312 research outputs found

    Early spears as thrusting weapons: Isolating force and impact velocities in human performance trials

    Get PDF
    Human hunting has been a cornerstone of research in human evolutionary studies, and decades worth of research programmes into early weapon systems have improved our understanding of the subsistence behaviours of our genus. Thrusting spears are potentially one of the earliest hunting weapons to be manufactured and used by humans. However, a dearth of data on the mechanics of thrusting spear use has hampered experimental research. This paper presents a human performance trial using military personnel trained in bayonet use. Participants thrusted replicas of Middle Pleistocene wooden spears into PermaGel™. For each spear thrust, impact velocity was recorded with high-speed video equipment, and force profiles were recorded using a force transducer. The results demonstrate that training improves performance when compared with previous experimental results using untrained participants, and that the mechanics and biomechanics of spear thrusting are complex. The trial confirms that previous spear thrusting experiments firing spears as projectiles are failing to replicate the entire spear thrusting event, and that crossbows are too powerful to replicate the low velocities involved in spear thrusting. In order to better understand evidence of spear thrusting in the archaeological record, experimental protocols accurately replicating and recording the mechanics of spear thrusting in the past are proposed

    Anormalidades morfológicas nucleares en hematíes del pez Prochilodus linneatus expuesto al clorpirifos

    Get PDF
    In recent years, the monitoring of xenobiotics (chemicals such as pesticides) in the environment has been very important, as the persistence of the biological activity of many of these compounds has been recognized. Chlorpyrifos is an organophosphorus insecticide of broad spectrum, used in agricultural and domestic activities. This pesticide as well as other chemicals may accidentally reach the aquatic ecosystem and the ictic fauna. Fish ingesting contaminated substances subsequently develop alterations due to bioaccumulation, becoming effective indicators of environmental pollution. The purpose of this study was to evaluate the genotoxicity of chlorpyrifos in P. linneatus (Pisces, Prochilodontidae) through the frequency of micronuclei (MN) and nuclear morphology alterations (AMN) in peripheral blood erythrocytes. After acclimatization the fish were divided into two control (C) and treated groups (T1 = 10 μg/l, T2 = 30 μg/l and T3 = 90 μg/l). Three replicates per group (C, T) were performed with a total of 3 animals per fishbowl. The animals remained in the aquariums for a period of 7 days. After this time they were sacrificed with an overdose of anaesthetic to extract blood from the caudal vein. Smears were stained with Giemsa. In the samples analyzed, the number of MN and AMN was determined after observation of 2000 cells per animal. Cells with intact cytoplasmic membrane were considered for the study. The analysis of blood smears in both groups revealed the presence of micronuclei and the following nuclear morphology alterations; notches, lobulated, evaginations, eigth shaped, segmentations and vacuolization nuclei. Individuals T3 showed significant variations in the frequency of MN and AMN with respect to the controls (p<0.05), but not the T1 and T2 specimens. We conclude that chlorpyrifos at a dose of 90 μg/l could be harmful to the environment.Recientemente adquirió importancia el monitoreo de xenobióticos (como pesticidas) en el medio ambiente, debido a la persistencia de la actividad biológica de muchos de ellos. Clorpirifos es un insecticida organofosforado empleado a nivel agrícola y doméstico. Este plaguicida puede alcanzar accidentalmente el ecosistema acuático y la fauna íctica. Al ingerir sustancias contaminadas, los peces desarrollan alteraciones debidas a la bioacumulación, constituyéndose en eficaces indicadores de polución ambiental. El propósito del estudio fue evaluar la genotoxicidad del clorpirifos en P. linneatus (Pisces, Prochilodontidae) a través de la frecuencia de micronúcleos (MN) y de alteraciones de la morfología nuclear (AMN) en eritrocitos de sangre periférica. Los ensayos se realizaron con clorpirifos en su forma pura (Sigma Aldrich). Los peces se dividieron en grupos control (C) y tratados (T1 = 10 μg/l; T2 = 30 μg/l y T3 = 90 μg/l). Se realizaron tres replicas por grupo, con un total de 3 animales por pecera, los cuales permanecieron allí durante 7 días, tras lo cual fueron sacrificados con sobredosis de anestésico. Se extrajo sangre de la vena caudal, realizándose frotis que se colorearon con Giemsa, determinándose el número de MN y AMN luego de la observación de 2000 células por animal. Para el estudio se consideraron las células con sus membranas citoplasmáticas intactas. En ambos grupos, los frotis sanguíneos revelaron la presencia de micronúcleos, así como algunas de las siguientes alteraciones de la morfología nuclear: muesca, lobulación, evaginación, forma de ocho, segmentación y vacuolización nuclear. Los individuos del grupo T3 mostraron variaciones significativas en la frecuencia de MN y AMN respecto a los controles (p<0,05), no así los ejemplares de los tratamientos T1 y T2. Por lo expuesto, surge que el clorpirifos a la dosis de 90 μg/l podría ser nocivo para el medio ambiente

    Gadolinium and nephrogenic systemic fibrosis: time to tighten practice

    Get PDF
    Nephrogenic systemic fibrosis (NSF) is a relatively new entity, first described in 1997. Few cases have been reported, but the disease has high morbidity and mortality. To date it has been seen exclusively in patients with renal dysfunction. There is an emerging link with intravenous injection of gadolinium contrast agents, which has been suggested as a main triggering factor, with a lag time of days to weeks. Risk factors include the severity of renal impairment, major surgery, vascular events and other proinflammatory conditions. There is no reason to believe that children have an altered risk compared to the adult population. It is important that the paediatric radiologist acknowledges emerging information on NSF but at the same time considers the risk:benefit ratio prior to embarking on alternative investigations, as children with chronic kidney disease require high-quality diagnostic imaging

    The association between clinical integration of care and transfer of veterans with acute coronary syndromes from primary care VHA hospitals

    Get PDF
    BACKGROUND: Few studies report on the effect of organizational factors facilitating transfer between primary and tertiary care hospitals either within an integrated health care system or outside it. In this paper, we report on the relationship between degree of clinical integration of cardiology services and transfer rates of acute coronary syndrome (ACS) patients from primary to tertiary hospitals within and outside the Veterans Health Administration (VHA) system. METHODS: Prospective cohort study. Transfer rates were obtained for all patients with ACS diagnoses admitted to 12 primary VHA hospitals between 1998 and 1999. Binary variables measuring clinical integration were constructed for each primary VHA hospital reflecting: presence of on-site VHA cardiologist; referral coordinator at the associated tertiary VHA hospital; and/or referral coordinator at the primary VHA hospital. We assessed the association between the integration variables and overall transfer from primary to tertiary hospitals, using random effects logistic regression, controlling for clustering at two levels and adjusting for patient characteristics. RESULTS: Three of twelve hospitals had a VHA cardiologist on site, six had a referral coordinator at the tertiary VHA hospital, and four had a referral coordinator at the primary hospital. Presence of a VHA staff cardiologist on site and a referral coordinator at the tertiary VHA hospital decreased the likelihood of any transfer (OR 0.45, 95% CI 0.27–0.77, and 0.46, p = 0.002, CI 0.27–0.78). Conversely, having a referral coordinator at the primary VHA hospital increased the likelihood of transfer (OR 6.28, CI 2.92–13.48). CONCLUSIONS: Elements of clinical integration are associated with transfer, an important process in the care of ACS patients. In promoting optimal patient care, clinical integration factors should be considered in addition to patient characteristics

    Imaging in the time of NFD/NSF: do we have to change our routines concerning renal insufficiency?

    Get PDF
    To date there are potential chronology-based but not conclusive reasons to believe that at least some of the gadolinium complexes play a causative role in the pathophysiology of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). Still, the exact pathogenesis and the risk for patients is unclear beside the obvious connection to moderate to severe renal insufficiency. So far, MR imaging with Gd-enhancement was regarded as the safest imaging modality in these patients—the recent development creates tremendous uncertainty in the MR-community. Nevertheless, one should remember that, despite the over 200 cases of NSF and about 100 with proven involvement of Gd3+, the vast majority of over 200 million patients exposed to gadolinium since the 1980s have tolerated these agents well. Importantly, NSF is a rare disease and does not appear to occur in patients without renal impairment. Many patients and researchers have undergone MR investigations with Gd exposure in the past. For those, it is essential to know about the safety of the agents at normal renal function. We can hope that pharmacoepidemiological and preclinical studies will allow us to better understand the pathophysiology and role of the various MR contrast agents in the near future

    Declining mortality following acute myocardial infarction in the Department of Veterans Affairs Health Care System

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Mortality from acute myocardial infarction (AMI) is declining worldwide. We sought to determine if mortality in the Veterans Health Administration (VHA) has also been declining.</p> <p>Methods</p> <p>We calculated 30-day mortality rates between 2004 and 2006 using data from the VHA External Peer Review Program (EPRP), which entails detailed abstraction of records of all patients with AMI. To compare trends within VHA with other systems of care, we estimated relative mortality rates between 2000 and 2005 for all males 65 years and older with a primary diagnosis of AMI using administrative data from the VHA Patient Treatment File and the Medicare Provider Analysis and Review (MedPAR) files.</p> <p>Results</p> <p>Using EPRP data on 11,609 patients, we observed a statistically significant decline in adjusted 30-day mortality following AMI in VHA from 16.3% in 2004 to 13.9% in 2006, a relative decrease of 15% and a decrease in the odds of dying of 10% per year (p = .011). Similar declines were found for in-hospital and 90-day mortality.</p> <p>Based on administrative data on 27,494 VHA patients age 65 years and older and 789,400 Medicare patients, 30-day mortality following AMI declined from 16.0% during 2000-2001 to 15.7% during 2004-June 2005 in VHA and from 16.7% to 15.5% in private sector hospitals. After adjusting for patient characteristics and hospital effects, the overall relative odds of death were similar for VHA and Medicare (odds ratio 1.02, 95% C.I. 0.96-1.08).</p> <p>Conclusion</p> <p>Mortality following AMI within VHA has declined significantly since 2003 at a rate that parallels that in Medicare-funded hospitals.</p

    Occupancy maps of 208 chromatin-associated proteins in one human cell type

    Get PDF
    Transcription factors are DNA-binding proteins that have key roles in gene regulation. Genome-wide occupancy maps of transcriptional regulators are important for understanding gene regulation and its effects on diverse biological processes. However, only a minority of the more than 1,600 transcription factors encoded in the human genome has been assayed. Here we present, as part of the ENCODE (Encyclopedia of DNA Elements) project, data and analyses from chromatin immunoprecipitation followed by high-throughput sequencing (ChIP–seq) experiments using the human HepG2 cell line for 208 chromatin-associated proteins (CAPs). These comprise 171 transcription factors and 37 transcriptional cofactors and chromatin regulator proteins, and represent nearly one-quarter of CAPs expressed in HepG2 cells. The binding profiles of these CAPs form major groups associated predominantly with promoters or enhancers, or with both. We confirm and expand the current catalogue of DNA sequence motifs for transcription factors, and describe motifs that correspond to other transcription factors that are co-enriched with the primary ChIP target. For example, FOX family motifs are enriched in ChIP–seq peaks of 37 other CAPs. We show that motif content and occupancy patterns can distinguish between promoters and enhancers. This catalogue reveals high-occupancy target regions at which many CAPs associate, although each contains motifs for only a minority of the numerous associated transcription factors. These analyses provide a more complete overview of the gene regulatory networks that define this cell type, and demonstrate the usefulness of the large-scale production efforts of the ENCODE Consortium

    Розрахунок та проектування окремого фундаменту будівлі на природній ґрунтовій основі. Методичні рекомендації до виконання практичних завдань та курсового проекту з дисципліни «Механіка ґрунтів, основи і фундаменти» сту- дентами напрямів підготовки 6.060101 Будівництво та 6.050301 Гірництво

    Get PDF
    Подано методичні рекомендації до виконання практичних завдань та кур- сового проекту з дисципліни «Механіка ґрунтів, основи і фундаменти» для сту- дентів напрямів підготовки 6.060101 Будівництво та 6.050301 Гірництво. Розглянуто порядок проектування фундаменту будівлі мілкого закладан- ня на природній ґрунтовій основі. Методичні рекомендації передбачають виконання курсового проекту «Розрахунок та проектування окремого фундаменту будівлі на природній ґрун- товій основі» як із викладачем, так і під час самостійної роботи. Можна використовувати також у підготовці курсового та дипломного про- ектування
    corecore