One of the key challenges for future electronic memory and logic devices is finding viable ways of moving from today's two-dimensional structures, which hold data in an x-y mesh of cells, to ...three-dimensional structures in which data are stored in an x-y-z lattice of cells. This could allow a many-fold increase in performance. A suggested solution is the shift register--a digital building block that passes data from cell to cell along a chain. In conventional digital microelectronics, two-dimensional shift registers are routinely constructed from a number of connected transistors. However, for three-dimensional devices the added process complexity and space needed for such transistors would largely cancel out the benefits of moving into the third dimension. 'Physical' shift registers, in which an intrinsic physical phenomenon is used to move data near-atomic distances, without requiring conventional transistors, are therefore much preferred. Here we demonstrate a way of implementing a spintronic unidirectional vertical shift register between perpendicularly magnetized ferromagnets of subnanometre thickness, similar to the layers used in non-volatile magnetic random-access memory. By carefully controlling the thickness of each magnetic layer and the exchange coupling between the layers, we form a ratchet that allows information in the form of a sharp magnetic kink soliton to be unidirectionally pumped (or 'shifted') from one magnetic layer to another. This simple and efficient shift-register concept suggests a route to the creation of three-dimensional microchips for memory and logic applications.
La chantilly est mauvaise pour la santé Auffret, Y.; Petit, C.; Lapostolle, F.
Annales françaises de médecine d'urgence,
10/2018, Letnik:
8, Številka:
5
Journal Article
We demonstrate the effectiveness of out-of-plane magnetized magnetic microdiscs for cancer treatment through mechanical cell disruption under an applied rotating magnetic field. The magnetic ...particles are synthetic antiferromagnets formed from a repeated motif of ultrathin CoFeB/Pt layers. In-vitro studies on glioma cells are used to compare the efficiency of the CoFeB/Pt microdiscs with Py vortex microdiscs. It is found that the CoFeB/Pt microdiscs are able to damage 62 ± 3% of cancer cells compared with 12 ± 2% after applying a 10 kOe rotating field for one minute. The torques applied by each type of particle are measured and are shown to match values predicted by a simple Stoner-Wohlfarth anisotropy model, giving maximum values of 20 fNm for the CoFeB/Pt and 75 fNm for the Py vortex particles. The symmetry of the anisotropy is argued to be more important than the magnitude of the torque in causing effective cell destruction in these experiments. This work shows how future magnetic particles can be successfully designed for applications requiring control of applied torques.
Hill stability in the AMD framework Petit, Antoine C.; Laskar, Jacques; Boué, Gwenaël
Astronomy & astrophysics,
09/2018, Letnik:
617
Journal Article
Recenzirano
Odprti dostop
In a two-planet system, a topological boundary that is created by Sundman (1912, Acta Math., 36, 105) inequality can forbid close encounters between the two planets for an infinite time. A system is ...said to be Hill stable if it verifies this topological condition. Hill stability is widely used in the study of extrasolar planet dynamics. However, the coplanar and circular orbit approximation is often used. In this paper, we explain how the Hill stability can be understood in the framework of angular momentum deficit (AMD). In the secular approximation, AMD allows us to discriminate between a priori stable systems and systems for which a more in-depth dynamical analysis is required. We show that the general Hill stability criterion can be expressed as a function of only semimajor axes, masses, and total AMD of the system. The proposed criterion is only expanded in the planets-to-star mass ratio ε and not in the semimajor axis ratio, eccentricities, nor the mutual inclination. Moreover, the expansion in ε remains excellent up to values of about 10−3 even for two planets with very different mass values. We performed numerical simulations in order to highlight the sharp change of behavior between Hill stable and Hill unstable systems. We show that Hill stable systems tend to be very regular, whereas Hill unstable systems often lead to rapid planet collisions. We also note that Hill stability does not provide protection from the ejection of the outer planet.
Clostridium difficile is responsible for 15–25% of cases of antibiotic-associated diarrhea (AAD) and for virtually all cases of antibiotic-associated pseudomembranous colitis (PMC). This anaerobic ...bacterium has been identified as the leading cause of nosocomial infectious diarrhea in adults and can be responsible for large outbreaks. Nosocomial C. difficile infection results in an increased length of stay in hospital ranging from 8 to 21 days. Risk factors for C. difficile-associated diarrhea include antimicrobial therapy, older age (>65 years), antineoplastic chemotherapy and length of hospital stay. Other interventions with high risk associations are enemas, nasogastric tubes, gastrointestinal surgery and antiperistaltic drugs. Prospective studies have shown that nosocomial transmission of C. difficile is frequent but often remains asymptomatic. Patients can be contaminated from environnemental surfaces, shared instrumentation, hospital personnel hands and infected roommates. Once an outbreak starts, C. difficile may be spread rapidly throughout the hospital environment where spores may persist for months. Measures that are effective in reducing incidence of C. difficile infections and cross-infection include: (i) an accurate and rapid diagnosis, (ii) appropriate treatment, (iii) implementation of enteric precautions for symptomatic patients, (iv) reinforcement of hand-washing, (v) daily environmental disinfection, and (vi) a restrictive antibiotic policy. C. difficile is a common cause of infectious diarrhea and should be therefore systematically investigated in patients with nosocomial diarrhea.
Abstract
The emergence of orbital resonances among planets is a natural consequence of the early dynamical evolution of planetary systems. While it is well established that convergent migration is ...necessary for mean-motion commensurabilities to emerge, recent numerical experiments have shown that the existing adiabatic theory of resonant capture provides an incomplete description of the relevant physics, leading to an erroneous mass scaling in the regime of strong dissipation. In this work, we develop a new model for resonance capture that self-consistently accounts for migration and circularization of planetary orbits, and derive an analytic criterion based upon stability analysis that describes the conditions necessary for the formation of mean-motion resonances. We subsequently test our results against numerical simulations and find satisfactory agreement. Our results elucidate the critical role played by adiabaticity and resonant stability in shaping the orbital architectures of planetary systems during the nebular epoch, and provide a valuable tool for understanding their primordial dynamical evolution.
Introduction Dans le diabète de type 1 traité par pompe, il n’existe pas de recommandations précises sur l’ajustement des doses d’insuline en cas d’activité physique (AP) lorsque celle-ci a lieu ...après un repas: vautil mieux réduire le débit de base (DB) ou le bolus ? Patients et méthodes Vingt patients DT1 sous pompe (HbA1c < 9 %, pratiquant l’IF et une AP de loisirs), après détermination de V02max, ont fait 2 sessions d’AP à 50 % V02max (30 min/vélo ergométrique), 90 minutes après le déjeuner, comparant réduction du bolus (-30/-50 %) vs réduction DB (-50/-80 % pendant AP + 2 heures) (ordre randomisé). Glycémie/insulinémie étaient mesurées pendant l’AP + 2 heures. Le critère principal était le nombre d’hypoglycémies sur courbe CGM (iPro2). Résultats Trente-sept sessions d’AP ont été collectées, avec la survenue d’une seule hypoglycémie. La comparaison réduction Bolus vs DB a montré les résultats suivants: l’après-midi, l’incidence des hypoglycémies tendait à être moindre ( p = 0,0689), différence non retrouvée la nuit. Le niveau glycémique, comparable avant le déjeuner était plus élevé juste avant l’AP avec la réduction du bolus p = 0,033. À la fin de l’activité, la chute glycémique était comparable (bolus: 71 mg/dL/DB: 77 mg/dL, p = 0,19). Les courbes CGM sont restées stables l’après-midi mais avec un niveau glycémique plus élevé avec la réduction du bolus (168 ± 46 vs 129 ± 47 mg/dL, p = 0,054). Le temps passé dans l’objectif 70 ; 180 mg/dL était comparable, celui à < 80 mg/dL était moindre (6,3 % vs 20 %, p = 0,04), celui passé > 180 mg/dl, plus conséquent (42 % vs 16 %, p = 0,057). Les niveaux glycémiques au dîner ainsi qu’au coucher étaient comparables ; les courbes CGM sont restées plates la nuit. Conclusion En cas d’AP après un repas, la réduction du bolus du repas précédent, s’accompagne d’une tendance à une moindre incidence des hypoglycémies par rapport à la réduction du DB au prix d’un niveau glycémique plus élevé l’après-midi. Lorsque l’AP peut être anticipée, la réduction du bolus paraît donc être l’option la plus sûre. Déclaration d’intérêt Les auteurs déclarent ne pas avoir d’intérêt direct ou indirect (financier ou en nature) avec un organisme privé, industriel ou commercial en relation avec le sujet présenté.
Magnetic particles that can be precisely controlled under a magnetic field and transduce energy from the applied field open the way for innovative cancer treatment. Although these particles represent ...an area of active development for drug delivery and magnetic hyperthermia, the in vivo anti-tumor effect under a low-frequency magnetic field using magnetic particles has not yet been demonstrated. To-date, induced cancer cell death via the oscillation of nanoparticles under a low-frequency magnetic field has only been observed in vitro. In this report, we demonstrate the successful use of spin-vortex, disk-shaped permalloy magnetic particles in a low-frequency, rotating magnetic field for the in vitro and in vivo destruction of glioma cells. The internalized nanomagnets align themselves to the plane of the rotating magnetic field, creating a strong mechanical force which damages the cancer cell structure inducing programmed cell death. In vivo, the magnetic field treatment successfully reduces brain tumor size and increases the survival rate of mice bearing intracranial glioma xenografts, without adverse side effects. This study demonstrates a novel approach of controlling magnetic particles for treating malignant glioma that should be applicable to treat a wide range of cancers.
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Context.
Shadows in scattered light images of protoplanetary disks are a common feature and support the presence of warps or misalignments between disk regions. These warps are possibly caused by an ...inclined (sub-)stellar companion embedded in the disk.
Aims.
We aim to study the morphology of the protoplanetary disk around the Herbig Ae star HD 139614 based on the first scattered light observations of this disk, which we model with the radiative transfer code
MCMax3D
.
Methods.
We obtained
J
- and
H
-band observations that show strong azimuthal asymmetries in polarized scattered light with VLT/SPHERE. In the outer disk, beyond ~30 au, a broad shadow spans a range of ~240 deg in position angle, in the east. A bright ring at ~16 au also shows an azimuthally asymmetric brightness, with the faintest side roughly coincidental with the brightest region of the outer disk. Additionally, two arcs are detected at ~34 and ~50 au. We created a simple four-zone approximation to a warped disk model of HD 139614 in order to qualitatively reproduce these features. The location and misalignment of the disk components were constrained from the shape and location of the shadows they cast.
Results.
We find that the shadow on the outer disk covers a range of position angles too wide to be explained by a single inner misaligned component. Our model requires a minimum of two separate misaligned zones – or a continuously warped region – to cast this broad shadow on the outer disk. A small misalignment of ~4° between adjacent components can reproduce most of the observed shadow features.
Conclusions.
Multiple misaligned disk zones, potentially mimicking a warp, can explain the observed broad shadows in the HD 139614 disk. A planetary mass companion in the disk, located on an inclined orbit, could be responsible for such a feature and for the dust-depleted gap responsible for a dip in the SED.
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