3,186 research outputs found
Implications of Constraints on Mass Parameters in the Higgs Sector of the Nonlinear Supersymmetric SU(5) Model
The Higgs sector of the minimal nonlinear supersymmetric SU(5) model contains
three mass parameters. Although these mass parameters are essentially free at
the electroweak scale, they might have particular values if they evolve from a
particular constraints at the GUT scale through the RG equations. By assuming a
number of simple constraints on these mass parameters at the GUT scale, we
obtain their values at the electroweak scale through the RG equations in order
to investigate the phenomenological implications. Some of them are found to be
consistent with the present experimental data.Comment: 23 pages, 10 figure
Search for Sterile Neutrinos with a Radioactive Source at Daya Bay
The far site detector complex of the Daya Bay reactor experiment is proposed
as a location to search for sterile neutrinos with > eV mass. Antineutrinos
from a 500 kCi 144Ce-144Pr beta-decay source (DeltaQ=2.996 MeV) would be
detected by four identical 20-ton antineutrino targets. The site layout allows
flexible source placement; several specific source locations are discussed. In
one year, the 3+1 sterile neutrino hypothesis can be tested at essentially the
full suggested range of the parameters Delta m^2_{new} and sin^22theta_{new}
(90% C.L.). The backgrounds from six nuclear reactors at >1.6 km distance are
shown to be manageable. Advantages of performing the experiment at the Daya Bay
far site are described
Flight testing and frequency domain analysis for rotorcraft handling qualities characteristics
A demonstration of frequency domain flight testing techniques and analyses was performed on a U.S. Army OH-58D helicopter in support of the OH-58D Airworthiness and Flight Characteristics Evaluation and the Army's development and ongoing review of Aeronautical Design Standard 33C, Handling Qualities Requirements for Military Rotorcraft. Hover and forward flight (60 knots) tests were conducted in 1 flight hour by Army experimental test pilots. Further processing of the hover data generated a complete database of velocity, angular rate, and acceleration frequency responses to control inputs. A joint effort was then undertaken by the Airworthiness Qualification Test Directorate (AQTD) and the U.S. Army Aeroflightdynamics Directorate (AFDD) to derive handling qualities information from the frequency response database. A significant amount of information could be extracted from the frequency domain database using a variety of approaches. This report documents numerous results that have been obtained from the simple frequency domain tests; in many areas, these results provide more insight into the aircraft dynamics that affect handling qualities than to traditional flight tests. The handling qualities results include ADS-33C bandwidth and phase delay calculations, vibration spectral determinations, transfer function models to examine single axis results, and a six degree of freedom fully coupled state space model. The ability of this model to accurately predict aircraft responses was verified using data from pulse inputs. This report also documents the frequency-sweep flight test technique and data analysis used to support the tests
Orbital liquid in three dimensional Mott insulator:
We present a theory of spin and orbital states in Mott insulator .
The spin-orbital superexchange interaction between ions in cubic
crystal suffers from a pathological degeneracy of orbital states at classical
level. Quantum effects remove this degeneracy and result in the formation of
the coherent ground state, in which the orbital moment of level is
fully quenched. We find a finite gap for orbital excitations. Such a disordered
state of local degrees of freedom on unfrustrated, simple cubic lattice is
highly unusual. Orbital liquid state naturally explains observed anomalies of
.Comment: 5 pages, 3 figure
Neutral Higgs bosons in the MNMSSM with explicit CP violation
Within the framework of the minimal non-minimal supersymmetric standard model
(MNMSSM) with tadpole terms, CP violation effects in the Higgs sector are
investigated at the one-loop level, where the radiative corrections from the
loops of the quark and squarks of the third generation are taken into account.
Assuming that the squark masses are not degenerate, the radiative corrections
due to the stop and sbottom quarks give rise to CP phases, which trigger the CP
violation explicitly in the Higgs sector of the MNMSSM. The masses, the
branching ratios for dominant decay channels, and the total decay widths of the
five neutral Higgs bosons in the MNMSSM are calculated in the presence of the
explicit CP violation. The dependence of these quantities on the CP phases is
quite recognizable, for given parameter values.Comment: 25 pages, 8 figure
Method of extending hyperfine coherence times in Pr^3+:Y_2SiO_5
In this letter we present a method for increasing the coherence time of
praseodymium hyperfine ground state transitions in Pr^3+:Y_2SiO_5 by the
application of a specific external magnetic field. The magnitude and angle of
the external field is applied such that the Zeeman splitting of a hyperfine
transition is at a critical point in three dimensions, making the first order
Zeeman shift vanishingly small for the transition. This reduces the influence
of the magnetic interactions between the praseodymium ions and the spins in the
host lattice on the transition frequency. Using this method a phase memory time
of 82ms was observed, a value two orders of magnitude greater than previously
reported. It is shown that the residual dephasing is amenable quantum error
correction
Pain, Physical and Social Functioning, and Quality of Life in Individuals with Multiple Hereditary Exostoses in the Netherlands
Background: This study aimed to assess pain and quality of life in a large cohort of patients with multiple hereditary exostoses. Methods: All 322 known patients with multiple hereditary exostoses in the Netherlands were asked to participate. An age-specific questionnaire was sent to children (less than eighteen years old) and adults. The questionnaire focused on pain, daily activities, and school and/or professional situation. Adults also filled out the RAND-36 questionnaire.Results were statistically analyzed with use of the SPSS 15.0 software and with the chi-square test and multiple logistic regression. A p value of <0.05 was regarded as significant. Results: Two hundred and eighty-three patients (88%), including 184 adults (65%) and ninety-nine children (35%), completed the questionnaire. Multiple hereditary exostoses resulted in various physical and social consequences. The majority of adults (119) were employed; however, thirty-three (28%) had changed jobs because of the symptoms of multiple hereditary exostoses and twenty-five (21%) required adjustments in their working environment. Of the sixty-five adults who were not employed, thirteen were medically unfit to work. Of eighty-five children attending school, forty-five (53%) experienced problems at school. The symptoms of multiple hereditary exostoses caused twenty-seven children (27%) and eighty-five adults (46%) to stop participating in sporting activities. Pain was the greatest problem, with sixty-two children (63%) and 152 adults (83%) who reported recent pain. On multivariate analysis, pain in adults was correlated most significantly with age and problems at work, and pain in children was correlated with the perception of the disease and problems at school. Adult patients with multiple hereditary exostoses had a lower quality of life than the Dutch reference groups, with lower scores on six of eight RAND-36 subscales. Conclusions: Our study confirms that multiple hereditary exostoses is a chronic disease causing a profound impact on quality of life. The results suggest that pain is not the only problem associated with multiple hereditary exostoses, as it has an extensive influence on daily activities, as well as on social and psychological well-being, causing significant disability
Effect of stress relieving heat treatment on surface topography and dimensional accuracy of incrementally formed grade 1 titanium sheet parts
The forming of parts with an optimized surface roughness and high dimensional accuracy is important in many applications of incremental sheet forming (ISF). To realize this, the effect of stress relieving heat treatment of grade-1 Ti parts performed before and after forming on the surface finish and dimensional accuracy was studied. It was found that heat treatment at a temperature of 540 °C for 2 h improves the surface finish of formed parts resulting in a surface with little or no visible tool marks. Additionally, it improves the dimensional accuracy of parts after unclamping from the rig used for forming, in particular, that of parts with shallow wall angles (typically <25°). It was also noted that post-forming heat treatment improves the surface finish of parts. The surface topography of formed parts was studied using interferometry to yield areal surface roughness parameters and subsequently using secondary electron imaging. Back-scatter electron microscopy imaging results coupled with energy-dispersive X-ray (EDX) analysis showed that heat treatment prior to forming leads to tool wear as indicated by the presence of Fe in samples. Furthermore, post-forming heat treatment prevents curling up of formed parts due to compressive stresses if the formed part is trimmed
- …