2,716 research outputs found
Health risks of irrigation with untreated urban wastewater in the southern Punjab, Pakistan
Irrigation water / Water quality / Water reuse / Waste waters / Risks / Public health / Diseases / Farmers / Pakistan / Southern Punjab / Haroonabad
Nanolithography with metastable helium atoms in a high-power standing-wave light field
We have created periodic nanoscale structures in a gold substrate with a
lithography process using metastable triplet helium atoms that damage a
hydrofobic resist layer on top of the substrate. A beam of metastable helium
atoms is transversely cooled and guided through an intense standing-wave light
field. Compared to commonly used low-power optical masks, a high-power light
field (saturation parameter of 10E7) increases the confinement of the atoms in
the standing-wave considerably, and makes the alignment of the experimental
setup less critical. Due to the high internal energy of the metastable helium
atoms (20 eV), a dose of only one atom per resist molecule is required. With an
exposure time of only eight minutes, parallel lines with a separation of 542 nm
and a width of 100 nm (1/11th of the wavelength used for the optical mask) are
created.Comment: 5 pages, 5 figure
Supporting and being supported: Receiving and providing social support in mothers of young children
Social support research has long focused on one aspect of support, receiving support. The present study expands social support to include both receiving and providing support, applies the ideas of social exchange theory to this expanded concept, and test hypotheses pertaining to this broader definition of social support. The emotional, tangible, and information/advice support received from and provided to sixty-five mothers of young children in their relationships with their spouse, parents, and others was assessed on a weekly basis for four weeks. Greater perceived support from friends and family and greater support received and provided in the relationship with spouse was related to lower stress, greater satisfaction with parenting, lower depression, and more positive coping. Mothers tended to both receive and provide in their relationships. Except for the relationship with spouse, where mothers were equally likely to fall into the over benefited, balanced, and under benefited groups, in each of their relationships mothers were more likely have balanced support over the time period than to have an imbalance of support. Contrary to expectations, support balance over the time period was not related to symptoms of depression, satisfaction with parenting, subjective well-being, or coping as assessed at the end of the calling period. Possible reasons for lack of connection between support balance and outcomes are discussed. Issues pertaining to the measurement of balance of support, as well as participant factors, are considered. Future directions for research on receiving and providing support and support balance are suggested
Perfectionism and Honors Students: Cautious Good News
Psychoeducational research differentiates adaptive and maladaptive forms of perfectionism. This study considers personal-strivings and evaluativeconcerns perfectionism in relation to procrastination, stress, anxiety, well-being, and academic achievement among students (n = 147) of all undergraduate levels and across disciplines, with honors representing a little over a quarter. While results show evaluative-concerns perfectionism to positively correlate to stress and anxiety and negatively correlate with well-being, no correlation is found relative to procrastination and GPA. Conversely, personal-strivings perfectionism negatively correlates with procrastination and stress and positively with well-being and GPA. Honors students show a higher degree of the more adaptive personal-strivings perfectionism than their undergraduate counterparts but do not differ in the maladaptive form. Data suggest that this is good news for honors students: they have more adaptive perfectionism and are in no more danger from its maladaptive type than other students
On narrowing coated conductor film: emergence of granularity-induced field hysteresis of transport critical current
Critical current density Jc in polycrystalline or granular superconducting
material is known to be hysteretic with applied field H due to the focusing of
field within the boundary between adjacent grains. This is of concern in the
so-called coated conductors wherein superconducting film is grown on a
granular, but textured surface of a metal substrate. While previous work has
mainly been on Jc determined using induced or magnetization currents, the
present work utilizes transport current via an applied potential in strip
geometry. It is observed that the effect is not as pronounced using transport
current, probably due to a large difference in criterion voltage between the
two types of measurements. However, when the films are narrowed by patterning
into 200-, 100-, or 80-micron, the hysteresis is clearly seen, because of the
forcing of percolation across higher-angle grain boundaries. This effect is
compared for films grown on ion-beam-assisted-deposited (IBAD) YSZ substrate
and those grown on rolling-assisted-biaxially-textures substrates (RABiTS)
which have grains that are about ten times larger. The hysteresis is more
pronounced for the latter, which is more likely to have a weak grain boundary
spanning the width of the microbridge. This is also of concern to applications
in which coated conductors will be striated in order to reduce of AC losses.Comment: text-only: 10 pages, plus 5 figures on 5 page
Microwave Near-Field Imaging of Electric Fields in a Superconducting Microstrip Resonator
We describe the use of a cryogenic near-field scanning microwave microscope
to image microwave electric fields from superconducting and normal-metal
microstrip resonators. The microscope employs an open-ended coaxial probe and
operates from 77 to 300 K in the 0.01-20 GHz frequency range with a spatial
resolution of about 200 mm. We describe the operation of the system and present
microwave images of Cu and Tl2Ba2CaCu2O8 microstrip resonators, showing
standing wave patterns at the fundamental and second harmonic frequencies.Comment: 9 pages, 3 eps figure
Numerical simulations on the motion of atoms travelling through a standing-wave light field
The motion of metastable helium atoms travelling through a standing light
wave is investigated with a semi-classical numerical model. The results of a
calculation including the velocity dependence of the dipole force are compared
with those of the commonly used approach, which assumes a conservative dipole
force. The comparison is made for two atom guiding regimes that can be used for
the production of nanostructure arrays; a low power regime, where the atoms are
focused in a standing wave by the dipole force, and a higher power regime, in
which the atoms channel along the potential minima of the light field. In the
low power regime the differences between the two models are negligible and both
models show that, for lithography purposes, pattern widths of 150 nm can be
achieved. In the high power channelling regime the conservative force model,
predicting 100 nm features, is shown to break down. The model that incorporates
velocity dependence, resulting in a structure size of 40 nm, remains valid, as
demonstrated by a comparison with quantum Monte-Carlo wavefunction
calculations.Comment: 9 pages, 4 figure
Near-Field Scanning Microwave Microscopy: Measuring Local Microwave Properties and Electric Field Distributions
We describe the near-field microwave microscopy of microwave devices on a
length scale much smaller than the wavelength used for imaging. Our microscope
can be operated in two possible configurations, allowing a quantitative study
of either material properties or local electric fields.Comment: 4 pages, 8 figures, minor corrections to text and 2 figure
Frequency Following Imaging of Electric Fields from Resonant Superconducting Devices using a Scanning Near-Field Microwave Microscope
We have developed a scanning near-field microwave microscope that operates at
cryogenic temperatures. Our system uses an open-ended coaxial probe with a 200
mm inner conductor diameter and operates from 77 to 300 K in the 0.01-20 GHz
frequency range. In this paper, we present microwave images of the electric
field distribution above a Tl2Ba2CaCu2O8 microstrip resonator at 77 K, measured
at several heights. In addition, we describe the use of a frequency-following
circuit to study the influence of the probe on the resonant frequency of the
device.Comment: 4 pages, postscript file with 6 figures conference proceeding for the
Applied Superconductivity Conference 199
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