128 research outputs found
Microwave radiation induced magneto-oscillations in the longitudinal and transverse resistance of a two dimensional electron gas
We confirm the existance of magneto-resistance oscillations in a
microwave-irradiated two-dimensional electron gas, first reported in a series
of papers by Zhudov et al. and Mani et al. In our experiments, on a sample with
a more moderate mobility, the microwave induced oscillations are observed not
only in the longitudinal - but also in the transverse-resistance (Hall
resistance). The phase of the oscillations is such that the decrease (increase)
in the longitudinal resistance is accompanied by an increase (decrease) in the
absolute value of the Hall resistance. We believe that these new results
provide valuable new information to better understand the origin of this
interesting phenomenon.Comment: Accepted for publication in journal of Solid State Comunication
Measuring service quality of public dental health care facilities in Kelantan, Malaysia
This study investigates patients' expectations and perceptions of service quality in public dental health care and measures their "satisfaction gap." This descriptive study involved 481 dental outpatients in Kelantan, Malaysia. A modified SERVQUAL 20-item instrument was used to assess patients' expectations before and perceptions after receiving dental treatment. The "satisfaction gap" was then measured. Results showed that patients visiting for management of dental pain were more satisfied (P = .007) than those visiting with appointment. The most significant service quality dimensions were related to responsiveness, assurance, and empathy of the dental health care providers. There was a significant difference between the patients' expectations and their perceptions of service provided (P < .01) with regard to all dimensions. In conclusion, dental service providers should give emphasis to the compassionate and emotional aspects of care and to remember that they are integral components of quality service
The microwave induced resistance response of a high mobility 2DEG from the quasi-classical limit to the quantum Hall regime
Microwave induced resistance oscillations (MIROs) were studied experimentally
over a very wide range of frequencies ranging from ~20 GHz up to ~4 THz, and
from the quasi-classical regime to the quantum Hall effect regime. At low
frequencies regular MIROs were observed, with a periodicity determined by the
ratio of the microwave to cyclotron frequencies. For frequencies below 150 GHz
the magnetic field dependence of MIROs waveform is well described by a
simplified version of an existing theoretical model, where the damping is
controlled by the width of the Landau levels. In the THz frequency range MIROs
vanish and only pronounced resistance changes are observed at the cyclotron
resonance. The evolution of MIROs with frequency are presented and discussed.Comment: 4 pages, presented at EP2DS, to be published in Physica
Radiation-induced oscillatory magnetoresistance as a sensitive probe of the zero-field spin splitting in high mobility GaAs/AlGaAs devices
We suggest an approach for characterizing the zero-field spin splitting of
high mobility two-dimensional electron systems, when beats are not readily
observable in the Shubnikov-de Haas effect. The zero-field spin splitting and
the effective magnetic field seen in the reference frame of the electron is
evaluated from a quantitative study of beats observed in radiation-induced
magnetoresistance oscillations.Comment: 4 pages, 4 color figure
Denture marking: a mandatory procedure to aid forensic identification
Purpose - The purpose of this paper is to highlight the significance of placing identification marks on dentures. Design/methodology/approach - This paper reviews the legislation with regard to denture marking in certain countries, various methods of denture marking and describes a simple, inexpensive, paper-based labelling system. Findings - Various methods have been proposed for denture marking but it is important to use a method that is simple, practical, affordable and universally acceptable. Practical implications - The identification of unknown or missing persons by means of denture marking is a very successful method of identification in forensic investigation. It is also useful for patients residing in hospitals and community homes where dentures could be misplaced, particularly during cleaning by personnel where there is a chance of loss or mix-up. The importance of denture marking should be emphasized by all law-enforcing authorities and should be promoted among all dentists, towards making it a compulsory routine dental procedure throughout the world. Originality/value - In Malaysia, denture marking, as recommended by its Ministry of Health, uses a unique coding system which can readily provide information about the wearer in whichever part of the world the person is found. The method applied is simple, practical and affordable and can easily be adapted by others. It can be of great value during times of crisis
Rapid and deep-scale ubiquitylation profiling for biology and translational research
Protein ubiquitylation is involved in a plethora of cellular processes. While antibodies directed at ubiquitin remnants (K-ɛ-GG) have improved the ability to monitor ubiquitylation using mass spectrometry, methods for highly multiplexed measurement of ubiquitylation in tissues and primary cells using sub-milligram amounts of sample remains a challenge. Here, we present a highly sensitive, rapid and multiplexed protocol termed UbiFast for quantifying ~10,000 ubiquitylation sites from as little as 500 μg peptide per sample from cells or tissue in a TMT10plex in ca. 5 h. High-field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) is used to improve quantitative accuracy for posttranslational modification analysis. We use the approach to rediscover substrates of the E3 ligase targeting drug lenalidomide and to identify proteins modulated by ubiquitylation in models of basal and luminal human breast cancer. The sensitivity and speed of the UbiFast method makes it suitable for large-scale studies in primary tissue samples
Far-infrared photo-conductivity of electrons in an array of nano-structured antidots
We present far-infrared (FIR) photo-conductivity measurements for a
two-dimensional electron gas in an array of nano-structured antidots. We
detect, resistively and spectrally resolved, both the magnetoplasmon and the
edge-magnetoplasmon modes. Temperature-dependent measurements demonstrates that
both modes contribute to the photo resistance by heating the electron gas via
resonant absorption of the FIR radiation. Influences of spin effect and phonon
bands on the collective excitations in the antidot lattice are observed.Comment: 5 pages, 3 figure
Clusters in the inner spiral arms of M51: the cluster IMF and the formation history
We study the cluster population in a region of 3.2x3.2 kpc^2 in the inner
spiral arms of the intergacting galaxy M51, at a distance of about 1 to 3 kpc
from the nucleus, based on HST--WFPC2 images taken through five broadband and
two narrowband filters. We found 877 cluster candidates and we derived their
ages, initial masses and extinctions by comparing their energy distribution
with the Starburst99 cluster models. We describe the 3 and 2-dimensional
least-square energy fitting method that was used (3DEF, 2DEF). The lack of
[OIII] emission in even the youngest clusters with strong H-alpha emission,
indicates the absence of the most massive stars and suggests a mass upper limit
of about 25 to 30 solar masses. The mass versus age distribution of the
clusters shows a drastic decrease in the number of clusters with age, which
indicates that cluster disruption is occurring on a timescale of about 10 Myr
for low mass clusters. The cluster initial mass function for clusters younger
than 10 Myr has an exponent of alpha = 2.0 (+- 0.05) We derived the cluster
formation history from clusters with an initial mass larger than 10^4 solar
masses. There is no evidence for a peak in the cluster formation rate within a
factor two at about 200 to 400 Myr ago, i.e. at the time of the interaction
with the companion galaxy NGC 5194.Comment: 15 pages, 15 figures. Accepted for publication by Astronomy and
Astrophysic
Magnetotransport in two-dimensional electron gas at large filling factors
We derive the quantum Boltzmann equation for the two-dimensional electron gas
in a magnetic field such that the filling factor . This equation
describes all of the effects of the external fields on the impurity collision
integral including Shubnikov-de Haas oscillations, smooth part of the
magnetoresistance, and non-linear transport. Furthemore, we obtain quantitative
results for the effect of the external microwave radiation on the linear and
non-linear transport in the system. Our findings are relevant for the
description of the oscillating resistivity discovered by Zudov {\em et al.},
zero-resistance state discovered by Mani {\em et al.} and Zudov {\em et al.},
and for the microscopic justification of the model of Andreev {\em et al.}. We
also present semiclassical picture for the qualitative consideration of the
effects of the applied field on the collision integral.Comment: 28 pages, 19 figures; The discussion of the role of the effect of the
microwave field on the distribution function is revised (see also
cond-mat/0310668). Accepted in Phys. Rev.
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