We present the results of a first search for self-annihilating dark matter in nearby galaxies and galaxy clusters using a sample of high-energy neutrinos acquired in 339.8 days of live time during ...2009/10 with the IceCube neutrino observatory in its 59-string configuration. The targets of interest include the Virgo and Coma galaxy clusters, the Andromeda galaxy, and several dwarf galaxies. We obtain upper limits on the cross section as a function of the weakly interacting massive particle mass between 300 GeV and 100 TeV for the annihilation into bb, W super(+)W super(-), tau super(+)tau super(-), and nunu. A limit derived for the Virgo cluster, when assuming a large effect from subhalos, challenges the weakly interacting massive particle interpretation of a recently observed GeV positron excess in cosmic rays.
We have searched for extremely high energy neutrinos using data taken with the IceCube detector between May 2010 and May 2012. Two neutrino-induced particle shower events with energies around 1 PeV ...were observed, as reported previously. In this work, we investigate whether these events could originate from cosmogonic neutrinos produced in the interactions of ultrahigh energy cosmic rays with ambient photons while propagating through intergalactic space. Exploiting IceCube's large exposure for extremely high energy neutrinos and the lack of observed events above 100 PeV, we can rule out the corresponding models at more than 90% confidence level. The model-independent quasidifferential 90% C.L. upper limit, which amounts to E super(2)varphi sub(nue+nu mu +nutau) = 1.2 x 10 super(-7) GeV cm super(-2) s super(-1) sr super(-1) at 1 EeV, provides the most stringent constraint in the energy range from 10 PeV to 10 EeV. Our observation disfavors strong cosmological evolution of the highest energy cosmic-ray sources such as the Fanaroff-Riley type II class of radio galaxies.
In cosmic ray air showers, the muon lateral separation from the center of the shower is a measure of the transverse momentum that the muon parent acquired in the cosmic ray interaction. IceCube has ...observed cosmic ray interactions that produce muons laterally separated by up to 400 m from the shower core, a factor of 6 larger distance than previous measurements. These muons originate in high pT (> 2 GeV /c) interactions from the incident cosmic ray, or high-energy secondary interactions. The separation distribution shows a transition to a power law at large values, indicating the presence of a hard pT component that can be described by perturbative quantum chromodynamics. However, the rates and the zenith angle distributions of these events are not well reproduced with the cosmic ray models tested here, even those that include charm interactions. This discrepancy may be explained by a larger fraction of kaons and charmed particles than is currently incorporated in the simulations.
A bot is an application used to automate a repeatable task that can be remotely executed by a command and control system. Often, rootkit technology is used to compromise the host system and hide the ...presence of the bot so that the user is unaware that bot-enabled software is installed and functioning on their computer. Botnets are groups of computers running the bots and are the weapon of choice in the facilitation of Distributed Denial of Service Attacks (DDoS). The DDoS attack method is used to disrupt legitimate traffic from reaching a targeted website or Internet facing application. Individuals control hundreds or thousands of compromised computer systems to wage a coordinated DDoS attack against a single target (Alomari, Manickam, Gupta, Karuppayah, & Alfaris, 2012). To date, most research in this area has concentrated on detecting the DDoS via network-based sensors and blocking DDoS attack traffic from reaching the targeted system. The issue with this type of response is that it is reactive and victim-based. This proposal examines the feasibility of using deep packet inspection to identify systems which potentially serve as part of a botnet being employed to conduct a DDoS attack. The implementation of this concept will give companies the ability to limit their possible liability by quickly detecting botnet members on their local networks.
The Atlantic Multidecadal Oscillation (AMO) is a major mode of climate variability with important societal impacts. Most previous explanations identify the driver of the AMO as the ocean circulation, ...specifically the Atlantic Meridional Overturning Circulation (AMOC). Here we show that the main features of the observed AMO are reproduced in models where the ocean heat transport is prescribed and thus cannot be the driver. Allowing the ocean circulation to interact with the atmosphere does not significantly alter the characteristics of the AMO in the current generation of climate models. These results suggest that the AMO is the response to stochastic forcing from the mid-latitude atmospheric circulation, with thermal coupling playing a role in the tropics. In this view, the AMOC and other ocean circulation changes would be largely a response to, not a cause of, the AMO.
Although most college students are identified as adults as they enter post secondary educational institutions, self-esteem and self-image are areas of significant struggle. The self-image of ...Americans, both male and female, has been on the decline for the past three decades. Research literature has linked low self-esteem and body image with depression, disordered eating, and social anxiety. This study examined if college students who participated in a Personal Health and Wellness course utilizing two intentional teaching strategies, self-directed exercise and instruction on media influence, experienced changes in their perceptions regarding body image. The Multidimensional Body-Self Relations Questionnaire (MBSRQ) was administered in pretest and posttest forms to collect data from two sections of students enrolled in a Personal Health and Wellness course to investigate the impact of the intentional teaching strategies on the ten components of body image perception. The data were analyzed using descriptive and inferential statistics. Students in this study had a more positive feeling of physical attractiveness and better perception of their actual weight after the Personal Health & Wellness class. Male students in this study perceived themselves as more physically fit than female students. Athletes in this study identified themselves as more physically fit than non-athletes. Intentional teaching strategies are helpful in developing healthy body perceptions of college students particularly related to weight and appearance. Teaching strategies that are gender specific may be important in developing successful health curricula addressing body image.
We evaluate the response to regional and latitudinal changes in aircraft NOx emissions using several climate metrics (radiative forcing (RF), Global Warming Potential (GWP), Global Temperature change ...Potential (GTP)). Global chemistry transport model integrations were performed with sustained perturbations in regional aircraft and aircraft-like NOx emissions. The RF due to the resulting ozone and methane changes is then calculated. We investigate the impact of emission changes for specific geographical regions (approximating to USA, Europe, India and China) and cruise altitude emission changes in discrete latitude bands covering both hemispheres. We find that lower latitude emission changes (per Tg N) cause ozone and methane RFs that are about a factor of 6 larger than those from higher latitude emission changes. The net RF is positive for all experiments. The meridional extent of the RF is larger for low latitude emissions. GWPs for all emission changes are positive, with tropical emissions having the largest values; the sign of the GTP depends on the choice of time horizon.
► Global model study on climate response to regional/latitudinal aircraft NOx changes. ► RF impacts from O3 and CH4 are larger for changes at lower than at higher latitudes. ► GWPs for all latitudes are positive whereas the GTP can exhibit a change in sign.
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