3,084 research outputs found

    Integrating archaeology and ancient DNA analysis to address invasive species colonization in the Gulf of Alaska

    Get PDF
    The intentional and unintentional movement of plants and animals by humans has transformed ecosystems and landscapes globally. Assessing when and how a species was introduced are central to managing these transformed landscapes, particularly in island environments. In the Gulf of Alaska, there is considerable interest in the history of mammal introductions and rehabilitating Gulf of Alaska island environments by eradicating mammals classified as invasive species. The Arctic ground squirrel (Urocitellus parryii) is of concern because it affects vegetation and seabirds on Gulf of Alaska islands. This animal is assumed to have been introduced by historic settlers; however, ground squirrel remains in the prehistoric archaeological record of Chirikof Island, Alaska, challenge this timeline and suggest they colonized the islands long ago. We used 3 lines of evidence to address this problem: direct radiocarbon dating of archaeological squirrel remains; evidence of prehistoric human use of squirrels; and ancient DNA analysis of dated squirrel remains. Chirikof squirrels dated to at least 2000 years ago, and cut marks on squirrel bones suggested prehistoric use by people. Ancient squirrels also shared a mitochondrial haplotype with modern Chirikof squirrels. These results suggest that squirrels have been on Chirikof longer than previously assumed and that the current population of squirrels is closely related to the ancient population. Thus, it appears ground squirrels are not a recent, human‐mediated introduction and may have colonized the island via a natural dispersal event or an ancient human translocation.We thank T. Rick, D. Grayson, R. Fleischer, M. Hawkins, A. West, and C. Mikeska for their contributions to this research. We also thank 3 reviewers and the editors of Conservation Biology who greatly improved this paper. This work was funded by the National Geographic Society, the University of Maine, the Smithsonian Institution, and Boston University. The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the U.S. Fish and Wildlife Service. (National Geographic Society; University of Maine; Smithsonian Institution; Boston University)Published versio

    KNEE JOINT LIGAMENT RECONSTRUCTION: ON PRETENSION AND COUPLING IN CRUCIATE LIGAMENTS

    Get PDF
    Wide range of knee cruciate ligament reconstruction procedures with different materials, stiffness, pretensions, orientations, and insertion locations are currently used with the primary goal to restore the joint laxity. With the general lack of success in preservation of force in the reconstructed ligament, the concern, not yet addressed, arises as to the effect of reconstruction on the other intact cruciate ligament. Using a 3-D finite element model, we examined this hypothesis by varying the pretension in each ligament under flexion ±A-P loads and quantifying the extent of coupling between cruciate ligaments. A remarkable coupling was predicted. Moreover, changes in laxity and in ligament forces as ligament pretension was altered varied with flexion and loads. These findings have important consequences in proper management and rehabilitation of the joint ligament disorders

    Group A �-hemolytic streptococcal infection in children and the resultant neuro-psychiatric disorder; a cross sectional study; Tehran, Iran

    Get PDF
    Introduction: Group A Beta-Hemolytic Streptococcus (GABHS) can induce PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection). GABHS is the most important and common bacterial cause of acute pharyngitis in Iranian children. We studied the role of GABHS (anti-streptococcal antibodies) in suspected cases of PANDAS in a cross sectional studies. Methods: Across sectional study was done in 2 pediatric psychiatric/and neurologic clinics in Tehran (Rasul Akram and Aliasghar Hospital) during 2008-2010. We studied serum antistreptococcal antibodies (anti streptolysin O, anti Deoxyribonuclease B, and anti-streptokinase (ABcam-ELISA, USA) in 76 cases with psychiatric manifestation (OCD, ADHD) in compare with 39 healthy controls. These antibodies were studied in 53 cases with movement disorders (Tic/Tourette syndrome) in compare with 76 healthy controls. Sensitivity, specificity and positive predictive value of tests were calculated. Results: In movement disorders ASOT, Anti-DNase and Anti streptokinase was significantly higher than controls (p 200IU/ml) had 75 sensitivity; 84 specificity and 80 PPV; Antistreptokinase (cut off level> 332 IU/ml) had 34 sensitivity; 85 specificity, and 72 PPV; Anti-DNase (cut off level> 140IU/ml) had 70 sensitivity; 99 specificity and PPV 90 for differentiating the group. ASOT, Anti-DNase and Anti streptokinase titer was significantly higher than controls (p<0.0001, p=0.000, p<0.0001). ASOT had 90 sensitivity; 82 specificity, PPV 92; Anti streptokinase: 82 sensitivity; 82 specificity, PPV 95; Anti DNase: 92 sensitivity; 82 specificity, PPV 92 for differentiation the cases from normal controls. Discussion: These findings support that a post infectious immune mechanism to GABHS may play a role in the pathogenesis of PANDAS in our children. A combination of throat culture, rapid antigen detection test, and serologic testing for GABHS is required to achieve maximum sensitivity and specificity for diagnosis. We prefer to use antibiotic prophylaxis in PANDAS cases for preventing recurrent streptococcal infections. Ongoing research is needed for identifying optimum diagnostic, prevention and therapeutic approach especially, aggressive treatment (intravenous immunoglobulin, plasmaphresis)

    Hybrid self-organizing feature map (SOM) for anomaly detection in cloud infrastructures using granular clustering based upon value-difference metrics

    Get PDF
    We have witnessed an increase in the availability of data from diverse sources over the past few years. Cloud computing, big data and Internet-of-Things (IoT) are distinctive cases of such an increase which demand novel approaches for data analytics in order to process and analyze huge volumes of data for security and business use. Cloud computing has been becoming popular for critical structure IT mainly due to cost savings and dynamic scalability. Current offerings, however, are not mature enough with respect to stringent security and resilience requirements. Mechanisms such as anomaly detection hybrid systems are required in order to protect against various challenges that include network based attacks, performance issues and operational anomalies. Such hybrid AI systems include Neural Networks, blackboard systems, belief (Bayesian) networks, case-based reasoning and rule-based systems and can be implemented in a variety of ways. Traffic in the cloud comes from multiple heterogeneous domains and changes rapidly due to the variety of operational characteristics of the tenants using the cloud and the elasticity of the provided services. The underlying detection mechanisms rely upon measurements drawn from multiple sources. However, the characteristics of the distribution of measurements within specific subspaces might be unknown. We argue in this paper that there is a need to cluster the observed data during normal network operation into multiple subspaces each one of them featuring specific local attributes, i.e. granules of information. Clustering is implemented by the inference engine of a model hybrid NN system. Several variations of the so-called value-difference metric (VDM) are investigated like local histograms and the Canberra distance for scalar attributes, the Jaccard distance for binary word attributes, rough sets as well as local histograms over an aggregate ordering distance and the Canberra measure for vectorial attributes. Low-dimensional subspace representations of each group of points (measurements) in the context of anomaly detection in critical cloud implementations is based upon VD metrics and can be either parametric or non-parametric. A novel application of a Self-Organizing-Feature Map (SOFM) of reduced/aggregate ordered sets of objects featuring VD metrics (as obtained from distributed network measurements) is proposed. Each node of the SOFM stands for a structured local distribution of such objects within the input space. The so-called Neighborhood-based Outlier Factor (NOOF) is defined for such reduced/aggregate ordered sets of objects as a value-difference metric of histogrammes. Measurements that do not belong to local distributions are detected as anomalies, i.e. outliers of the trained SOFM. Several methods of subspace clustering using Expectation-Maximization Gaussian Mixture Models (a parametric approach) as well as local data densities (a non-parametric approach) are outlined and compared against the proposed method using data that are obtained from our cloud testbed in emulated anomalous traffic conditions. The results—which are obtained from a model NN system—indicate that the proposed method performs well in comparison with conventional techniques

    TEMPERATURE-DEPENDENT PHYSICAL CHARACTERISTICS OF THE ROTATING NONLOCAL NANOBEAMS SUBJECT TO A VARYING HEAT SOURCE AND A DYNAMIC LOAD

    Get PDF
    In this article, the influence of thermal conductivity on the dynamics of a rotating nanobeam is established in the context of nonlocal thermoelasticity theory. To this end, the governing equations are derived using generalized heat conduction including phase lags on the basis of the Euler–Bernoulli beam theory. The thermal conductivity of the proposed model linearly changes with temperature and the considered nanobeam is excited with a variable harmonic heat source and exposed to a time-dependent load with exponential decay. The analytic solutions for bending moment, deflection and temperature of rotating nonlocal nanobeams are achieved by means of the Laplace transform procedure. A qualitative study is conducted to justify the soundness of the present analysis while the impact of nonlocal parameter and varying heat source are discussed in detail. It also shows the way in which the variations of physical properties due to temperature changes affect the static and dynamic behavior of rotating nanobeams. It is found that the physical fields strongly depend on the nonlocal parameter, the change of the thermal conductivity, rotation speed and the mechanical loads and, therefore, it is not possible to neglect their effects on the manufacturing process of precise/intelligent machines and devices

    Gene Expression and Structural Skeletal Responses to Long-Duration Simulated Microgravity in Rats

    Get PDF
    Spaceflight has deleterious effects on skeletal structure and function, specifically causingprofound loss in bone mass, density, and strength, as well as changes in expression levels of genes related to oxidative stress [Hyeon et al., Smith et al.]. It is known that bone resorption remains elevated after spaceflight and that bone density and strength fail to recover completely even years following spaceflight [Smith et al., Carpenter et al.]. However, our current understanding of the signaling pathways and molecular mechanisms that control bone loss and that link oxidative stress, bone resorption, and mechanical unloading of skeletal tissue is incomplete. Here, we aim to examine skeletal responses to simulated long-duration spaceflight on bone loss using the ground-based hindlimb unloading (HU) model in adult (9 months old) male rats. We hypothesized that simulated microgravity leads to the temporal regulation of oxidative-defense genes and pro-osteoclastogenic factors, showing progression and eventual plateau during long-term unloading, and that transient changes at early timepoints in these pathways precede skeletal adaptations to long-duration unloading. We will identify oxidativestress and bone resorption-related changes using global gene expression analysis (Affymetrix arrays) for both acute (within 14 days) and long-term timepoints (90 days). We will also use quantitative PCR to examine changes in expression of genes related to oxidative metabolism (e.g. Nrf2, SOD-1), bone turnover (resorption and formation markers, e.g. TRAP, osteocalcin respectively, SOST), and osteoclastogenesis (e.g. RANKL, OPG) at both early and late timepoints. We will then use detailed microarchitectural and structural analysis through microcomputed tomography to relate gene expression changes with structural changes in bone, expecting that plateaus in gene expression correlate with long-term changes in bone microarchitecture

    An open trial of citalopram in children and adolescents with depression

    Get PDF
    Objective: The aim of this study was to collect pilot data on the magnitude of effect and tolerability of citalopram in early-onset major depressive disorder (MDD). Method: This study was performed in two academic child and adolescent psychiatric clinics (2000 through 2002). Thirty children and adolescents, 8-17 years of age (mean age, 13.57 ± 2.5), of both sexes (53.3 girls; 46.7 boys) and diagnosed with MDD by means of clinical psychiatric evaluation, Diagnostic Interview for Children and Adolescents (DICA) and the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria, were studied in an open-label clinical trial with 10-40 mg/day of citalopram for 6 weeks. The out-come measures were the Hamilton Depression Rating Scale (HDRS), the Children Global Assessment Scale (CGAS), and the New York State Psychiatric Institute side-effect form. Results: Moderate (50-70 change in HDRS and CGAS) to large (> 70 change in HDRS and CGAS) effect were seen in 91.7 of children (22/24). There were significant changes on HDRS (X = 22.78; t = -14.12; p < 0.000) and CGAS (X = 26.02; t = 9.68; p < 0.000) between base-line and the 6th week. Mild side effects were reported in 2 patients (8.3). Adverse effects that contributed to discontinuation were nausea and vomiting in 3.3 (n = 1) of patients and unexpectedly switching to mania in 16.7 (n = 5) of patients. Conclusion: Citalopram may be an efficatious treatment in early-onset MDD. However, the high switch rate to mania warrants further investigations, as well as cautions, in using it

    Effects of Multiple Bouts of Long-duration Hindlimb Unloading and Recovery on Rat Plantaris Muscle

    Get PDF
    Exposure to microgravity results in a rapid reduction of muscle mass. However, few studies exist designed to examine the effects of multiple long-term exposures to microgravity with alternating recovery periods on skeletal muscle. To determine what happens to the recovery of skeletal muscle when faced with subsequent unloading and recovery periods. Male Sprague-Dawley (6 mo) were assigned to the following groups as shown in figure 1 below: 28d hindlimb unloading (1HU), 28d HU session followed by a 56d recovery bout of normal cage ambulation at 1g (1HU+REC), 2 cycles of 28d HU with a 56d recovery period between unloadings (2HU), 2 cycles of 28d HU as in the 2HU group, but followed by an additional 56d recovery at 1g (2HU+REC), and an age- and housing-matched control group (CON). On the final day of the experimental period, plantaris muscles were excised and weighed. The 1HU+REC (0.548 ± 0.012), 2HU+REC (0.562 ± 0.015), and CON (0.550 ± 0.013) showed no statistical difference (p\u3e0.05) between each other. The 1 HU (0.442 ± 0.020) and 2 HU (0.431 ± 0.011) groups were significantly less (p\u3c0.001) than recovery and aged control animals but were not significantly different from each other. The results show that the plantaris muscle presented reduction of muscle mass with initial and subsequent exposures to microgravity. However, with the recovery period, animals were able to regain lost muscle mass, similar to age-matched controls. These findings would be relevant for astronauts participating in multiple long-duration missions throughout their career

    Effects of piracetam as an adjuvant therapy on Attention-Deficit/Hyperactivity Disorder: A randomized, double-blind, placebo-controlled trial

    Get PDF
    Background: Stimulants are highly effective in controlling symptoms of Attention-deficit/hyperactivity disorder (ADHD), but 30 of individuals with ADHD do not respond to them or cannot tolerate their side effects; thus, alternative treatment approaches need to be considered. Objectives: To evaluate the effect and safety of piracetam as an adjuvant therapy plus methylphenidate (MPH) in children with ADHD. Methods: Thirty-six children with ADHD (6-16 years old), admitted to three academic outpatient child psychiatric clinics in the second half of 2015, were randomly assigned to the "methylphenidate plus piracetam group"and the "methylphenidate plus placebo"group, in a double-blind, placebo-controlled study, for 6 weeks. The "Conner's Parents' Rating Scale-Revised (CPRS-R), Children Symptom Inventory-4 (CSI-4), Clinical Global Impression-Improvement scale (CGI-I), and Children' Global Assessment Scale (CGAS) were completed at baseline and at the ends of the third and the sixth week, and the New York State Psychiatric Institute side effect forms were completed weekly, as outcome measures. Results: The level of improvement in CPRS-R, CSI-4, and CGI-I scales were significantly higher in the "methylphenidate plus piracetam"group compared with the "methylphenidate plus placebo"group. Side effects were not remarkable in any group. Conclusions: Piracetam as a short-term adjuvant treatment to methylphenidate can have considerable therapeutic effect and safety profile in children with ADHD and deserves further exploration to assess its potentialities in ADHD treatment. Copyright © 2021, Author(s)
    corecore