168 research outputs found

    On the scattering of D and D* mesons off the X(3872)

    Full text link
    Both the mass (just below the D^{*0}Dbar^0 threshold) and the likely quantum numbers (J^{PC}=1^{++}) of the X(3872) suggest that it is either a weakly-bound hadronic ``molecule'' or a virtual state of charmed mesons. Assuming the X(3872) is a weakly-bound molecule, the scattering of neutral D and D* mesons off the X(3872) can be predicted from the X(3872) binding energy. We calculate the phase shifts and cross section for scattering of D^0 and D^{*0} mesons and their antiparticles off the X(3872) in an effective field theory for short-range interactions. This provides another example of a three-body process, along with those in nuclear and atomic systems, that displays universal properties. It may be possible to extract the scattering within the final state interactions of B_c decays and/or other LHC events.Comment: 12 pages, 5 figures, revtex

    Matched sizes of activating and inhibitory receptor/ligand pairs are required for optimal signal integration by human Natural Killer cells

    Get PDF
    It has been suggested that receptor-ligand complexes segregate or co-localise within immune synapses according to their size, and this is important for receptor signaling. Here, we set out to test the importance of receptor-ligand complex dimensions for immune surveillance of target cells by human Natural Killer (NK) cells. NK cell activation is regulated by integrating signals from activating receptors, such as NKG2D, and inhibitory receptors, such as KIR2DL1. Elongating the NKG2D ligand MICA reduced its ability to trigger NK cell activation. Conversely, elongation of KIR2DL1 ligand HLA-C reduced its ability to inhibit NK cells. Whereas normal-sized HLA-C was most effective at inhibiting activation by normal-length MICA, only elongated HLA-C could inhibit activation by elongated MICA. Moreover, HLA-C and MICA that were matched in size co-localised, whereas HLA-C and MICA that were different in size were segregated. These results demonstrate that receptor-ligand dimensions are important in NK cell recognition, and suggest that optimal integration of activating and inhibitory receptor signals requires the receptor-ligand complexes to have similar dimensions

    Robust reduction of graphene fluoride using an electrostatically biased scanning probe

    Get PDF
    ABSTRACT We report a novel and easily accessible method to chemically reduce graphene fluoride (GF) sheets with nanoscopic precision using high electrostatic fields generated between an atomic force microscope (AFM) tip and the GF substrate. Reduction of fluorine by the electric field produces graphene nanoribbons (GNR) with a width of 105-1,800 nm with sheet resistivity drastically decreased from >1 TΩ·sq. -1 (GF) down to 46 kΩ·sq. -1 (GNR). Fluorine reduction also changes the topography, friction, and work function of the GF. Kelvin probe force microscopy measurements indicate that the work function of GF is 180-280 meV greater than that of graphene. The reduction process was optimized by varying the AFM probe velocity between 1.2 μm·s -1 and 12 μm·s -1 and the bias voltage applied to the sample between -8 and -12 V. The electrostatic field required to remove fluorine from carbon is ~1.6 V·nm -1 . Reduction of the fluorine may be due to the softening of the C-F bond in this intense field or to the accumulation and hydrolysis of adventitious water into a meniscus

    The Role of Spirituality Healing with Perceptions of the Medical Encounter among Latinos

    Get PDF
    Little is known about the relationship between spirituality healing and perceptions about the medical encounter among Latinos. To examine the association between spirituality healing and attitudes of self-reported perceptions about the medical encounter. A cross-sectional telephone survey. 3,728 Latinos aged ≥18 years residing in the United States from Wave 1 of the Pew Hispanic Center/Robert Wood Johnson Foundation Latino Health Survey. Dependent variables were ever prayed for healing (yes/no), ever asked others to pray for healing (yes/no), considered important spiritual healing (very vs. somewhat or not important), and ever consulted a ‘curandero’ (folk healer in Latin America) (yes/no). The primary independent variables were feelings about the last time seeing a Doctor (confused by information given, or frustrated by lack of information) and perception of quality of medical care (excellent, good, fair or poor) within the past 12 months. Six percent of individuals reported that they had ever consulted a curandero, 60% prayed for healing, 49% asked others to pray for healing, and 69% considered spiritual healing as very important. In multivariable analyses, feeling confused was associated with increased odds of consulting a curandero (OR = 1.58; 95% CI, 1.02–2.45), praying for healing (OR = 1.30; 95% CI, 1.03–1.64), asking others to pray for healing (OR = 1.29; 95% CI, 1.03–1.62), and considering spiritual healing as very important (OR = 1.30; 95% CI, 1.01–1.66). Feeling frustrated by a lack of information was associated with asking others to pray for healing (OR = 1.29; 95% CI, 1.04–1.60). A better perception of quality of medical care was associated with lower odds of consulting a curandero (OR = 0.83; 95% CI, 0.70–0.98). Feelings about the medical encounter were associated with spirituality healing, praying for healing, and asking others to pray for healing. Feeling confused and perception of poor quality of medical care were associated with consulting a curandero

    Determination of freedom-from-rabies for small Indian mongoose populations in the United States Virgin Islands, 2019–2020

    Get PDF
    Mongooses, a nonnative species, are a known reservoir of rabies virus in the Caribbean region. A cross-sectional study of mongooses at 41 field sites on the US Virgin Islands of St. Croix, St. John, and St. Thomas captured 312 mongooses (32% capture rate). We determined the absence of rabies virus by antigen testing and rabies virus exposure by antibody testing in mongoose populations on all three islands. USVI is the first Caribbean state to determine freedom-from-rabies for its mongoose populations with a scientifically-led robust cross-sectional study. Ongoing surveillance activities will determine if other domestic and wildlife populations in USVI are rabies-free

    Diverse University Students Across the United States Reveal Promising Pathways to Hunter Recruitment and Retention

    Get PDF
    Declining participation in hunting, especially among young adult hunters, affects the ability of state and federal agencies to achieve goals for wildlife management and decreases revenue for conservation. For wildlife agencies hoping to engage diverse audiences in hunter recruitment, retention, and reactivation (R3) efforts, university settings provide unique advantages: they contain millions of young adults who are developmentally primed to explore new activities, and they cultivate a social atmosphere where new identities can flourish. From 2018 to 2020, we surveyed 17,203 undergraduate students at public universities across 22 states in the United States to explore R3 potential on college campuses and assess key demographic, social, and cognitive correlates of past and intended future hunting behavior. After weighting to account for demographic differences between our sample and the larger student population, 29% of students across all states had hunted in the past. Students with previous hunting experience were likely to be white, male, from rural areas or hunting families, and pursuing degrees related to natural resources. When we grouped students into 1 of 4 categories with respect to hunting (i.e., non-hunters [50%], potential hunters [22%], active hunters [26%], and lapsed hunters [3%]), comparisons revealed differences based on demographic attributes, beliefs, attitudes, and behaviors. Compared to active hunters, potential hunters were more likely to be females or racial and ethnic minorities, and less likely to experience social support for hunting. Potential hunters valued game meat and altruistic reasons for hunting, but they faced unique constraints due to lack of hunting knowledge and skills. Findings provide insights for marketing and programming designed to achieve R3 objectives with a focus on university students. © 2021 The Wildlife Society

    Constraints on perception of information from obstacles during foot clearance in people with chronic stroke

    Get PDF
    The aim of this study was to examine effects of different types of task constraints on coupling of perception and action in people with chronic stroke when crossing obstacles during a walking task. Ten participants with hemiplegic chronic stroke volunteered to walk over a static obstacle under two distinct task constraints: simple and dual task. Under simple task constraints, without specific instructions, participants walked at their preferred speed and crossed over an obstacle. Under dual task constraints the same individuals were required to subtract numbers whilst walking. Under both distinct task constraints, we examined emergent values of foot distance when clearing a static obstacle in both affected and unaffected legs, measured by a 3D motion tracking system. Principal Component Analysis was used to quantify task performance and discriminant analysis was used to compare gait performance between task constraints. Results suggested that patients, regardless of affected body side, demonstrated differences in perception of distance information from the obstacle, which constrained gait differences in initial swing, mid-swing and crossing phases. Further, dual task constraints, rather than hemiplegic body side, was a significant discriminator in patients' perceptions of distance and height information to the obstacle. These findings suggested how performance of additional cognitive tasks might constrain perception of information from an obstacle in people with chronic stroke during different phases of obstacle crossing, and thus may impair their adaptive ability to successfully manoeuvre around objects

    Mongooses (\u3ci\u3eUrva auropunctata\u3c/i\u3e) as reservoir hosts of leptospira species in the United States Virgin Islands, 2019–2020

    Get PDF
    During 2019–2020, the Virgin Islands Department of Health investigated potential animal reservoirs of Leptospira spp., the bacteria that cause leptospirosis. In this cross-sectional study, we investigated Leptospira spp. exposure and carriage in the small Indian mongoose (Urva auropunctata, syn: Herpestes auropunctatus), an invasive animal species. This study was conducted across the three main islands of the U.S. Virgin Islands (USVI), which are St. Croix, St. Thomas, and St. John. We used the microscopic agglutination test (MAT), fluorescent antibody test (FAT), real-time polymerase chain reaction (lipl32 rt-PCR), and bacterial culture to evaluate serum and kidney specimens and compared the sensitivity, specificity, positive predictive value, and negative predictive value of these laboratory meth-ods. Mongooses (n = 274) were live-trapped at 31 field sites in ten regions across USVI and humanely euthanized for Leptospira spp. testing. Bacterial isolates were sequenced and evaluated for species and phylogenetic analysis using the ppk gene. Anti-Leptospira spp. antibodies were detected in 34% (87/256) of mongooses. Reactions were observed with the following serogroups: Sejroe, Icterohaemorrhagiae, Pyrogenes, Mini, Cynopteri, Australis, Hebdomadis, Autumnalis, Mankarso, Pomona, and Ballum. Of the kidney specimens exam-ined, 5.8% (16/270) were FAT-positive, 10% (27/274) were culture-positive, and 12.4% (34/ 274) were positive by rt-PCR. Of the Leptospira spp. isolated from mongooses, 25 were L. borgpetersenii, one was L. interrogans, and one was L. kirschneri. Positive predictive values of FAT and rt-PCR testing for predicting successful isolation of Leptospira by culture were 88% and 65%, respectively. The isolation and identification of Leptospira spp. in mongooses highlights the potential role of mongooses as a wildlife reservoir of leptospirosis; mongooses could be a source of Leptospira spp. infections for other wildlife, domestic animals, and humans

    School's out: what are urban children doing? The Summer Activity Study of Somerville Youth (SASSY)

    Get PDF
    Background: Research indicates that in the United States, children experience healthier BMI and fitness levels during school vs. summer, but research is limited. The primary goal of this pilot study was to assess where children spend their time during the months that school is not in session and to learn about the different types of activities they engage in within different care settings. A secondary goal of this pilot study was to learn what children eat during the summer months. Methods: A nine-week summer study of 57 parents of second and third grade students was conducted in an economically, racial/ethnically and linguistically diverse US urban city. Weekly telephone interviews queried time and activities spent on/in 1) the main caregiver’s care 2) someone else’s care 3) vacation 4) and camp. Activities were categorised as sedentary, light, moderate, or vigorous (0-3 scale). For each child, a mean activity level was calculated and weighted for proportion of time spent in each care situation, yielding a weighted activity index. On the last phone call, parents answered questions about their child’s diet over the summer. Two post-study focus groups were conducted to help interpret findings from the weekly activity interviews. Results: The mean activity index was 1.05 ± 0.32 and differed between gender (p = 0.07), education (p = 0.08) and primary language spoken in the household (p = 0.01). Children who spent a greater percentage of time in parent care had on average a lower activity index (β = -0.004, p = 0.01) while children who spent a greater percentage of time in camp had a higher activity index (β = 0.004, p = 0.03). When stratified into type of camp, percentage of time spent in active camp was also positively associated with mean activity index (β = 0.005, p =\u3c 0.001). With regards to diet, after adjusting for maternal education, children who attended less than five weeks of camp were four times more likely to eat their meals in front of the TV often/almost all of the time (OR = 4.0, 95%CI 1.0-16.2, p \u3c 0.06). Conclusions: Summer activities and some dietary behaviours are influenced by situation of care and sociodemographic characteristics. In particular, children who spend a greater proportion of time in structured environments appear to be more active. We believe that this pilot study is an important first step in our understanding of what children do during the summer months

    Homeotic Evolution in the Mammalia: Diversification of Therian Axial Seriation and the Morphogenetic Basis of Human Origins

    Get PDF
    Despite the rising interest in homeotic genes, little has been known about the course and pattern of evolution of homeotic traits across the mammalian radiation. An array of emerging and diversifying homeotic gradients revealed by this study appear to generate new body plans and drive evolution at a large scale.This study identifies and evaluates a set of homeotic gradients across 250 extant and fossil mammalian species and their antecedents over a period of 220 million years. These traits are generally expressed as co-linear gradients along the body axis rather than as distinct segmental identities. Relative position or occurrence sequence vary independently and are subject to polarity reversal and mirroring. Five major gradient modification sets are identified: (1)--quantitative changes of primary segmental identity pattern that appeared at the origin of the tetrapods ; (2)--frame shift relation of costal and vertebral identity which diversifies from the time of amniote origins; (3)--duplication, mirroring, splitting and diversification of the neomorphic laminar process first commencing at the dawn of mammals; (4)--emergence of homologically variable lumbar lateral processes upon commencement of the radiation of therian mammals and ; (5)--inflexions and transpositions of the relative position of the horizontal septum of the body and the neuraxis at the emergence of various orders of therian mammals. Convergent functional changes under homeotic control include laminar articular engagement with septo-neural transposition and ventrally arrayed lumbar transverse process support systems.Clusters of homeotic transformations mark the emergence point of mammals in the Triassic and the radiation of therians in the Cretaceous. A cluster of homeotic changes in the Miocene hominoid Morotopithecus that are still seen in humans supports establishment of a new "hominiform" clade and suggests a homeotic origin for the human upright body plan
    corecore