10,193 research outputs found
An Effective Cutoff for the Isolalated Lepton Background from Bottom Decay --
There is a strong correlation between the and isolation of the lepton
coming from decay. Consequently the isolated lepton background from
decay goes down rapidly with increasing lepton ; and there is a
cutoff beyond which it effectively vanishes. For the isolation cut of GeV, appropriate for LHC, the lepton cutoff is 80 GeV. This can be
exploited to effectively eliminate the background from the like sign
dilepton channel apropriate for Majorana particle searches, as well as the
unlike sign dilepton and the single lepton channels appropriate for the top
quark search. We illustrate this with a detailed analysis of the background
in these channels along with the signals at LHC energy using both parton level
MC and ISAJET programs.Comment: TIFR/TH/93-23 (LATEX, 20 pages, 7 figures available on request
Dielectric anomaly at the orbital order-disorder transition in LaMnO_(3+delta)
We report a novel dielectric anomaly around the Jahn-Teller orbital
order-disorder transition temperature T_JT in LaMnO_(3+delta). The transition
has been characterized by resistivity (rho)versus temperature (T), calorimetry,
and temperature-dependent X-ray diffraction studies. Measurements of complex
dielectric permittivity epsilon* (= epsilon'-i.epsilon'') over a low-frequency
range (1 Hz - 10 MHz)across T_JT reveal a distinct anomaly. This observation,
and the reported relatively high static dielectric constant at T = 0 (epsilon0
\~18-20), possibly indicate that the orbital order gives rise to intrinsic
polarization that undergoes transition at T_JT. The frequency dispersion of the
dielectric response at any given temperature, however, reveals that the
dielectric response consists of Maxwell-Wagner component, due to interfaces,
within such a low frequency range. The T_JT and the nature of the anomaly in
epsilon'(omega,T), epsilon''(omega,T) at T_JT, of course, vary - from a sharp
upward feature to a smeared plateau and then a downward trend - depending on
the Mn^4+ concentration of the sample. The observation of an intrinsic
dielectric response due to long-range orbital order in LaMnO_3 - where no
ferroelectric order is possible due to the absence of off-centre distortion in
MnO_6 octahedra - may throw a new light onto these classes of materials
vis-a-vis multiferroic materials.Comment: 22 pages including 7 figures; pdf only; accepted for publication in
J.Phys.:Condens. Matte
The Evolution of Natriuretic Peptide Augmentation in Management of Heart Failure and the Role of Sacubitril/valsartan
Heart failure (HF) is one of the leading causes of morbidity, mortality, and health care expenditures in the US and worldwide. For three decades, the pillars of treatment of HF with reduced ejection fraction (HFrEF) were medications that targeted the sympathetic nervous system (SNS) and the renin-angiotensin-aldosterone system (RAAS). Prior attempts to augment the natriuretic peptide system (NPS) for the management of HF failed either due to lack of significant clinical benefit or due to the unacceptable side effect profile. This review article will discuss the NPS, the failure of early drugs which targeted the NPS as therapies for HF, and the sequence of events which led to the development of sacubitril plus valsartan (Entresto; LCZ696; Novartis). LCZ696 has been shown to be superior to the standard of care available for treatment of HFrEF in several substantial hard endpoints including heart failure hospitalizations, cardiovascular mortality, and all-cause mortality
Closed Cell Aluminium Composite Foam for Crashworthiness Applications
Closed cell aluminium foams with various densities have been made through stir casting technique. The crucible temperature and melt temperature have been controlled to control the foaming temperature for controlling foam cell size and foam densities. The foam made has been then characterized for their micro-architectural characteristics as well as deformation responses. The crash of vehicle takes place at very high speed and therefore, the foams have been tested both at quasi-static and dynamic conditions. It is noted that at dynamic conditions the foams exhibit much higher strength and energy absorption. Then the foams have been filled manually inside the commercially available crash-box and tested using drop weight test methodology. The weight is varied up to 375 kg and speed is varied up to 55 km/h. The deformation behavior of bare foam blocks, foam filled crash box and empty crash boxes have been studied. It is observed that the foam synthesized through this technique is excellent for crash energy absorption. It is also noted that hardly any significant weight will be added into the vehicle. These closed cell foam has also the potential to be used in other transport sectors
Long-term stability test of a triple GEM detector
The main aim of the study is to perform the long-term stability test of gain
of the single mask triple GEM detector. A simple method is used for this long-
term stability test using a radioactive X-ray source with high activity. The
test is continued till accumulation of charge per unit area > 12.0 mC/mm2. The
details of the chamber fabrication, the test set-up, the method of measurement
and the test results are presented in this paper.Comment: 8 pages, 5 figure
Polymorphism, thermodynamic anomalies and network formation in an atomistic model with two internal states
Using molecular dynamics simulations we study the temperature-density phase
diagram of a simple model system of particles in two dimensions. In addition to
translational degrees of freedom, each particle has two internal states and
interacts with a modified Lennard-Jones potential which depends on relative
positions as well as the internal states. We find that, despite its simplicity,
the model has a rich phase diagram showing many features of common
network-forming liquids such as water and silica, including polymorphism and
thermodynamic anomalies. We believe our model may be useful for studies
concerning generic features of such complex liquids.Comment: 7 pages, 8 pdf figure
Electric and magnetic polarizabilities of hexagonal Ln2CuTiO6 (Ln=Y, Dy, Ho, Er and Yb)
We investigated the rare-earth transition metal oxide series, Ln2CuTiO6
(Ln=Y, Dy, Ho, Er and Yb), crystallizing in the hexagonal structure with
non-centrosymmetric P63cm space group for possible occurrences of multiferroic
properties. Our results show that while these compounds, except Ln=Y, exhibit a
low temperature antiferromagnetic transition due to the ordering of the
rare-earth moments, the expected ferroelectric transition is frustrated by the
large size difference between Cu and Ti at the B-site. Interestingly, this
leads these compounds to attain a rare and unique combination of desirable
paraelectric properties with high dielectric constants, low losses and weak
temperature and frequency dependencies. First-principles calculations establish
these exceptional properties result from a combination of two effects. A
significant difference in the MO5 polyhedral sizes for M = Cu and M = Ti
suppress the expected co-operative tilt pattern of these polyhedra, required
for the ferroelectric transition, leading to relatively large values of the
dielectric constant for every compound investigated in this series.
Additionally, it is shown that the majority contribution to the dielectric
constant arises from intermediate-frequency polar vibrational modes, making it
relatively stable against any temperature variation. Changes in the temperature
stability of the dielectric constant amongst different members of this series
are shown to arise from changes in relative contributions from soft polar
modes.Comment: Accepted for publication in Phys. Rev. B (21 pages, 2 Table, 8
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