255 research outputs found
Selecting informative food items for compiling food-frequency questionnaires: comparison of procedures
The authors automated the selection of foods in a computer system that compiles and processes tailored FFQ. For the selection of food items, several methods are available. The aim of the present study was to compare food lists made by MOM2, which identifies food items with highest between-person variance in intake of the nutrients of interest without taking other items into account, with food lists made by forward regression. The name MOM2 refers to the variance, which is the second moment of the nutrient intake distribution. Food items were selected for the nutrients of interest from 2 d of recorded intake in 3524 adults aged 25–65 years. Food lists by 80 % MOM2 were compared to those by 80 % explained variance for regression on differences between the number and type of food items, and were evaluated on (1) the percentage of explained variance and (2) percentage contribution to population intake computed for the selected items on the food list. MOM2 selected the same food items for Ca, a few more for fat and vitamin C, and a few less for carbohydrates and dietary fibre than forward regression. Food lists by MOM2 based on 80 % of variance in intake covered 75–87 % of explained variance for different nutrients by regression and contributed 53–75 % to total population intake. Concluding, for developing food lists of FFQ, it appears sufficient to select food items based on the contribution to variance in nutrient intake without taking covariance into accoun
Calorimetric tunneling study of heat generation in metal-vacuum-metal tunnel junction
We have proposed novel calorimetric tunneling (CT) experiment allowing exact
determination of heat generation (or heat sinking) in individual tunnel
junction (TJ) electrodes which opens new possibilities in the field of design
and development of experimental techniques for science and technology. Using
such experiment we have studied the process of heat generation in normal-metal
electrodes of the vacuum-barrier tunnel junction (VBTJ). The results show there
exists dependence of the mutual redistribution of the heat on applied bias
voltage and the direction of tunnel current, although the total heat generated
in tunnel process is equal to Joule heat, as expected. Moreover, presented
study indicates generated heat represents the energy of non-equilibrium
quasiparticles coming from inelastic electron processes accompanying the
process of elastic tunneling.Comment: 8 pages, 3 figures, LaTe
A Cadaveric Pilot Study
This study investigates the adhesion capacity of a polyglycolic acid- (PGA-)
hyaluronan scaffold with a structural modification based on a planar polymer
(PM) surface in a cadaver cartilage defect model. Two cadaver specimens were
used to serially test multiple chondral matrices. In a cadaver hip model, cell
free polymer-based cartilage implants with a planar bioinspired PM surface
(PGA-PM-scaffolds) were implanted arthroscopically on 10 mm × 15 mm full-
thickness femoral hip cartilage lesions. Unprocessed cartilage implants
without a bioinspired PM surface were used as control group. The cartilage
implants were fixed without and with the use of fibrin glue on femoral hip
cartilage defects. After 50 movement cycles and removal of the distraction, a
rearthroscopy was performed to assess the outline attachment and integrity of
the scaffold. The fixation techniques without and with fibrin fixation showed
marginal differences for outline attachment, area coverage, scaffold
integrity, and endpoint fixation after 50 cycles. The PGA-PM-scaffolds with
fibrin fixation achieved a higher score in terms of the attachment, integrity,
and endpoint fixation than the PGA-scaffold on the cartilage defect. Relating
to the outline attachment, area coverage, scaffold integrity, and endpoint
fixation, the fixation with PGA-PM-scaffolds accomplished significantly better
results compared to the PGA-scaffolds . PGA-PM-scaffolds demonstrate increased
observed initial fixation strength in cadaver femoral head defects relative to
PGA-scaffold, particularly when fibrin glue is used for fixation
Arthroscopic Fixation of Cell Free Polymer-Based Cartilage Implants with a Bioinspired Polymer Surface on the Hip Joint: A Cadaveric Pilot Study
This study investigates the adhesion capacity of a polyglycolic acid-(PGA-) hyaluronan scaffold with a structural modification based on a planar polymer (PM) surface in a cadaver cartilage defect model. Two cadaver specimens were used to serially test multiple chondral matrices. In a cadaver hip model, cell free polymer-based cartilage implants with a planar bioinspired PM surface (PGA-PM-scaffolds) were implanted arthroscopically on 10 mm x 15 mm full-thickness femoral hip cartilage lesions. Unprocessed cartilage implants without a bioinspired PM surface were used as control group. The cartilage implants were fixed without and with the use of fibrin glue on femoral hip cartilage defects. After 50 movement cycles and removal of the distraction, a rearthroscopy was performed to assess the outline attachment and integrity of the scaffold. The fixation techniques without and with fibrin fixation showed marginal differences for outline attachment, area coverage, scaffold integrity, and endpoint fixation after 50 cycles. The PGA-PM-scaffolds with fibrin fixation achieved a higher score in terms of the attachment, integrity, and endpoint fixation than the PGA-scaffold on the cartilage defect. Relating to the outline attachment, area coverage, scaffold integrity, and endpoint fixation, the fixation with PGA-PM-scaffolds accomplished significantly better results compared to the PGA-scaffolds (P = 0.03752, P = 0.03078, P = 0.00512, P = 0.00512). PGA-PM-scaffolds demonstrate increased observed initial fixation strength in cadaver femoral head defects relative to PGA-scaffold, particularly when fibrin glue is used for fixation
Temperature and junction-type dependency of Andreev reflection in MgB2
We studied the voltage and temperature dependency of the dynamic conductance
of normal metal-MgB2 junctions obtained either with the point-contact technique
(with Au and Pt tips) or by making Ag-paint spots on the surface of
high-quality single-crystal-like MgB2 samples. The fit of the conductance
curves with the generalized BTK model gives evidence of pure s-wave gap
symmetry. The temperature dependency of the gap, measured in Ag-paint junctions
(dirty limit), follows the standard BCS curve with 2Delta/kTc = 3.3. In
out-of-plane, high-pressure point contacts we obtained almost ideal Andreev
reflection characteristics showing a single small s-wave gap Delta = 2.6 +/-
0.2 (clean limit). These results support the two-gap model of
superconductivity, the presence of a modified layer at the surface of the
crystals and an important and non-conventional role of the impurities in MgB2.Comment: 5 pages, 4 eps figures, SNS 2001 conferenc
Andreev reflection in Au/La_{2-x}Sr_{x}CuO_{4} point-contact junctions: separation between pseudogap and phase-coherence gap
We made point-contact measurements with Au tips on La_{2-x}Sr_{x}CuO_{4}
samples with 0.08 < x < 0.20 to investigate the relationship between
superconducting gap and pseudogap. We obtained junctions whose conductance
curves presented typical Andreev reflection features at all temperatures from
4.2 K up to T_c^A close to the bulk T_c. Their fit with the
BTK-Tanaka-Kashiwaya model gives good results if a (s+d)-wave gap symmetry is
used. The doping dependence of the low temperature dominant isotropic gap
component Delta_{s} follows very well the T_{c} vs. x curve. These results
support the separation between the superconducting (Andreev) gap and the
pseudogap measured by angle-resolved photoemission spectroscopy (ARPES) and
tunneling.Comment: 4 pages, 5 eps figures, 1 table. SNS 2001 Conferenc
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