168 research outputs found
Qubit Motion as a Microscopic Model for the Dynamical Casimir Effect
The generation of photons from the vacuum by means of the movement of a
mirror is known as the dynamical Casimir effect (DCE). In general, this
phenomenon is effectively described by a field with time-dependent boundary
conditions. Alternatively, we consider a microscopic model of the DCE capable
of reproducing the effect with no time-dependent boundary conditions. Besides
the field, such a model comprises a subsystem modeling the mirror's internal
structure. In this work, we study the most straightforward system for the
mirror: a qubit moving in a cavity and coupled to one of the bosonic modes. We
find that under certain conditions on the qubit's movement that do not depend
on its physical properties, a large number of photons may be generated without
changing the qubit state, as should be expected for a microscopic model of the
mirror.Comment: Main text: 4 pages, 4 figures. Appendices: 5 pages, 5 figure
Entanglement of superconducting qubits via acceleration radiation
We show that simulated relativistic motion can generate entanglement between artificial atoms and protect them from spontaneous emission. We consider a pair of superconducting qubits coupled to a resonator mode, where the modulation of the coupling strength can mimic the harmonic motion of the qubits at relativistic speeds, generating acceleration radiation. We find the optimal feasible conditions for generating a stationary entangled state between the qubits when they are initially prepared in their ground state. Furthermore, we analyse the effects of motion on the probability of spontaneous emission in the standard scenarios of single-atom and two-atom superradiance, where one or two excitations are initially present. Finally, we show that relativistic motion induces sub-radiance and can generate a Zeno-like effect, preserving the excitations from radiative decay.This work was supported by a UPV/EHU PhD grant, UPV/EHU EHUA15/17, UPV/EHU UFI 11/55, Spanish MINECO/FEDER FIS2015-69983-P and FIS2015-70856-P, Basque Government grant IT986-16, CAM PRICYT Project QUITEMAD + S2013/ICE-2801, University Sorbonne Paris Cite EQDOL contract, and Fundacion General CSIC (Programa ComFuturo)
An unsaturated four-coordinate dimethyl dimolybdenum complex with a molybdenum-molybdenum quadruple bond
We describe the synthesis and the molecular and electronic structures of the complex [Mo2Me2{mu-HC(NDipp)(2)}(2)] (2; Dipp=2,6-iPr(2)C(6)H(3)), which contains a dimetallic core with an Mo-Mo quadruple bond and features uncommon four-coordinate geometry and has a fourteen-electron count for each molybdenum atom. The coordination polyhedron approaches a square pyramid, with one of the molybdenum atoms nearly co-planar with the basal square plane, in which the trans coordination position with respect to the Mo-Me bond is vacant. The other three sites are occupied by two trans nitrogen atoms of different amidinate ligands and the methyl group. The second Mo atom occupies the apex of the pyramid and forms an Mo-Mo bond of length 2.080(1) angstrom, consistent with a quadruple bond. Compound 2 reacts with tetrahydrofuran (THF) and trimethylphosphine to yield the mono-adducts [Mo2Me(mu-Me){mu-HC(NDipp)(2)}(2)(L)] (3 center dot THF and 3 center dot PMe3, respectively) with one terminal and one bridging methyl group. In contrast, 4-dimethylaminopyridine (dmap) forms the bis-adduct [Mo2Me2{mu-HC(NDipp)(2)}(2)(dmap)(2)] (4), with terminally coordinated methyl groups. Hydrogenolysis of complex 2 leads to the bis(hydride) [Mo2H2{mu-HC(NDipp)(2)}(2)(thf)(2)] (5 center dot THF) with elimination of CH4. Computational, kinetic, and mechanistic studies, which included the use of D-2 and of complex 2 labelled with C-13 (99%) at the Mo-CH3 sites, supported the intermediacy of a methyl-hydride reactive species. A computational DFT analysis of the terminal and bridging coordination of the methyl groups to the Mo Mo core is also reported
Fiabilidad interexaminador de un sistema de segmentación semiautomàtica para el cálculo del volumen del bulbo y tracto olfatorio mediante resonancia magnética
El transtorn de l'olfacte a la malaltia d'Alzheimer (MA) és freqüent i precoç. Per determinar la relació entre la MA i el volum del bulb i tracte olfactori, és necessari un instrument que ens permeti realitzar el càlcul d'aquest volum a partir d'imatges obtingudes per ressonància magnètica. S'ha desenvolupat un software específic i s'ha realitzat un estudi observacional i transversal de fiabilitat en una mostra de pacients. S'ha calculat el volum de forma semiautomàtica per dos observadors independents. El coeficient de correlació intraclasse obtingut ens permet concloure que la fiabilitat interexaminador és apropiada.El trastorno del olfato en la enfermedad de Alzheimer (EA) es frecuente y precoz. Para determinar la relación entre la EA y el volumen del bulbo y tracto olfatorio, es necesario un instrumento que nos permita realizar el cálculo de dicho volumen a partir de imágenes obtenidas por resonancia magnética. Se ha desarrollado un software específico y se ha realizado un estudio observacional y transversal de fiabilidad en una muestra de pacientes. Se ha calculado el volumen de forma semiautomática por dos observadores independientes. El coeficiente de correlación intraclase obtenido nos permite concluir que la fiabilidad interexaminador es apropiada
Evaluación de la eficacia y seguridad del tratamiento con tetratiomolibdato de amonio en la enfermedad de Wilson con afectación neurológica
El tractament actual de la malaltia de Wilson amb afectació neurològica és controvertit. Els fàrmacs actuals s'associen a risc de deteriorament neurològic (50% amb penicilamina i 26% amb trientine). El nou medicament tetratiomolibdat s'està estudiant perquè sembla tenir menor freqüència d'empitjorament neurològic. S'associa a efectes secundaris lleus i generalment reversibles. A la nostra sèrie de cinc pacients vàrem observar una milloria significativa dels símptomes després del tractament amb tetratiomolibdat. No es va detectar cap empitjorament neurològic. En dos casos va haver també una millora radiològica. Un pacient va presentar lleu anèmia, leucopènia i elevació de les transaminases reversible.: El tratamiento actual de la enfermedad de Wilson con síntomas neurológicos es controvertido. Los fármacos actuales parecen asociarse a riesgo de empeoramiento neurológico (50% con penicilamina y 26% con trientine). El nuevo medicamento tetratiomolibdato está siendo investigado porque parece presentar menor empeoramiento neurológico. Se asocia a efectos secundarios leves y generalmente reversibles. En nuestra serie de cinco pacientes hubo una mejoría significativa de los síntomas tras el tratamiento con tetratiomolibdato. No se detectó ningún empeoramiento neurológico. En dos casos existió también mejoría radiológica. Un paciente presentó leve anemia, leucopenia y elevación de transaminasas que fue reversible
New insights into the biosynthesis pathway of polyketide alkaloid argimycins P in Streptomyces argillaceus
Blood Biomarkers to Predict Long-Term Mortality after Ischemic Stroke
Altres ajuts: This work has been funded by La Fundació La Marató (Reg. 84/240 proj. 201702).Stroke is a major cause of disability and death globally, and prediction of mortality represents a crucial challenge. We aimed to identify blood biomarkers measured during acute ischemic stroke that could predict long-term mortality. Nine hundred and forty-one ischemic stroke patients were prospectively recruited in the Stroke-Chip study. Post-stroke mortality was evaluated during a median 4.8-year follow-up. A 14-biomarker panel was analyzed by immunoassays in blood samples obtained at hospital admission. Biomarkers were normalized and standardized using Z -scores. Multiple Cox regression models were used to identify clinical variables and biomarkers independently associated with long-term mortality and mortality due to stroke. In the multivariate analysis, the independent predictors of long-term mortality were age, female sex, hypertension, glycemia, and baseline National Institutes of Health Stroke Scale (NIHSS) score. Independent blood biomarkers predictive of long-term mortality were endostatin > quartile 2, tumor necrosis factor receptor-1 (TNF-R1) > quartile 2, and interleukin (IL)-6 > quartile 2. The risk of mortality when these three biomarkers were combined increased up to 69%. The addition of the biomarkers to clinical predictors improved the discrimination (integrative discriminative improvement (IDI) 0.022 (0.007-0.048), p quartile 3 was an independent predictor of mortality due to stroke. Altogether, endostatin, TNF-R1, and IL-6 circulating levels may aid in long-term mortality prediction after stroke
Características clínico-epidemiológicas em pacientes com estenose hipertrófica do piloro. Estudo de 15 anos em um centro terciário
La estenosis hipertrófica del píloro está caracterizada por una hipertrofia e hiperplasia de las fibras musculares y estrechamiento del canal pilórico, que provoca vómitos no biliosos, dando lugar a una de las causas más comunes de tratamiento quirúrgico en la etapa de recién nacido. Se realizó un estudio descriptivo retrospectivo en 119 pacientes con el diagnóstico de estenosis hipertrófica del píloro en el Hospital Pediátrico Universitario “William Soler” desde el año 2000 al 2015. El 70,6% de los niños tenía entre tres y cinco semanas de nacido y el 83,2% un peso al diagnóstico entre 2500 g a 4500 g. El vómito estuvo presente en todos los pacientes, las alteraciones del peso corporal en 79,8% y los desequilibrios hidroelectrolíticos y acido básico en el 53,8%. El sexo masculino, apariencia racial blanca, ser primogénito y la lactancia artificial o mixta, fueron factores de riesgos prevalentes significativos asociados a la enfermedad (p<0.05). La estenosis hipertrófica del píloro se diagnosticó con mayor frecuencia a la 4ta semana de vida y en niños con un peso entre 3000 a 4500 g. Las variaciones ponderales denotan la importancia del seguimiento de la curva de peso en estos pacientes.Hypertrophic pyloric stenosis is characterized by hypertrophy and hyperplasia of the muscle fibers and narrowing of the pyloric canal, which causes non-bilious vomiting, giving rise to one of the most common causes of surgical treatment in the newborn stage. A retrospective descriptive study was carried out in 119 patients with a diagnosis of hypertrophic pyloric stenosis at the “William Soler” University Pediatric Hospital from 2000 to 2015. 70.6% of the children were between three and five weeks old and 83.2% a weight at diagnosis between 2500 g to 4500 g. Vomiting was present in all patients, alterations in body weight in 79.8% and hydroelectrolyte and basic acid imbalances in 53.8%. Male sex, white racial appearance, being first-born, and artificial or mixed breastfeeding were significant prevalent risk factors associated with the disease (p <0.05). Hypertrophic pyloric stenosis was most frequently diagnosed at the 4th week of life and in children weighing between 3000 and 4500 g. The weight variations denote the importance of following the weight curve in these patients.A estenose hipertrófica do piloro é caracterizada por hipertrofia e hiperplasia das fibras musculares e estreitamento do canal pilórico, que causa vômitos não biliosos, sendo uma das causas mais comuns de tratamento cirúrgico na fase neonatal. Um estudo descritivo retrospectivo foi realizado em 119 pacientes com diagnóstico de estenose pilórica hipertrófica no Hospital Pediátrico da Universidade “William Soler” de 2000 a 2015. 70,6% das crianças tinham entre três e cinco semanas de idade e 83,2% com peso ao diagnóstico entre 2500 ga 4500 g. Vômito esteve presente em todos os pacientes, alteração do peso corporal em 79,8% e desequilíbrio hidroeletrolítico e ácido básico em 53,8%. Sexo masculino, raça branca, primogênito e amamentação artificial ou mista foram fatores de risco prevalentes e significativos associados à doença (p <0,05). A estenose hipertrófica do piloro foi diagnosticada com maior frequência na 4ª semana de vida e em crianças com peso entre 3.000 e 4.500 g. As variações de peso denotam a importância de seguir a curva de peso nesses pacientes
Endocannabinoid levels in peripheral blood mononuclear cells of multiple sclerosis patients treated with dimethyl fumarate.
The endocannabinoid system (ECS), a signalling network with immunomodulatory properties, is
a potential therapeutic target in multiple sclerosis (MS). Dimethyl fumarate (DMF) is an approved
drug for MS whose mechanism of action has not been fully elucidated; the possibility exists that its
therapeutic effects could imply the ECS. With the aim of studying if DMF can modulate the ECS, the
endocannabinoids 2-arachidonoylglycerol (2-AG), anandamide (AEA), oleoylethanolamide (OEA)
and palmitoylethanolamide (PEA) were determined by liquid chromatography-mass spectrometry
in peripheral blood mononuclear cells from 21 healthy donors (HD) and 32 MS patients at baseline
and after 12 and 24 months of DMF treatment. MS patients presented lower levels of 2-AG and PEA
compared to HD. 2-AG increased at 24 months, reaching HD levels. AEA and PEA remained stable at
12 and 24 months. OEA increased at 12 months and returned to initial levels at 24 months. Patients
who achieved no evidence of disease activity (NEDA3) presented the same modulation over time as
EDA3 patients. PEA was modulated differentially between females and males. Our results show that
the ECS is dysregulated in MS patients. The increase in 2-AG and OEA during DMF treatment suggests
a possible role of DMF in ECS modulation.post-print1392 K
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