1,587 research outputs found
Sphenomenology --- An Overview, with a Focus on a Higgsino LSP World, and on Eventual Tests of String Theory
In this talk, as requested, I begin with a overview and with some basic
reminders about how evidence for supersymmetry in nature might appear -- in
particular, how SUSY signatures are never clear so it is difficult to search
for them without major theoretical input. Models can be usefully categorized
phenomenologically by naming their LSP -- that is, once the LSP is
approximately fixed so is the behavior of the observables, and the resulting
behavior is generally very different for different LSPs. Next I compare the
three main LSP-models (gravitino, bino, higgsino). Hints from data suggest
taking the higgsino-LSP world very seriously, so I focus on it, and describe
its successful prediction of reported events from the 1996 LEP runs. SUSY
signatures in the LSP world are very different from those that are
usually studied. Then I briefly discuss how to measure the parameters of the
effective Lagrangian from collider and decay data. Finally I turn to how data
will test and help extract the implications of string theories.Comment: Uses espcrc2.st
Assessment of agreement between invasive blood pressure measured centrally and peripherally and the influence of different haemodynamic states in anaesthetised horses
Objective
To determine the agreement of invasive blood pressure measured in the facial artery, the metatarsal artery and the carotid. Additionally, to evaluate the effects of two haemodynamic conditions on agreement.
Study design
Prospective, randomized study.
Animals
Eight horses aged 7 (4 -23) years with a body weight of 493 ± 33 kg.
Methods
Horses were anaesthetized and positioned in dorsal recumbency. Invasive blood pressure was measured simultaneously via catheters placed in the facial, metatarsal and carotid artery. Cardiovascular function and agreement between arteries was assessed before and during administration of phenylephrine and sodium nitroprusside. These were administered until carotid mean pressure (MAPc) increased or decreased from baseline (65 ± 5 mmHg) to > 90 mmHg or < 50 mmHg, respectively. Data recorded at each sample time included systolic (SAP), mean (MAP) and diastolic (DAP) for carotid (c), facial (f) and metatarsal (m) artery as well as cardiac output (Q̇t) and systemic vascular resistance (SVR). Bland-Altman analysis was used to assess agreement between peripheral and central sites and regression analysis was used to determine influence of Q̇t and SVR.
Results
The largest difference was observed in SAPc and SAPm with a bias and limits of agreement (LOA) of 2 (-15 to 19) mmHg. The bias (LOA) for MAPc and MAPf was 2 (-4 to 9) mmHg and for MAPc and MAPm was 5 (-4 to 14) mmHg. The best agreement for DAP was seen between DAPc and DAPf with bias (LOA) of 1 (-3 to 5) mmHg. Regression analysis indicated marginal influence on agreement by Q̇t on MAPc and MAPf.
Conclusion
and clinical relevance The MAP and DAP of the carotid was generally higher compared to the peripheral arteries, which may lead to overzealous treatment of hypotension, albeit maintaining central pressures. Cardiac output and systemic vascular resistance did not largely influence the difference between sites
The Amundsen Sea Polynya International Research Expedition (ASPIRE)
In search of an explanation for some of the greenest waters ever seen in coastal Antarctica and their possible link to some of the fastest melting glaciers and declining summer sea ice, the Amundsen Sea Polynya International Research Expedition (ASPIRE) challenged the capabilities of the US Antarctic Program and RVIB Nathaniel B. Palmer during Austral summer 2010–2011. We were well rewarded by both an extraordinary research platform and a truly remarkable oceanic setting. Here we provide further insights into the key questions that motivated our sampling approach during ASPIRE and present some preliminary findings, while highlighting the value of the Palmer for accomplishing complex, multifaceted oceanographic research in such a challenging environment
Preceding rule induction with instance reduction methods
A new prepruning technique for rule induction is presented which applies instance reduction before rule induction. An empirical evaluation records the predictive accuracy and size of rule-sets generated from 24 datasets from the UCI Machine Learning Repository. Three instance reduction algorithms (Edited Nearest Neighbour, AllKnn and DROP5) are compared. Each one is used to reduce the size of the training set, prior to inducing a set of rules using Clark and Boswell's modification of CN2. A hybrid instance reduction algorithm (comprised of AllKnn and DROP5) is also tested. For most of the datasets, pruning the training set using ENN, AllKnn or the hybrid significantly reduces the number of rules generated by CN2, without adversely affecting the predictive performance. The hybrid achieves the highest average predictive accuracy
Supernova Neutrinos, Neutrino Oscillations, and the Mass of the Progenitor Star
We investigate the initial progenitor mass dependence of the early-phase
neutrino signal from supernovae taking neutrino oscillations into account. The
early-phase analysis has advantages in that it is not affected by the time
evolution of the density structure of the star due to shock propagation or
whether the remnant is a neutron star or a black hole. The initial mass affects
the evolution of the massive star and its presupernova structure, which is
important for two reasons when considering the neutrino signal. First, the
density profile of the mantle affects the dynamics of neutrino oscillation in
supernova. Second, the final iron core structure determines the features of the
neutrino burst, i.e., the luminosity and the average energy. We find that both
effects are rather small. This is desirable when we try to extract information
on neutrino parameters from future supernova-neutrino observations. Although
the uncertainty due to the progenitor mass is not small for intermediate
(), we
can, nevertheless, determine the character of the mass hierarchy and whether
is very large or very small.Comment: 8 pages, 15 figure
Itinerant ferromagnetism in half-metallic CoS_2
We have investigated electronic and magnetic properties of the pyrite-type
CoS_2 using the linearized muffin-tin orbital (LMTO) band method. We have
obtained the ferromagnetic ground state with nearly half-metallic nature. The
half-metallic stability is studied by using the fixed spin moment method. The
non-negligible orbital magnetic moment of Co 3d electrons is obtained as in the local spin density approximation (LSDA). The calculated
ratio of the orbital to spin angular momenta / = 0.15 is
consistent with experiment. The effect of the Coulomb correlation between Co 3d
electrons is also explored with the LSDA + U method. The Coulomb correlation at
Co sites is not so large, eV, and so CoS_2 is possibly
categorized as an itinerant ferromagnet. It is found that the observed
electronic and magnetic behaviors of CoS_2 can be described better by the LSDA
than by the LSDA + U.Comment: 4 pages, 3 postscript figure
Recognizing Superpartners at LEP
There is a class of supersymmetric models which is well-motivated by hints of
evidence for SUSY and consistent with all existing data. It is important to
study the predictions of these models. They are characterized by M(N3) > M(C1)
> M(snu) > M(N1) (where Ni and Ci are neutralino and chargino mass
eigenstates), |mu| ~< M1 ~< M2 ~= M(Z), mu < 0, and tan(beta) near 1. Their LEP
signatures are mostly unusual. Most produced superpartners are invisible! A
good signature is two photons plus large missing energy. There are also excess
events at large recoil mass in the single photon plus nothing channel. We list
the main signatures for charginos, stops, etc., which are also likely to be
unconventional. This class of models will be definitively tested at LEP194 with
100 pb^{-1} per detector, and almost definitively tested at LEP184.Comment: 15 pages, revtex, 1 figure (included). We include a paragraph on the
improved understanding of the SM background for gamma-gamma-Emiss events that
has occurred since our original posting. We also emphasize the softness of
the leptons from chargino decays in our models. Our conclusions are unchange
A new silicon tracker for proton imaging and dosimetry
For many years, silicon micro-strip detectors have been successfully used as tracking detectors for particle and nuclear physics experiments. A new application of this technology is to the field of particle therapy where radiotherapy is carried out by use of charged particles such as protons or carbon ions. Such a treatment has been shown to have advantages over standard x-ray radiotherapy and as a result of this, many new centres offering particle therapy are currently under construction around the world today. The Proton Radiotherapy, Verification and Dosimetry Applications (PRaVDA) consortium are developing instrumentation for particle therapy based upon technology from high-energy physics. The characteristics of a new silicon micro-strip tracker for particle therapy will be presented. The array uses specifically designed, large area sensors with technology choices that follow closely those taken for the ATLAS experiment at the HL-LHC. These detectors will be arranged into four units each with three layers in an x–u–v configuration to be suitable for fast proton tracking with minimal ambiguities. The sensors will form a tracker capable of tracing the path of ~200Â MeV protons entering and exiting a patient allowing a new mode of imaging known as proton computed tomography (pCT). This will aid the accurate delivery of treatment doses and in addition, the tracker will also be used to monitor the beam profile and total dose delivered during the high fluences used for treatment. We present here details of the design, construction and assembly of one of the four units that will make up the complete tracker along with its characterisation using radiation tests carried out using a 90 Sr source in the laboratory and a 60Â MeV proton beam at the Clatterbridge Cancer Centre
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