Upper Bounds on the Neutrino-Nucleon Inelastic Cross Section

Extraterrestrial neutrinos can initiate deeply developing air showers, and those that traverse the atmosphere unscathed may produce cascades in the ice or water. Up to now, no such events have been observed. This can be translated into upper limits on the diffuse neutrino flux. On the other hand, the observation of cosmic rays with primary energies > 10^{10} GeV suggests that there is a guaranteed flux of cosmogenic neutrinos, arising from the decay of charged pions (and their muon daughters) produced in proton interactions with the cosmic microwave background. In this work, armed with these cosmogenic neutrinos and the increased exposure of neutrino telescopes we bring up-to-date model-independent upper bounds on the neutrino-nucleon inelastic cross section. Uncertainties in the cosmogenic neutrino flux are discussed and taken into account in our analysis. The prospects for improving these bounds with the Pierre Auger Observatory are also estimated. The unprecedented statistics to be collected by this experiment in 6 yr of operation will probe the neutrino-nucleon inelastic cross section at the level of Standard Model predictions.Comment: To be published in JCA

The Physics of Gamma-Ray Bursts

Gamma-Ray Bursts (GRBs), short and intense pulses of low energy gamma-rays, have fascinated astronomers and astrophysicists since their unexpected discovery in the late sixties. During the last decade, several space missions: BATSE (Burst and Transient Source Experiment) on Compton Gamma-Ray Observatory, BeppoSAX and now HETE II (High-Energy Transient Explorer), together with ground optical, infrared and radio observatories have revolutionized our understanding of GRBs showing that they are cosmological, that they are accompanied by long lasting afterglows and that they are associated with core collapse Supernovae. At the same time a theoretical understanding has emerged in the form of the fireball internal-external shocks model. According to this model GRBs are produced when the kinetic energy of an ultra-relativistic flow is dissipated in internal collisions. The afterglow arises when the flow is slowed down by shocks with the surrounding circum-burst matter. This model has numerous successful predictions like the prediction of the afterglow itself, the prediction of jet breaks in the afterglow light curve and of an optical flash that accompanies the GRBs themselves. In this review I focus on theoretical aspects and on physical processes believed to take place in GRBs.Comment: 159 pages, 33 figures, accepted for publication in Reviews of Modern Physic

Combined dark matter searches towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS

Cosmological and astrophysical observations suggest that 85% of the total matter of the Universe is made of Dark Matter (DM). However, its nature remains one of the most challenging and fundamental open questions of particle physics. Assuming particle DM, this exotic form of matter cannot consist of Standard Model (SM) particles. Many models have been developed to attempt unraveling the nature of DM such as Weakly Interacting Massive Particles (WIMPs), the most favored particle candidates. WIMP annihilations and decay could produce SM particles which in turn hadronize and decay to give SM secondaries such as high energy \u1d6fe rays. In the framework of indirect DM search, observations of promising targets are used to search for signatures of DM annihilation. Among these, the dwarf spheroidal galaxies (dSphs) are commonly favored owing to their expected high DM content and negligible astrophysical background. In this work, we present the very first combination of 20 dSph observations, performed by the Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS collaborations in order to maximize the sensitivity of DM searches and improve the current results. We use a joint maximum likelihood approach combining each experiment’s individual analysis to derive more constraining upper limits on the WIMP DM self-annihilation cross-section as a function of DM particle mass. We present new DM constraints over the widest mass range ever reported, extending from 5 GeV to 100 TeV thanks to the combination of these five different \u1d6fe-ray instruments

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Expanding Knowledge on Occupations, One Harmful Occupation at a Time

Humans are both natural doers and occupational beings, but in order to consider them as such, one must understand all occupational choices, the meanings and human behavior behind the choices, and the environment in which the choices take place (Helbig & McKay, 2003). Considering self-harm, substance abuse, and addiction as occupations advances this understanding of humans as occupational in nature who are molded by their occupational choices and factors surrounding them (Wasmuth, Brandon-Friedman, & Olesek, 2016). This study aimed to gain an understanding of the occupational nature of humans that engage in occupations defined as harmful by society in order to expand on the overly positive view of occupation. The current focus on occupation has silenced a compelling part of the experiences of humans due to the inherent focus on the health-enhancing capabilities of occupation. Using themes gathered from a literature review to guide observation of video testimonials, a qualitative analysis was done with the aim of acknowledging engagement in substance abuse, self-harm, and addiction as occupational in nature, and to broaden the understanding of occupations and their relationship to health and well-being. Specific accounts of engagement from the video testimonials were interpreted by the researcher and classified into three categories developed from existing literature. The results were discussed in relation to the three categories, and connections from the testimonials were made to ideas in the existing literature

Sexuality and Spinal Cord Injury: Final Culminating Project

Extensive research on addressing sexuality within the spinal cord injury (SCI) population was reviewed for six weeks prior to starting the development of an educational training program for the Sheltering Arms Institute (SAI) rehabilitation team. The research is presented in the form of a literature review and revealed an approximate gap of around 22 years in which health care professionals failed to implement knowledge translation techniques in the area of sexuality within the SCI population. Along with this evidence from the literature review, results from a survey distributed to staff at SAI working on the SCI unit also provided sufficient evidence to support my capstone project of developing a sexuality educational program for staff, and providing structure for the overall implementation of sexuality rehabilitation for the Sheltering Arms Institute SCI unit. Throughout the capstone experience various projects were completed to support the planning, development, and implementation of the first phase of a sexuality rehabilitation program at Sheltering Arms Institute on the SCI unit

Proper Straight Cane Positioning to Decrease Upper Extremity Force on the Targeted Lower Extremity while Reaching in Preparation for an ADL Task

Purpose: This study assessed which cane height and reaching height elicits decreased upper extremity (UE) muscular force for optimal cane positioning. A cane can facilitate engagement in activities of daily living. It is proposed that incorrect cane height and usage requires increased energy. Limited research exists regarding the impact of cane height on energy expenditure during reaching. Method: Forty-seven adult participants performed reaching tasks at three heights utilizing two different cane heights. The triceps and wrist extensors on the cane UE and deltoid on the reaching UE were recorded by electromyography (EMG). Results: There were no statistically significant differences between the cane adjusted at wrist and one inch higher. Additional median EMG results for the 60-degree reaching height showed lower energy expenditure for both cane heights. Conclusions: These findings suggest that cane height does not significantly impact energy expenditure, although, increased energy conservation while reaching for items on shelf at a lower height was noted