492 research outputs found
Exploiting non-constant safe memory in resilient algorithms and data structures
We extend the Faulty RAM model by Finocchi and Italiano (2008) by adding a
safe memory of arbitrary size , and we then derive tradeoffs between the
performance of resilient algorithmic techniques and the size of the safe
memory. Let and denote, respectively, the maximum amount of
faults which can happen during the execution of an algorithm and the actual
number of occurred faults, with . We propose a resilient
algorithm for sorting entries which requires time and uses safe memory words. Our
algorithm outperforms previous resilient sorting algorithms which do not
exploit the available safe memory and require time. Finally, we exploit our sorting algorithm for
deriving a resilient priority queue. Our implementation uses safe
memory words and faulty memory words for storing keys, and
requires amortized time for each insert and
deletemin operation. Our resilient priority queue improves the amortized time required by the state of the art.Comment: To appear in Theoretical Computer Science, 201
Space-charge effects in high-energy photoemission
Pump-and-probe photoelectron spectroscopy (PES) with femtosecond pulsed
sources opens new perspectives in the investigation of the ultrafast dynamics
of physical and chemical processes at the surfaces and interfaces of solids.
Nevertheless, for very intense photon pulses a large number of photoelectrons
are simultaneously emitted and their mutual Coulomb repulsion is sufficiently
strong to significantly modify their trajectory and kinetic energy. This
phenomenon, referred as space-charge effect, determines a broadening and shift
in energy for the typical PES structures and a dramatic loss of energy
resolution. In this article we examine the effects of space charge in PES with
a particular focus on time-resolved hard X-ray (~10 keV) experiments. The
trajectory of the electrons photoemitted from pure Cu in a hard X-ray PES
experiment has been reproduced through -body simulations and the broadening
of the photoemission core-level peaks has been monitored as a function of
various parameters (photons per pulse, linear dimension of the photon spot,
photon energy). The energy broadening results directly proportional to the
number of electrons emitted per pulse (mainly represented by secondary
electrons) and inversely proportional to the linear dimension of the photon
spot on the sample surface, in agreement with the literature data about
ultraviolet and soft X-ray experiments. The evolution in time of the energy
broadening during the flight of the photoelectrons is also studied. Despite its
detrimental consequences on the energy spectra, we found that space charge has
negligible effects on the momentum distribution of photoelectrons and a
momentum broadening is not expected to affect angle-resolved experiments.
Strategy to reduce the energy broadening and the feasibility of hard X-ray PES
experiments at the new free-electron laser facilities are discussed.Comment: 15 pages, 2 tables, 8 figure
Insight on Hole-Hole Interaction and Magnetic Order from Dichroic Auger-Photoelectron Coincidence Spectra
The absence of sharp structures in the core-valence-valence Auger line shapes
of partially filled bands has severely limited the use of electron spectroscopy
in magnetic crystals and other correlated materials. Here by a novel interplay
of experimental and theoretical techniques we achieve a combined understanding
of the Photoelectron, Auger % and Auger-Photoelectron
Coincidence Spectra (APECS) of CoO. This is a prototype antiferromagnetic
material in which the recently discovered Dichroic Effect in Angle Resolved
(DEAR) APECS reveals a complex pattern in the strongly correlated Auger line
shape. A calculation of the \textit{unrelaxed} spectral features explains the
pattern in detail, labeling the final states by the total spin. The present
theoretical analysis shows that the dichroic effect arises from a
spin-dependence of the angular distribution of the photoelectron-Auger electron
pair detected in coincidence, and from the selective power of the dichroic
technique in assigning different weights to the various spin components. Since
the spin-dependence of the angular distribution exists in the antiferromagnetic
state but vanishes at the N\'eel temperature, the DEAR-APECS technique detects
the phase transition from its local effects, thus providing a unique tool to
observe and understand magnetic correlations in such circumstances, where the
usual methods (neutron diffraction, specific heat measurements) are not
applicable.Comment: Accepted by: Physical Review Letter
Automatic Dehumanization Across Menstrual Cycle
In the current study we address the role of hormonal
fluctuations across menstrual cycle in female dehumanization
of women and men. Using a sequential priming procedure in a
lexical decision task, we test whether increased levels of
conception risk lead to dehumanization of other women and
men on both animal and human dimensions. Results showed
that for word woman as the prime, animal words were more
accessible in the high than in the low conception risk of the
menstrual cycle; whereas human words were more inhibited
in the high compared to the low conception risk. As for word
man prime, no difference in terms of accessibility was found
between the high and the low conception risk on both animaland
human-words. This study demonstrates that
dehumanization of women is automatically elicited by
menstrual cycleârelated processes and associated with
womenâs mate-attraction goals
On the notion of sequentially Cohen-Macaulay modules
In this survey paper we first present the main properties of sequentially
Cohen-Macaulay modules. Some basic examples are provided to help the reader
with quickly getting acquainted with this topic. We then discuss two
generalizations of the notion of sequential Cohen-Macaulayness which are
inspired by a theorem of J\"urgen Herzog and the third author
Association of regional bioelectrical phase angle with physical performance: a pilot study in elite rowers
Background. This study aimed to examine the association between regional Phase Angle (PhA) and physical performance in athletes where the use of specific body segments is required.Methods. Sixteen elite-level rowers (13 male aged 17.6 +/- 2.1 yr; 3 female aged 21.0 +/- 4.4 yr) participated in this investigation. Raw bioimpedance parameters were obtained with a phase-sensitive 50 kHz bioelectrical impedance analysis (BIA) device and fat-free mass, percentage of fat mass (FM%), and arms and legs lean soft tissue (ALST and LLST, respectively) were estimated using specific BIA-equation developed for athletes. The time (2000t) and the mean power (MP) expressed during the 2000 m test performed on a rowing ergometer were measured.Results. The major findings of the study were that upper hemisome PhA (UPhA) were more strongly related with 2000t (R2 = 0.35, p = 0.015) and MP (R2 = 0.40, p = 0.009) than whole-body PhA. Additionally, not only UPhA maintained a significant relationship with 2000t (p = 0.001) and MP (p = 0.001), even after adjustment for the co-variables sex, ALST, and FM%, but the explained variance increased to R2 = 0.72 and R2 = 0.78, respectively.Conclusions. These results suggest that the regional PhA might be used as a tool for evaluating performance related parameters in sports where specific body segments are involved, preferring it to the whole-body measured value
Use of Scanner Data to Analyze the Table Wine Demand in the Italian Major Retailing Trade
ABSTRACT While the utilization of scanner data for food demand analyses has become increasingly popular in the United States, few food demand studies, and in particular none on table wine, have been conducted using scanner data in Italy+ This paper presents a first attempt to estimate a demand system for selected brands of red tetra-packaged, plastic packaged, and bag-in-box table wine using scanner data providing new and useful insights into the marketing of Italian wine+ Price and expenditure elasticities of Italian red table wine demand drawn from a linear almost ideal demand system are provided+ Results suggest a partially loyal market of table wine, showing a tendency to substitution across brands and a degree of competition among the leading brands+ @EconLit citations: Q110, Q130#
Reduced GABA Content in the Motor Thalamus during Effective Deep Brain Stimulation of the Subthalamic Nucleus
Deep brain stimulation (DBS) of the subthalamic nucleus (STN), in Parkinson's disease (PD) patients, is a well established therapeutic option, but its mechanisms of action are only partially known. In our previous study, the clinical transitions from OFF- to ON-state were not correlated with significant changes of GABA content inside GPi or substantia nigra reticulata. Here, biochemical effects of STN-DBS have been assessed in putamen (PUT), internal pallidus (GPi), and inside the antero-ventral thalamus (VA), the key station receiving pallidothalamic fibers. In 10 advanced PD patients undergoing surgery, microdialysis samples were collected before and during STN-DBS. cGMP, an index of glutamatergic transmission, was measured in GPi and PUT by radioimmunoassay, whereas GABA from VA was measured by HPLC. During clinically effective STN-DBS, we found a significant decrease in GABA extracellular concentrations in VA (â30%). Simultaneously, cGMP extracellular concentrations were enhanced in PUT (+200%) and GPi (+481%). These findings support a thalamic dis-inhibition, in turn re-establishing a more physiological corticostriatal transmission, as the source of motor improvement. They indirectly confirm the relevance of patterning (instead of mere changes of excitability) and suggest that a rigid interpretation of the standard model, at least when it indicates the hyperactive indirect pathway as key feature of hypokinetic signs, is unlikely to be correct. Finally, given the demonstration of a key role of VA in inducing clinical relief, locally administration of drugs modulating GABA transmission in thalamic nuclei could become an innovative therapeutic strategy
Single molecule experiments emphasize GM1 as a key player of the different cytotoxicity of structurally distinct Aβ1-42 oligomers
Respiratory dysfunction by AFG3L2 deficiency causes decreased mitochondrial calcium uptake via organellar network fragmentation
The mitochondrial protein AFG3L2 forms homo-oligomeric and hetero-oligomeric complexes with paraplegin in the inner mitochondrial membrane, named m-AAA proteases. These complexes are in charge of quality control of misfolded proteins and participate in the regulation of OPA1 proteolytic cleavage, required for mitochondrial fusion. Mutations in AFG3L2 cause spinocerebellar ataxia type 28 and a complex neurodegenerative syndrome of childhood. In this study, we demonstrated that the loss of AFG3L2 in mouse embryonic fibroblasts (MEFs) reduces mitochondrial Ca2+ uptake capacity. This defect is neither a consequence of global alteration in cellular Ca2+ homeostasis nor of the reduced driving force for Ca2+ internalization within mitochondria, since cytosolic Ca2+ transients and mitochondrial membrane potential remain unaffected. Moreover, experiments in permeabilized cells revealed unaltered mitochondrial Ca2+ uptake speed in Afg3l2â/â cells, indicating the presence of functional Ca2+ uptake machinery. Our results show that the defective Ca2+ handling in Afg3l2â/â cells is caused by fragmentation of the mitochondrial network, secondary to respiratory dysfunction and the consequent processing of OPA1. This leaves a number of mitochondria devoid of connections to the ER and thus without Ca2+ elevations, hampering the proper Ca2+ diffusion along the mitochondrial network. The recovery of mitochondrial fragmentation in Afg3l2â/â MEFs by overexpression of OPA1 rescues the impaired mitochondrial Ca2+ buffering, but fails to restore respiration. By linking mitochondrial morphology and Ca2+ homeostasis, these findings shed new light in the molecular mechanisms underlining neurodegeneration caused by AFG3L2 mutation
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