2,408 research outputs found
TEM Study of Niobium Surfaces Treated by Different Polishing Techniques
TEM cross-section observation on Nb surfaces has been a challenge to our superconducting radio frequency (SRF) community due to the highly reactive nature of Nb. Although it was demonstrated in an early attempt1 that under a suitable sample preparation procedure reasonably clear cross-section images of Nb could be obtained, to the best of our knowledge good atomically resolved images had never been obtained. In this report, it is shown that by modifying the sample preparation procedure adopted in reference 1 it is possible to obtain good cross-section images of Nb surfaces with atomic resolution routinely. Surface atomic structures of Nb samples prepared by buffered electropolishing (BEP), buffered chemical polishing (BCP), and an untreated sample will be reported and compared
Reproductive Tract Disorders among Afghan Refugee Women Attending Health Clinics in Haripur, Pakistan
Afghans comprise one of the largest groups of refugees in the world, with the majority living in Pakistan. The objective of this study was to identify commonly-occurring reproductive tract infections (RTIs), describe knowledge of women about RTIs, and assess physical and behavioural factors contributing to the development of RTIs. Afghan women presenting at Basic Health Units in refugee camps in Haripur, Pakistan, with reproductive health-related complaints, were included in the study (n=634). Data collection included implementation of an interviewer-administered questionnaire, along with a physical examination and laboratory tests. A descriptive analysis was conducted first. Qualitative data were coded and analyzed using predetermined themes. Chi-square test was used for determining the possible relationships between a binary outcome and categorical risk factors. Over three-fourths (76.7%) of those who reported to the health clinics with reproductive complaints had an RTI. Nearly half (49.5%) of these women were diagnosed with some form of vaginitis, and 14.7% were diagnosed with clinical suspicion of pelvic inflammatory disease (PID). Women with cervical prolapse (p=0.033) or who cleansed after intercourse (p=0.002) were more likely to have vaginitis. There was a significant difference (p=0.017) in the prevalence of suspected PID among women who used mud only (11.1%), any water (18.8%), and an old cloth or toilet paper (9.8%) for cleansing after defaecation. Specific physical and behavioural contributors to the high prevalence of RTIs in this population were identified, and recommendations to ameliorate these factors are offered
Single photon emitters based on Ni/Si related defects in single crystalline diamond
We present investigations on single Ni/Si related color centers produced via
ion implantation into single crystalline type IIa CVD diamond. Testing
different ion dose combinations we show that there is an upper limit for both
the Ni and the Si dose 10^12/cm^2 and 10^10/cm^2 resp.) due to creation of
excess fluorescent background. We demonstrate creation of Ni/Si related centers
showing emission in the spectral range between 767nm and 775nm and narrow
line-widths of 2nm FWHM at room temperature. Measurements of the intensity
auto-correlation functions prove single-photon emission. The investigated color
centers can be coarsely divided into two groups: Drawing from photon statistics
and the degree of polarization in excitation and emission we find that some
color centers behave as two-level, single-dipole systems whereas other centers
exhibit three levels and contributions from two orthogonal dipoles. In
addition, some color centers feature stable and bright emission with saturation
count rates up to 78kcounts/s whereas others show fluctuating count rates and
three-level blinking.Comment: 7 pages, submitted to Applied Physics B, revised versio
Impurity and strain effects on the magnetotransport of La1.85Sr0.15Cu(1-y)Zn(y)O4 films
The influence of zinc doping and strain related effects on the normal state
transport properties(the resistivity, the Hall angle and the orbital magneto-
resistance(OMR) is studied in a series of La1.85Sr0.15Cu(1-y)Zn(y)O4 films with
values of y between 0 and 0.12 and various degrees of strain induced by the
mismatch between the films and the substrate. The zinc doping affects only the
constant term in the temperature dependence of cotangent theta but the strain
affects both the slope and the constant term, while their ratio remains
constant.OMR is decreased by zinc doping but is unaffected by strain. The ratio
delta rho/(rho*tan^2 theta) is T-independent but decreases with impurity
doping. These results put strong constraints on theories of the normal state of
high- temperature superconductors
Properties of the random field Ising model in a transverse magnetic field
We consider the effect of a random longitudinal field on the Ising model in a
transverse magnetic field. For spatial dimension , there is at low
strength of randomness and transverse field, a phase with true long range order
which is destroyed at higher values of the randomness or transverse field. The
properties of the quantum phase transition at zero temperature are controlled
by a fixed point with no quantum fluctuations. This fixed point also controls
the classical finite temperature phase transition in this model. Many critical
properties of the quantum transition are therefore identical to those of the
classical transition. In particular, we argue that the dynamical scaling is
activated, i.e, the logarithm of the diverging time scale rises as a power of
the diverging length scale
Dietary patterns during high school and risk of colorectal adenoma in a cohort of middle-aged women
Adolescent diet may be etiologically relevant for later risk of colorectal adenoma, a precursor of colorectal cancer. We aimed to examine associations between adolescent dietary patterns (derived using factor analysis) and risk of colorectal adenoma in middle adulthood. We analyzed data from 17,221 women participating in the Nurses' Health Study II, who had completed a validated high school (HS) food frequency questionnaire in 1998 when they were 34-51 years old, and had subsequently undergone at least one lower bowel endoscopy. Between 1998 and 2007, 1,299 women were diagnosed with at least one colorectal adenoma. In multivariable models adjusted for adult dietary patterns, a higher "prudent" pattern during HS, characterized by high consumption of vegetables, fruit and fish was associated with a statistically significantly lower risk of rectal (odds ratio [OR] highest vs. lowest quintile, 0.45, 95% CI 0.27-0.75, p-trend=0.005), but not colon adenomas. A higher "Western" pattern during HS, characterized by high consumption of desserts and sweets, snack foods and red and processed meat, was significantly associated with rectal (OR 1.78, 95% CI 1.12-2.85, p-trend=0.005) and advanced (OR 1.58, 95% CI 1.07-2.33, p-trend=0.08), but not associated with colon or non-advanced adenomas. This study suggests that overall eating patterns during high school may influence later risk of rectal and advanced adenoma, independent of adult diet. Our results support the hypothesis that diet during early life may influence colorectal carcinogenesis
Strongly interacting Fermi gases
Strongly interacting gases of ultracold fermions have become an amazingly rich test-bed for many-body theories of fermionic matter. Here we present our recent experiments on these systems. Firstly, we discuss high-precision measurements on the thermodynamics of a strongly interacting Fermi gas across the superfluid transition. The onset of superfluidity is directly observed in the compressibility, the chemical potential, the entropy, and the heat capacity. Our measurements provide benchmarks for current many-body theories on strongly interacting fermions. Secondly, we have studied the evolution of fermion pairing from three to two dimensions in these gases, relating to the physics of layered superconductors. In the presence of p-wave interactions, Fermi gases are predicted to display toplogical superfluidity carrying Majorana edge states. Two possible avenues in this direction are discussed, our creation and direct observation of spin-orbit coupling in Fermi gases and the creation of fermionic molecules of [superscript 23]Naâ[superscript 40]K that will feature strong dipolar interactions in their absolute ground state
Spin oscillations in transient diffusion of a spin pulse in n-type semiconductor quantum wells
By studying the time and spatial evolution of a pulse of the spin
polarization in -type semiconductor quantum wells, we highlight the
importance of the off-diagonal spin coherence in spin diffusion and transport.
Spin oscillations and spin polarization reverse along the the direction of spin
diffusion in the absence of the applied magnetic field are predicted from our
investigation.Comment: 5 pages, 4 figures, accepted for publication in PR
Polyhedral vesicles
Polyhedral vesicles with a large bending modulus of the membrane such as the
gel phase lipid membrane were studied using a Brownian dynamics simulation. The
vesicles exhibit various polyhedral morphologies such as tetrahedron and cube
shapes. We clarified two types of line defects on the edges of the polyhedrons:
cracks of both monolayers at the spontaneous curvature of monolayer , and a crack of the inner monolayer at . Around the
latter defect, the inner monolayer curves positively. Our results suggested
that the polyhedral morphology is controlled by .Comment: 4 pages, 5 figure
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