367 research outputs found
Density dependence of the Ionization Avalanche in ultracold Rydberg gases
We report on the behaviour of the ionization avalanche in an ensemble of
ultracold 87Rb atoms coupled to a high lying Rydberg state and investigate
extensions to the current model by including the effects of three-body
recombination and plasma expansion. To separate the two effects we study the
time dependence of the plasma formation at various densities as well as for
different nS and nD states. At medium densities and low n we observe the onset
of the avalanche as has been reported in other experiments, as well as a
subsequent turn-off of the avalanche for longer excitation times, which we
associate with plasma expansion. At higher densities and for higher lying
Rydberg states we observe a disappearance of the avalanche signature, which we
attribute to three-body recombination.Comment: 5 pages, 4 figure
Herbal Remedies for Combating Irradiation: a Green Antiirradiation Approach
Plants play important roles in human life not only as suppliers of oxygen but also as a fundamental resource to sustain the human race on this earthly plane. Plants also play a major role in our nutrition by converting energy from the sun during photosynthesis. In addition, plants have been used extensively in traditional medicine since time immemorial. Information in the biomedical literature has indicated that many natural herbs have been investigated for their efficacy against lethal irradiation. Pharmacological studies by various groups of investigators have shown that natural herbs possess significant radioprotective activity. In view of the immense medicinal importance of natural product based radioprotective agents, this review aims at compiling all currently available information on radioprotective agents from medicinal plants and herbs, especially the evaluation methods and mechanisms of action. In this review we particularly emphasize on ethnomedicinal uses, botany, phytochemistry, mechanisms of action and toxicology. We also describe modern techniques for evaluating herbal samples as radioprotective agents. The usage of herbal remedies for combating lethal irradiation is a green antiirradiation approach for the betterment of human beings without high cost, side effects and toxicity
Spotsize Effects on Guinea Pig Skin Following Pulsed Irradiation
Laser irradiation parameters such as wavelength, irradiance (W/cm2), and pulse duration have been clearly shown to influence the extent to which tissue is damaged. The careful choice of these parameters can result in confining laser injury to specific targets in tissue. Spotsize, a parameter not commonly appreciated in the application of lasers to medicine and surgery, has been shown, in this study, to contribute to the ultimate outcome of laser effects in tissue. A series of histological events occurring in the skin are demonstrated to be directly related to the effects of spotsize on tissue at a fixed exposure time and wavelength. Many of these changes could contribute to unwanted adverse effects, such as scarring, which occur following certain laser therapies
Rate of Convergence Towards Hartree Dynamics
We consider a system of N bosons interacting through a two-body potential
with, possibly, Coulomb-type singularities. We show that the difference between
the many-body Schr\"odinger evolution in the mean-field regime and the
effective nonlinear Hartree dynamics is at most of the order 1/N, for any fixed
time. The N-dependence of the bound is optimal.Comment: 26 page
Rate of Convergence Towards Semi-Relativistic Hartree Dynamics
We consider the semi-relativistic system of gravitating Bosons with
gravitation constant . The time evolution of the system is described by the
relativistic dispersion law, and we assume the mean-field scaling of the
interaction where and while fixed. In
the super-critical regime of large , we introduce the regularized
interaction where the cutoff vanishes as . We show that the
difference between the many-body semi-relativistic Schr\"{o}dinger dynamics and
the corresponding semi-relativistic Hartree dynamics is at most of order
for all , i.e., the result covers the sub-critical regime and
the super-critical regime. The dependence of the bound is optimal.Comment: 29 page
Detection of the gas–liquid two-phase flow regimes using non-intrusive microwave cylindrical cavity sensor
Gas–liquid two-phase flow phenomenon occurs in various engineering applications and the measurement of it is important. A microwave sensor in the form of a cylindrical cavity has been designed to operate between 5 and 5.7 GHz. The aim is to analyse a two phase gas–liquid flow regime in a pipeline. LabVIEW software is utilised to capture the data, process them and display the results in real time. The results have shown that the microwave sensor has successfully detected the two-phase flow regimes in both the static and dynamic flow environments with reasonable accuracy. The study has also shown the independence of the technique and its accuracy to the temperature change (28–83 °C). Several flow regimes of the gas–liquid two-phase flow have been discussed. The system is also able to detect the stratified, wavy, elongated bubbles and homogeneous flow regimes
Quantum Diamond Microscope for Dynamic Imaging of Magnetic Fields
Wide-field imaging of magnetic signals using ensembles of nitrogen-vacancy
(NV) centers in diamond has garnered increasing interest due to its combination
of micron-scale resolution, millimeter-scale field of view, and compatibility
with diverse samples from across the physical and life sciences. Recently,
wide-field NV magnetic imaging based on the Ramsey protocol has achieved
uniform and enhanced sensitivity compared to conventional measurements. Here,
we integrate the Ramsey-based protocol with spin-bath driving to extend the NV
spin dephasing time and improve magnetic sensitivity. We also employ a
high-speed camera to enable dynamic wide-field magnetic imaging. We benchmark
the utility of this quantum diamond microscope (QDM) by imaging magnetic fields
produced from a fabricated wire phantom. Over a field of view, a median per-pixel
magnetic sensitivity of
is realized with a
spatial resolution
and
sub-millisecond temporal resolution. Importantly, the spatial magnetic noise
floor can be reduced to the picotesla scale by time-averaging and signal
modulation, which enables imaging of a magnetic-field pattern with a
peak-to-peak amplitude difference of about .
Finally, we discuss potential new applications of this dynamic QDM in studying
biomineralization and electrically-active cells.Comment: 18 Pages, 13 figure
Can computers be teammates?
This study investigated the claim that humans will readily form team relationships with computers . Drawing from the group dynamic literature in human -human interactions , a laboratory experiment ( n ϭ 56) manipulated identity and interdependence to create team af filiation in a human -computer interaction . The data show that subjects who are told they are interdependent with the computer af filiate with the computer as a team . The data also show that the ef fects of being in a team with a computer are the same as the ef fects of being in a team with another human : subjects in the interdependence conditions perceived the computer to be more similar to themselves , saw themselves as more cooperative , were more open to influence from the computer , thought the information from the computer was of higher quality , found the information from the computer friendlier , and conformed more to the computer's information . Subjects in the identity conditions showed neither team af filiation nor the ef fects of team af filiation
Infection with hepatitis B virus carrying novel pre-S/S gene mutations in female siblings vaccinated at birth: two case reports
<p>Abstract</p> <p>Introduction</p> <p>After the initiation of a mass hepatitis B vaccination program in Taiwan, the prevalence of hepatitis B virus infection has declined progressively. However, about 1 percent of the young generation, who received hepatitis B vaccination at birth, remain carriers. Infection with vaccine-escape hepatitis B virus mutants always occurs shortly after birth. Here, we report two female siblings in whom the infection occurred in their adolescence. This report raises the question of whether a booster for hepatitis B vaccination is needed.</p> <p>Case presentation</p> <p>Two 19 and 14-year-old Taiwanese female siblings were born to a mother infected with hepatitis B virus and received a complete course of hepatitis B vaccination at birth. They remained negative for serum hepatitis B surface antigen and positive for serum anti-hepatitis B surface antibody throughout their childhood. However, both were infected with the hepatitis B virus in their adolescence. Hepatitis B virus DNA was extracted from serum samples from the mother and two siblings. Hepatitis B virus pre-S/S sequence was amplified by polymerase chain reaction followed by nucleotide sequencing. When compared with the sequence obtained from the mother, multiple amino acid substitutions located near or in the major hydrophilic region of the surface antigen were identified in the elder sister. Four of these mutations (sL97S, sL98S, sG102R, and sA159P) were novel. A novel in-frame deletion (14 amino acids deleted, pre-S 127-140) was found in the hepatitis B virus pre-S2 region in the younger sister.</p> <p>Conclusions</p> <p>Despite having received hepatitis B vaccination at birth, hepatitis B virus infection can still occur in adolescence with the emergence of novel mutations in the pre-S/S gene. This is a rare event and, to the best of our knowledge, has not been previously reported.</p
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