1,743 research outputs found
Temperature dependence of Raman vibrational bandwidths in poly(rA) and rAMP
Isotropic and anisotropic spontaneous Raman spectra were obtained from solutions of poly(ra) and rAMP in buffer. The temperature dependence of these spectra was measured to elucidate the influence of macromolecular dynamics and solvent dynamics on the bandwidths of base vibrations in the single stranded polynucleotide poly(rA). The temperature dependence of a bandwidth depends upon the particular vibration under study. The bands can for the larger part be described by Lorentz functions. When fitted by Voigt functions, maximally 10% of each bandprofile of the adenine base vibrations can be attributed to a Gaussian component. The second moment has been determined from the spectra for the 725 cm¿1 band. From the second moment and the bandwidth, we were able to deduce that the vibrational oscillator is in the fast modulation limit. The determined timescale (perturbation correlation time 0.13 ps) eliminate perturbations connected to long range diffusion like concentration fluctuations (timescale in the order of 10 ps). The spectra were analyzed by an extensive curve fitting procedure providing accurate bandparameters (position, width and integrated intensity). The 725 cm¿1 band of adenine has a bandwidth which is dependent upon the degree of polymerization. In RAMP it is 17.6 cm¿1, in stacked (i.e. low temperature 5°C) poly(rA) it is 11.5 cm¿1. The bandwidth of the adenine vibration at 1336 cm¿1 cm¿1 has a temperature dependence which is similar to the intensity changes of the Raman and the absorption hypochromic effect as a function of temperature. The melting transition can therefore be followed by the changes in bandwidth of suitable vibrations
Fabrication of 45 degrees template grain boundary junctions using a CaO lift-off technique
45 degrees grain boundary junctions have been made using (100) MgO substrates, a CeO2 template layer and an YBa2Cu3O7 top layer. To minimize the damage to the MgO surface, which will occur if the CeO2 is structured using ion milling, the CeO2 layer has been structured using the CaO lift-off technique. Electrical measurements of these junctions as a function of temperature, microwave irradiation and magnetic field will be discussed in this paper
Plural policing in Western Europe: a comparison
One of the almost undisputed findings of contemporary policing studies is that the past few decades have witnessed a far-reaching pluralization of policing. Many countries, in different regions of the world, were confronted with the rise of new non-police providers of policing services. Increasingly, the myth of one organization (the public police) with a monopoly on policing lost its power of persuasion as a valid description of reality. Generally, the new agencies of policing concentrate on the management of petty crime and social disorder in public places. With this new situation, multiple providers, both public and private, have become involved in the prevention and management of crime and social disorder. It is often assumed that this development of the past three decades created a more or less quiet revolution (or what Bayley and Shearing (1996) called a ‘watershed’) in the systems of crime control and law enforcement. Although this claim has been disputed, also in the Anglo-Saxon world (Jones & Newburn, 2002), the proposition of the pluralization of policing often seems to have reached the status of a universal, world-wide trend. Until recently, however, outside the Anglo-Saxon world there has been a lack of empirical studies on plural policing. With the exception of the collection edited by Jones and Newburn (2006), the recent study by Terpstra, Van Stokkom & Spreeuwers (2013), and the volume edited by Edwards et al. (2014), there were no other international comparative studies of this issue. As a result, until now the claim of a universally similar trend of plural policing has remained largely uncontested. In fact, the absence of international comparisons implied that theories and explanations of plural policing were based only on a limited (Anglo-Saxon) sample of countries. As a consequence, there was an unanswered question concerning the extent to which descriptions and explanations of plural policing were also relevant to understanding recent changes elsewhere. For example, one question that must be asked is if there is something like a Western-European style of plural policing? Or are the differences between these European countries so great that the developments in policing cannot be gathered under a single conceptual label
Multilayer studies and applications in template bi-epitaxial DC SQUIDS
Multilayer deposition for the creation of a well-defined grain boundary, based on different in-plane orientations of c-axis oriented thin YBa2O2Cu3O7-δ layers on a single substrate, has been performed on three different kinds of substrates: (1102)-oriented Al2O3 , (100) SrTiO3, and (100) MgO. The multilayers consist of combinations of SrTiO3, MgO, CeO2, and YBa2O2Cu3O7-δ. The YBa 2O2Cu3O7-δ top layers on (1102) Al2O3 and (100) SrTiO3 were polycrystalline. Josephson junctions and DC superconducting quantum interference devices (SQUIDs) have been structured in the layers on MgO. Shapiro steps were observed. The Jcρn-product of the junctions at 4.2 K is on the order of 1 mV. The critical current decreases in good approximation linearly with increasing temperature, whereas the normal state resistance is nearly temperature independent. Voltage modulation was observed at temperatures up to 77 K
Coexistence of antiferrodistortive and ferroelectric distortions at the PbTiO (001) surface
The c(22) reconstruction of (001) PbTiO surfaces is studied by
means of first principles calculations for paraelectric (non-polar) and
ferroelectric ([001] polarized) films. Analysis of the atomic displacements in
the near-surface region shows how the surface modifies the antiferrodistortive
(AFD) instability and its interaction with ferroelectric (FE) distortions. The
effect of the surface is found to be termination dependent. The AFD instability
is suppressed at the TiO termination while it is strongly enhanced,
relative to the bulk, at the PbO termination resulting in a c(2x2) surface
reconstruction which is in excellent agreement with experiments. We find that,
in contrast to bulk PbTiO, in-plane ferroelectricity at the PbO termination
does not suppress the AFD instability. The AFD and the in-plane FE distortions
are instead concurrently enhanced at the PbO termination. This leads to a novel
surface phase with coexisting FE and AFD distortions which is not found in
PbTiO bulk
Early and Late Results Following Choledochoduodenostomy and Choledochojejunostomy
Objective —To evaluate the results and complications of choledochoduodenostomy
and choledochojejunostomy for benign and malignant disease and to review
them in the light of the survival of the underlying disorders
More than fear induction: Toward an understanding of people's motivation to be well-prepared for emergencies in flood prone areas
This article examines the extent and manner to which evaluations of flood-related precautions are affected by an individual's motivation and perception of context. It argues that the relationship between risk perception and flood risk preparedness can be fruitfully specified in terms of vulnerability and efficacy if these concepts are put into the perspective of prevention-focused motivation. This relationship was empirically examined in a risk communication experiment in a delta area of the Netherlands (n = 1,887). Prevention-focused motivation was induced by contextualized risk information. The results showed that prevention-focused individuals were more sensitive to the relevance of potential precautions for satisfying their needs in the context they found themselves in. The needs included, but were not limited to, fear reduction. Due to the heterogeneity of the residents, the evaluations reflected individual differences in the intensity and the selectivity of precautionary processes. Four types of persons could be distinguished according to their evaluation of precautionary measures: a high-scoring minority, two more selective types, and a low-scoring minority. For policymakers and risk communicators it is vital to consider the nature of prevention motivation and the context in which it is likely to be high
Detecting time-fragmented cache attacks against AES using Performance Monitoring Counters
Cache timing attacks use shared caches in multi-core processors as side
channels to extract information from victim processes. These attacks are
particularly dangerous in cloud infrastructures, in which the deployed
countermeasures cause collateral effects in terms of performance loss and
increase in energy consumption. We propose to monitor the victim process using
an independent monitoring (detector) process, that continuously measures
selected Performance Monitoring Counters (PMC) to detect the presence of an
attack. Ad-hoc countermeasures can be applied only when such a risky situation
arises. In our case, the victim process is the AES encryption algorithm and the
attack is performed by means of random encryption requests. We demonstrate that
PMCs are a feasible tool to detect the attack and that sampling PMCs at high
frequencies is worse than sampling at lower frequencies in terms of detection
capabilities, particularly when the attack is fragmented in time to try to be
hidden from detection
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