3,791 research outputs found
Where Will Consumers Find Privacy Protection From RFIDs?: A Case for Federal Legislation
With the birth of RFID technology, businesses gained the ability to tag products with practically invisible computer chips that relay information about consumer behavior to remote databases. Such tagging permits retailers and manufacturers to track the purchases, identities, and movements of their customers. In the absence of enforceable regulations, society risks being subjected to an unprecedented level of Orwellian surveillance. This iBrief addresses consumer privacy concerns stemming from the proliferation of RFID technology. It discusses why tort law, state legislation, FTC guidelines, and proposed regulations are insufficient methods to alleviate consumer privacy concerns and suggests amending various federal privacy laws, thereby prohibiting the underlying RFID tracking behavior
Effective destruction of CO by cosmic rays: implications for tracing H gas in the Universe
We report on the effects of cosmic rays (CRs) on the abundance of CO in clouds under conditions typical for star-forming galaxies in the Universe.
We discover that this most important molecule for tracing H gas is very
effectively destroyed in ISM environments with CR energy densities , a range expected in numerous
star-forming systems throughout the Universe. This density-dependent effect
operates volumetrically rather than only on molecular cloud surfaces (i.e.
unlike FUV radiation that also destroys CO), and is facilitated by: a) the
direct destruction of CO by CRs, and b) a reaction channel activated by
CR-produced He. The effect we uncover is strong enough to render
Milky-Way type Giant Molecular Clouds (GMCs) very CO-poor (and thus
CO-untraceable), even in ISM environments with rather modestly enhanced average
CR energy densities of . We conclude
that the CR-induced destruction of CO in molecular clouds, unhindered by dust
absorption, is perhaps the single most important factor controlling the
CO-visibility of molecular gas in vigorously star-forming galaxies. We
anticipate that a second order effect of this CO destruction mechanism will be
to make the H distribution in the gas-rich disks of such galaxies appear
much clumpier in CO =1--0, 2--1 line emission than it actually is. Finally
we give an analytical approximation of the CO/H abundance ratio as a
function of gas density and CR energy density for use in galaxy-size or
cosmological hydrodynamical simulations, and propose some key observational
tests.Comment: Accepted for publication in ApJ, 29 page
An Alternative Accurate Tracer of Molecular Clouds: The "-Factor"
We explore the utility of CI as an alternative high-fidelity gas mass tracer
for Galactic molecular clouds. We evaluate the X-factor for the 609
m carbon line, the analog of the CO X-factor, which is the ratio of the
H column density to the integrated CO(1-0) line intensity. We use
3D-PDR to post-process hydrodynamic simulations of turbulent, star-forming
clouds. We compare the emission of CI and CO for model clouds irradiated by 1
and 10 times the average background and demonstrate that CI is a comparable or
superior tracer of the molecular gas distribution for column densities up to cm. Our results hold for both reduced and full chemical
networks. For our fiducial Galactic cloud we derive an average of
cmKkms and of cmKkms.Comment: 5 pages, 4 figures, 1 table, accepted to MNRAS Letter
Measurements of the CERN PS longitudinal resistive coupling impedance
The longitudinal coupling impedance of the CERN PS has been studied in the past years in order to better understand collective effects which could produce beam intensity limitations for the LHC Injectors Upgrade project. By measuring the incoherent quadrupole synchrotron frequency vs beam intensity, the inductive impedance was evaluated and compared with the impedance model obtained by taking into account the contribution of the most important machine devices. In this paper, we present the results of the measurements performed during a dedicated campaign, of the real part of the longitudinal coupling impedance by means of the synchronous phase shift vs beam intensity. The phase shift has been measured by using two different techniques: in one case, we injected in the machine two bunches, one used as a reference with constant intensity, and the second one changing its intensity; in the second case, more conventional, we measured the bunch position with respect to the RF signal of the 40 MHz cavities. The obtained dependence
of the synchrotron phase with intensity is then related to the loss factor and the resistive coupling impedance, which is compared to the real part of the PS impedance model
Orofacial muscles activity in children with swallowing dysfunction and removable functional appliances
Swallowing dysfunction is a frequent disorder among children and refers to an altered tongue posture and abnormal tongue movement during swallowing. Removable functional appliance is one of the treatments applied by dentistry to correct this disorder. The aim of this study was to evaluate any differences on orofacial muscles activity in children with swallowing dysfunction with and without removable functional appliances. 68 children were eligible for the study and divided into the orthodontic group (OG) and the no-orthodontic group (NO-OG). Both groups performed a dental occlusion-class evaluation, a swallowing function test and a myoscan analysis in order to measure perioral forces (i.e. tongue extension force, lip pressure, masseter contraction force). Our results showed a significant difference (P=0.02) between OG and NO-OG for the tongue extension force, whereas no significant differences (P>0.05) were found for the other parameters. Our findings suggest that children with swallowing dysfunction and removable functional appliance show orofacial muscles activity within the range of reference values (except for the lip pressure). However, we hypothesize that orthodontic treatment can achieve more effective results with integration of myofunctional therapy
Percolation transition and distribution of connected components in generalized random network ensembles
In this work, we study the percolation transition and large deviation
properties of generalized canonical network ensembles. This new type of random
networks might have a very rich complex structure, including high heterogeneous
degree sequences, non-trivial community structure or specific spatial
dependence of the link probability for networks embedded in a metric space. We
find the cluster distribution of the networks in these ensembles by mapping the
problem to a fully connected Potts model with heterogeneous couplings. We show
that the nature of the Potts model phase transition, linked to the birth of a
giant component, has a crossover from second to first order when the number of
critical colors in all the networks under study. These results shed
light on the properties of dynamical processes defined on these network
ensembles.Comment: 27 pages, 15 figure
Cryptocurrencies activity as a complex network: Analysis of transactions graphs
The number of users approaching the world of cryptocurrencies exploded in the last years, and consequently the daily interactions on their underlying distributed ledgers have intensified. In this paper, we analyze the flow of these digital transactions in a certain period of time, trying to discover important insights on the typical use of these technologies by studying, through complex network theory, the patterns of interactions in four prominent and different Distributed Ledger Technologies (DLTs), namely Bitcoin, DogeCoin, Ethereum, Ripple. In particular, we describe the Distributed Ledger Network Analyzer (DiLeNA), a software tool for the investigation of the transactions network recorded in DLTs. We show that studying the network characteristics and peculiarities is of paramount importance, in order to understand how users interact in the DLT. For instance, our analyses reveal that all transaction graphs exhibit small world properties
Superconductivity in NdFe1-xCoxAsO (0.05 < x < 0.20) and rare-earth magnetic ordering in NdCoAsO
The phase diagram of NdFe1-xCoxAsO for low cobalt substitution consists of a
superconducting dome (0.05 < x < 0.20) with a maximum critical temperature of
16.5(2) K for x = 0.12. The x = 1 end member, NdCoAsO, is an itinerant
ferromagnet (TC = 85 K) with an ordered moment of 0.30(1) BM at 15 K. Below TN
= 9 K, Nd spin-ordering results in the antiferromagnetic coupling of the
existing ferromagnetic planes. Rietveld analysis reveals that the
electronically important two-fold tetrahedral angle increases from 111.4 to
115.9 deg. in this series. Underdoped samples with x = 0.046(2) and x =
0.065(2) show distortions to the orthorhombic Cmma structure at 72(2) and 64(2)
K, respectively. The temperature dependences of the critical fields Hc2(T) near
Tc are linear with almost identical slopes of 2.3(1) T K-1 for x = 0.065(2), x
= 0.118(2) and x = 0.172(2). The estimated critical field Hc2(0) and
correlation length for optimally doped samples are 26(1) T and 36(1) Angstrom.
A comparison of the maximum reported critical temperatures of
well-characterized cobalt doped 122- and 1111-type superconductors is
presented.Comment: accepted to PR
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