Simulations of events for the LUX-ZEPLIN (LZ) dark matter experiment

The LUX-ZEPLIN dark matter search aims to achieve a sensitivity to the WIMP-nucleon spin-independent cross-section down to (1–2)×10−12 pb at a WIMP mass of 40 GeV/c2. This paper describes the simulations framework that, along with radioactivity measurements, was used to support this projection, and also to provide mock data for validating reconstruction and analysis software. Of particular note are the event generators, which allow us to model the background radiation, and the detector response physics used in the production of raw signals, which can be converted into digitized waveforms similar to data from the operational detector. Inclusion of the detector response allows us to process simulated data using the same analysis routines as developed to process the experimental data

Projected WIMP sensitivity of the LUX-ZEPLIN dark matter experiment

LUX-ZEPLIN (LZ) is a next-generation dark matter direct detection experiment that will operate 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. Using a two-phase xenon detector with an active mass of 7 tonnes, LZ will search primarily for low-energy interactions with weakly interacting massive particles (WIMPs), which are hypothesized to make up the dark matter in our galactic halo. In this paper, the projected WIMP sensitivity of LZ is presented based on the latest background estimates and simulations of the detector. For a 1000 live day run using a 5.6-tonne fiducial mass, LZ is projected to exclude at 90% confidence level spin-independent WIMP-nucleon cross sections above 1.4×10-48 cm2 for a 40 GeV/c2 mass WIMP. Additionally, a 5σ discovery potential is projected, reaching cross sections below the exclusion limits of recent experiments. For spin-dependent WIMP-neutron(-proton) scattering, a sensitivity of 2.3×10-43 cm2 (7.1×10-42 cm2) for a 40 GeV/c2 mass WIMP is expected. With underground installation well underway, LZ is on track for commissioning at SURF in 2020

Novelty Response of Wild African Apes to Camera Traps

Temperament and personality research in humans and nonhuman animals measures behavioral variation in individual, population, or species-specific traits with implications for survival and fitness, such as social status, foraging and mating success [1–5]. Curiosity and risk-taking tendencies have been studied extensively across taxa by measuring boldness and exploration responses to experimental novelty exposure [3,4,6–15]. Here, we conduct a natural field experiment using wildlife monitoring technology to test variation in the reaction of wild great apes (43 groups of naïve chimpanzees, bonobos and western gorillas, across 14 field sites in Africa) to a novel object, the camera-trap. Bonobo and gorilla groups demonstrated a stronger looking impulse towards the camera-trap device compared to chimpanzees, suggesting higher visual attention and curiosity. Bonobos were also more likely to show alarm and other fearful behaviors, although such neophobic (and conversely, neophilic) responses were generally rare. Among all three species, individuals looked at cameras longer when they were young, were associating with fewer individuals, and did not live near a long-term research site. Overall, these findings partially validate results from great ape novelty paradigms in captivity [7,8]. We further suggest that species-typical leadership styles [16] and social and environmental effects, including familiarity with humans, best explain novelty responses of wild great apes. In sum, this study illustrates the feasibility of large-scale field experiments and the importance of both intrinsic and extrinsic factors in shaping animal curiosity

Thoracic costotransverse joint pain patterns: a study in normal volunteers

<p>Abstract</p> <p>Background</p> <p>Pain referral patterns of asymptomatic costotransverse joints have not been established. The objective of this study was to determine the pain referral patterns of asymptomatic costotransverse joints via provocative intra-articular injection.</p> <p>Methods</p> <p>Eight asymptomatic male volunteers received a combined total of 21 intra-articular costotransverse joint injections. Fluoroscopic imaging was used to identify and isolate each costotransverse joint and guide placement of a 25 gauge, 2.5 inch spinal needle into the costotransverse joint. Following contrast medium injection, the quality, intensity, and distribution of the resultant pain produced were recorded.</p> <p>Results</p> <p>Of the 21 costotransverse joint injections, 16 (76%) were classified as being intra-articular via arthrograms taken at the time of injection, and 14 of these injections produced a pain sensation distinctly different from that of needle placement. Average pain produced was 3.3/10 on a 0–10 verbal pain scale. Pain was described generally as a deep, dull ache, and pressure sensation. Pain patterns were located superficial to the injected joint, with only the right T2 injections showing referred pain 2 segments cranially and caudally. No chest wall, upper extremity or pseudovisceral pains were reported.</p> <p>Conclusion</p> <p>This study provides preliminary data of the pain referral patterns of costotransverse joints. Further research is needed to compare these findings with those elicited from symptomatic subjects.</p

Thoracic spine pain in the general population: Prevalence, incidence and associated factors in children, adolescents and adults. A systematic review

<p>Abstract</p> <p>Background</p> <p>Thoracic spine pain (TSP) is experienced across the lifespan by healthy individuals and is a common presentation in primary healthcare clinical practice. However, the epidemiological characteristics of TSP are not well documented compared to neck and low back pain. A rigorous evaluation of the prevalence, incidence, correlates and risk factors needs to be undertaken in order for epidemiologic data to be meaningfully used to develop evidence-based prevention and treatment recommendations for TSP.</p> <p>Methods</p> <p>A systematic review method was followed to report the evidence describing prevalence, incidence, associated factors and risk factors for TSP among the general population. Nine electronic databases were systematically searched to identify studies that reported either prevalence, incidence, associated factors (cross-sectional study) or risk factors (prospective study) for TSP in healthy children, adolescents or adults. Studies were evaluated for level of evidence and method quality.</p> <p>Results</p> <p>Of the 1389 studies identified in the literature, 33 met the inclusion criteria for this systematic review. The mean (SD) quality score (out of 15) for the included studies was 10.5 (2.0). TSP prevalence data ranged from 4.0–72.0% (point), 0.5–51.4% (7-day), 1.4–34.8% (1-month), 4.8–7.0% (3-month), 3.5–34.8% (1-year) and 15.6–19.5% (lifetime). TSP prevalence varied according to the operational definition of TSP. Prevalence for any TSP ranged from 0.5–23.0%, 15.8–34.8%, 15.0–27.5% and 12.0–31.2% for 7-day, 1-month, 1-year and lifetime periods, respectively. TSP associated with backpack use varied from 6.0–72.0% and 22.9–51.4% for point and 7-day periods, respectively. TSP interfering with school or leisure ranged from 3.5–9.7% for 1-year prevalence. Generally, studies reported a higher prevalence for TSP in child and adolescent populations, and particularly for females. The 1 month, 6 month, 1 year and 25 year incidences were 0–0.9%, 10.3%, 3.8–35.3% and 9.8% respectively. TSP was significantly associated with: concurrent musculoskeletal pain; growth and physical; lifestyle and social; backpack; postural; psychological; and environmental factors. Risk factors identified for TSP in adolescents included age (being older) and poorer mental health.</p> <p>Conclusion</p> <p>TSP is a common condition in the general population. While there is some evidence for biopsychosocial associations it is limited and further prospectively designed research is required to inform prevention and management strategies.</p

Thoracic spine pain in the general population: Prevalence, incidence and associated factors in children, adolescents and adults. A systematic review

<p>Abstract</p> <p>Background</p> <p>Thoracic spine pain (TSP) is experienced across the lifespan by healthy individuals and is a common presentation in primary healthcare clinical practice. However, the epidemiological characteristics of TSP are not well documented compared to neck and low back pain. A rigorous evaluation of the prevalence, incidence, correlates and risk factors needs to be undertaken in order for epidemiologic data to be meaningfully used to develop evidence-based prevention and treatment recommendations for TSP.</p> <p>Methods</p> <p>A systematic review method was followed to report the evidence describing prevalence, incidence, associated factors and risk factors for TSP among the general population. Nine electronic databases were systematically searched to identify studies that reported either prevalence, incidence, associated factors (cross-sectional study) or risk factors (prospective study) for TSP in healthy children, adolescents or adults. Studies were evaluated for level of evidence and method quality.</p> <p>Results</p> <p>Of the 1389 studies identified in the literature, 33 met the inclusion criteria for this systematic review. The mean (SD) quality score (out of 15) for the included studies was 10.5 (2.0). TSP prevalence data ranged from 4.0–72.0% (point), 0.5–51.4% (7-day), 1.4–34.8% (1-month), 4.8–7.0% (3-month), 3.5–34.8% (1-year) and 15.6–19.5% (lifetime). TSP prevalence varied according to the operational definition of TSP. Prevalence for any TSP ranged from 0.5–23.0%, 15.8–34.8%, 15.0–27.5% and 12.0–31.2% for 7-day, 1-month, 1-year and lifetime periods, respectively. TSP associated with backpack use varied from 6.0–72.0% and 22.9–51.4% for point and 7-day periods, respectively. TSP interfering with school or leisure ranged from 3.5–9.7% for 1-year prevalence. Generally, studies reported a higher prevalence for TSP in child and adolescent populations, and particularly for females. The 1 month, 6 month, 1 year and 25 year incidences were 0–0.9%, 10.3%, 3.8–35.3% and 9.8% respectively. TSP was significantly associated with: concurrent musculoskeletal pain; growth and physical; lifestyle and social; backpack; postural; psychological; and environmental factors. Risk factors identified for TSP in adolescents included age (being older) and poorer mental health.</p> <p>Conclusion</p> <p>TSP is a common condition in the general population. While there is some evidence for biopsychosocial associations it is limited and further prospectively designed research is required to inform prevention and management strategies.</p

Role of Innate Immunity in the Pathogenesis of Chronic Rhinosinusitis: Progress and New Avenues

Chronic rhinosinusitis is a heterogeneous and multifactorial disease with unknown etiology. Aberrant responses to microorganisms have been suggested to play a role in the pathophysiology of the disease. Research has focused on the presence, detection, response to, and eradication of these potential threats. Main topics seem to center on the contribution of structural cells such as epithelium and fibroblasts, on the consequences of activation of pattern-recognition receptors, and on the role of antimicrobial agents. This research should be viewed not only in the light of a comparison between healthy and diseased individuals, but also in a comparison between patients who do or do not respond to treatment. New players that could play a role in the pathophysiology seem to surface at regular intervals, adding to our understanding (and the complexity) of the disease and opening new avenues that may help fight this incapacitating disease

Measurement of the gamma ray background in the Davis cavern at the Sanford Underground Research Facility

Deep underground environments are ideal for low background searches due to the attenuation of cosmic rays by passage through the earth. However, they are affected by backgrounds from γ-rays emitted by 40K and the 238U and 232Th decay chains in the surrounding rock. The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a liquid xenon TPC located within the Davis campus at the Sanford Underground Research Facility, Lead, South Dakota, at the 4850-foot level. In order to characterise the cavern background, in-situ γ-ray measurements were taken with a sodium iodide detector in various locations and with lead shielding. The integral count rates (0–3300 keV) varied from 596 Hz to 1355 Hz for unshielded measurements, corresponding to a total flux from the cavern walls of 1.9 ± 0.4 γ cm−2s−1. The resulting activity in the walls of the cavern can be characterised as 220 ± 60 Bq/kg of 40K, 29 ± 15 Bq/kg of 238U, and 13 ± 3 Bq/kg of 232Th

Projected sensitivity of the LUX-ZEPLIN experiment to the two-neutrino and neutrinoless double β decays of Xe 134

The projected sensitivity of the LUX-ZEPLIN (LZ) experiment to two-neutrino and neutrinoless double β decay of Xe134 is presented. LZ is a 10-tonne xenon time-projection chamber optimized for the detection of dark matter particles and is expected to start operating in 2021 at Sanford Underground Research Facility, USA. Its large mass of natural xenon provides an exceptional opportunity to search for the double β decay of Xe134, for which xenon detectors enriched in Xe136 are less effective. For the two-neutrino decay mode, LZ is predicted to exclude values of the half-life up to 1.7×1024 years at 90% confidence level (CL) and has a three-sigma observation potential of 8.7×1023 years, approaching the predictions of nuclear models. For the neutrinoless decay mode LZ, is projected to exclude values of the half-life up to 7.3×1024 years at 90% CL

Cosmogenic production of {37}^Ar in the context of the LUX-ZEPLIN experiment

We estimate the amount of {37}^Ar produced in natural xenon via cosmic-ray-induced spallation, an inevitable consequence of the transportation and storage of xenon on the Earth’s surface. We then calculate the resulting {37}^Ar concentration in a 10-tonne payload (similar to that of the LUX-ZEPLIN experiment) assuming a representative schedule of xenon purification, storage, and delivery to the underground facility. Using the spallation model by Silberberg and Tsao, the sea-level production rate of {37}^Ar in natural xenon is estimated to be 0.024 atoms/kg/day. Assuming the xenon is successively purified to remove radioactive contaminants in 1-tonne batches at a rate of 1 tonne/month, the average {37}^Ar activity after 10 tons are purified and transported underground is 0.058 - 0.090 μ Bq/kg, depending on the degree of argon removal during above-ground purification. Such cosmogenic {37}^Ar will appear as a noticeable background in the early science data, while decaying with a 35-day half-life. This newly noticed production mechanism of {37}^Ar should be considered when planning for future liquid-xenon-based experiments