A Monte Carlo simulation program for the radio detection of Ultra High Energy (UHE) neutrino interactions in the Antarctic ice as viewed by the Antarctic Impulsive Transient Antenna (ANITA) is ...described in this article. The program, icemc, provides an input spectrum of UHE neutrinos, the parametrization of the Askaryan radiation generated by their interaction in the ice, and the propagation of the radiation through ice and air to a simulated model of the third and fourth ANITA flights. This paper provides an overview of the icemc simulation, descriptions of the physics models used and of the ANITA electronics processing chain, data/simulation comparisons to validate the predicted performance, and a summary of the impact of published results.
The baculovirus inhibitor of apoptosis gene, iap, can impede cell death in insect cells. Here we show that iap can also prevent cell death in mammalian cells. The ability of iap to regulate ...programmed cell death in widely divergent species raised the possibility that cellular homologs of iap might exist. Consistent with this hypothesis, we have isolated Drosophila and human genes which encode IAP‐like proteins (dILP and hILP). Like IAP, both dILP and hILP contain amino‐terminal baculovirus IAP repeats (BIRs) and carboxy‐terminal RING finger domains. Human ilp encodes a widely expressed cytoplasmic protein that can suppress apoptosis in transfected cells. An analysis of the expressed sequence tag database suggests that hilp is one of several human genes related to iap. Together these data suggest that iap and related cellular genes play an evolutionarily conserved role in the regulation of apoptosis.
Background Pancreatoduodenectomy (PD) provides the best chance for cure in the treatment of patients with localized pancreatic head cancer. In patients with a suspected, clinically resectable ...pancreatic head malignancy, the need for histologic confirmation before proceeding with PD has not historically been required, but remains controversial. Methods An international panel of pancreatic surgeons working in well-known, high-volume centers reviewed the literature and worked together to establish a consensus on when to perform a PD in the absence of positive histology. Results The incidence of benign disease after PD for a presumed malignancy is 5–13%. Diagnosis by endoscopic cholangiopancreatography brushings and percutaneous fine-needle aspiration are highly specific, but poorly sensitive. Aspiration biopsy guided by endoscopic ultrasonography (EUS) has greater sensitivity, but it is highly operator dependent and increases expense. The incidence of autoimmune pancreatitis (AIP) in the benign resected specimens is 30–43%. EUS-guided Trucut biopsy, serum levels of immunoglobulin G4, and HISORt (Histology, Imaging, Serology, Other organ involvement, and Response to therapy) are used for diagnosis. If AIP is suspected but not confirmed, the response to a short course of steroids is helpful for diagnosis. Conclusion In the presence of a solid mass suspicious for malignancy, consensus was reached that biopsy proof is not required before proceeding with resection. Confirmation of malignancy, however, is mandatory for patients with borderline resectable disease to be treated with neoadjuvant therapy before exploration for resection. When a diagnosis of AIP is highly suspected, a biopsy is recommended, and a short course of steroid treatment should be considered if the biopsy does not reveal features suspicious for malignancy.
Recently, the ANITA collaboration reported on two upward-going extensive air shower events consistent with a primary particle that emerges from the surface of the Antarctic ice sheet. These events ...may be of ντ origin, in which the neutrino interacts within the Earth to produce a τ lepton that emerges from the Earth, decays in the atmosphere, and initiates an extensive air shower. In this paper we estimate an upper bound on the ANITA acceptance to a diffuse ντ flux detected via τ-lepton-induced air showers within the bounds of standard model uncertainties. Furthermore, by comparing this estimate with the acceptance of Pierre Auger Observatory and IceCube and assuming standard model interactions, we conclude that a ντ origin of these events would imply a neutrino flux at least two orders of magnitude above current bounds.
Abstract
The balloon-borne ANITA 1 experiment is designed to detect
ultra-high energy neutrinos via radio emissions produced by in-ice
showers. Although initially purposed for interactions within the
...Antarctic ice sheet, ANITA also demonstrated the ability to
self-trigger on radio emissions from ultra-high energy charged
cosmic rays 2 (CR) interacting in the Earth's atmosphere. For
showers produced above the Antarctic ice sheet, reflection of the
down-coming radio signals at the Antarctic surface should result in
a polarity inversion prior to subsequent observation at the ∼35–40
km altitude ANITA gondola. Based on data taken during the ANITA-1
and ANITA-3 flights, ANITA published two anomalous instances of
upcoming cosmic-rays with measured polarity opposite the remaining
sample of ∼50 UHECR signals 3, 4. The steep observed upwards
incidence angles (25–30 degrees relative to the horizontal) require
non-Standard Model physics if these events are due to in-ice
neutrino interactions, as the Standard Model cross-section would
otherwise prohibit neutrinos from penetrating the long required
chord of Earth. Shoemaker et al. 5 posit that glaciological
effects may explain the steep observed anomalous events. We herein
consider the scenarios offered by Shoemaker et al. and find them to
be disfavored by extant ANITA and HiCal experimental data. We note
that the recent report of four additional near-horizon anomalous
ANITA-4 events 6, at >3σ significance, are incompatible with
their model, which requires significant signal transmission into the
ice.
We describe herein a measurement of the Antarctic surface “roughness” performed by the balloon‐borne ANITA (Antarctic Impulsive Transient Antenna) experiment. Originally purposed for cosmic ray ...astrophysics, the radio frequency (RF) receiver ANITA gondola, from its 38 km altitude vantage point, can scan a disk of snow surface 600 km in radius. The primary purpose of ANITA is to detect RF emissions from cosmic rays incident on Antarctica, such as neutrinos which penetrate through the atmosphere and interact within the ice, resulting in signal directed upward which then refracts at the ice‐air interface and up and out to ANITA, or high‐energy nuclei (most likely irons or protons), which interact in the upper atmosphere (at altitudes below ANITA) and produce a spray of down‐coming RF which reflects off the snow surface and back up to the gondola. The energy of such high‐energy nuclei can be inferred from the observed reflected signal only if the surface reflectivity is known. We describe herein an attempt to quantify the Antarctic surface reflectivity, using the Sun as a constant, unpolarized RF source. We find that the reflectivity of the surface generally follows the expectations from the Fresnel equations, lending support to the use of those equations to give an overall correction factor to calculate cosmic ray energies for all locations in Antarctica. The analysis described below is based on ANITA‐II data. After launching from McMurdo Station in December 2008, ANITA‐II was aloft for a period of 31 days with a typical instantaneous duty cycle exceeding 95%.
Key Points
Solar radio radiation is used to determine Antarctic albedo
Reflection coefficients agree with Fresnel predictions at high incidence angles
Reflection coefficients are lower than expected at glancing incidence angles
We have recently augmented the electronics for our neutron monitor (NM) latitude survey so as to record the elapsed time (δT) between detected neutrons in each proportional tube, in order to examine ...time correlations in the data as a function of cutoff rigidity and primary spectrum. We quantify the dependence of counting rate on dead time, with particular focus on the longer dead times that were once employed in FSU/Russian stations. Our observations show that monitor dead time has little influence on the observed depth of Forbush decreases, indicating that the cosmic ray spectral shape is little changed in the decrease. However, the use of a different dead time significantly alters the response of the monitor as a function of cutoff rigidity. In spite of the general success of our calculation in reproducing the data, unexplained discrepancies are still present.
TcR α, β, and γ chain negative cytotoxic NK-like cells were cloned from alloantigen-stimulated PBL obtained from naı̈ve channel catfish. Stimulation with allogeneic cells and growth promoting factors ...are required for their continued in vitro proliferation and cytotoxic activity. These granular cells kill not only the stimulating allogeneic cells, but also unrelated allogeneic targets by a perforin/granzyme-mediated apoptosis pathway. In addition, they are negative for markers that define neutrophils, monocytes/macrophages, and non-specific cytotoxic cells. Although these NK-like clones kill a number of different allogeneic targets, they display interclonal variation in cytotoxicity toward a panel of allogeneic targets, i.e. some clones have no apparent target specificity, while others display a target preference. In addition, flow cytometric analyses revealed that expression of a putative FcμR, an LFA-1-like molecule, and a putative thymocyte/T cell antigen varies among the different clones, with no clear correlation between surface antigen expression and cytotoxic activity. Although not all clones express a putative FcμR, it was noted that they all expressed an ITAM containing FcεR γ chain homolog. This finding suggests that the catfish FcεR γ chain may potentially be used as an accessory molecule for not only FcμRs, but also for other unknown activation receptors. These results support the hypothesis that catfish NK-like cells are heterogeneous in terms of target specificities and cell surface phenotype.
We present a comprehensive report on the experimental details of the Antarctic Impulsive Transient Antenna (ANITA) long-duration balloon payload, including the design philosophy and realization, ...physics simulations, performance of the instrument during its first Antarctic flight completed in January of 2007, and expectations for the limiting neutrino detection sensitivity.
We set the first limits on the ultra-high energy (UHE) neutrino fluence at energies greater than 109 GeV from gamma-ray bursts (GRBs) based on data from the second flight of the Antarctic Impulsive ...Transient Antenna (ANITA). During the 31 day flight of ANITA-II, 26 GRBs were recorded by Swift or Fermi. Of these, we analyzed the 12 GRBs which occurred during quiet periods when the payload was away from anthropogenic activity. In a blind analysis, we observe 0 events on a total background of 0.0044 events in the combined prompt window for all 12 low-background bursts. We also observe 0 events from the remaining 14 bursts. We place a 90% confidence level limit on the E --4 prompt neutrino fluence between 108 GeV < E < 1012 GeV of E 4 Delta *Q = 2.5 X 1017 GeV3 cm--2 from GRB090107A. This is the first reported limit on the UHE neutrino fluence from GRBs above 109 GeV, and the strongest limit above 108 GeV.
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