2,008 research outputs found
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 author’s knowledge, this represents the first integration of the topic into a digital forensics programme by a higher education provider
Universal Features of Terahertz Absorption in Disordered Materials
Using an analytical theory, experimental terahertz time-domain spectroscopy
data and numerical evidence, we demonstrate that the frequency dependence of
the absorption coupling coefficient between far-infrared photons and atomic
vibrations in disordered materials has the universal functional form, C(omega)
= A + B*omega^2, where the material-specific constants A and B are related to
the distributions of fluctuating charges obeying global and local charge
neutrality, respectively.Comment: 5 pages, 3 fig
Deconstruct and preserve (DaP): a method for the preservation of digital evidence on solid state drives (SSD)
Imaging SSDs is problematic due to TRIM commands and garbage collectors that make the SSD behave inconsistently over time. It is this inconsistency that can cause a difference between images taken of the SSD. These differences result in unmatched hash number gener-ation and would normally be attributed to contamination or spoliation of digital evidence. DaP is a proposed method that ensures all images taken of the SSD are consistent and removes the volatility normally as-sociated with these devices. DaP is not focused with the recoverability of deleted data, however DaP does stabilise the device to prevent uninten-tional contamination due to garbage collection. Experiments show that the DaP method works on a range of devices and consistently produces the hash-identical images. The conclusions are to consider DaP as a new Standard Operating Procedure (SOP) when imaging SSDs
Do correlations create an energy gap in electronic bilayers? Critical analysis of different approaches
This paper investigates the effect of correlations in electronic bilayers on
the longitudinal collective mode structure. We employ the dielectric
permeability constructed by means of the classical theory of moments. It is
shown that the neglection of damping processes overestimates the role of
correlations. We conclude that the correct account of damping processes leads
to an absence of an energy gap.Comment: 4 page
In-depth proteomics identifies a role for autophagy in controlling reactive oxygen species mediated endothelial permeability
Endothelial cells (ECs) form the inner layer of blood vessels and physically separate the blood from the surrounding tissue. To support tissues with nutrients and oxygen, the endothelial monolayer is semipermeable. When EC permeability is altered, blood vessels are not functional, and this is associated with disease. A comprehensive knowledge of the mechanisms regulating EC permeability is key in developing strategies to target this mechanism in pathologies. Here we have used an in vitro model of human umbilical vein endothelial cells mimicking the formation of a physiologically permeable vessel and performed time-resolved in-depth molecular profiling using stable isotope labeling by amino acids in cell culture mass spectrometry (MS)-proteomics. Autophagy is induced when ECs are assembled into a physiologically permeable monolayer. By using siRNA and drug treatment to block autophagy in combination with functional assays and MS proteomics, we show that ECs require autophagy flux to maintain intracellular reactive oxygen species levels, and this is required to maintain the physiological permeability of the cells
Tectonic controls on residual oil saturation below the present-day fluid contact level in reservoirs of the Persian Gulf
Acknowledgments The authors would like to acknowledge, and gratefully appreciate the support of, the Aberdeen Formation Evaluation Society for their sponsorship, and Emerson (Paradigm) for providing the Geology software for the development of this study.Peer reviewedPostprin
Self-reported nature exposure and its association with well-being as measured with affect and cognition
Utilizing the publicly available MIDUS II Refresher datasets (Ryff et al., 2017) with hundreds of respondents across the United States, the authors attempted to (1) replicate and (2) extend their previous findings with the original MIDUS II data on the relationship between self-reported frequency of nature exposure and well-being, the latter holistically measured by emotional, physiological and cognitive variables (Craig, Menon, & Klein, 2015; Craig, Neilson, & Overbeek, 2016).In the original published research, Craig and colleagues (2015) first observed an association between a 3-pt scale in which middle-aged participants reported the frequency that they appreciated nature and other reported questionnaire measures. These measures included subscales of the Mood Affective Symptoms Questionnaire (MASQ), the Perceived Stress Scale, and scales measuring well-being constructs such as life satisfaction and gratitude. This was followed up with a second study, which found an observed relationship between reported nature exposure with a 7-pt scale and measured physiological variables relevant to emotion and cognition, specifically asymmetrical EEG and eye-blink startle response (Craig et al., 2016). However, the prior research was exploratory and correlational in nature, which many would argue necessitates replication.The original MIDUS II datasets used in the previous investigations (Ryff & Davidson, 2010; Ryff, Seeman, & Weinstein, 2010) were recollected by the original team with a new cohort (Ryff et al., 2017), allowing for a nearly direct replication of the previous analyses (Craig et al., 2015; 2016). Because positive effects associated with nature exposure may be a function of both exposure frequency and degree of appreciation, the first set of analyses replicating and extending the results of Craig and colleagues (2015) used an averaged composite score of two 3-pt scale questions measuring both frequency and degree of nature appreciation, instead of only frequency of nature appreciation as conducted in the original analysis. The second set of analyses that attempted to replicate Craig and colleagues (2016) used the original 7-pt nature exposure scale.For the replication (goal 1), controlling for factors such as age, gender, exercise, and education, multiple regression analyses with the new datasets replicated the association between nature exposure and positive emotions, perceived stress, and metrics such as gratitude and perception of work value. However, there were mixed results for depressive affect, and the previously observed correspondence between nature exposure and emotional reactivity measures, such as eyeblink startle response and epinephrine, did not replicate.For extending the original research (goal 2), exploratory analyses were conducted to explore (1) previously unanalyzed variables related to well-being, and (2) previously unanalyzed cognitive variables. There was an observed and potentially beneficial relationship between self-reported nature exposure, sleep quality, self-control, and low-frequency (.04 - .15 Hz) heart-rate variability. A follow-up analysis focusing on cognitive test batteries including the CANTAB and BTACT mostly did not observe any associations between self-reported frequency of nature exposure and cognitive performance. However, a tentative relationship was noted between nature exposure and category fluency, which should be tested with future research.To clearly demonstrate the effects of nature on general well-being, an exploratory principle components analysis was conducted on 18 measures presently observed to be significantly associated with nature exposure, with a varimax rotation and the extraction based on the Kaiser criterion. Of five identified factors, one appeared to capture a construct akin to well-being (e.g., positive affect, reduced stress, gratitude, cognitive control, anger management, sleep score, work value). Therefore, a single well-being composite variable was computed (regression-weighted) based on the observed factor loadings after standardizing the component variables. A regression of the well-being composite score on the standardized nature exposure composite score (n = 788) was found to be significant, R2 = .095, F(1,786) = 82.81, p < .001.One of the limitations of this study is nature exposure was measured with a single variable, and the type of exposure (nature trails, window scenery) and type of nature (green vs. blue nature) was not explored. Also, the current analysis looked at a large set of survey data and produced relatively small effect sizes, which is understandable given the large number of potentially intervening variables and the imprecision of the survey measurements. Further, the findings here are correlational and precise design recommendations are not warranted, but there may be several avenues to implement nature in and around built spaces. With careful design, even urban scenery designed with components akin to nature could be helpful in improving well-being. Future research could assess whether the amount of time in nature may lead to greater improvement
A review of the limitations of Attention Restoration Theory and the importance of its future research for the improvement of well-being in urban living
While there are benefits to urbanization, deviations from a rural lifestyle can pose an issue for psychological well-being, as there is limited access to restorative environments (e.g., nature; van den Berg, Hartig, & Staats, 2007). Given these concerns associated with increased urbanization, how can we implement components of restorative environments into urban settings? Towards that end, an understanding of the attributes of restorative environments is needed. Attention Restoration Theory (ART; Kaplan, 1995) is the predominant theory identifying characteristics of nature that are thought to make it restorative. Albeit, these characteristics lack operational definitions, thus generating several methodological challenges in critically assessing ART. For example, a major component of restoration within the ART framework is soft fascination, which is an involuntary capturing of attention, but not in a dramatic fashion. However, there is no empirical support of nature’s ability to innately hold attention, and this poor understanding contributes to the challenges in developing an operational definition of soft fascination. We describe attributes of stimuli that are known to capture visual attention (e.g., salience; Ruz & Lupiáñez, 2002) and consider whether such attributes are consistent with the notion of soft fascination. Since ART evolved from literature on aesthetics and environmental preferences (e.g., Kaplan, 1987), a review of this literature may inspire new ways to define restorative characteristics of nature, and thereby, promote the implementation of these characteristics into built environments. Thus, the purpose of this paper is to integrate relevant literature from multiple subfields of psychology to inspire research that can employ new methodology and ultimately better our understanding of the mechanisms underlying restorative environments
On the evolutionary and pulsation mass of Classical Cepheids: III. the case of the eclipsing binary Cepheid CEP0227 in the Large Magellanic Cloud
We present a new Bayesian approach to constrain the intrinsic parameters
(stellar mass, age) of the eclipsing binary system CEP0227 in the LMC. We
computed evolutionary models covering a broad range in chemical compositions
and in stellar mass. Independent sets of models were constructed either by
neglecting or by including a moderate convective core overshooting (beta=0.2)
during central H-burning phases. Models were also constructed either by
neglecting or by assuming a canonical (eta=0.4,0.8) or an enhanced (eta=4) mass
loss rate. The solutions were computed in three different planes:
luminosity-temperature, mass-radius and gravity-temperature. By using the Bayes
Factor, we found that the most probable solutions were obtained in the
gravity-temperature plane with a Gaussian mass prior distribution. The
evolutionary models constructed by assuming a moderate convective core
overshooting (beta=0.2) and a canonical mass loss rate (eta=0.4) give stellar
masses for the primary Cepheid M=4.14^{+0.04}_{-0.05} M_sun and for the
secondary M=4.15^{+0.04}_{-0.05} M_sun that agree at the 1% level with
dynamical measurements. Moreover, we found ages for the two components and for
the combined system t=151^{+4}_{-3} Myr that agree at the 5% level. The
solutions based on evolutionary models that neglect the mass loss attain
similar parameters, while those ones based on models that either account for an
enhanced mass loss or neglect convective core overshooting have lower Bayes
Factors and larger confidence intervals. The dependence on the mass loss rate
might be the consequence of the crude approximation we use to mimic this
phenomenon. By using the isochrone of the most probable solution and a Gaussian
prior on the LMC distance, we found a distance modulus 18.53^{+0.02}_{-0.02}
mag and a reddening value E(B-V)= 0.142^{+0.005}_{-0.010} mag that agree well
with literature estimates.Comment: Accepted for publication in ApJ. 17 pages, 9 figure
Note: Autonomous Pulsed Power Generator Based on Transverse Shock Wave Depolarization of Ferroelectric Ceramics
Autonomous pulsed generators utilizing transverse shock wave depolarization (shock front propagates across the polarization vector P0) of Pb(Zr0.52Ti0.48)O3 poled piezoelectric ceramics were designed, constructed, and experimentally tested. It was demonstrated that generators having total volume of 50 cm3 were capable of producing the output voltage pulses with amplitude up to 43 kV with pulse duration 4 µs. A comparison of high-voltage operation of transverse and longitudinal shock wave ferroelectric generators is given
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