11,770 research outputs found
Anomalous Crossing Frequency in Odd Proton Nuclei
A generic explanation for the recently observed anomalous crossing
frequencies in odd proton rare earth nuclei is given. As an example, the proton
band in Ta is discussed in detail by using the
angular momentum projection theory. It is shown that the quadrupole pairing
interaction is decisive in delaying the crossing point and the changes in
crossing frequency along the isotope chain are due to the different neutron
shell fillings
Kinetic simulations of ladder climbing by electron plasma waves
The energy of plasma waves can be moved up and down the spectrum using
chirped modulations of plasma parameters, which can be driven by external
fields. Depending on whether the wave spectrum is discrete (bounded plasma) or
continuous (boundless plasma), this phenomenon is called ladder climbing (LC)
or autoresonant acceleration of plasmons. It was first proposed by Barth
\textit{et al.} [PRL \textbf{115}, 075001 (2015)] based on a linear fluid
model. In this paper, LC of electron plasma waves is investigated using fully
nonlinear Vlasov-Poisson simulations of collisionless bounded plasma. It is
shown that, in agreement with the basic theory, plasmons survive substantial
transformations of the spectrum and are destroyed only when their wave numbers
become large enough to trigger Landau damping. Since nonlinear effects decrease
the damping rate, LC is even more efficient when practiced on structures like
quasiperiodic Bernstein-Greene-Kruskal (BGK) waves rather than on Langmuir
waves \textit{per~se}
Bitcoin forensics: a tutorial
Over the past eighteen months, the digital cryptocurrency Bitcoin has experienced significant growth in terms of usage and adoption. It has also been predicted that if this growth continues then it will become an increasingly useful tool for various illegal activities. Against this background, it seems safe to assume that students and professionals of digital forensics will require an understanding of the subject. New technologies are often a major challenge to the field of digital forensics due to the technical and legal challenges they introduce. This paper provides a set of tutorials for Bitcoin that allows for leaners from both backgrounds to be taught how it operates, and how it may impact on their working practice. Earlier this year they were delivered to a cohort of third year undergraduates. To the authorâs knowledge, this represents the first integration of the topic into a digital forensics programme by a higher education provider
Conductance of a single molecule anchored by an isocyanide substituent to gold electrodes
The effect of anchoring group on the electrical conductance of a single
molecule bridging two Au electrodes was studied using di-substituted
(isocyanide (CN-), thiol (S-) or cyanide (NC-)) benzene. The conductance of a
single Au/1,4-diisocyanobenzene/Au junction anchored by isocyanide via a C atom
(junction with the Au-CN bond) was (). The
value was comparable to of a single
Au/1,4-benzenedithiol/Au junction with the Au-S bond. The
Au/1,4-dicyanobenzene/Au molecular junction with the Au-NC bond did not show
well-defined conductance values. The metal-molecule bond strength was estimated
by the distance over which the molecular junction was stretched before
breakdown. The stretched length of the molecular junction with the Au-CN bond
was comparable to that of the Au junction, indicating that the Au-CN bond was
stronger than the Au-Au bond.Comment: 3 figures, to be appear in Appl. Phys. Let
1D Modeling for Temperature-Dependent Upflow in the Dimming Region Observed by Hinode/EIS
We have previously found a temperature-dependent upflow in the dimming region
following a coronal mass ejection (CME) observed by the {\it Hinode} EUV
Imaging Spectrometer (EIS). In this paper, we reanalyzed the observations along
with previous work on this event, and provided boundary conditions for
modeling. We found that the intensity in the dimming region dramatically drops
within 30 minutes from the flare onset, and the dimming region reaches the
equilibrium stage after 1 hour later. The temperature-dependent upflows
were observed during the equilibrium stage by EIS. The cross sectional area of
the fluxtube in the dimming region does not appear to expand significantly.
From the observational constraints, we reconstructed the temperature-dependent
upflow by using a new method which considers the mass and momentum conservation
law, and demonstrated the height variation of plasma conditions in the dimming
region. We found that a super radial expansion of the cross sectional area is
required to satisfy the mass conservation and momentum equations. There is a
steep temperature and velocity gradient of around 7 Mm from the solar surface.
This result may suggest that the strong heating occurred above 7 Mm from the
solar surface in the dimming region. We also showed that the ionization
equilibrium assumption in the dimming region is violated especially in the
higher temperature range.Comment: accepted for publication in The Astrophysical Journa
Experiences of African international students in a South African university â A qualitative study
South Africa has in latter decades embraced the growing trend of internationalization in higher education leading to greater international mobility of staff and students. Compared to other countries in most of the sub-Saharan Africa region, South Africa has a larger capacity to meet the tertiary needs of students within the region. An increasing number of international students has implications for their academic success, adaptation and wellbeing once in their host country. The current study explored the lived experiences of international students in a South African university, from 5 other African countries. The study adopted a qualitative design, using semi-structured in-depth interviews and open-ended questions. Nine mainly postgraduate students (4 males and 5 females) were recruited using convenient and snowball sampling methods. Data were analysed using thematic content analysis and revealed 5 themes namely âInternationalisationâ, âexperiencing the unforeseenâ, âaccessâ, âsocial supportâ and âstructural supportâ, with several sub-themes emerging from these. A resulting framework shows âempowermentâ, âalienationâ and âadaptationâ as over-arching themes in experiencing the phenomenon of being an African foreign student in South Africa
Analysis of the superdefomed rotational bands
All available experimental data for the transition energies in
superdeformed bands are analyzed by using a new one-point formula. The
existence of deviations from the smooth behavior is confirmed in many bands.
However, we stress that one cannot necessarily speak about staggering patterns
as they are mostly irregular. Simulations of the experimental data suggest that
the irregularities may stem from the presence of irregular kinks in the
rotational spectra. This could be a clue but, at the moment, where such kinks
come from is an open question.Comment: 6 pages, RevTex, 7 p.s. figures, submitted to P.R.
Pengaruh Pemotongan Dengan Dan Tanpa Cairan Pendingin Terhadap Daya Potong Pada Proses Turning
In this study whether the effect of cuts without using coolant differ significantly by cutting use liquid cooling to the power cut. To get the effect these cuts do testing on a lathe with a cutting speed varied. The results of this study, based on cutting anlisis detected by the fifth variation of the cutting speed will affect the power cut. With the greater the cutting speed will increase cutting power, good for lathing process with and without coolant. The process of turning the cooling liquid tends to be greater influence on cutting power compared to the lathing process without coolant. Based anlisis regression and correlation with level of 5% error hypothesis test two directions is known that in the process of turning cutting speed without coolant does not affect the power cut amounted to 73.48%. While in the process of turning to liquid cooling effect on the cut of 97.56%
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