6,925 research outputs found
Bow-Tie Microstrip Antenna Design
In this paper, the bow-tie microstrip antennas have been designed with two different angles of 40Ă° and 80Ă°. An investigaton on the effect of the angle to the return loss and radiation patterns had been carried out. The impedance matching network with the niicrostrip transmission line feeding was used in this study. Simulation and measurement results for the return loss and radiation patterns were presented
The Twin Higgs: Natural Electroweak Breaking from Mirror Symmetry
We present `twin Higgs models', simple realizations of the Higgs as a
pseudo-Goldstone boson that protect the weak scale from radiative corrections
up to scales of order 5 - 10 TeV. In the ultra-violet these theories have a
discrete symmetry which interchanges each Standard Model particle with a
corresponding particle which transforms under a twin or mirror Standard Model
gauge group. In addition, the Higgs sector respects an approximate global SU(4)
symmetry. When this global symmetry is broken, the discrete symmetry tightly
constrains the form of corrections to the pseudo-Goldstone Higgs potential,
allowing natural electroweak symmetry breaking. Precision electroweak
constraints are satisfied by construction. These models demonstrate that,
contrary to the conventional wisdom, stabilizing the weak scale does not
require new light particles charged under the Standard Model gauge groups.Comment: 5 pages. Updated to the journal versio
Nephrectomy for a case of intrarenal dermoid cyst: was it an appropriate decision?
Dermoid cyst in a kidney is rarely seen. We report a case of intrarenal dermoid cyst which mimics malignant renal tumour and discuss the dilemma in managing this disease
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Patient-Related Barriers to Timely Dialysis Access Preparation: A Qualitative Study of the Perspectives of Patients, Family Members, and Health Care Providers
Rational & Objective
A key aspect of smooth transition to dialysis is the timely creation of a permanent access. Despite early referral to kidney care, initiation onto dialysis is still suboptimal for many patients, which has clinical and cost implications. This study aimed to explore perspectives of various stakeholders on barriers to timely access creation.
Study Design
Qualitative study.
Setting & Participants
Semi-structured interviews with 96 participants (response rate, 67%), including patients with stage 4 chronic kidney disease (n = 30), new hemodialysis patients with (n = 18) and without (n = 20) permanent access (arteriovenous fistula), family members (n = 19), and kidney health care providers (n = 9).
Analytical Approach
Thematic analysis.
Results
Patients reported differential levels of behavioral activation toward access creation: avoidance/denial, wait and see, or active intention. 6 core themes were identified: (1) lack of symptoms, (2) dialysis fear and practical concerns (exaggerated fear, pain, cost, lifestyle disruptions, work-related concerns, burdening their families), (3) evaluating value against costs/risks of access creation (benefits, threat of operation, viability, prompt for early initiation), (4) preference for alternatives, (5) social influences (hearsay, family involvement, experiences of others), and (6) health care provider interactions (mistrust, interpersonal tension, lack of clarity on information). Themes were common to all groups, whereas nuanced perspectives of family members and health care providers were noted in some subthemes.
Limitations
Response bias.
Conclusions
Individual, interpersonal, and psychosocial factors compromise dialysis preparation and contribute to suboptimal dialysis initiation. Our findings support the need for interventions to improve patient and family engagement and address emotional concerns and misperceptions about preparing for dialysis
Pair production of charged Higgs bosons in the Left-Right Twin Higgs model at the ILC and LHC
Left-Right twin Higgs(LRTH) model predicts the existence of a pair of charged
Higgs . In this paper, we study the production of the charged Higgs
bosons pair via the process at
the International Linear Collider(ILC). The numerical results show that the
production rates are at the level of several tens fb, this process can produce
the adequate distinct multi-jet final states and the SM background can be
efficiently reduced. We also discuss the charged Higgs boson pair production
via the process at the Large Hadron
Collider(LHC) and estimate there production rates. We find that, as long as the
charged Higgs bosons are not too heavy, they can be abundantly produced at the
LHC. The possible signatures of these new particles might be detected at the
ILC and LHC experiments.Comment: 15 pages, 5 figures, discussion extended, reference added, typos
fixed, revised version to be published in Eur.Phys.J.
Nambu-Goldstone Dark Matter and Cosmic Ray Electron and Positron Excess
We propose a model of dark matter identified with a pseudo-Nambu-Goldstone
boson in the dynamical supersymmetry breaking sector in a gauge mediation
scenario. The dark matter particles annihilate via a below-threshold narrow
resonance into a pair of R-axions each of which subsequently decays into a pair
of light leptons. The Breit-Wigner enhancement explains the excess electron and
positron fluxes reported in the recent cosmic ray experiments PAMELA, ATIC and
PPB-BETS without postulating an overdensity in halo, and the limit on
anti-proton flux from PAMELA is naturally evaded.Comment: 3 figure
Disappearing scales in carps: Re-visiting Kirpichnikov's model on the genetics of scale pattern formation
The body of most fishes is fully covered by scales that typically form tight, partially overlapping rows. While some of the genes controlling the formation and growth of fish scales have been studied, very little is known about the genetic mechanisms regulating scale pattern formation. Although the existence of two genes with two pairs of alleles (S&s and N&n) regulating scale coverage in cyprinids has been predicted by Kirpichnikov and colleagues nearly eighty years ago, their identity was unknown until recently. In 2009, the âSâ gene was found to be a paralog of fibroblast growth factor receptor 1, fgfr1a1, while the second gene called âNâ has not yet been identified. We re-visited the original model of Kirpichnikov that proposed four major scale pattern types and observed a high degree of variation within the so-called scattered phenotype due to which this group was divided into two sub-types: classical mirror and irregular. We also analyzed the survival rates of offspring groups and found a distinct difference between Asian and European crosses. Whereas nude Ă nude crosses involving at least one parent of Asian origin or hybrid with Asian parent(s) showed the 25% early lethality predicted by Kirpichnikov (due to the lethality of the NN genotype), those with two Hungarian nude parents did not. We further extended Kirpichnikov's work by correlating changes in phenotype (scale-pattern) to the deformations of fins and losses of pharyngeal teeth. We observed phenotypic changes which were not restricted to nudes, as described by Kirpichnikov, but were also present in mirrors (and presumably in linears as well; not analyzed in detail here). We propose that the gradation of phenotypes observed within the scattered group is caused by a gradually decreasing level of signaling (a dose-dependent effect) probably due to a concerted action of multiple pathways involved in scale formation
Chemical Pressure and Physical Pressure in BaFe_2(As_{1-x}P_{x})_2
Measurements of the superconducting transition temperature, T_c, under
hydrostatic pressure via bulk AC susceptibility were carried out on several
concentrations of phosphorous substitution in BaFe_2(As_{1-x}P_x)_2. The
pressure dependence of unsubstituted BaFe_2As_2, phosphorous concentration
dependence of BaFe_2(As_{1-x}P_x)_2, as well as the pressure dependence of
BaFe_2(As_{1-x}P_x)_2 all point towards an identical maximum T_c of 31 K. This
demonstrates that phosphorous substitution and physical pressure result in
similar superconducting phase diagrams, and that phosphorous substitution does
not induce substantial impurity scattering.Comment: 5 pages, 4 figures, to be published in Journal of the Physical
Society of Japa
Economic Constrained Transfer Capability Assessment
Following the deregulation of electric power utilities around the globe, it has been widely acknowledged that quantifying power system transfer capability is of increasingly importance in today's large-scale and interconnected power system operation and planning procedures. This paper introduces a novel framework to evaluate transfer capability incorporating electricity market dispatching considerations, which we termed it as economic constrained transfer capability (ETC) problem. A mathematical model of a multi-objective optimization (MOOP) approach is presented to solve this ETC problem. The proposed methodology has been tested on a classical 3-machine 9-bus system and the IEEE 30-bus system. Preliminary simulation results from several case studies are presented with relevant analyses and discussions
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