221 research outputs found
Sediment Micromorphology and Site Formation Processes During the Middle to Later Stone Ages at the Haua Fteah Cave, Cyrenaica, Libya
Understanding the timing, conditions, and characteristics of the Middle to Later Stone Age (MSA/LSA) transition in North Africa is critical for debates regarding the evolution and past population dynamics of Homo sapiens, especially their dispersals within, out of, and back into, Africa. As with many cultural transitions during the Palaeolithic, our understanding is based predominantly on archaeological and paleoenvironmental records preserved within a small number of deep cave sediment sequences. To use such sequences as chronological cornerstones we must develop a robust understanding of the formation processes that created them. This paper utilizes geoarchaeological analyses (field observations, sediment micromorphology, bulk sedimentology) to examine site formation processes and stratigraphic integrity during the MSA/LSA at the Haua Fteah cave, Libya, one of North Africa's longest cultural sequences. The depositional processes identified vary in mode and energy, from eolian deposition/reworking to mass colluvial mudflows. These changing processes impact greatly on the interpretation of the paleoenvironmental and archaeological records, not least in identifying potential colluvial sediment deposition and reworking in layers identified as containing the MSA/LSA transition. This study highlights the importance of developing geoarchaeological analyses of cultural sequences to fully unravel the limitations and potential of their contained archaeological and paleoenvironmental records.ERC, NER
Factors associated with tocolytic hospitalizations in Taiwan: evidence from a population-based and longitudinal study from 1997 to 2004
<p>Abstract</p> <p>Background</p> <p>The use of tocolytic hospitalization in antenatal care is controversial and worthy of more research. We investigated individual, institutional, and area factors that affect the use of tocolytic hospitalizations in Taiwan where fertility has rapidly declined.</p> <p>Methods</p> <p>Longitudinal data from the 1996 to 2004 National Health Insurance Research Database in Taiwan were used to identify tocolytic hospitalizations. The probit model was used to estimate factors associated with tocolytic hospitalizations.</p> <p>Results</p> <p>The decline in fertility was significantly associated with the probability of tocolytic hospitalizations. Several physician and institutional factors-including physician's age, hospital ownership, accreditation status, bed size, and teaching status-were also significantly correlated to the dependent variables.</p> <p>Conclusions</p> <p>The provision of inpatient tocolysis is influenced not only by clinical considerations but also by physician, institutional, and area factors unrelated to clinical need. Fertility declines in Taiwan may have led obstetricians/gynecologists to provide more tocolysis to make up for their lost income. If the explanation is further validated, reimbursement policies may need to be reviewed to correct for overuse of inpatient tocolysis. The correlation could also be explained by the increasing use of artificial reproductive technologies and higher social value of newborns. In addition, the physician and institutional variations observed in the study indicate potential misuse of inpatient tocolysis that warrant further investigation.</p
Secretion of Clostridium difficile Toxins A and B Requires the Holin-like Protein TcdE
The pathogenesis of Clostridium difficile, the major cause of antibiotic-associated diarrhea, is mainly associated with the production and activities of two major toxins. In many bacteria, toxins are released into the extracellular environment via the general secretion pathways. C. difficile toxins A and B have no export signature and their secretion is not explainable by cell lysis, suggesting that they might be secreted by an unusual mechanism. The TcdE protein encoded within the C. difficile pathogenicity locus (PaLoc) has predicted structural features similar to those of bacteriophage holin proteins. During many types of phage infection, host lysis is driven by an endolysin that crosses the cytoplasmic membrane through a pore formed by holin oligomerization. We demonstrated that TcdE has a holin-like activity by functionally complementing a λ phage deprived of its holin. Similar to λ holin, TcdE expressed in Escherichia coli and C. difficile formed oligomers in the cytoplamic membrane. A C. difficile tcdE mutant strain grew at the same rate as the wild-type strain, but accumulated a dramatically reduced amount of toxin proteins in the medium. However, the complemented tcdE mutant released the toxins efficiently. There was no difference in the abundance of tcdA and tcdB transcripts or of several cytoplasmic proteins in the mutant and the wild-type strains. In addition, TcdE did not overtly affect membrane integrity of C. difficile in the presence of TcdA/TcdB. Thus, TcdE acts as a holin-like protein to facilitate the release of C. difficile toxins to the extracellular environment, but, unlike the phage holins, does not cause the non-specific release of cytosolic contents. TcdE appears to be the first example of a bacterial protein that releases toxins into the environment by a phage-like system
Variable population size and evolution acceleration: a case study with a parallel evolutionary algorithm
Smoking, alcohol consumption, physical activity, and family history and the risks of acute myocardial infarction and unstable angina pectoris: a prospective cohort study
<p>Abstract</p> <p>Background</p> <p>Few studies investigated the association between smoking, alcohol consumption, or physical activity and the risk of unstable angina pectoris (UAP), while the strength of these associations may differ compared to other coronary diseases such as acute myocardial infarction (AMI). Therefore, we investigated whether the associations of these lifestyle factors with UAP differed from those with AMI. Additionally, we investigated whether these effects differed between subjects with and without a family history of myocardial infarction (MI).</p> <p>Methods</p> <p>The CAREMA study consists of 21,148 persons, aged 20-59 years at baseline and randomly sampled from the Maastricht region in 1987-1997. At baseline, all participants completed a self-administered questionnaire. After follow-up of maximally 16.9 years, 420 AMI and 274 UAP incident cases were registered. Incidence rate ratios (RRs) were estimated using Cox proportional hazards models.</p> <p>Results</p> <p>For both diseases, smoking increased the risk while alcohol consumption was associated with a protective effect. Associations with both risk factors were stronger for AMI than UAP, although this difference was only statistically significant for smoking. In men, an inverse association was found with physical activity during leisure time which seemed to be stronger for the risk of UAP than of AMI. On the contrary, physical activity during leisure time was associated with an increased risk of both AMI and UAP in women which seemed to be weaker for UAP than for AMI. Except for occupational physical activity in women, no significant interactions on a multiplicative scale were found between the lifestyle factors and family history of MI. Nevertheless, the highest risks were found in subjects with both a positive family history and the most unfavorable level of the lifestyle factors.</p> <p>Conclusions</p> <p>The strength of the associations with the lifestyle factors did not differ between AMI and UAP, except for smoking. Furthermore, the effects of the lifestyle factors on the risk of both coronary diseases were similar for subjects with and without a positive family history.</p
A development study and randomised feasibility trial of a tailored intervention to improve activity and reduce falls in older adults with mild cognitive impairment and mild dementia
Background:
People with dementia progressively lose abilities and are prone to falling. Exercise- and activity-based interventions hold the prospect of increasing abilities, reducing falls, and slowing decline in cognition. Current falls prevention approaches are poorly suited to people with dementia, however, and are of uncertain effectiveness. We used multiple sources, and a co-production approach, to develop a new intervention, which we will evaluate in a feasibility randomised controlled trial (RCT), with embedded adherence, process and economic analyses.
Methods:
We will recruit people with mild cognitive impairment or mild dementia from memory assessment clinics, and a family member or carer. We will randomise participants between a therapy programme with high intensity supervision over 12 months, a therapy programme with moderate intensity supervision over 3 months, and brief falls assessment and advice as a control intervention. The therapy programmes will be delivered at home by mental health specialist therapists and therapy assistants. We will measure activities of daily living, falls and a battery of intermediate and distal health status outcomes, including activity, balance, cognition, mood and quality of life. The main aim is to test recruitment and retention, intervention delivery, data collection and other trial processes in advance of a planned definitive RCT. We will also study motivation and adherence, and conduct a process evaluation to help understand why results occurred using mixed methods, including a qualitative interview study and scales measuring psychological, motivation and communication variables. We will undertake an economic study, including modelling of future impact and cost to end-of-life, and a social return on investment analysis.
Discussion:
In this study, we aim to better understand the practicalities of both intervention and research delivery, and to generate substantial new knowledge on motivation, adherence and the approach to economic analysis. This will enable us to refine a novel intervention to promote activity and safety after a diagnosis of dementia, which will be evaluated in a definitive randomised controlled trial.\ud
Trial registration:
ClinicalTrials.gov: NCT02874300; ISRCTN 10550694
Double jeopardy:subordinates' worldviews and poor performance as predictors of abusive supervision
Purpose - To test a moderated mediation model where a positive relationship between subordinates’ perceptions of a dangerous world—the extent to which an individual views the world as a dangerous place—and supervisory abuse is mediated by their submission to authority figures, and that this relationship is heightened for more poorly performing employees. Design/Methodology/Approach - Data were obtained from 173 subordinates and 45 supervisors working in different private sector organizations in Pakistan. Findings - Our model was supported. It appears that subordinates’ dangerous worldviews are positively associated with their perceptions of abusive supervision and that this is because such views are likely to lead to greater submission to authority figures. But this is only for those employees who are performing more poorly. Implications - We highlight the possibility that individual differences (worldviews, attitudes to authority figures, and performance levels) may lead employees to become victims of abusive supervision. As such, our research informs organizations on how they may better support supervisors in managing effectively their subordinate relationships and, in particular, subordinate poor performance. Originality/Value - We add to recent work exploring subordinate-focused antecedents of abusive supervision, finding support for the salience of the previously untested constructs of individual worldviews, authoritarian submission, and individual job performance. In so doing we also extend research on dangerous worldviews into a new organizational setting. Finally, our research takes place within a new Pakistani context, adding to the burgeoning non-US based body of empirical work into the antecedents and consequences of abusive supervision
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