance

DEFF Research Database (Denmark)

Wu, Guanglei; Bai, Shaoping; Kepler, Jørgen Asbøl

2012-01-01

In this paper, the stiffness of 3-PPR planar parallel manipulator (PPM) is analyzed with the consideration of nonlinear actuation compliance. The characteristics of the stiffness matrix pertaining to the planar parallel manipulators are analyzed and discussed. Graphic representation of the stiffn...... of the stiffness characteristics by means of translational and rotational stiffness mapping is developed. The developed method is illustrated with an unsymmetrical 3-PPR PPM, being compared with its structure-symmetrical counterpart....

Role of flexural stiffness of leukocyte microvilli in adhesion dynamics

Science.gov (United States)

Wu, Tai-Hsien; Qi, Dewei

2018-03-01

Previous work reported that microvillus deformation has an important influence on dynamics of cell adhesion. However, the existing studies were limited to the extensional deformation of microvilli and did not consider the effects of their bending deformation on cell adhesion. This Rapid Communication investigates the effects of flexural stiffness of microvilli on the rolling process related to adhesion of leukocytes by using a lattice-Boltzmann lattice-spring method (LLM) combined with adhesive dynamics (AD) simulations. The simulation results reveal that the flexural stiffness of microvilli and their bending deformation have a profound effect on rolling velocity and adhesive forces. As the flexural stiffness of the microvilli decreases, their bending angles increase, resulting in an increase in the number of receptor-ligand bonds and adhesive bonding force and a decrease in the rolling velocity of leukocytes. The effects of flexural stiffness on deformation and adhesion represent crucial factors involved in cell adhesion.

Down Syndrome = Sindrome de Down.

Science.gov (United States)

Pueschel, S. M.; Glasgow, R. E.

Presented both in English and Spanish, the brochure is primarily concerned with biological and developmental characteristics of the person with Down's syndrome. An emphasis is on the valuable humanizing influence these individuals have on society. Brief sections in the document discuss the delayed developmental aspects of Down's syndrome; the…

[A zoocentric Capgras syndrome].

Science.gov (United States)

Ehrt, U

1999-01-01

Capgras syndrome is a delusional misidentification, a phenomenon where a person believes delusionally that another person (in most cases closely related) has been replaced by a double or impostor of identical appearance. It is usually a symptom of a functional psychosis but sometimes it is also associated with organic cerebral dysfunction. We present a case of a 23-year old women who had the delusional belief that her cat had been replaced by the cat of her former boy-friend. Reviewing the literature we found that such a case is very rare. The association between Capgras syndrome and depersonalisation-derealisation phenomena is also pointed out.

Evaluation of arterial stiffness in nondiabetic chronic kidney disease patients

Directory of Open Access Journals (Sweden)

Bodanapu Mastanvalli

2017-01-01

Full Text Available Chronic kidney disease (CKD is a growing problem worldwide. Clinical and epidemiologic studies have shown that structural and functional changes that occur in major arteries are a major contributing factor to the high mortality in uremic patients. Recent studies have shown a stepwise increase of the carotid-femoral pulse wave velocity (cfPWV from CKD Stage 1 to Stage 5. We evaluated the cfPWV and augmentation index (AIx, as indirect markers of arterial stiffness in patients with nondiabetic CKD and compared the values with normal population; we also evaluated the relationship between various stages of CKD and arterial stiffness markers. This cross-sectional study was carried out in the Department of Nephrology for a duration of two years from January 15, 2012, to January 14, 2014. Fifty patients with nondiabetic CKD were studied along with 50 healthy volunteers who did not have CKD, who served as controls. Assessment of arterial stiffness (blood pressure, PWV, heart rate, aortic augmentation pressure, and AIx was performed using the PeriScope device. PWV positively correlated with systolic and diastolic blood pressure, mean aortic arterial pressure, serum creatinine, and serum uric acid and negatively correlated with estimated glomerular filtration rate. Arterial stiffness increased as CKD stage increased and was higher in nondiabetic CKD group than in the general population. Arterial stiffness progressed gradually from CKD Stage 2 to 5, and then abruptly, in dialysis patients. Measures to decrease the arterial stiffness and its influence on decreasing cardiovascular events need further evaluation.

Vascular Stiffness and Increased Pulse Pressure in the Aging Cardiovascular System

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Jochen Steppan

2011-01-01

Full Text Available Aging leads to a multitude of changes in the cardiovascular system, including systolic hypertension, increased central vascular stiffness, and increased pulse pressure. In this paper we will review the effects of age-associated increased vascular stiffness on systolic blood pressure, pulse pressure, augmentation index, and cardiac workload. Additionally we will describe pulse wave velocity as a method to measure vascular stiffness and review the impact of increased vascular stiffness as an index of vascular health and as a predictor of adverse cardiovascular outcomes. Furthermore, we will discuss the underlying mechanisms and how these may be modified in order to change the outcomes. A thorough understanding of these concepts is of paramount importance and has therapeutic implications for the increasingly elderly population.

One-loop potential in the new string model with negative stiffness

International Nuclear Information System (INIS)

Kleinert, H.; Chervyakov, A.M.; Nesterenko, V.V.

1996-01-01

The color-electric flux tube between quarks has a finite thickness therefore also a finite curvature stiffness. Contrary to earlier rigid-string proposal by Polyakov and Kleinert and motivated by the properties of a magnetic flux tube in a type-II superconductor, we put forward the hypothesis that the stiffness is negative. We set up and study the properties of an idealized string model with such negative stiffness. In contrast to the rigid string, the propagator in the new model has no unphysical pole. One-loop calculations show that the model generates an interquark potential which does not contain the square root singularity even for moderate values of a negative stiffness. At large distances, the potential has usual linearly rising term with the universal Luescher correction

A two-year follow-up case of chronic fatigue syndrome: substantial improvement in personality following a yoga-based lifestyle intervention.

Science.gov (United States)

Yadav, Raj Kumar; Sarvottam, Kumar; Magan, Dipti; Yadav, Rashmi

2015-04-01

Chronic Fatigue Syndrome (CFS) is characterized by excessive fatigue after minimal physical or mental exertion, muscle and joint pain, poor concentration, dizziness, and sleep disturbances. We report here the effect of a yoga-based lifestyle intervention in a 30-year old male patient with a documented diagnosis of CFS with compromised quality of life (QoL) and altered personality. The patient initially attended a short-term yoga-based lifestyle intervention program that consisted of yoga-postures, breathing exercises (pranayama), meditation, group discussions, and individualized advice on stress management, diet and physical activity besides group support. Thereafter, patient attended 5 more such programs. There was a notable and consistent improvement in his clinical profile, positive aspects of personality and subjective well-being, and reduction in anxiety following this yoga-based lifestyle intervention. Overall, the results suggest that lifestyle intervention may improve clinical condition and personality in patients with CFS.

MINIMUM BRACING STIFFNESS FOR MULTI-COLUMN SYSTEMS: THEORY

OpenAIRE

ARISTIZÁBAL-OCHOA, J. DARÍO

2011-01-01

A method that determines the minimum bracing stiffness required by a multi-column elastic system to achieve non-sway buckling conditions is proposed. Equations that evaluate the required minimum stiffness of the lateral and torsional bracings and the corresponding “braced" critical buckling load for each column of the story level are derived using the modified stability functions. The following effects are included: 1) the types of end connections (rigid, semirigid, and simple); 2) the bluepr...

Demens hos personer med Downs syndrom

DEFF Research Database (Denmark)

Salem, Lise Cronberg; Jørgensen, Kasper

2014-01-01

In developed countries the population of elderly people with Down syndrome expands resulting in an increasing incidence of age-related diseases, including dementia. The assessment of dementia in individuals with intellectual disability is often complicated due to large intra-individual variability...... in cognitive functioning prior to dementia and to lack of standardised measures to detect dementia. Structured observations of symptoms of dementia and assessment techniques tailored for people with intellectual disability are increasingly needed....

Online Identification and Verification of the Elastic Coupling Torsional Stiffness

Directory of Open Access Journals (Sweden)

Wanyou Li

2016-01-01

Full Text Available To analyze the torsional vibration of a diesel engine shaft, the torsional stiffness of the flexible coupling is a key kinetic parameter. Since the material properties of the elastic element of the coupling might change after a long-time operation due to the severe working environment or improper use and the variation of such properties will change dynamic feature of the coupling, it will cause a relative large calculation error of torsional vibration to the shaft system. Moreover, the torsional stiffness of the elastic coupling is difficult to be determined, and it is inappropriate to measure this parameter by disassembling the power unit while it is under normal operation. To solve these problems, this paper comes up with a method which combines the torsional vibration test with the calculation of the diesel shafting and uses the inherent characteristics of shaft torsional vibration to identify the dynamic stiffness of the elastic coupling without disassembling the unit. Analysis results show that it is reasonable and feasible to identify the elastic coupling dynamic torsional stiffness with this method and the identified stiffness is accurate. Besides, this method provides a convenient and practical approach to examine the dynamic behavior of the long running elastic coupling.

STUDIES ON THE SYNDROME OF FAT EMBOLIZATION.

Science.gov (United States)

SPROULE, B J; BRADY, J L; GILBERT, J A

1964-05-30

Three patients, all of whom were well-muscled young adult males who had suffered fractures of long bones, were studied by means of measurement of ventilatory function and arterial blood gases. They had degrees of mental change varying from mild confusion to stupor. Anemia, hypocalcemia, skin petechiae and radiologic pulmonary infiltrates were demonstrated in all three.In the absence of any clinical cyanosis, profound arterial O(2) desaturation was demonstrated in all. Physiologic studies indicated that the desaturation was the result of a diffusion defect early in the course of the syndrome and later from venous admixture. The lungs were stiff and the work of breathing was increased. The anemia appeared to be hemolytic in type.It is suggested that anemia, hypocalcemia and arterial O(2) desaturation may contribute significantly to the cerebral symptomatology associated with the syndrome of fat embolization.

The effect of eccentric and concentric calf muscle training on Achilles tendon stiffness.

Science.gov (United States)

Morrissey, Dylan; Roskilly, Anna; Twycross-Lewis, Richard; Isinkaye, Tomide; Screen, Hazel; Woledge, Roger; Bader, Dan

2011-03-01

To compare in vivo effects of eccentric and concentric calf muscle training on Achilles tendon stiffness, in subjects without tendinopathy. Thirty-eight recreational athletes completed 6 weeks eccentric (6 males, 13 females, 21.6  ±  2.2 years) or concentric training (8 males, 11 females, 21.1  ±  2.0 years). Achilles tendon stiffness, tendon modulus and single-leg jump height were measured before and after intervention. Exercise adherence was recorded using a diary. All data are reported as mean  ±  SD. Groups were matched for height and weight but the eccentric training group were more active at baseline (P Tendon stiffness was higher in the eccentrically trained group at baseline compared to the concentrically trained group (20.9  ±  7.3 N/mm v 13.38  ±  4.66 N/mm; P = 0.001) and decreased significantly after eccentric training (to 17.2 ( ±  5.9) N/mm (P = 0.035)). There was no stiffness change in the concentric group (P = 0.405). Stiffness modulus showed similar changes to stiffness. An inverse correlation was found between initial, and subsequent, reduction in stiffness (r = -0.66). Jump height did not change and no correlation between stiffness change and adherence was observed in either group (r = 0.01). Six weeks of eccentric training can alter Achilles tendon stiffness while a matched concentric programme shows no similar effects. Studies in patients with Achilles tendinopathy are warranted.

Matrix Stiffness Corresponding to Strictured Bowel Induces a Fibrogenic Response in Human Colonic Fibroblasts

Science.gov (United States)

Johnson, Laura A.; Rodansky, Eva S.; Sauder, Kay L.; Horowitz, Jeffrey C.; Mih, Justin D.; Tschumperlin, Daniel J.; Higgins, Peter D.

2013-01-01

Background Crohn’s disease is characterized by repeated cycles of inflammation and mucosal healing which ultimately progress to intestinal fibrosis. This inexorable progression towards fibrosis suggests that fibrosis becomes inflammation-independent and auto-propagative. We hypothesized that matrix stiffness regulates this auto-propagation of intestinal fibrosis. Methods The stiffness of fresh ex vivo samples from normal human small intestine, Crohn’s disease strictures, and the unaffected margin were measured with a microelastometer. Normal human colonic fibroblasts were cultured on physiologically normal or pathologically stiff matrices corresponding to the physiological stiffness of normal or fibrotic bowel. Cellular response was assayed for changes in cell morphology, α-smooth muscle actin (αSMA) staining, and gene expression. Results Microelastometer measurements revealed a significant increase in colonic tissue stiffness between normal human colon and Crohn’s strictures as well as between the stricture and adjacent tissue margin. In Ccd-18co cells grown on stiff matrices corresponding to Crohn’s strictures, cellular proliferation increased. Pathologic stiffness induced a marked change in cell morphology and increased αSMA protein expression. Growth on a stiff matrix induced fibrogenic gene expression, decreased matrix metalloproteinase and pro-inflammatory gene expression, and was associated with nuclear localization of the transcriptional cofactor MRTF-A. Conclusions Matrix stiffness, representative of the pathological stiffness of Crohn’s strictures, activates human colonic fibroblasts to a fibrogenic phenotype. Matrix stiffness affects multiple pathways suggesting the mechanical properties of the cellular environment are critical to fibroblast function and may contribute to autopropagation of intestinal fibrosis in the absence of inflammation, thereby contributing to the intractable intestinal fibrosis characteristic of Crohn’s disease. PMID

Delay-controlled primary and stochastic resonances of the SD oscillator with stiffness nonlinearities

Science.gov (United States)

Yang, Tao; Cao, Qingjie

2018-03-01

This work presents analytical studies of the stiffness nonlinearities SD (smooth and discontinuous) oscillator under displacement and velocity feedback control with a time delay. The SD oscillator can capture the qualitative characteristics of quasi-zero-stiffness and negative-stiffness. We focus mainly on the primary resonance of the quasi-zero-stiffness SD oscillator and the stochastic resonance (SR) of the negative-stiffness SD oscillator. Using the averaging method, we have been analyzed the amplitude response of the quasi-zero-stiffness SD oscillator. In this regard, the optimum time delay for changing the control intensity according to the optimization standard proposed can be obtained. For the optimum time delay, increasing the displacement feedback intensity is advantageous to suppress the vibrations in resonant regime where vibration isolation is needed, however, increasing the velocity feedback intensity is advantageous to strengthen the vibrations. Moreover, the effects of time-delayed feedback on the SR of the negative-stiffness SD oscillator are investigated under harmonic forcing and Gaussian white noise, based on the Langevin and Fokker-Planck approaches. The time-delayed feedback can enhance the SR phenomenon where vibrational energy harvesting is needed. This paper established the relationship between the parameters and vibration properties of a stiffness nonlinearities SD which provides the guidance for optimizing time-delayed control for vibration isolation and vibrational energy harvesting of the nonlinear systems.

Stiffness Matters: Part II - The Effects of Plate Stiffness on Load-Sharing and the Progression of Fusion Following ACDF In Vivo.

Science.gov (United States)

Peterson, Joshua M; Chlebek, Carolyn; Clough, Ashley M; Wells, Alexandra K; Batzinger, Kathleen E; Houston, John M; Kradinova, Katerina; Glennon, Joseph C; DiRisio, Darryl J; Ledet, Eric H

2018-03-19

Real time in vivo measurement of forces in the cervical spine of goats following anterior cervical discectomy and fusion (ACDF). To measure interbody forces in the cervical spine during the time course of fusion following ACDF with plates of different stiffnesses. Following ACDF, the biomechanics of the arthrodesis is largely dictated by the plate. The properties of the plate prescribe the extent of load-sharing through the disc space versus the extent of stress-shielding. Load-sharing promotes interbody bone formation and stress-shielding can inhibit maturation of bone. However, these principles have never been validated in vivo. Measuring in vivo biomechanics of the cervical spine is critical to understanding the complex relationships between implant design, interbody loading, load-sharing, and the progression of fusion. Anterior cervical plates of distinct bending stiffnesses were placed surgically following ACDF in goats. A validated custom force-sensing interbody implant was placed in the disc space to measure load-sharing in the spine. Interbody loads were measured in vivo in real time during the course of fusion for each plate. Interbody forces during flexion/extension were highly dynamic. In animals that received high stiffness plates, maximum forces were in extension whereas in animals that received lower stiffness plates, maximum forces were in flexion. As fusion progressed, interbody load magnitude decreased. The magnitude of interbody forces in the cervical spine is dynamic and correlates to activity and posture of the head and neck. The magnitude and consistency of forces in the interbody space correlates to plate stiffness with more compliant plates resulting in more consistent load-sharing. The magnitude of interbody forces decreases as fusion matures suggesting that smart interbody implants may be used as a diagnostic tool to indicate the progression of interbody fusion. N/A.

Probing the stiffness of isolated nucleoli by atomic force microscopy.

Science.gov (United States)

Louvet, Emilie; Yoshida, Aiko; Kumeta, Masahiro; Takeyasu, Kunio

2014-04-01

In eukaryotic cells, ribosome biogenesis occurs in the nucleolus, a membraneless nuclear compartment. Noticeably, the nucleolus is also involved in several nuclear functions, such as cell cycle regulation, non-ribosomal ribonucleoprotein complex assembly, aggresome formation and some virus assembly. The most intriguing question about the nucleolus is how such dynamics processes can occur in such a compact compartment. We hypothesized that its structure may be rather flexible. To investigate this, we used atomic force microscopy (AFM) on isolated nucleoli. Surface topography imaging revealed the beaded structure of the nucleolar surface. With the AFM's ability to measure forces, we were able to determine the stiffness of isolated nucleoli. We could establish that the nucleolar stiffness varies upon drastic morphological changes induced by transcription and proteasome inhibition. Furthermore, upon ribosomal proteins and LaminB1 knockdowns, the nucleolar stiffness was increased. This led us to propose a model where the nucleolus has steady-state stiffness dependent on ribosome biogenesis activity and requires LaminB1 for its flexibility.

Stiff, light, strong and ductile: nano-structured High Modulus Steel.

Science.gov (United States)

Springer, H; Baron, C; Szczepaniak, A; Uhlenwinkel, V; Raabe, D

2017-06-05

Structural material development for lightweight applications aims at improving the key parameters strength, stiffness and ductility at low density, but these properties are typically mutually exclusive. Here we present how we overcome this trade-off with a new class of nano-structured steel - TiB 2 composites synthesised in-situ via bulk metallurgical spray-forming. Owing to the nano-sized dispersion of the TiB 2 particles of extreme stiffness and low density - obtained by the in-situ formation with rapid solidification kinetics - the new material has the mechanical performance of advanced high strength steels, and a 25% higher stiffness/density ratio than any of the currently used high strength steels, aluminium, magnesium and titanium alloys. This renders this High Modulus Steel the first density-reduced, high stiffness, high strength and yet ductile material which can be produced on an industrial scale. Also ideally suited for 3D printing technology, this material addresses all key requirements for high performance and cost effective lightweight design.

MR elastography analysis of stiffness change induced by muscle contraction. President award proceedings

International Nuclear Information System (INIS)

Hata, Junichi; Yano, Keichi; Numano, Tomokazu; Yagi, Kazuo; Mizuhara, Kazuyuki; Washio, Toshikatsu; Homma, Kazuhiro; Takamoto, Koichi; Saijyo, Toshio

2012-01-01

Magnetic resonance elastography (MRE) was originally advocated in 1995 and has been the subject of recent attention. We employed MRE to characterize the stiffness of skeletal muscle of the lower thigh and changes in that stiffness. We obtained MRE images using a gradient recalled echo pulse sequence with parameters: repetition time (TR)/echo time (TE), 20/3.6 ms; number of excitations (NEX), 3; flip angle, 20deg; matrix, 512 x 512; scan time, 32 s; flex coil; and vibration frequency, 50 Hz. We made a vibration pad of 2 divergence types to excite the lower thigh from both sides evenly. When contraction and relaxation about the skeletal muscles, we enforced MRE. We drew regions of interest (ROI) on the stiffness images and measured it by using sclerometer to compare stiffness. We MRE enabled visualization of changes in the stiffness of skeletal muscles as a result of contraction and relaxation. The lateral gastrocnemius and soleus muscle demonstrated significant difference in stiffness at muscle contraction. MRE also permitted measurement of deep muscle using the muscle sclerometer. MRE allows evaluation of stiffness in a given biological section from the surface to deep tissue. (author)

The conundrum of arterial stiffness, elevated blood pressure, and aging.

Science.gov (United States)

AlGhatrif, Majd; Lakatta, Edward G

2015-02-01

Isolated systolic hypertension is a major health burden that is expanding with the aging of our population. There is evidence that central arterial stiffness contributes to the rise in systolic blood pressure (SBP); at the same time, central arterial stiffening is accelerated in patients with increased SBP. This bidirectional relationship created a controversy in the field on whether arterial stiffness leads to hypertension or vice versa. Given the profound interdependency of arterial stiffness and blood pressure, this question seems intrinsically challenging, or probably naïve. The aorta's function of dampening the pulsatile flow generated by the left ventricle is optimal within a physiological range of distending pressure that secures the required distal flow, keeps the aorta in an optimal mechanical conformation, and minimizes cardiac work. This homeostasis is disturbed by age-associated, minute alterations in aortic hemodynamic and mechanical properties that induce short- and long-term alterations in each other. Hence, it is impossible to detect an "initial insult" at an epidemiological level. Earlier manifestations of these alterations are observed in young adulthood with a sharp decline in aortic strain and distensibility accompanied by an increase in diastolic blood pressure. Subsequently, aortic mechanical reserve is exhausted, and aortic remodeling with wall stiffening and dilatation ensue. These two phenomena affect pulse pressure in opposite directions and different magnitudes. With early remodeling, there is an increase in pulse pressure, due to the dominance of arterial wall stiffness, which in turn accelerates aortic wall stiffness and dilation. With advanced remodeling, which appears to be greater in men, the effect of diameter becomes more pronounced and partially offsets the effect of wall stiffness leading to plateauing in pulse pressure in men and slower increase in pulse pressure (PP) than that of wall stiffness in women. The complex nature of

Cultural influences on personality.

Science.gov (United States)

Triandis, Harry C; Suh, Eunkook M

2002-01-01

Ecologies shape cultures; cultures influence the development of personalities. There are both universal and culture-specific aspects of variation in personality. Some culture-specific aspects correspond to cultural syndromes such as complexity, tightness, individualism, and collectivism. A large body of literature suggests that the Big Five personality factors emerge in various cultures. However, caution is required in arguing for such universality, because most studies have not included emic (culture-specific) traits and have not studied samples that are extremely different in culture from Western samples.

Evidence that breast tissue stiffness is associated with risk of breast cancer.

Science.gov (United States)

Boyd, Norman F; Li, Qing; Melnichouk, Olga; Huszti, Ella; Martin, Lisa J; Gunasekara, Anoma; Mawdsley, Gord; Yaffe, Martin J; Minkin, Salomon

2014-01-01

Evidence from animal models shows that tissue stiffness increases the invasion and progression of cancers, including mammary cancer. We here use measurements of the volume and the projected area of the compressed breast during mammography to derive estimates of breast tissue stiffness and examine the relationship of stiffness to risk of breast cancer. Mammograms were used to measure the volume and projected areas of total and radiologically dense breast tissue in the unaffected breasts of 362 women with newly diagnosed breast cancer (cases) and 656 women of the same age who did not have breast cancer (controls). Measures of breast tissue volume and the projected area of the compressed breast during mammography were used to calculate the deformation of the breast during compression and, with the recorded compression force, to estimate the stiffness of breast tissue. Stiffness was compared in cases and controls, and associations with breast cancer risk examined after adjustment for other risk factors. After adjustment for percent mammographic density by area measurements, and other risk factors, our estimate of breast tissue stiffness was significantly associated with breast cancer (odds ratio = 1.21, 95% confidence interval = 1.03, 1.43, p = 0.02) and improved breast cancer risk prediction in models with percent mammographic density, by both area and volume measurements. An estimate of breast tissue stiffness was associated with breast cancer risk and improved risk prediction based on mammographic measures and other risk factors. Stiffness may provide an additional mechanism by which breast tissue composition is associated with risk of breast cancer and merits examination using more direct methods of measurement.

Fibromyalgia syndrome: considerations for dental hygienists.

Science.gov (United States)

Walters, Amber; Tolle, Susan L; McCombs, Gayle M

2015-04-01

Fibromyalgia syndrome (FMS) is a neurosensory disorder characterized by widespread musculoskeletal pain. Typically persistent fatigue, depression, limb stiffness, non-refreshing sleep and cognitive deficiencies are also experienced. Oral symptoms and pain are common, requiring adaptations in patient management strategies and treatment interventions. Appropriate dental hygiene care of patients suffering with this disorder is contingent upon an understanding of disease epidemiology, pathophysiology, clinical characteristics, oral signs and symptoms, as well as treatment approaches. With this information dental hygienists will be better prepared to provide appropriate and effective treatment to patients with FMS. Copyright © 2015 The American Dental Hygienists’ Association.

A variable stiffness mechanism for steerable percutaneous instruments: integration in a needle.

Science.gov (United States)

De Falco, Iris; Culmone, Costanza; Menciassi, Arianna; Dankelman, Jenny; van den Dobbelsteen, John J

2018-06-04

Needles are advanced tools commonly used in minimally invasive medical procedures. The accurate manoeuvrability of flexible needles through soft tissues is strongly determined by variations in tissue stiffness, which affects the needle-tissue interaction and thus causes needle deflection. This work presents a variable stiffness mechanism for percutaneous needles capable of compensating for variations in tissue stiffness and undesirable trajectory changes. It is composed of compliant segments and rigid plates alternately connected in series and longitudinally crossed by four cables. The tensioning of the cables allows the omnidirectional steering of the tip and the stiffness tuning of the needle. The mechanism was tested separately under different working conditions, demonstrating a capability to exert up to 3.6 N. Afterwards, the mechanism was integrated into a needle, and the overall device was tested in gelatine phantoms simulating the stiffness of biological tissues. The needle demonstrated the capability to vary deflection (from 11.6 to 4.4 mm) and adapt to the inhomogeneity of the phantoms (from 21 to 80 kPa) depending on the activation of the variable stiffness mechanism. Graphical abstract ᅟ.

Fabrication of hydrogels with steep stiffness gradients for studying cell mechanical response.

Directory of Open Access Journals (Sweden)

Raimon Sunyer

Full Text Available Many fundamental cell processes, such as angiogenesis, neurogenesis and cancer metastasis, are thought to be modulated by extracellular matrix stiffness. Thus, the availability of matrix substrates having well-defined stiffness profiles can be of great importance in biophysical studies of cell-substrate interaction. Here, we present a method to fabricate biocompatible hydrogels with a well defined and linear stiffness gradient. This method, involving the photopolymerization of films by progressively uncovering an acrylamide/bis-acrylamide solution initially covered with an opaque mask, can be easily implemented with common lab equipment. It produces linear stiffness gradients of at least 115 kPa/mm, extending from ∼1 kPa to 240 kPa (in units of Young's modulus. Hydrogels with less steep gradients and narrower stiffness ranges can easily be produced. The hydrogels can be covalently functionalized with uniform coatings of proteins that promote cell adhesion. Cell spreading on these hydrogels linearly correlates with hydrogel stiffness, indicating that this technique effectively modifies the mechanical environment of living cells. This technique provides a simple approach that produces steeper gradients, wider rigidity ranges, and more accurate profiles than current methods.

Measurement of stiffness of standing trees and felled logs using acoustics: A review.

Science.gov (United States)

Legg, Mathew; Bradley, Stuart

2016-02-01

This paper provides a review on the use of acoustics to measure stiffness of standing trees, stems, and logs. An outline is given of the properties of wood and how these are related to stiffness and acoustic velocity throughout the tree. Factors are described that influence the speed of sound in wood, including the different types of acoustic waves which propagate in tree stems and lumber. Acoustic tools and techniques that have been used to measure the stiffness of wood are reviewed. The reasons for a systematic difference between direct and acoustic measurements of stiffness for standing trees, and methods for correction, are discussed. Other techniques, which have been used in addition to acoustics to try to improve stiffness measurements, are also briefly described. Also reviewed are studies which have used acoustic tools to investigate factors that influence the stiffness of trees. These factors include different silvicultural practices, geographic and environmental conditions, and genetics.

Response of stiff piles in sand to long-term cyclic lateral loading

DEFF Research Database (Denmark)

Bakmar, Christian LeBlanc; Houlsby, Guy T.; Byrne, Byron W.

2010-01-01

. To address this, a series of laboratory tests were conducted where a stiff pile in drained sand was subjected to between 8000 and 60000 cycles of combined moment and horizontal loading. A typical design for an offshore wind turbine monopile was used as a basis for the study, to ensure that pile dimensions...... and loading ranges were realistic. A complete non-dimensional framework for stiff piles in sand is presented and applied to interpret the test results. The accumulated rotation was found to be dependent on relative density and was strongly affected by the characteristics of the applied cyclic load. The pile...... stiffness increased with number of cycles, which contrasts with the current methodology where static p - y curves are degraded to account for cyclic loading. Methods are presented to predict the change in stiffness and the accumulated rotation of a stiff pile due to long-term cyclic loading. The use...

Vibration Isolation System Using Negative Stiffness(Advances in Motion and Vibration Control Technology)

OpenAIRE

水野, 毅; 高崎, 正也

2003-01-01

A new vibration isolation system using negative stiffness realized by active control technique is proposed in this paper. The serial connection of a normal spring and a suspension system with negative stiffness enables the isolation system to have low stiffness for vibration from the ground and high (theoretically infinite) stiffness against direct disturbance acting on the isolation table. A control method of realizing negative stiffness with a linear actuator is presented in an analytical f...

Modifiable risk factors for increased arterial stiffness in outpatient nephrology.

Directory of Open Access Journals (Sweden)

Usama Elewa

Full Text Available Arterial stiffness, as measured by pulse wave velocity (PWV, is an independent predictor of cardiovascular events and mortality. Arterial stiffness increases with age. However, modifiable risk factors such as smoking, BP and salt intake also impact on PWV. The finding of modifiable risk factors may lead to the identification of treatable factors, and, thus, is of interest to practicing nephrologist. We have now studied the prevalence and correlates of arterial stiffness, assessed by PWV, in 191 patients from nephrology outpatient clinics in order to identify modifiable risk factors for arterial stiffness that may in the future guide therapeutic decision-making. PWV was above normal levels for age in 85/191 (44.5% patients. Multivariate analysis showed that advanced age, systolic BP, diabetes mellitus, serum uric acid and calcium polystyrene sulfonate therapy or calcium-containing medication were independent predictors of PWV. A new parameter, Delta above upper limit of normal PWV (Delta PWV was defined to decrease the weight of age on PWV values. Delta PWV was calculated as (measured PWV - (upper limit of the age-adjusted PWV values for the general population. Mean±SD Delta PWV was 0.76±1.60 m/sec. In multivariate analysis, systolic blood pressure, active smoking and calcium polystyrene sulfonate therapy remained independent predictors of higher delta PWV, while age, urinary potassium and beta blocker therapy were independent predictors of lower delta PWV. In conclusion, arterial stiffness was frequent in nephrology outpatients. Systolic blood pressure, smoking, serum uric acid, calcium-containing medications, potassium metabolism and non-use of beta blockers are modifiable factors associated with increased arterial stiffness in Nephrology outpatients.

Study of stiffness and bearing capacity degradation of reinforced concrete beams under constant-amplitude fatigue.

Science.gov (United States)

Liu, Fangping; Zhou, Jianting; Yan, Lei

2018-01-01

For a reinforced concrete beam subjected to fatigue loads, the structural stiffness and bearing capacity will gradually undergo irreversible degeneration, leading to damage. Moreover, there is an inherent relationship between the stiffness and bearing capacity degradation and fatigue damage. In this study, a series of fatigue tests are performed to examine the degradation law of the stiffness and bearing capacity. The results pertaining to the stiffness show that the stiffness degradation of a reinforced concrete beam exhibits a very clear monotonic decreasing "S" curve, i.e., the stiffness of the beam decreases significantly at the start of the fatigue loading, it undergoes a linear decline phase in the middle for a long loading period, and before the failure, the bearing capacity decreases drastically again. The relationship between the residual stiffness and residual bearing capacity is determined based on the assumption that the residual stiffness and residual bearing capacity depend on the same damage state, and then, the bearing capacity degradation model of the reinforced concrete beam is established based on the fatigue stiffness. Through the established model and under the premise of the known residual stiffness degradation law, the degradation law of the bearing capacity is determined by using at least one residual bearing capacity test data, for which the parameters of the stiffness degradation function are considered as material constants. The results of the bearing capacity show that the bearing capacity degradation of the reinforced concrete beam also exhibits a very clear monotonic decreasing "S" curve, which is consistent with the stiffness degradation process and in good agreement with the experiment. In this study, the stiffness and bearing capacity degradation expressions are used to quantitatively describe their occurrence in reinforced concrete beams. In particular, the expression of the bearing capacity degradation can mitigate numerous

Longitudinal relaxation of initially straight flexible and stiff polymers

Science.gov (United States)

Dimitrakopoulos, Panagiotis; Dissanayake, Inuka

2004-11-01

The present talk considers the relaxation of a single flexible or stiff polymer chain from an initial straight configuration in a viscous solvent. This problem commonly arises when strong flows are turned off in both industrial and biological applications. The problem is also motivated by recent experiments with single biopolymer molecules relaxing after being fully extended by applied forces as well as by the recent development of micro-devices involving stretched tethered biopolymers. Our results are applicable to a wide array of synthetic polymers such as polyacrylamides, Kevlar and polyesters as well as biopolymers such as DNA, actin filaments, microtubules and MTV. In this talk we discuss the mechanism of the polymer relaxation as was revealed through Brownian Dynamics simulations covering a broad range of time scales and chain stiffness. After the short-time free diffusion, the chain's longitudinal reduction at early intermediate times is shown to constitute a universal behavior for any chain stiffness caused by a quasi-steady relaxation of tensions associated with the deforming action of the Brownian forces. Stiff chains are shown to exhibit a late intermediate-time longitudinal reduction associated with a relaxation of tensions affected by the deforming Brownian and the restoring bending forces. The longitudinal and transverse relaxations are shown to obey different laws, i.e. the chain relaxation is anisotropic at all times. In the talk, we show how from the knowledge of the relaxation mechanism, we can predict and explain the polymer properties including the polymer stress and the solution birefringence. In addition, a generalized stress-optic law is derived valid for any time and chain stiffness. All polymer properties which depend on the polymer length are shown to exhibit two intermediate-time behaviors with the early one to constitute a universal behavior for any chain stiffness. This work was supported in part by the Minta Martin Research Fund. The

Music decreases aortic stiffness and wave reflections.

Science.gov (United States)

Vlachopoulos, Charalambos; Aggelakas, Angelos; Ioakeimidis, Nikolaos; Xaplanteris, Panagiotis; Terentes-Printzios, Dimitrios; Abdelrasoul, Mahmoud; Lazaros, George; Tousoulis, Dimitris

2015-05-01

Music has been related to cardiovascular health and used as adjunct therapy in patients with cardiovascular disease. Aortic stiffness and wave reflections are predictors of cardiovascular risk. We investigated the short-term effect of classical and rock music on arterial stiffness and wave reflections. Twenty healthy individuals (22.5±2.5 years) were studied on three different occasions and listened to a 30-min music track compilation (classical, rock, or no music for the sham procedure). Both classical and rock music resulted in a decrease of carotid-femoral pulse wave velocity (PWV) immediately after the end of music listening (all pclassical or rock music in a more sustained way (nadir by 6.0% and 5.8%, respectively, at time zero post-music listening, all pmusic preference was taken into consideration, both classical and rock music had a more potent effect on PWV in classical aficionados (by 0.20 m/s, p=0.003 and 0.13 m/s, p=0.015, respectively), whereas there was no effect in rock aficionados (all p=NS). Regarding wave reflections, classical music led to a more potent response in classical aficionados (AIx decrease by 9.45%), whereas rock led to a more potent response to rock aficionados (by 10.7%, all pMusic, both classical and rock, decreases aortic stiffness and wave reflections. Effect on aortic stiffness lasts for as long as music is listened to, while classical music has a sustained effect on wave reflections. These findings may have important implications, extending the spectrum of lifestyle modifications that can ameliorate arterial function. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

A comparative study on free vibration analysis of delaminated torsion stiff and bending stiff composite shells

International Nuclear Information System (INIS)

Dey, Sudip; Karmakar, Amit

2013-01-01

This paper presents a finite element method to compare the effects of delamination on free vibration of graphite-epoxy bending stiff and torsion stiff composite pretwisted shallow conical shells. The generalized dynamic equilibrium equation is derived from Lagrange's equation of motion neglecting the Coriolis effect for moderate rotational speeds. An eight noded isoparametric plate bending element is employed incorporating rotary inertia and effects of transverse shear deformation based on Mindlin's theory. The multipoint constraint; algorithm is utilized to ensure the compatibility of deformation and equilibrium of resultant forces and moments at the delamination crack front. The standard eigen value problem is solved by applying the QR iteration algorithm. Mode shapes for typical configurations are also depicted. Numerical results obtained are the first known non-dimensional frequencies which could serve as reference solutions for the future investigators.

Dynamic Bending and Torsion Stiffness Derivation from Modal Curvatures and Torsion Rates

Science.gov (United States)

MAECK, J.; DE ROECK, G.

1999-08-01

In order to maintain the reliability of civil engineering structures, considerable effort is currently spent on developing a non-destructive vibration testing method for monitoring the structural integrity of constructions. The technique must be able to observe damage, secondly to localize the damage; and finally to give an idea of the severity of the damage. Within the framework of relating changes of measured modal parameters to changes in the integrity of the structure, it is important to be able to determine the dynamic stiffness in each section of the structure from measured modal characteristics.A damaged structure results in a dynamic stiffness reduction of the cracked sections. The dynamic stiffnesses provide directly an indication of the extension of the cracked zones in the structure. The dynamic stiffness reduction can also be associated with a degree of cracking in a particular zone.In an experimental programme, a concrete beam of 6 m length is subjected to an increasing static load to produce cracks. After each static perload, the beam is tested dynamically in a free-free set-up. The change in modal parameters is then related to damage in the beam.The technique that will be presented in the paper to predict the damage location and intensity is a direct stiffness derivation from measured modal displacement derivatives. Using the bending modes, the dynamic bending stiffness can be derived from modal curvatures. Using the torsional modes, the dynamic torsion stiffness can be derived from modal torsion rates.

Comparison of cervical spine stiffness in individuals with chronic nonspecific neck pain and asymptomatic individuals.

Science.gov (United States)

Ingram, Lewis A; Snodgrass, Suzanne J; Rivett, Darren A

2015-03-01

Clinical measurement, cross-sectional. To determine if spinal joint stiffness is different in individuals with nonspecific neck pain, and whether stiffness magnitude is associated with pain intensity and disability. Manual therapists commonly evaluate spinal joint stiffness in patients presenting with nonspecific neck pain. However, a relationship between stiffness and neck pain has not yet been demonstrated. Spinal stiffness at C7 was objectively measured in participants with chronic nonspecific neck pain whose symptomatic spinal level was identified as C7 (n = 12) and in age- and sex-matched asymptomatic controls (n = 12). Stiffness (slope of the linear region of the force-displacement curve) was quantified using a device that applied 5 standardized mechanical force cycles to the C7 spinous process, while concurrently measuring displacement and resistance to movement. Stiffness was compared between groups using an independent t test. Spearman rho and Pearson r were used to determine the extent to which stiffness magnitude was associated with pain intensity (visual analog scale) and level of disability (Neck Disability Index), respectively, in the group with neck pain. Participants with nonspecific neck pain had greater spinal joint stiffness at C7 compared with asymptomatic individuals (mean difference, 1.78 N/mm; 95% confidence interval: 0.28, 3.27; P = .022). However, stiffness magnitude in the group with neck pain was not associated (P>.05) with pain intensity or level of disability. These preliminary results suggest that cervical spine stiffness may be greater in the presence of nonspecific neck pain. However, judgments regarding pain intensity and level of disability should not be inferred from examinations of spinal joint stiffness.

A prototype of a novel energy efficient variable stiffness actuator

NARCIS (Netherlands)

Visser, L.C.; Carloni, Raffaella; Klijnstra, F.; Stramigioli, Stefano

In this work, we present a proof of concept of a novel variable stiffness actuator. The actuator design is based on the conceptual design proposed in earlier work, and is such that the apparent output stiffness of the actuator can be changed independently of the output position and without any

Inverse axial mounting stiffness design for lithographic projection lenses.

Science.gov (United States)

Wen-quan, Yuan; Hong-bo, Shang; Wei, Zhang

2014-09-01

In order to balance axial mounting stiffness of lithographic projection lenses and the image quality under dynamic working conditions, an easy inverse axial mounting stiffness design method is developed in this article. Imaging quality deterioration at the wafer under different axial vibration levels is analyzed. The desired image quality can be determined according to practical requirements, and axial vibrational tolerance of each lens is solved with the damped least-squares method. Based on adaptive interval adjustment, a binary search algorithm, and the finite element method, the axial mounting stiffness of each lens can be traveled in a large interval, and converges to a moderate numerical solution which makes the axial vibrational amplitude of the lens converge to its axial vibrational tolerance. Model simulation is carried out to validate the effectiveness of the method.

Bio-inspired composites with functionally graded platelets exhibit enhanced stiffness.

Science.gov (United States)

Tapse, Sanjay; S, Anup

2017-11-09

Unidirectional composites inspired from biological materials such as nacre, are composed of stiff platelets arranged in a staggered manner within a soft matrix. Elaborate analyses have been conducted on the aforementioned composites and they are found to have excellent mechanical properties like stiffness, strength and fracture toughness. The superior properties exhibited by these composites have been proved to be the result of its unique structure. An emerging development in the field of composite structures is Functionally Graded Composites(FGC), whose properties vary spatially and possess enhanced thermo-mechanical properties. In this paper, the platelets are functionally graded with its Young's Modulus varying parabolically along the length. Two different models - namely, Tension Shear Chain Model and Minimisation of Complementary Energy Model have been employed to obtain the stiffness of the overall composite analytically. The effect of various parameters that define the composite model such as overlapping length between any two neighbouring platelets, different gradation parameters and platelet aspect ratio on the overall mechanical properties have been studied. Composites with functionally graded platelets are found to possess enhanced stiffness (upto 14% higher) for certain values of these parameters. The obtained solutions have been validated using Finite Element Analysis. Bio-inspired composites with functionally graded platelets can be engineered for structural applications, such as in automobile, aerospace and aircraft industry, where stiffness plays a crucial role. © 2017 IOP Publishing Ltd.

Electrothermally Actuated Microbeams With Varying Stiffness

KAUST Repository

Tella, Sherif Adekunle

2017-11-03

We present axially loaded clamped-guided microbeams that can be used as resonators and actuators of variable stiffness, actuation, and anchor conditions. The applied axial load is implemented by U-shaped electrothermal actuators stacked at one of the beams edges. These can be configured and wired in various ways, which serve as mechanical stiffness elements that control the operating resonance frequency of the structures and their static displacement. The experimental results have shown considerable increase in the resonance frequency and mid-point deflection of the microbeam upon changing the end conditions of the beam. These results can be promising for applications requiring large deflection and high frequency tunability, such as filters, memory devices, and switches. The experimental results are compared to multi-physics finite-element simulations showing good agreement among them.

Substrate stiffness promotes latent TGF-β1 activation in hepatocellular carcinoma

International Nuclear Information System (INIS)

Pang, Mingshu; Teng, Yao; Huang, Jianyong; Yuan, Yuan; Lin, Feng; Xiong, Chunyang

2017-01-01

Hepatocellular carcinoma (HCC) was usually coupled with increased stiffness of the extracellular matrix (ECM) and elevated level of transforming growth factor-β1 (TGF-β1). However, the mechanism by which substrate rigidity modulated TGF-β1 signaling transduction remained unknown. This paper investigated the molecular mechanism of how matrix stiffness regulating TGF-β1 signaling in HCC cells. By means of stiffness tunable collagen I-coated polyacrylamide (PA) gels, we found that the expressions of β1 integrin, p-FAK Y397 and p-Smad2 upregulated on stiffer gels as well as the content of TGF-β1 in culture media of HCC cells, which were inhibited by RGD blocking peptides, Y-27632 (ROCK inhibitor) or Blebbistatin (myosin II inhibitor). Cellular traction force was also significantly higher when plated on stiffer substrates but dramatically decreased after treatment with Y-27632 or Blebbistatin. Furthermore, the upregulation of p-Smad2 in the HCC cells on stiffer PA gels induced by exogenetic latent TGF-β1 was downregulated in the presence of RGD peptides. The nuclear translocation of Smad2 induced by latent TGF-β1 was inhibited by Y-27632 or Blebbistatin. Our results suggested that the extracellular matrix stiffness regulated latent TGF-β1 activation by cytoskeletal tension in HCC cells, showing that matrix stiffness was a key regulator involving the TGF-β1 activity in HCC cells. The current study presented a mechanism of how hepatocirrhosis developed into liver cancer. - Highlights: • TGF-β1 signaling pathway regulated by ECM stiffness was studied in hepatocellular carcinoma. • Matrix stiffness promoted latent TGF-β1 activation via β1 integrin-FAK-Rho GTPase pathway. • A mechanism of how hepatocirrhosis developed into liver cancer was presented.

Investigating the effect of cell substrate on cancer cell stiffness by optical tweezers.

Science.gov (United States)

Yousafzai, Muhammad Sulaiman; Coceano, Giovanna; Bonin, Serena; Niemela, Joseph; Scoles, Giacinto; Cojoc, Dan

2017-07-26

The mechanical properties of cells are influenced by their microenvironment. Here we report cell stiffness alteration by changing the cell substrate stiffness for isolated cells and cells in contact with other cells. Polydimethylsiloxane (PDMS) is used to prepare soft substrates with three different stiffness values (173, 88 and 17kPa respectively). Breast cancer cells lines, namely HBL-100, MCF-7 and MDA-MB-231 with different level of aggressiveness are cultured on these substrates and their local elasticity is investigated by vertical indentation of the cell membrane. Our preliminary results show an unforeseen behavior of the MDA-MB-231 cells. When cultured on glass substrate as isolated cells, they are less stiff than the other two types of cells, in agreement with the general statement that more aggressive and metastatic cells are softer. However, when connected to other cells the stiffness of MDA-MB-231 cells becomes similar to the other two cell lines. Moreover, the stiffness of MDA-MB-231 cells cultured on soft PDMS substrates is significantly higher than the stiffness of the other cell types, demonstrating thus the strong influence of the environmental conditions on the mechanical properties of the cells. Copyright © 2017. Published by Elsevier Ltd.

Comparative study on stiffness properties of WOODCAST and conventional casting materials.

Science.gov (United States)

Pirhonen, Eija; Pärssinen, Antti; Pelto, Mika

2013-08-01

Plaster-of-Paris and synthetic materials (e.g. fibreglass) have been in clinical use as casting materials for decades. An innovative casting material, WOODCAST, brings interesting alternatives to the traditional materials. The aim of this study was to compare the stiffness properties of the WOODCAST material to traditional casting materials. In immobilization by casting, materials with variable stiffness properties are required. Ring stiffness of cylindrical samples correlates well with cast rigidity. For load-bearing structures, the use of the WOODCAST Splint is recommended as equally high stiffness was obtained with the WOODCAST Splint as was with fibreglass. The WOODCAST 2 mm product is optimal for structures where some elasticity is required, and WOODCAST Ribbon can be used in any WOODCAST structure where further reinforcement is needed. The results show that WOODCAST material can be used in replacing traditional casting materials used in extremity immobilization. The mechanical properties of casting material play an important role in safe and effective fracture immobilization. Stiffness properties of the WOODCAST casting material and conventional materials - fibreglass and plaster-of-Paris - were analysed in this study. The WOODCAST Splint appears to compare favorably with traditional materials such as Scotchcast.

Inheritance and performance of the stiff-strawed mutant in Vicia faba L

International Nuclear Information System (INIS)

Frauen, M.; Sass, O.

1990-01-01

Full text: The tall and leafy types are considered to produce more vegetative mass than is necessary for high grain yield. A mutant with stunted growth, smaller leaves with dark green colour, and a stiff stem showing excellent lodging resistance, found special interest among breeders. This stiff-stem growth-type was selected as a spontaneous mutation in a breeding population. A stiff-stem line was crossed with the varieties 'Alfred' and 'Minica'. The stiff-stem recombinants showed a 20% shorter plant height, excellent lodging resistance, higher harvest index and a promise of 30% yield increase. The monogenic inheritance of the mutant trait is an advantage for further breeding work. We propose the symbol st for the new allele. (author)

Use of medications by people with chronic fatigue syndrome and healthy persons: a population-based study of fatiguing illness in Georgia.

Science.gov (United States)

Boneva, Roumiana S; Lin, Jin-Mann S; Maloney, Elizabeth M; Jones, James F; Reeves, William C

2009-07-20

Chronic fatigue syndrome (CFS) is a debilitating condition of unknown etiology and no definitive pharmacotherapy. Patients are usually prescribed symptomatic treatment or self-medicate. We evaluated prescription and non-prescription drug use among persons with CFS in Georgia and compared it to that in non-fatigued Well controls and also to chronically Unwell individuals not fully meeting criteria for CFS. A population-based, case-control study. To identify persons with possible CFS-like illness and controls, we conducted a random-digit dialing telephone screening of 19,807 Georgia residents, followed by a detailed telephone interview of 5,630 to identify subjects with CFS-like illness, other chronically Unwell, and Well subjects. All those with CFS-like illness (n = 469), a random sample of chronically Unwell subjects (n = 505), and Well individuals (n = 641) who were age-, sex-, race-, and geographically matched to those with CFS-like illness were invited for a clinical evaluation and 783 participated (48% overall response rate). Clinical evaluation identified 113 persons with CFS, 264 Unwell subjects with insufficient symptoms for CFS (named ISF), and 124 Well controls; the remaining 280 subjects had exclusionary medical or psychiatric conditions, and 2 subjects could not be classified. Subjects were asked to bring all medications taken in the past 2 weeks to the clinic where a research nurse viewed and recorded the name and the dose of each medication. More than 90% of persons with CFS used at least one drug or supplement within the preceding two weeks. Among users, people with CFS used an average of 5.8 drugs or supplements, compared to 4.1 by ISF and 3.7 by Well controls. Persons with CFS were significantly more likely to use antidepressants, sedatives, muscle relaxants, and anti-acids than either Well controls or the ISF group. In addition, persons with CFS were significantly more likely to use pain-relievers, anti-histamines and cold/sinus medications than

Controlling cyclic stiffness of a foundation, by manipulating the deformation history

DEFF Research Database (Denmark)

Sabaliauskas, Tomas; Ibsen, Lars Bo

2018-01-01

Offshore wind turbines are slender structures, dynamic response of which depends on foundation stiffness. Unfortunately, foundations embedded in sand can become disturbed, their stiffness can increase and decrease episodically. To investigate the phenomenon governing loss and recovery of stiffnes...

Contact stiffness considerations when simulating tyre/road noise

Science.gov (United States)

Winroth, Julia; Kropp, Wolfgang; Hoever, Carsten; Höstmad, Patrik

2017-11-01

Tyre/road simulation tools that can capture tyre vibrations, rolling resistance and noise generation are useful for understanding the complex processes that are involved and thereby promoting further development and optimisation. The most detailed tyre/road contact models use a spatial discretisation of the contact and assume an interfacial stiffness to account for the small-scale roughness within the elements. This interfacial stiffness has been found to have a significant impact on the simulated noise emissions but no thorough investigations of this sensitivity have been conducted. Three mechanisms are thought to be involved: The horn effect, the modal composition of the vibrational field of the tyre and the contact forces exciting the tyre vibrations. This study used a numerical tyre/road noise simulation tool based on physical relations to investigate these aspects. The model includes a detailed time-domain contact model with linear or non-linear contact springs that accounts for the effect of local tread deformation on smaller length scales. Results confirm that an increase in contact spring stiffness causes a significant increase of the simulated tyre/road noise. This is primarily caused by a corresponding increase in the contact forces, resulting in larger vibrational amplitudes. The horn effect and the modal composition are relatively unaffected and have minor effects on the radiated noise. A more detailed non-linear contact spring formulation with lower stiffness at small indentations results in a reduced high-frequency content in the contact forces and the simulated noise.

Force and stiffness characteristics of superconducting bearing prototype

International Nuclear Information System (INIS)

Matveev, V.; Nizhelskiy, N.; Poluschenko, O.

2004-01-01

The radial-axial superconducting bearing prototype was designed, fabricated and tested. The YBaCuO high-temperature superconducting (HTS) monodomain disks diameter 28 mm and thickness of h = 4; 6; 8; 10 mm, capable to trap magnetic field 1 T, were fabricated to be employed in bearing prototype. Force interaction of single field cooled HTS disks with NdFeB magnets depending on disk thickness under 1 mm magnet air gap was studied. It was found that the increase in disk thickness results in reducing radial stiffness and in growing axial one. The results obtained were used for optimization of HTS-PM arrangement, and for developing the bearing design. The designed bearing incorporates a rotor with 7 HTS disks of 4 mm thickness, total mass 90 g, and stator with two pairs of permanent annular magnets of NdFeB. It is established that the force-displacement dependencies of the bearing have three zones: non-hysteresis (elastic) zone with high stiffness up to 560 N/mm; zone of elastic interaction with stiffness 190 N/mm; hysteretic zone with stiffness 150 N/mm in which a rotor residual displacement being observed after unloading. The outer bearing diameter is 130 mm, thickness 30 mm, and mass 1.8 kg. The maximal radial load capacity of the bearing is 190 N at the rotor displacement of 1.3 mm, and the maximal axial load capacity is 85 N at the displacement of 1 mm

Fenton's syndrome

International Nuclear Information System (INIS)

Rimondi, E.; Albasini, V.

1989-01-01

The authors report two recent cases of Fenton's syndrome, a very rare carpal fracture-dislocation. After some anatomophysiopathological considerations and a review of the literature, a wider nosographic frame is proposed in which the entity of the dislocation of the head of capitate bone is not essential. According to both the literature and personal findings, the authors remark that this syndrome is always found in the presence of two morphological variants of the distal radioulnar joint. Finally, the authors stress the importance of a corect diagnosis of this lesion to avoid unnecessary attempts of reduction

Measurements of the weak bonding interfacial stiffness by using air-coupled ultrasound

Directory of Open Access Journals (Sweden)

Wen-Lin Wu

2017-12-01

Full Text Available An air-coupled ultrasonic method, focusing on the problem that weak bonding interface is difficult to accurately measure using conventional nondestructive testing technique, is proposed to evaluate the bond integrity. Based on the spring model and the potential function theory, a theoretical model is established to predict the through-transmission spectrum in double-layer adhesive structure. The result of a theoretical algorithm shows that all the resonant transmission peaks move towards higher frequency with the increase of the interfacial stiffness. The reason for these movements is related to either the normal stiffness (KN or the transverse stiffness (KT. A method to optimize the measurement parameters (i.e. the incident angle and testing frequency is put forward through analyzing the relationship between the resonant transmission peaks and the interfacial spring stiffness at the frequency below 1MHz. The air-coupled ultrasonic testing experiments at the normal and oblique incident angle respectively are carried out to verify the theoretical analysis and to accurately measure the interfacial stiffness of double-layer adhesive composite plate. The experimental results are good agreement with the results from the theoretical algorithm, and the relationship between bonding time and interfacial stiffness is presented at the end of this paper.

Shoe midsole longitudinal bending stiffness and running economy, joint energy, and EMG.

Science.gov (United States)

Roy, Jean-Pierre R; Stefanyshyn, Darren J

2006-03-01

It has been shown that mechanical energy is dissipated at the metatarsophalangeal (MTP) joint during running and jumping. Furthermore, increasing the longitudinal bending stiffness of the midsole significantly reduced the energy dissipated at the MTP joint and increased jump performance. It was hypothesized that increasing midsole longitudinal bending stiffness would also lead to improvements in running economy. This study investigated the influence of midsole longitudinal bending stiffness on running economy (performance variable) and evaluated the local effects on joint energetics and muscular activity. Carbon fiber plates were inserted into running shoe midsoles and running economy, joint energy, and electromyographic (EMG) data were collected on 13 subjects. Approximately a 1% metabolic energy savings was observed when subjects ran in a stiff midsole relative to the control midsole. Subjects with a greater body mass had a greater decrease in oxygen consumption rates in the stiff midsole relative to the control midsole condition. The stiffer midsoles showed no significant differences in energy absorption at the MTP joint compared with the control shoe. Finally, no significant changes were observed in muscular activation. Increasing midsole longitudinal bending stiffness led to improvements in running economy, yet the underlying mechanisms that can be attributed to this improvement are still not fully understood.

Three new models for evaluation of standard involute spur gear mesh stiffness

Science.gov (United States)

Liang, Xihui; Zhang, Hongsheng; Zuo, Ming J.; Qin, Yong

2018-02-01

Time-varying mesh stiffness is one of the main internal excitation sources of gear dynamics. Accurate evaluation of gear mesh stiffness is crucial for gear dynamic analysis. This study is devoted to developing new models for spur gear mesh stiffness evaluation. Three models are proposed. The proposed model 1 can give very accurate mesh stiffness result but the gear bore surface must be assumed to be rigid. Enlighted by the proposed model 1, our research discovers that the angular deflection pattern of the gear bore surface of a pair of meshing gears under a constant torque basically follows a cosine curve. Based on this finding, two other models are proposed. The proposed model 2 evaluates gear mesh stiffness by using angular deflections at different circumferential angles of an end surface circle of the gear bore. The proposed model 3 requires using only the angular deflection at an arbitrary circumferential angle of an end surface circle of the gear bore but this model can only be used for a gear with the same tooth profile among all teeth. The proposed models are accurate in gear mesh stiffness evaluation and easy to use. Finite element analysis is used to validate the accuracy of the proposed models.

Tourette Syndrome: Classroom Implications

Science.gov (United States)

Chaturvedi, Amrita; Gartin, Barbara C.; Murdick, Nikki L.

2011-01-01

Tourette Syndrome (TS) is a neurobiological disorder characterized by various involuntary motor movements and vocal tics. Symptoms of TS emerge between the ages of 3 to 8 years old, are most severe when an individual reaches puberty, and decrease by the time a person is 20 years old. Additionally, persons with TS may have secondary disabilities of…

Artificial neural networks for stiffness estimation in magnetic resonance elastography.

Science.gov (United States)

Murphy, Matthew C; Manduca, Armando; Trzasko, Joshua D; Glaser, Kevin J; Huston, John; Ehman, Richard L

2018-07-01

To investigate the feasibility of using artificial neural networks to estimate stiffness from MR elastography (MRE) data. Artificial neural networks were fit using model-based training patterns to estimate stiffness from images of displacement using a patch size of ∼1 cm in each dimension. These neural network inversions (NNIs) were then evaluated in a set of simulation experiments designed to investigate the effects of wave interference and noise on NNI accuracy. NNI was also tested in vivo, comparing NNI results against currently used methods. In 4 simulation experiments, NNI performed as well or better than direct inversion (DI) for predicting the known stiffness of the data. Summary NNI results were also shown to be significantly correlated with DI results in the liver (R 2  = 0.974) and in the brain (R 2  = 0.915), and also correlated with established biological effects including fibrosis stage in the liver and age in the brain. Finally, repeatability error was lower in the brain using NNI compared to DI, and voxel-wise modeling using NNI stiffness maps detected larger effects than using DI maps with similar levels of smoothing. Artificial neural networks represent a new approach to inversion of MRE data. Summary results from NNI and DI are highly correlated and both are capable of detecting biologically relevant signals. Preliminary evidence suggests that NNI stiffness estimates may be more resistant to noise than an algebraic DI approach. Taken together, these results merit future investigation into NNIs to improve the estimation of stiffness in small regions. Magn Reson Med 80:351-360, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Longitudinal Changes in Segmental Aortic Stiffness Determined by Cardiac Magnetic Resonance in Children and Young Adults With Connective Tissue Disorders (the Marfan, Loeys-Dietz, and Ehlers-Danlos Syndromes, and Nonspecific Connective Tissue Disorders).

Science.gov (United States)

Merlocco, Anthony; Lacro, Ronald V; Gauvreau, Kimberlee; Rabideau, Nicole; Singh, Michael N; Prakash, Ashwin

2017-10-01

Aortic stiffness measured by cardiac magnetic resonance (CMR) in connective tissue disorder (CTD) patients has been previously shown to be abnormal and to be associated with adverse aortic outcomes. The rate of increase in aortic stiffness with normal aging has been previously described. However, longitudinal changes in aortic stiffness have not been characterized in CTD patients. We examined longitudinal changes in CMR-derived aortic stiffness in children and young adults with CTDs. A retrospective analysis of 50 children and young adults (median age, 20 years; range, 0.2 to 49; 40% age, whereas the β stiffness index increased at all aortic segments. The average rates of decline in distensibility (x10 -3  mm Hg -1 per 10-year increase in age) were 0.7, 1.3, and 1 at the AoR, ascending aorta, and descending aorta, respectively. The rates of decline in distensibility were not associated with the rates of AoR dilation or surgical AoR replacement. In conclusion, on serial CMR measurements in children and young adults with CTDs, aortic stiffness progressively increased with age, with rates of change only slightly higher than those previously reported in healthy adults. Copyright © 2017 Elsevier Inc. All rights reserved.

Integración por cuantificación de sistemas stiff

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Gustavo Migoni

2007-07-01

Full Text Available Resumen: Este artículo presenta un nuevo método de integración numérica de ecuaciones diferenciales ordinarias basado en la cuantificación de las variables de estado. Utilizando conceptos de integración implícita, el nuevo método denominado BQSS (Backward Quantized State Systems permite integrar sistemas stiff de manera eficiente. Siendo el primer método de cuantificación para sistemas stiff, BQSS es en sí un método explícito, por lo que la contribución es importante en el contexto general de los métodos de integración numérica. Además de presentar el método, el artículo estudia las principales propiedades teóricas del mismo, aborda aspectos prácticos de la implementación del algoritmo y presenta resultados de simulación sobre dos sistemas stiff. Palabras clave: Métodos de Integración Numérica, Sistemas Stiff, Integración por Cuantificación

Treatment of Hantavirus Pulmonary Syndrome

Science.gov (United States)

2007-10-14

femoral artery and vein. The bed is versity of New Mexico. . Antiviral therapy Ribavirin was tested for efficacy in HFRS patients in China nd shown to...Weis- senbacher, M.C., 1996. Hantavirus pulmonary syndrome in Argentina. Possibility of person to person transmission. Medicina (B. Aires) 56, 709–711

Comparative numerical solutions of stiff Ordinary differential equations using magnus series expansion method

Directory of Open Access Journals (Sweden)

SURE KÖME

2014-12-01

Full Text Available In this paper, we investigated the effect of Magnus Series Expansion Method on homogeneous stiff ordinary differential equations with different stiffness ratios. A Magnus type integrator is used to obtain numerical solutions of two different examples of stiff problems and exact and approximate results are tabulated. Furthermore, absolute error graphics are demonstrated in detail.

An EKF-based approach for estimating leg stiffness during walking.

Science.gov (United States)

Ochoa-Diaz, Claudia; Menegaz, Henrique M; Bó, Antônio P L; Borges, Geovany A

2013-01-01

The spring-like behavior is an inherent condition for human walking and running. Since leg stiffness k(leg) is a parameter that cannot be directly measured, many techniques has been proposed in order to estimate it, most of them using force data. This paper intends to address this problem using an Extended Kalman Filter (EKF) based on the Spring-Loaded Inverted Pendulum (SLIP) model. The formulation of the filter only uses as measurement information the Center of Mass (CoM) position and velocity, no a priori information about the stiffness value is known. From simulation results, it is shown that the EKF-based approach can generate a reliable stiffness estimation for walking.

Influence of inhaled nicotine source on arterial stiffness.

Science.gov (United States)

Szołtysek-Bołdys, Izabela; Sobczak, Andrzej; Zielińska-Danch, Wioleta; Bartoń, Aleksandra; Koszowski, Bartosz; Kośmider, Leon

2014-01-01

Tobacco smoking leads to changes in hemodynamic parameters such as heart rate and systolic or diastolic blood pressure. It has a direct influence on the elasticity of blood vessels and increases arterial stiffness, which can result in development of atherosclerosis. Data show that the nicotine in tobacco smoke probably is responsible for these changes. Electronic cigarettes (e-cigarettes) were supposedly a healthier alternative to combustible cigarettes because they imitate a process of cigarettes smoking but generate nicotine aerosol without the toxic substances from tobacco combustion. However, the use of e-cigarettes is still controversial because their toxicity, safety and long term use health impact have not been sufficiently studied. The aim of this study was to evaluate changes in arterial stiffness parameters after smoking a cigarette or e-cigarette use. Fifteen healthy women, aged 19-25 years old, smoking ≥5 cigarettes per day for at least two years participated in the study. A non-invasive measurement of arterial stiffness parameters - Stiffness Index (SI) and Reflection Index (RI) - was conducted and systolic and diastolic blood pressure and heart rate were measured before and after smoking a conventional cigarette as well as use of an e-cigarette. Statistically significant changes in the SI and RI were observed before and after smoking of a conventional cigarette [SI: 6.75m/s (6.66 - 6.85, 95% CI) vs 6.56m/s (6.46 - 6.65. 95% CI), p=0.0056; RI: 54.0% (51.5 - 56.7, 95% CI) vs 49.6% (47.5 - 51.8, 95% CI), p=0.010]. The use of e-cigarettes resulted in no statistically significant changes in the SI and RI. After both product use systolic and diastolic blood pressure and heart rate increased but the changes were not statistically significant. In contrast to conventional cigarette use, the use of electronic cigarettes causes no changes in arterial stiffness. This may indicate lower bioavailability of nicotine from the e-cigarette or an additional effect of

Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

Science.gov (United States)

Worsley, Marcus A.; Kucheyev, Sergei O.; Baumann, Theodore F.; Kuntz, Joshua D.; Satcher, Jr., Joe H.; Hamza, Alex V.

2015-07-21

Using SWNT-CA as scaffolds to fabricate stiff, highly conductive polymer (PDMS) composites. The SWNT-CA is immersing in a polymer resin to produce a SWNT-CA infiltrated with a polymer resin. The SWNT-CA infiltrated with a polymer resin is cured to produce the stiff and electrically conductive composite of carbon nanotube aerogel and polymer.

Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Worsley, Marcus A.; Kucheyev, Sergei O.; Baumann, Theodore F.; Kuntz, Joshua D.; Satcher, Jr., Joe H.; Hamza, Alex V.

2017-10-17

Using SWNT-CA as scaffolds to fabricate stiff, highly conductive polymer (PDMS) composites. The SWNT-CA is immersing in a polymer resin to produce a SWNT-CA infiltrated with a polymer resin. The SWNT-CA infiltrated with a polymer resin is cured to produce the stiff and electrically conductive composite of carbon nanotube aerogel and polymer.

Current front stiffness of European vehicles with regard to compatibility

NARCIS (Netherlands)

Huibers, J.; Beer, E. de

2001-01-01

EuroNCAP tests are carried out since 1997. The test procedure in general is comparable to the EC Directive 96/79 with a test speed of 64 km/h. This increased test speed implies a higher frontal stiffness for new vehicle designs in order to achieve a high ranking. This frontal stiffness is one of the

Risk factors and prevalence of burnout syndrome in the nursing profession.

Science.gov (United States)

Cañadas-De la Fuente, Guillermo A; Vargas, Cristina; San Luis, Concepción; García, Inmaculada; Cañadas, Gustavo R; De la Fuente, Emilia I

2015-01-01

The burnout syndrome is beginning to be regarded as an occupational illness of high prevalence among nursing in Spain. Individuals suffering from the syndrome manifest important health problems. More information about prevalence and risk factors for burnout is needed to prevent the syndrome and to determine the most appropriate clinical interventions when the disorder appears. Burnout levels were evaluated in a group of nurses. The objectives of this study were to estimate the prevalence of burnout, to identify the variables related to burnout and to propose a risk profile for this syndrome among the nursing personnel. The study was carried out in public health centers in Andalusia (Spain). The sample consisted of 676 nursing professionals from public health centers. Dependent variables were the three Burnout dimensions: emotional exhaustion, depersonalization and personal accomplishment. Independent variables were socio-demographic, organizational, personality-related variables. The nurses manifested average to high burnout levels. There were statistically significant differences in burnout levels associated with the following variables: age, gender, marital status, having children, level of healthcare, type of work shift, healthcare service areas and conducting administrative tasks. Burnout was also associated with personality-related variables. The prevalence of burnout among nursing professionals is high. Gender, age, marital status, level of healthcare, work shift and healthcare service areas predicted at least one of the dimensions of the syndrome. Neuroticism, agreeability, extraversion and conscientiousness are personality traits that predict at least two of the dimensions of burnout syndrome in nurses. Therefore, personality factors should be considered in any theory of risk profiles for developing burnout syndrome in the nursing profession. Copyright © 2014 Elsevier Ltd. All rights reserved.

Application of force-length curve for determination of leg stiffness during a vertical jump.

Science.gov (United States)

Struzik, Artur; Zawadzki, Jerzy

2016-01-01

The aim of this study was to present the methodology for estimation of a leg stiffness during a countermovement jump. The question was asked whether leg stiffness in the countermovement and take-off phases are similar to each other as demonstrated in previous reports. It was also examined whether the stiffness in left lower limb is similar to the one in right lower limb. The research was conducted on 35 basketball players. Each participant performed three countermovement jumps with arm swing to the maximum height. Measurements employed a Kistlerforce plate and a BTS SMART system for motion analysis. Leg stiffness (understood as an inclination of the curve of ground reaction forces vs. length) was computed for these parts of countermovement and take-off phases where its value was relatively constant and F(Δl) relationship was similar to linear. Mean value (±SD) of total stiffness of both lower limbs in the countermovement phase was 7.1 ± 2.3 kN/m, whereas this value in the take-off phase was 7.5 ± 1 kN/m. No statistically significant differences were found between the leg stiffness in the countermovement and the take-off phases. No statistically significant differences were found during the comparison of the stiffness in the right and left lower limb. The calculation methodology allows us to estimate the value of leg stiffness based on the actual shape of F(Δl) curve rather than on extreme values of ΔF and Δl. Despite different tasks of the countermovement and the take-off phases, leg stiffness in these phases is very similar. Leg stiffness during a single vertical jump maintains a relatively constant value in the parts with a small value of acceleration.

Matrix stiffness reverses the effect of actomyosin tension on cell proliferation.

Science.gov (United States)

Mih, Justin D; Marinkovic, Aleksandar; Liu, Fei; Sharif, Asma S; Tschumperlin, Daniel J

2012-12-15

The stiffness of the extracellular matrix exerts powerful effects on cell proliferation and differentiation, but the mechanisms transducing matrix stiffness into cellular fate decisions remain poorly understood. Two widely reported responses to matrix stiffening are increases in actomyosin contractility and cell proliferation. To delineate their relationship, we modulated cytoskeletal tension in cells grown across a physiological range of matrix stiffnesses. On both synthetic and naturally derived soft matrices, and across a panel of cell types, we observed a striking reversal of the effect of inhibiting actomyosin contractility, switching from the attenuation of proliferation on rigid substrates to the robust promotion of proliferation on soft matrices. Inhibiting contractility on soft matrices decoupled proliferation from cytoskeletal tension and focal adhesion organization, but not from cell spread area. Our results demonstrate that matrix stiffness and actomyosin contractility converge on cell spreading in an unexpected fashion to control a key aspect of cell fate.

Impact of morning stiffness on working behaviour and performance in people with rheumatoid arthritis.

Science.gov (United States)

Mattila, Kalle; Buttgereit, Frank; Tuominen, Risto

2014-12-01

Work disability remains a considerable problem for many patients with rheumatoid arthritis (RA). Morning stiffness is a symptom of RA associated with early retirement from work and with impaired functional ability. We aimed to explore the patient's perception of the impact of morning stiffness on the working life of patients with RA. A survey was conducted in 11 European countries. Patients of working age, with RA for ≥6 months and morning stiffness ≥3 mornings a week, were interviewed by telephone using a structured questionnaire. Responses were assessed in the total sample and in subgroups defined by severity and duration of morning stiffness and by country. A total of 1,061 respondents completed the survey, 534 were working, 224 were retired and the rest were, i.e. homemakers and unemployed. Among the 534 working respondents, RA-related morning stiffness affected work performance (47 %), resulted in late arrival at work (33 %) and required sick leave in the past month (15 %). Of the 224 retired respondents, 159 (71 %) stopped working earlier than their expected retirement age, with 64 % giving RA-related morning stiffness as a reason. There was a differential impact of increasing severity and increasing duration of morning stiffness on the various parameters studied. There were notable inter-country differences in the impact of RA-related morning stiffness on ability to work and on retirement. This large survey showed that from the patient's perspective, morning stiffness reduces the ability to work in patients with RA and contributes to early retirement.

Effect of chain stiffness on the structure of single-chain polymer nanoparticles

DEFF Research Database (Denmark)

Moreno, Angel J; Bacova, Petra; Lo Verso, Federica

2018-01-01

of the domains is in all cases similar to that of Gaussian chains or rings, irrespective of the stiffness and degree of cross-linking. It is the spatial arrangement of the domains which determines the global structure of the SCNP (sparse Gaussian-like object or crumpled globule). Since intramolecular stiffness...... or 'crumpled' globular behaviour for very stiff SCNPs. We characterize domains in the SCNPs. These are weakly deformable regions that can be seen as disordered analogues of domains in disordered proteins. Increasing stiffness leads to bigger and less deformable domains. Surprisingly, the scaling behaviour...... can be varied through the specific chemistry of the precursor or by introducing bulky side groups in its backbone, our results propose a new strategy to tune the global structure of SCNPs. ....

On the influence of the foundation stiffness in the structural dynamic response

International Nuclear Information System (INIS)

Halbritter, A.L.; Koishi, N.; Stukart, R.N.L.

1984-01-01

To consider the influence of the foundation on the structural dynamic analysis, it is usual to represent the foundation stiffness by springs and the damping by snubbers, in the structural model. The stiffness and the damping values of the foundation can be determined by approximate methods based on simplifying assumptions, using, for example, the formula derived from the half space theory or numerical methods. The foundation stiffness has a great influence on the dynamic characteristics of the structure (eigenvalues and eigenvectors), and together with the damping influence the structural dynamic response. In this paper the influence of the foundation stiffness on the floor response spectra of the reactor building of a NPP of 1300 MW PWR of KWU type is studied. (Author) [pt

Gait Selection and Transition of Passivity-Based Bipeds with Adaptable Ankle Stiffness

Directory of Open Access Journals (Sweden)

Yan Huang

2012-10-01

Full Text Available Stable bipedal walking is one of the most important components of humanoid robot design, which can help us better understand natural human walking. In this paper, to study gait selection and gait transition of efficient bipedal walking, we proposed a dynamic bipedal walking model with an upper body, flat feet and compliant joints. The model can achieve stable cyclic motion with different walking gaits. The hip actuation and ankle stiffness behavior of the model are quite similar to those of human normal walking. In simulation, we studied the influence of hip actuation and ankle stiffness on walking performance of each gait. The effects of ankle stiffness on gait selection are also analyzed. Gait transition is realized by adjusting ankle stiffness during walking.

Personality Traits of Suicidality Are Associated with Premenstrual Syndrome and Premenstrual Dysphoric Disorder in a Suicidal Women Sample.

Directory of Open Access Journals (Sweden)

Déborah Ducasse

Full Text Available Both Premenstrual Syndrome (PMS and Premenstrual Dysphoric Disorder (PMDD might increase the risk of suicidal behavior. The aim of this study was to assess the relationship between personality dimensions specifically involved in suicidal vulnerability and PMS/PMDD.We collected data from 232 women consecutively hospitalized after a suicide attempt. We examined the relationship between impulsivity, aggressiveness/hostility, hopelessness, trait anger, affect intensity, emotional lability, and PMS/PMDD. Notably, we created an algorithm from the shortened Premenstrual Assessment form in order to assess PMDD status.The proportions of PMS and PMDD among female suicide attempters were 50% and 23% respectively. Women with PMS or PMDD were more likely to endorse most of these personality traits to than those without even after controlling for potential confounders. We found an impulsive-aggressive pattern of personality in women with PMS or PMDD, independently from the time of the menstrual cycle. Interestingly, trait anger remained associated with both PMS and PMDD independently of every other personality traits. The higher the anger level, the higher the risk was to suffer from both PMS and PMDD.This study demonstrates a strong, independent association between PMS/PMDD and trait anger among a representative sample of female suicide attempters. It is of major interest for clinicians in view of addressing a substantial public health problem among women of reproductive age.

Personality Traits of Suicidality Are Associated with Premenstrual Syndrome and Premenstrual Dysphoric Disorder in a Suicidal Women Sample.

Science.gov (United States)

Ducasse, Déborah; Jaussent, Isabelle; Olié, Emilie; Guillaume, Sébastien; Lopez-Castroman, Jorge; Courtet, Philippe

2016-01-01

Both Premenstrual Syndrome (PMS) and Premenstrual Dysphoric Disorder (PMDD) might increase the risk of suicidal behavior. The aim of this study was to assess the relationship between personality dimensions specifically involved in suicidal vulnerability and PMS/PMDD. We collected data from 232 women consecutively hospitalized after a suicide attempt. We examined the relationship between impulsivity, aggressiveness/hostility, hopelessness, trait anger, affect intensity, emotional lability, and PMS/PMDD. Notably, we created an algorithm from the shortened Premenstrual Assessment form in order to assess PMDD status. The proportions of PMS and PMDD among female suicide attempters were 50% and 23% respectively. Women with PMS or PMDD were more likely to endorse most of these personality traits to than those without even after controlling for potential confounders. We found an impulsive-aggressive pattern of personality in women with PMS or PMDD, independently from the time of the menstrual cycle. Interestingly, trait anger remained associated with both PMS and PMDD independently of every other personality traits. The higher the anger level, the higher the risk was to suffer from both PMS and PMDD. This study demonstrates a strong, independent association between PMS/PMDD and trait anger among a representative sample of female suicide attempters. It is of major interest for clinicians in view of addressing a substantial public health problem among women of reproductive age.

Assessment of impact factors on shear wave based liver stiffness measurement

Energy Technology Data Exchange (ETDEWEB)

Ling, Wenwu, E-mail: lingwenwubing@163.com [Department of Ultrasound, West China Hospital of Sichuan University, Chengdu 610041 (China); Lu, Qiang, E-mail: wsluqiang@126.com [Department of Ultrasound, West China Hospital of Sichuan University, Chengdu 610041 (China); Quan, Jierong, E-mail: quanjierong@163.com [Department of Ultrasound, West China Hospital of Sichuan University, Chengdu 610041 (China); Ma, Lin, E-mail: malin2010US@163.com [Department of Ultrasound, West China Hospital of Sichuan University, Chengdu 610041 (China); Luo, Yan, E-mail: huaxiluoyan@gmail.com [Department of Ultrasound, West China Hospital of Sichuan University, Chengdu 610041 (China)

2013-02-15

Shear wave based ultrasound elastographies have been implemented as non-invasive methods for quantitative assessment of liver stiffness. Nonetheless, there are only a few studies that have investigated impact factors on liver stiffness measurement (LSM). Moreover, standard examination protocols for LSM are still lacking in clinical practice. Our study aimed to assess the impact factors on LSM to establish its standard examination protocols in clinical practice. We applied shear wave based elastography point quantification (ElastPQ) in 21 healthy individuals to determine the impact of liver location (segments I–VIII), breathing phase (end-inspiration and end-expiration), probe position (sub-costal and inter-costal position) and examiner on LSM. Additional studies in 175 healthy individuals were also performed to determine the influence of gender and age on liver stiffness. We found significant impact of liver location on LSM, while the liver segment V displayed the lowest coefficient of variation (CV 21%). The liver stiffness at the end-expiration was significantly higher than that at the end-inspiration (P = 2.1E−05). The liver stiffness was 8% higher in men than in women (3.8 ± 0.7 kPa vs. 3.5 ± 0.4 kPa, P = 0.0168). In contrast, the liver stiffness was comparable in the different probe positions, examiners and age groups (P > 0.05). In conclusion, this study reveals significant impact from liver location, breathing phase and gender on LSM, while furthermore strengthening the necessity for the development of standard examination protocols on LSM.

Nature and Extent of Person Recognition Impairments Associated with Capgras Syndrome in Lewy Body Dementia

Directory of Open Access Journals (Sweden)

Chris M. Fiacconi

2014-09-01

Full Text Available Patients with Capgras Syndrome (CS adopt the delusional belief that persons well-known to them have been replaced by an imposter. Several current theoretical models of CS attribute such misidentification problems to deficits in covert recognition processes related to the generation of appropriate affective autonomic signals. These models assume intact overt recognition processes for the imposter and, more broadly, for other individuals. As such, it has been suggested that CS could reflect the ‘mirror image’ of prosopagnosia. The purpose of the current study was to determine whether overt person recognition abilities are indeed always spared in CS. Furthermore, we examined whether CS might be associated with any impairments in overt affective judgments of facial expressions. We pursued these goals by studying a patient with Lewy Body Dementia (DLB who showed clear signs of CS, and by comparing him to another patient with DLB who did not experience CS, as well as to a group of healthy control participants. We assessed overt person recognition with three fame recognition tasks, using faces, voices, and names as cues. We also included measures of confidence and probed pertinent semantic knowledge. In addition, participants rated the intensity of fearful facial expressions. We found that CS was associated with overt person recognition deficits when probed with faces and voices, but not with names. Critically, these deficits were not present in the DLB patient without CS. In addition, CS was associated with impairments in overt judgments of affect intensity. Taken together, our findings cast doubt on the traditional view that CS is the mirror-image of prosopagnosia and that it spares overt recognition abilities. These findings can still be accommodated by models of CS that emphasize deficits in autonomic responding, to the extent that the potential role of interoceptive awareness in overt judgments is taken into account.

Stigma in Iranian Down Syndrome

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Sahel Hemmati

2010-04-01

Full Text Available Objectives: Stigma is a negative value. Many behaviors are to ward Stigmatized people. Down syndrome is one of conditions with Stigma. The aim of this study is to determine the sources of labeling in iranian Down syndrome. Methods: The View of 105 Down syndrome families concerning stigma were conducted. All of Down syndrome was under 50 years. Results: A fair proportion of Down syndrome families perceived that stigma had a negative effect from social. Causes of stigma are different. Stigma due social interaction, Media and health professionals are significant than others. Discussion: The diagnostic label of Down syndrome may render the person and his family vulnerable to stigmatization. The most causes of stigma were determined therefore, in the destigmatization programs, they must be attended. Stigma must be detected, too.

A mechanism to compensate undesired stiffness in joints of prosthetic hands

NARCIS (Netherlands)

Smit, G.; Plettenbrug, D.H.; Van der Helm, F.C.T.

2014-01-01

Background: Cosmetic gloves that cover a prosthetic hand have a parasitic positive stiffness that counteracts the flexion of a finger joint. Objectives: Reducing the required input torque to move a finger of a prosthetic hand by compensating the parasitic stiffness of the cosmetic glove. Study

Ursodeoxycholic acid treatment is associated with improvement of liver stiffness in cystic fibrosis patients.

Science.gov (United States)

van der Feen, Cathelijne; van der Doef, Hubert P J; van der Ent, Cornelis K; Houwen, Roderick H J

2016-11-01

Ursodeoxycholic acid (UDCA) might prevent progression of cystic fibrosis liver disease, but objective parameters for its effect are lacking. We used liver stiffness measurements to evaluate the effect of Ursodeoxycholic acid. Paired measurements of liver stiffness were done in 73 patients without UDCA and in 32 patients with UDCA. In the latter group, 6 patients had cirrhosis; in 15 patients, UDCA was started based on Colombo criteria, and in 11 patients for other reasons. In patients without UDCA, liver stiffness increased: 0.19 (-0.03 to 0.59)kPa/year. Liver stiffness also increased in patients with cirrhosis: 4.6 (0.67-12.4)kPa/year. In patients who had UDCA based on Colombo criteria, a decrease of liver stiffness was observed: 0.70 (-1.6 to 0.55)kPa/year (P=0.01). In patients on UDCA for other reasons, liver stiffness increased: 0.23 (-0.20 to 0.51)kPa/year. UDCA reduced liver stiffness in patients with well-defined, mild liver disease. Copyright © 2016 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

A novel magnetorheological elastomer isolator with negative changing stiffness for vibration reduction

International Nuclear Information System (INIS)

Yang, J; Sun, S S; Li, W H; Alici, G; Du, H; Deng, H X

2014-01-01

Magneto-rheological elastomers (MREs) have attracted notable credits in the development of smart isolators and absorbers due to their controllable stiffness and damping properties. For the purpose of mitigating unwanted structural and/or machinery vibrations, the traditional MRE-based isolators have been generally proven effective because the MR effect can increase the stiffness when the magnetic field is strengthened. This study presents a novel MRE isolator that experienced reduced stiffness when the applied current was increased. This innovative work was accomplished by applying a hybrid magnet (electromagnet and permanent magnets) onto a multilayered MRE structure. To characterise this negative changing stiffness concept, a multilayered MRE isolator with a hybrid magnet was first designed, fabricated and then tested to measure its properties. An obvious reduction of the effective stiffness and natural frequency of the proposed MRE isolator occurred when the current was continuously adjusted. This device could also work as a conventional MRE isolator as its effective stiffness and natural frequency also increased when a negative current was applied. Further testing was carried out on a one-degree-of-freedom system to assess how effectively this device could isolate vibration. In this experiment, two cases were considered; in each case, the vibration of the primary system was obviously attenuated under ON-OFF control logic, thus demonstrating the feasibility of this novel design as an alternative adaptive vibration isolator. (paper)

Increased Stiffness in Aged Skeletal Muscle Impairs Muscle Progenitor Cell Proliferative Activity.

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Grégory Lacraz

Full Text Available Skeletal muscle aging is associated with a decreased regenerative potential due to the loss of function of endogenous stem cells or myogenic progenitor cells (MPCs. Aged skeletal muscle is characterized by the deposition of extracellular matrix (ECM, which in turn influences the biomechanical properties of myofibers by increasing their stiffness. Since the stiffness of the MPC microenvironment directly impacts MPC function, we hypothesized that the increase in muscle stiffness that occurs with aging impairs the behavior of MPCs, ultimately leading to a decrease in regenerative potential.We showed that freshly isolated individual myofibers from aged mouse muscles contain fewer MPCs overall than myofibers from adult muscles, with fewer quiescent MPCs and more proliferative and differentiating MPCs. We observed alterations in cultured MPC behavior in aged animals, where the proliferation and differentiation of MPCs were lower and higher, respectively. These alterations were not linked to the intrinsic properties of aged myofibers, as shown by the similar values for the cumulative population-doubling values and fusion indexes. However, atomic force microscopy (AFM indentation experiments revealed a nearly 4-fold increase in the stiffness of the MPC microenvironment. We further showed that the increase in stiffness is associated with alterations to muscle ECM, including the accumulation of collagen, which was correlated with higher hydroxyproline and advanced glycation end-product content. Lastly, we recapitulated the impaired MPC behavior observed in aging using a hydrogel substrate that mimics the stiffness of myofibers.These findings provide novel evidence that the low regenerative potential of aged skeletal muscle is independent of intrinsic MPC properties but is related to the increase in the stiffness of the MPC microenvironment.

Arterial Stiffness and Functional Outcome in Acute Ischemic Stroke

OpenAIRE

Lee, Yeong-Bae; Park, Joo-Hwan; Kim, Eunja; Kang, Chang-Ki; Park, Hyeon-Mi

2014-01-01

Objective Arterial stiffness is a common change associated with aging and can be evaluated by measuring pulse wave velocity (PWV) between sites in the arterial tree, with the stiffer artery having the higher PWV. Arterial stiffness is associated with the risk of stroke in the general population and of fatal stroke in hypertensive patients. This study is to clarify whether PWV value predicts functional outcome of acute ischemic stroke. Methods One hundred patients were enrolled with a diagnosi...

Personality characteristics and epilepsy

DEFF Research Database (Denmark)

Sørensen, A S; Hansen, H; Andersen, R

1989-01-01

Patients with a long history of temporal lobe epilepsy or primary generalized epilepsy entered a questionnaire study of personality characteristics, based on a modification of the Bear-Fedio inventory for temporal lobe behavioural syndrome. Psoriasis patients and healthy volunteers served...

Experimental challenges to stiffness as a transport paradigm

Science.gov (United States)

Luce, T. C.; Burrell, K. H.; Holland, C.; Marinoni, A.; Petty, C. C.; Smith, S. P.; Austin, M. E.; Grierson, B. A.; Zeng, L.

2018-02-01

Two power scans were carried out in H-mode plasmas in DIII-D; one employed standard co-current neutral beam injection (NBI), while the other used a mixture of co-current and counter-current NBI to scan power while holding the torque to a low fixed value. Analysis of the ion and electron heat transport, ion toroidal angular momentum transport, and thermal deuterium transport from these scans is presented. Invariance of the gradients or gradient scalelengths, as might be expected from stiff transport, was not generally observed. When invariance was seen, it was not accompanied by a strong increase in transport, except in the case of the absolute deuterium ion transport. Conduction in the ion channel is the dominant energy loss mechanism. The variation of the ion heat transport with applied power is similar for the co-injection and fixed torque scans, indicating that E  ×  B shearing is not determining the plasma response to additional power. There is however, a quantitative difference in the transport between the two scans, indicating E  ×  B shearing does play a role in the transport. Comparison of these results with a previous experiment that directly probed stiffness at a single radius leads to the following conclusion: while local stiffness as formally defined may hold, invariance of the gradients or normalized scalelengths does not follow from stiff transport in more practical scaling experiments, such as the power scans discussed here. Possible reasons for the lack of correspondence between the local picture and the global expectations are discussed.

Mixed, Nonsplit, Extended Stability, Stiff Integration of Reaction Diffusion Equations

KAUST Repository

Alzahrani, Hasnaa H.

2016-07-26

A tailored integration scheme is developed to treat stiff reaction-diffusion prob- lems. The construction adapts a stiff solver, namely VODE, to treat reaction im- plicitly together with explicit treatment of diffusion. The second-order Runge-Kutta- Chebyshev (RKC) scheme is adjusted to integrate diffusion. Spatial operator is de- scretised by second-order finite differences on a uniform grid. The overall solution is advanced over S fractional stiff integrations, where S corresponds to the number of RKC stages. The behavior of the scheme is analyzed by applying it to three simple problems. The results show that it achieves second-order accuracy, thus, preserving the formal accuracy of the original RKC. The presented development sets the stage for future extensions, particularly, to multidimensional reacting flows with detailed chemistry.

Linking behavioural syndromes and cognition: a behavioural ecology perspective.

Science.gov (United States)

Sih, Andrew; Del Giudice, Marco

2012-10-05

With the exception of a few model species, individual differences in cognition remain relatively unstudied in non-human animals. One intriguing possibility is that variation in cognition is functionally related to variation in personality. Here, we review some examples and present hypotheses on relationships between personality (or behavioural syndromes) and individual differences in cognitive style. Our hypotheses are based largely on a connection between fast-slow behavioural types (BTs; e.g. boldness, aggressiveness, exploration tendency) and cognitive speed-accuracy trade-offs. We also discuss connections between BTs, cognition and ecologically important aspects of decision-making, including sampling, impulsivity, risk sensitivity and choosiness. Finally, we introduce the notion of cognition syndromes, and apply ideas from theories on adaptive behavioural syndromes to generate predictions on cognition syndromes.

Borderline Personality in the Medical Setting

Science.gov (United States)

Sansone, Lori A.

2015-01-01

Objective: Individuals with borderline personality disorder in mental health settings tend to present with relationship difficulties, mood instability/dysphoria, and overt self-harm behavior. In contrast, it appears that individuals with borderline personality disorder in medical settings manifest physical symptoms that are medically difficult to substantiate. Through a review of the literature, we examine 2 symptom manifestations among patients with borderline personality in primary care and general medical settings—namely pain sensitivity and multiple somatic complaints. In addition to reviewing the research of others, we also highlight our own investigations into these 2 areas. Data Sources: We conducted a literature search of the PubMed database and a previous version of the PsycINFO search engine (no restrictions). Search terms included borderline personality, borderline personality disorder, personality disorders; chronic pain, pain, pain syndromes; and somatization disorder, Briquet’s syndrome, somatic preoccupation, somatic. Study Selection: Published articles related to borderline personality, pain and somatic symptoms (ie, somatization disorder, somatic preoccupation) were examined. Results: According to our review, the literature indicates higher-than-expected rates of borderline personality disorder among patients in primary care and general medical settings who present with chronic pain conditions and/or somatic preoccupation. Conclusions: Unlike patients with borderline personality disorder in mental health settings, who tend to present with relationship difficulties, mood instability/dysphoria, and overt self-harm behavior, patients with borderline personality disorder in primary care settings tend to present with unsubstantiated chronic pain of various types as well as somatic preoccupation. PMID:26644960

Stiffness analysis for the micromagnetic standard problem No. 4

International Nuclear Information System (INIS)

Tsiantos, Vassilios D.; Suess, Dieter; Schrefl, Thomas; Fidler, Josef

2001-01-01

In this article solutions to micromagnetic standard problem No. 4, a 500-nmx125-nm-wide NiFe film, are presented. A three-dimensional-finite element simulation based on the solution of the Gilbert equation has been used. The simulations show that two different reversal mechanisms occur for the two different applied fields. For a field at 170 degree counterclockwise from the saturation direction there is a nonuniform rotation of magnetization towards the direction of the applied field, with the magnetization at the ends rotating faster than the magnetization in the center. For a field at 190 degree counterclockwise from the saturation direction the magnetization at the ends and in the center rotate in opposite directions leading to the formation of a 360 degree wall after 0.22 ns associated with a peak in the exchange energy. Moreover, the time for the magnetization component parallel to the long axis to cross the zero is 0.136 and 0.135 ns for field 1 and field 2, respectively. The stiffness of the problem has been investigated solving the system of ordinary differential equations with a nonstiff method (Adams) and a stiff one (backward differentiation formula, BDF). For the measure of stiffness the ratio of the total number of time steps (nst) taken by the two solvers, that is nst(Adams)/nst(BDF), has been used. This ratio is 0.784 for field 1 and 0.593 for field 2, which means that the nonstiff method (Adams) uses larger time steps than the stiff method (BDF) and consequently the systems are not stiff. The average time step for the Adams method was 0.2 ps for both fields. [copyright] 2001 American Institute of Physics

Reduced prosthetic stiffness lowers the metabolic cost of running for athletes with bilateral transtibial amputations.

Science.gov (United States)

Beck, Owen N; Taboga, Paolo; Grabowski, Alena M

2017-04-01

Inspired by the springlike action of biological legs, running-specific prostheses are designed to enable athletes with lower-limb amputations to run. However, manufacturer's recommendations for prosthetic stiffness and height may not optimize running performance. Therefore, we investigated the effects of using different prosthetic configurations on the metabolic cost and biomechanics of running. Five athletes with bilateral transtibial amputations each performed 15 trials on a force-measuring treadmill at 2.5 or 3.0 m/s. Athletes ran using each of 3 different prosthetic models (Freedom Innovations Catapult FX6, Össur Flex-Run, and Ottobock 1E90 Sprinter) with 5 combinations of stiffness categories (manufacturer's recommended and ± 1) and heights (International Paralympic Committee's maximum competition height and ± 2 cm) while we measured metabolic rates and ground reaction forces. Overall, prosthetic stiffness [fixed effect (β) = 0.036; P = 0.008] but not height ( P ≥ 0.089) affected the net metabolic cost of transport; less stiff prostheses reduced metabolic cost. While controlling for prosthetic stiffness (in kilonewtons per meter), using the Flex-Run (β = -0.139; P = 0.044) and 1E90 Sprinter prostheses (β = -0.176; P = 0.009) reduced net metabolic costs by 4.3-4.9% compared with using the Catapult prostheses. The metabolic cost of running improved when athletes used prosthetic configurations that decreased peak horizontal braking ground reaction forces (β = 2.786; P = 0.001), stride frequencies (β = 0.911; P < 0.001), and leg stiffness values (β = 0.053; P = 0.009). Remarkably, athletes did not maintain overall leg stiffness across prosthetic stiffness conditions. Rather, the in-series prosthetic stiffness governed overall leg stiffness. The metabolic cost of running in athletes with bilateral transtibial amputations is influenced by prosthetic model and stiffness but not height. NEW & NOTEWORTHY We measured the

The Passive Series Stiffness That Optimizes Torque Tracking for a Lower-Limb Exoskeleton in Human Walking

Directory of Open Access Journals (Sweden)

Juanjuan Zhang

2017-12-01

Full Text Available This study uses theory and experiments to investigate the relationship between the passive stiffness of series elastic actuators and torque tracking performance in lower-limb exoskeletons during human walking. Through theoretical analysis with our simplified system model, we found that the optimal passive stiffness matches the slope of the desired torque-angle relationship. We also conjectured that a bandwidth limit resulted in a maximum rate of change in torque error that can be commanded through control input, which is fixed across desired and passive stiffness conditions. This led to hypotheses about the interactions among optimal control gains, passive stiffness and desired quasi-stiffness. Walking experiments were conducted with multiple angle-based desired torque curves. The observed lowest torque tracking errors identified for each combination of desired and passive stiffnesses were shown to be linearly proportional to the magnitude of the difference between the two stiffnesses. The proportional gains corresponding to the lowest observed errors were seen inversely proportional to passive stiffness values and to desired stiffness. These findings supported our hypotheses, and provide guidance to application-specific hardware customization as well as controller design for torque-controlled robotic legged locomotion.

Theoretical Design and Characteristics Analysis of a Quasi-Zero Stiffness Isolator Using a Disk Spring as Negative Stiffness Element

Directory of Open Access Journals (Sweden)

Lingshuai Meng

2015-01-01

Full Text Available This paper presents a novel quasi-zero stiffness (QZS isolator designed by combining a disk spring with a vertical linear spring. The static characteristics of the disk spring and the QZS isolator are investigated. The optimal combination of the configurative parameters is derived to achieve a wide displacement range around the equilibrium position in which the stiffness has a low value and changes slightly. By considering the overloaded or underloaded conditions, the dynamic equations are established for both force and displacement excitations. The frequency response curves (FRCs are obtained by using the harmonic balance method (HBM and confirmed by the numerical simulation. The stability of the steady-state solution is analyzed by applying Floquet theory. The force, absolute displacement, and acceleration transmissibility are defined to evaluate the isolation performance. Effects of the offset displacement, excitation amplitude, and damping ratio on the QZS isolator and the equivalent system (ELS are studied. The results demonstrate that the QZS isolator for overloaded or underloaded can exhibit different stiffness characteristics with changing excitation amplitude. If loaded with an appropriate mass, excited by not too large amplitude, and owned a larger damper, the QZS isolator can possess better isolation performance than its ELS in low frequency range.

Substrate Stiffness Controls Osteoblastic and Chondrocytic Differentiation of Mesenchymal Stem Cells without Exogenous Stimuli.

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Rene Olivares-Navarrete

Full Text Available Stem cell fate has been linked to the mechanical properties of their underlying substrate, affecting mechanoreceptors and ultimately leading to downstream biological response. Studies have used polymers to mimic the stiffness of extracellular matrix as well as of individual tissues and shown mesenchymal stem cells (MSCs could be directed along specific lineages. In this study, we examined the role of stiffness in MSC differentiation to two closely related cell phenotypes: osteoblast and chondrocyte. We prepared four methyl acrylate/methyl methacrylate (MA/MMA polymer surfaces with elastic moduli ranging from 0.1 MPa to 310 MPa by altering monomer concentration. MSCs were cultured in media without exogenous growth factors and their biological responses were compared to committed chondrocytes and osteoblasts. Both chondrogenic and osteogenic markers were elevated when MSCs were grown on substrates with stiffness <10 MPa. Like chondrocytes, MSCs on lower stiffness substrates showed elevated expression of ACAN, SOX9, and COL2 and proteoglycan content; COMP was elevated in MSCs but reduced in chondrocytes. Substrate stiffness altered levels of RUNX2 mRNA, alkaline phosphatase specific activity, osteocalcin, and osteoprotegerin in osteoblasts, decreasing levels on the least stiff substrate. Expression of integrin subunits α1, α2, α5, αv, β1, and β3 changed in a stiffness- and cell type-dependent manner. Silencing of integrin subunit beta 1 (ITGB1 in MSCs abolished both osteoblastic and chondrogenic differentiation in response to substrate stiffness. Our results suggest that substrate stiffness is an important mediator of osteoblastic and chondrogenic differentiation, and integrin β1 plays a pivotal role in this process.

Evaluation of stiffness feedback for hard nodule identification on a phantom silicone model

OpenAIRE

Li, M.; Konstantinova, J.; Xu, G.; He, B.; Aminzadeh, V.; Xie, J.; Wurdemann, H.; Althoefer, K.

2017-01-01

Haptic information in robotic surgery can significantly improve clinical outcomes and help detect hard soft-tissue inclusions that indicate potential abnormalities. Visual representation of tissue stiffness information is a cost-effective technique. Meanwhile, direct force feedback, although considerably more expensive than visual representation, is an intuitive method of conveying information regarding tissue stiffness to surgeons. In this study, real-time visual stiffness feedback by slidin...

Personality characteristics and epilepsy

DEFF Research Database (Denmark)

Sørensen, A S; Hansen, H; Andersen, R

1989-01-01

as controls. Four clinical meaningful dimensions of included personality traits were identified: ixoide, ideational, obsessive-compulsive and affective features. Analyses based on the Rasch model approved of all dimensions except for affective features. The epilepsy group obtained the highest scores on all 3......Patients with a long history of temporal lobe epilepsy or primary generalized epilepsy entered a questionnaire study of personality characteristics, based on a modification of the Bear-Fedio inventory for temporal lobe behavioural syndrome. Psoriasis patients and healthy volunteers served...... dysfunction in the epilepsy group, the mere presence of a chronic disorder with potential social stigmatization influences personality....

Vitamin E in aging persons with Down syndrome: A randomized, placebo-controlled clinical trial.

Science.gov (United States)

Sano, Mary; Aisen, Paul S; Andrews, Howard F; Tsai, Wei-Yann; Lai, Florence; Dalton, Arthur J

2016-05-31

To determine whether vitamin E would slow the progression of cognitive deterioration and dementia in aging persons with Down syndrome (DS). A randomized, double-blind controlled clinical trial was conducted at 21 clinical sites, and researchers trained in research procedures recruited adults with DS older than 50 years to participate. Participants were randomly assigned to receive 1,000 IU of vitamin E orally twice daily for 3 years or identical placebo. The primary outcome was change on the Brief Praxis Test (BPT). Secondary outcomes included incident dementia and measures of clinical global change, cognition, function, and behavior. A total of 337 individuals were randomized, 168 to vitamin E and 169 to placebo. Both groups demonstrated deterioration on the BPT with no difference between drug and placebo. At baseline, 26% were diagnosed with dementia and there was an overall rate of incident dementia of 11%/year with no difference between groups. There was no effect on the secondary outcome measures. Though numerically higher in the treatment group, there was no difference in the number of adverse events (p = 0.079) and deaths (p = 0.086) between groups. Vitamin E did not slow the progression of cognitive deterioration in older individuals with DS. This study provides Class II evidence that vitamin E does not significantly slow the progression of cognitive deterioration in aging persons with DS. © 2016 American Academy of Neurology.

Spleen Stiffness Correlates with the Presence of Ascites but Not Esophageal Varices in Chronic Hepatitis C Patients

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Kazuyo Mori

2013-01-01

Full Text Available Although spleen stiffness has recently been identified as potential surrogate marker for portal hypertension, the relationship between spleen stiffness and portal hypertension has not been fully elucidated. We attempted to determine the relationship between the liver or spleen stiffness and the presence of ascites or esophageal varices by acoustic radiation force impulse (ARFI imaging. A total of 33 chronic hepatitis C (CHC patients (median age 68; range 51–84 were enrolled. We evaluated the relationship between the liver or spleen stiffness and indicators of portal hypertension as well as clinical and biochemical parameters. Fourteen healthy volunteers were used for validating the accuracy of AFRI imaging. The liver and spleen stiffness increased significantly with progression of liver disease. A significant positive correlation was observed between the liver and spleen stiffness. However, spleen stiffness, but not liver stiffness, was significantly associated with the presence of ascites (, while there was no significant association between the spleen stiffness and spleen index/presence of esophageal varices in CHC patients. The area under the receiver operating characteristic curve based on the spleen stiffness was 0.80. In conclusion, spleen stiffness significantly correlates with the presence of ascites but not esophageal varices in CHC patients.

Syndrome of continuous muscle fiber activity: case report with 11-year follow-up

Directory of Open Access Journals (Sweden)

José Teotônio de Oliveira

1994-03-01

Full Text Available A 16-year-old male patient who presented with muscle stiffness and dysphonia is described. Electromyography revealed continuous motor activity that was unaffected by peripheral nerve block or general anaesthesia, but was abolished by curare. The patient had a marked improvement after using phenytoin. The follow-up 11-years later corroborates with the proposed benignity of this syndrome, in spite of being dependent on medication.

Effects of plyometric and isometric training on muscle and tendon stiffness in vivo.

Science.gov (United States)

Kubo, Keitaro; Ishigaki, Tomonobu; Ikebukuro, Toshihiro

2017-08-01

The purpose of this study was to compare the effects of plyometric and isometric training on tendon properties during ramp and ballistic contractions and muscle stiffness under passive and active conditions. Eleven subjects completed 12 weeks (3 days/week) of a unilateral training program for the plantar flexors. They performed plyometric training on one side (PLY) and isometric training on the other side (ISO). Active muscle stiffness in the medial gastrocnemius muscle was calculated according to changes in estimated muscle force and fascicle length during fast stretching after submaximal isometric contractions. Passive muscle stiffness was also calculated from estimated passive muscle force and fascicle length during slow passive stretching. Stiffness and hysteresis of tendon structures were measured using ultrasonography during ramp and ballistic contractions. Passive muscle stiffness and tendon hysteresis did not change for PLY or ISO Active muscle stiffness significantly increased for PLY, but not for ISO Tendon stiffness during ramp and ballistic contractions increased significantly for ISO, but not for PLY In addition, tendon elongation values at force production levels beyond 100 N during ballistic contractions increased for PLY These results suggest that plyometric training (but not isometric training) enhances the extensibility of tendon structures during ballistic contractions and active muscle stiffness during fast stretching, and these changes may be related to improved performances during stretch-shortening cycle exercises. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Effects of dysthymia on personality assessment.

Science.gov (United States)

Lecic-Tosevski, D; Divac-Jovanovic, M

1996-01-01

Twenty-eight dysthymic patients (82.1% with personality disorders) were investigated with questionnaires for personality and depression before and after treatment. When in asymptomatic state, defined by clinical criteria and HAM-D score 6 or lower, the personality profile of 15 patients (group I) was significantly changed from the one before treatment (avoidant, passive-aggressive, borderline and schizotypal dimensions were lower, and narcissistic dimension higher [P personality dimension. The second group manifested a permanent characterological affective syndrome, or a core borderline personality disorder. The limitations of personality assessment during affective episodes are discussed as well as the borderline level of functioning related to it.

Hemodynamic and arterial stiffness differences between African-Americans and Caucasians after maximal exercise.

Science.gov (United States)

Yan, Huimin; Ranadive, Sushant M; Heffernan, Kevin S; Lane, Abbi D; Kappus, Rebecca M; Cook, Marc D; Wu, Pei-Tzu; Sun, Peng; Harvey, Idethia S; Woods, Jeffrey A; Wilund, Kenneth R; Fernhall, Bo

2014-01-01

African-American (AA) men have higher arterial stiffness and augmentation index (AIx) than Caucasian-American (CA) men. Women have greater age-associated increases in arterial stiffness and AIx than men. This study examined racial and sex differences in arterial stiffness and central hemodynamics at rest and after an acute bout of maximal exercise in young healthy individuals. One hundred young, healthy individuals (28 AA men, 24 AA women, 25 CA men, and 23 CA women) underwent measurements of aortic blood pressure (BP) and arterial stiffness at rest and 15 and 30 min after an acute bout of graded maximal aerobic exercise. Aortic BP and AIx were derived from radial artery applanation tonometry. Aortic stiffness (carotid-femoral) was measured via pulse wave velocity. Aortic stiffness was increased in AA subjects but not in CA subjects (P < 0.05) after an acute bout of maximal cycling exercise, after controlling for body mass index. Aortic BP decreased after exercise in CA subjects but not in AA subjects (P < 0.05). Women exhibited greater reductions in AIx after maximal aerobic exercise compared with men (P < 0.05). In conclusion, race and sex impact vascular and central hemodynamic responses to exercise. Young AA and CA subjects exhibited differential responses in central stiffness and central BP after acute maximal exercise. Premenopausal women had greater augmented pressure at rest and after maximal aerobic exercise than men. Future research is needed to examine the potential mechanisms.

Stiffness, resilience, compressibility

Energy Technology Data Exchange (ETDEWEB)

Leu, Bogdan M. [Argonne National Laboratory, Advanced Photon Source (United States); Sage, J. Timothy, E-mail: jtsage@neu.edu [Northeastern University, Department of Physics and Center for Interdisciplinary Research on Complex Systems (United States)

2016-12-15

The flexibility of a protein is an important component of its functionality. We use nuclear resonance vibrational spectroscopy (NRVS) to quantify the flexibility of the heme iron environment in the electron-carrying protein cytochrome c by measuring the stiffness and the resilience. These quantities are sensitive to structural differences between the active sites of different proteins, as illustrated by a comparative analysis with myoglobin. The elasticity of the entire protein, on the other hand, can be probed quantitatively from NRVS and high energy-resolution inelastic X-ray scattering (IXS) measurements, an approach that we used to extract the bulk modulus of cytochrome c.