695 research outputs found
Social flocculation in plantâanimal worms
Individual animals can often move more safely or more efficiently as members of a group. This can be as simple as safety in numbers or as sophisticated as aerodynamic or hydrodynamic cooperation. Here, we show that individual plantâanimal worms (Symsagittifera roscoffensis) can move to safety more quickly through flocculation. Flocs form in response to turbulence that might otherwise carry these beach-dwelling worms out to sea. They allow the worms to descend much more quickly to the safety of the substrate than single worms could swim. Descent speed increases with floc size such that larger flocs can catch up with smaller ones and engulf them to become even larger and faster. To our knowledge, this is the first demonstration of social flocculation in a wild, multicellular organism. It is also remarkable that such effective flocculation occurs where the components are comparatively large multicellular organisms organized as entangled ensembles
The Impact of NOD2 Variants on Fecal Microbiota in Crohn's Disease and Controls Without Gastrointestinal Disease.
BACKGROUND/AIMS: Current models of Crohn's disease (CD) describe an inappropriate immune response to gut microbiota in genetically susceptible individuals. NOD2 variants are strongly associated with development of CD, and NOD2 is part of the innate immune response to bacteria. This study aimed to identify differences in fecal microbiota in CD patients and non-IBD controls stratified by NOD2 genotype. METHODS: Patients with CD and non-IBD controls of known NOD2 genotype were identified from patients in previous UK IBD genetics studies and the Cambridge bioresource (genotyped/phenotyped volunteers). Individuals with known CD-associated NOD2 mutations were matched to those with wild-type genotype. We obtained fecal samples from patients in clinical remission with low fecal calprotectin (<250 Âľg/g) and controls without gastrointestinal disease. After extracting DNA, the V1-2 region of 16S rRNA genes were polymerase chain reaction (PCR)-amplified and sequenced. Analysis was undertaken using the mothur package. Volatile organic compounds (VOC) were also measured. RESULTS: Ninety-one individuals were in the primary analysis (37 CD, 30 bioresource controls, and 24 household controls). Comparing CD with nonIBD controls, there were reductions in bacterial diversity, Ruminococcaceae, Rikenellaceae, and Christensenellaceae and an increase in Enterobacteriaceae. No significant differences could be identified in microbiota by NOD2 genotype, but fecal butanoic acid was higher in Crohn's patients carrying NOD2 mutations. CONCLUSIONS: In this well-controlled study of NOD2 genotype and fecal microbiota, we identified no significant genotype-microbiota associations. This suggests that the changes associated with NOD2 genotype might only be seen at the mucosal level, or that environmental factors and prior inflammation are the predominant determinant of the observed dysbiosis in gut microbiota.Funding was supported by CORE, the Digestive Diseases Foundation and the Wellcome Trust [grant number 097943 to NAK, 093885 to CAL and 098051 to Alan W Walker and Julian Parkhill . Dr. Walker receives core funding support from the Scottish Government Rural and Environmental Science and Analysis Service (RESAS). We also acknowledge the NIHR Biomedical Research Centre awards to Addenbrookeâs Hospital/University of Cambridge School of Clinical Medicine and acknowledge the NIHR Newcastle Biomedical Research Centre
Associations between health-related quality of life, physical function and fear of falling in older fallers receiving home care
Falls and injuries in older adults have significant consequences and costs, both personal and to society. Although having a high incidence of falls, high prevalence of fear of falling and a lower quality of life, older adults receiving home care are underrepresented in research on older fallers. The objective of this study is to determine the associations between health-related quality of life (HRQOL), fear of falling and physical function in older fallers receiving home care
Integrating isotopes and documentary evidence : dietary patterns in a late medieval and early modern mining community, Sweden
We would like to thank the Archaeological Research Laboratory, Stockholm University, Sweden and the Tandem Laboratory (Ă
ngstrĂśm Laboratory), Uppsala University, Sweden, for undertaking the analyses of stable nitrogen and carbon isotopes in both human and animal collagen samples. Also, thanks to Elin Ahlin Sundman for providing the δ13C and δ15N values for animal references from VästerĂĽs. This research (BäckstrĂśmâs PhD employment at Lund University, Sweden) was supported by the Berit Wallenberg Foundation (BWS 2010.0176) and Jakob and Johan SĂśderbergâs foundation. The âSala projectâ (excavations and analyses) has been funded by Riksens Clenodium, Jernkontoret, Birgit and Gad Rausingâs Foundation, SAUâs Research Foundation, the Royal Physiographic Society of Lund, Berit Wallenbergs Foundation, Ă
ke Wibergs Foundation, Lars Hiertas Memory, Helge Ax:son Johnsonâs Foundation and The Royal Swedish Academy of Sciences.Peer reviewedPublisher PD
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The effect of bleach duration and age on the ERG photostress test
Background: The ERG photostress test assesses the recovery of the focal 41 Hz ERG following exposure to a bright light that bleaches a significant proportion of photopigment. The aims of this study were: 1) to compare the repeatability of the ERG photostress test recovery time constant following long and short duration light exposure, and 2) to determine the effect of age on the ERG photostress test recovery time constant.
Methods: Focal 41 Hz ERGs were recorded from 23 participants (age range 20â71 years) at 20-second intervals for 5 minutes following either a short-duration (photoflash) or long-duration (equilibrium) light exposure. After a 5-minute wash-out period, the procedure was repeated using the second bleach modality. The time constant of cone recovery was determined by fitting an exponential model to the amplitude recovery data. The whole procedure was repeated on a second occasion. The co-efficient of repeatability (CoR) was calculated for each bleaching technique. The relationship between the time constant of recovery and age was investigated (Pearsonâs correlation coefficient).
Results: The time constant of recovery following an equilibrium bleach was more repeatable than recovery following a photoflash (CoRâ=â85s and 184s respectively). Eight trials (from seven participants) failed to show a reduction in amplitude following the photoflash, suggesting that a blink or fixation loss had occurred. All participants were reliably light-adapted by the equilibrium bleach. For the equilibrium bleach data, the time constant of recovery increased with age at a rate of 27 seconds per decade.
Conclusions: The equilibrium bleach was more reliable and repeatable than the photoflash. Increasing participant age was shown to result in a lengthening of the recovery time constant, of a magnitude comparable to previously published psychophysical data
Scattering Theory and -Symmetry
We outline a global approach to scattering theory in one dimension that
allows for the description of a large class of scattering systems and their
-, -, and -symmetries. In
particular, we review various relevant concepts such as Jost solutions,
transfer and scattering matrices, reciprocity principle, unidirectional
reflection and invisibility, and spectral singularities. We discuss in some
detail the mathematical conditions that imply or forbid reciprocal
transmission, reciprocal reflection, and the presence of spectral singularities
and their time-reversal. We also derive generalized unitarity relations for
time-reversal-invariant and -symmetric scattering
systems, and explore the consequences of breaking them. The results reported
here apply to the scattering systems defined by a real or complex local
potential as well as those determined by energy-dependent potentials, nonlocal
potentials, and general point interactions.Comment: Slightly expanded revised version, 38 page
Adult mortality in subâSaharan Africa: Crossâsectional study of causes of death in Zambia
Objective
To describe the ageâsex pattern and socioeconomic differentials in causes of death among adults between the ages of 15 and 59 years in Zambia.
Methods
Using data from the 2010â2012 Zambia sample vital registration with verbal autopsy survey, we calculated the percentage share of causes of death, the ageâsex causeâspecific death ratio, and causeâeliminated life expectancy at age 15.
Results
HIV/AIDS was the leading cause of death across all socioeconomic subgroups contributing 40.7% of total deaths during the study period. This was followed by deaths due to injury and accidents (11.2%). Causeâspecific death ratios due to HIV/AIDS increased by age and peaked in the 35âtoâ39 age group, and were higher among females than males. The second leading cause of death was injuries and accidents for females and tuberculosis for males. The third leading cause of death was cardiovascular diseases for females and tuberculosis for males. Cause of death patterns varied notably by socioeconomic characteristics. Deaths attributable to nonâcommunicable diseases were more evident in adults aged 45 to 59 years. Eliminating HIV/AIDS in Zambia as a cause of death could raise life expectancy at age 15 by 5.77 years for males and by 6.40 years for females.
Conclusion
HIV/AIDSârelated health programmes and interventions should be further supported and strengthened, as they would significantly contribute to the reduction of adult mortality in Zambia
Long-Term Opioid Contract Use for Chronic Pain Management in Primary Care Practice. A Five Year Experience
BACKGROUND: The use of opioid medications to manage chronic pain is complex and challenging, especially in primary care settings. Medication contracts are increasingly being used to monitor patient adherence, but little is known about the long-term outcomes of such contracts. OBJECTIVE: To describe the long-term outcomes of a medication contract agreement for patients receiving opioid medications in a primary care setting. DESIGN: Retrospective cohort study. SUBJECTS: All patients placed on a contract for opioid medication between 1998 and 2003 in an academic General Internal Medicine teaching clinic. MEASUREMENTS: Demographics, diagnoses, opiates prescribed, urine drug screens, and reasons for contract cancellation were recorded. The association of physician contract cancellation with patient factors and medication types were examined using the Chi-square test and multivariate logistic regression. RESULTS: A total of 330 patients constituting 4% of the clinic population were placed on contracts during the study period. Seventy percent were on indigent care programs. The majority had low back pain (38%) or fibromyalgia (23%). Contracts were discontinued in 37%. Only 17% were cancelled for substance abuse and noncompliance. Twenty percent discontinued contract voluntarily. Urine toxicology screens were obtained in 42% of patients of whom 38% were positive for illicit substances. CONCLUSIONS: Over 60% of patients adhered to the contract agreement for opioids with a median follow-up of 22.5Â months. Our experience provides insight into establishing a systematic approach to opioid administration and monitoring in primary care practices. A more structured drug testing strategy is needed to identify nonadherent patients
The relationship between the preoperative systemic inflammatory response and cancer-specific survival in patients undergoing potentially curative resection for renal clear cell cancer
The relationship between tumour stage, grade (Fuhrman), performance status (ECOG), a combined score (UCLA Integrated Staging System, UISS), systemic inflammatory response (elevated C-reactive protein concentration), and cancer-specific survival was examined in patients undergoing potentially curative resection for renal clear cell cancer (n=100). On univariate survival analysis, sex (P=0.050), tumour stage (P=0.001), Fuhrman grade (P<0.001), UISS (P<0.001), C-reactive protein (P=0.002) were significant predictors of survival. On multivariate analysis with sex, UISS and C-reactive protein entered as covariates, only UISS (HR 2.70, 95% CI 1.00â7.30, P=0.050) and C-reactive protein (HR 4.00, 95% CI 1.21â13.31, P=0.024) were significant independent predictors of survival. The presence of a preoperative systemic inflammatory response predicts poor cancer-specific survival in patients who have undergone potentially curative resection for renal clear cell cancer
Autism as a disorder of neural information processing: directions for research and targets for therapy
The broad variation in phenotypes and severities within autism spectrum disorders suggests the involvement of multiple predisposing factors, interacting in complex ways with normal developmental courses and gradients. Identification of these factors, and the common developmental path into which theyfeed, is hampered bythe large degrees of convergence from causal factors to altered brain development, and divergence from abnormal brain development into altered cognition and behaviour. Genetic, neurochemical, neuroimaging and behavioural findings on autism, as well as studies of normal development and of genetic syndromes that share symptoms with autism, offer hypotheses as to the nature of causal factors and their possible effects on the structure and dynamics of neural systems. Such alterations in neural properties may in turn perturb activity-dependent development, giving rise to a complex behavioural syndrome many steps removed from the root causes. Animal models based on genetic, neurochemical, neurophysiological, and behavioural manipulations offer the possibility of exploring these developmental processes in detail, as do human studies addressing endophenotypes beyond the diagnosis itself
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