Could 2S 0114+650 be a magnetar?

We investigate the spin evolution of the binary X-ray pulsar 2S 0114+650, which possesses the slowest known spin period of $\sim 2.7$ hours. We argue that, to interpret such long spin period, the magnetic field strength of this pulsar must be initially \gsim 10^{14} G, that is, it was born as a magnetar. Since the pulsar currently has a normal magnetic field $\sim 10^{12}$ G, our results present support for magnetic field decay predicted by the magnetar model.Comment: 7 pages, 1 figure, accepted for publication in ApJ

Ultrasonic tracking of a sinking ball in a vibrated dense granular suspension

Observing and understanding the movement of an intruder through opaque dense suspensions such as quicksand remains a practical and conceptual challenge. Here we use an ultrasonic probe to investigate the dynamics of a steel ball sinking in a 3D dense glass bead packing saturated by water. We show that the frictional model developed for dry granular media can be used to describe the ball motion induced by horizontal vibration. From this rheology we infer the static friction coefficient and effective viscosity that decrease when increasing the vibration intensity. Our main finding is that the vibration-induced reduction of the yield stress and increase of the sinking depth are presumably due to induced slipping at the grain contacts but without visible plastic rearrangements of grains, in contrast to dry granular packings. To explain these results, we propose a mechanism of acoustic lubrication that reduces the inter-particle friction and leads to a decrease of the yield stress. This scenario is different from the mechanism of liquefaction usually invoked in loosely packed quicksands where the vibration-induced compaction increases the pore pressure and decreases the confining pressure on the solid skeleton, thus reducing the granular resistance to external load.Comment: 9 pages and 5 figures, plus the supplemental information (1 page, 2 movies, 1 figure

Cortical and structural connectivity damage correlated with impaired syntactic processing

Problems with sentence processing and production are not exclusive to speakers with agrammatic aphasia. Besides peripheral problems with auditory processing or articulatory control, lexical retrieval, attention and short-term memory deficits may all underlie difficulties with organizing words into sentences, applying inflectional morphology and correctly accessing and processing verb argument structure. Lesions that result in sentence processing problems are therefore not homogeneously limited to a small region. However, sentence processing and production can be broken up into components, in order to investigate the brain-behavior relationship in greater detail. The Northwestern Assessment of Verbs and Sentences (NAVS) allows for such investigations, as it consists of several tasks that tap into different components of syntactic processing (Cho-Reyes & Thompson, 2012). In particular, the NAVS focuses on the pivotal role of verbs and verb argument structure in sentence (de)construction. With respect to structural syntactic features that affect sentence processing, it is of interest to investigate deficits that are characterized by greater problems with noncanonical sentence structures, compared to canonical structures. Patients with such a pattern of impairment may be considered to have a specific deficit in complex syntactic processing. Brain-behavior investigations that focus on such patterns may yield greater insight into regions and/or networks that serve a particular role in the syntactic computations that underlie the relation between canonical and noncanonical sentences (Magnusdottir et al., 2013). As part of a larger study into correlations between brain damage and functional deficits, we submitted participants to an MRI scanning protocol that included anatomical scans, diffusion tensor imaging, resting state functional imaging, and perfusion imaging. Such a combination of methods reduces the chance of underestimating the extent of stroke-induced brain damage and its effect on patient symptoms. We investigated correlations with performance on NAVS subtests, as well as with the ratio of performance on canonical versus noncanonical sentence structures

A New Estimation of Mass Accumulation Efficiency in Helium Shell Flashes toward Type Ia Supernova Explosions

We have calculated the mass accumulation efficiency during helium shell flashes to examine whether or not a carbon-oxygen white dwarf (C+O WD) grows up to the Chandrasekhar mass limit to ignite a Type Ia supernova explosion. It has been frequently argued that luminous super-soft X-ray sources and symbiotic stars are progenitors of SNe Ia. In such systems, a C+O WD accretes hydrogen-rich matter from a companion and burns hydrogen steadily on its surface. The WD develops a helium layer underneath the hydrogen-rich envelope and undergoes periodic helium shell flashes. Using OPAL opacity, we have reanalyzed a full cycle of helium shell flashes on a 1.3 M_\odot C+O WD and confirmed that the helium envelope of the WD expands to blow a strong wind. A part of the accumulated matter is lost by the wind. The mass accumulation efficiency is estimated as \eta_{He} = -0.175 (\log \dot M + 5.35)^2 + 1.05, for -7.3 < \log \dot M < -5.9, where the mass accretion rate \dot M is in units of M_\odot yr^{-1}. In relatively high mass accretion rates as expected in recent SN Ia progenitor models, the mass accumulation efficiency is large enough for C+O WDs to grow to the Chandrasekhar mass, i.e., \eta_{He} = 0.9 for \log \dot M = -6.3, and \eta_{He}=0.57 for \log \dot M = -7.0. The wind velocity (\sim 1000 km/s) is much faster than the orbital velocity of the binary (< 300 km/s) and therefore, the wind cannot be accelerated further by the companion's motion.Comment: 11 pages including 4 eps-files, accepted for publication in ApJ Letter

The development of a resource-efficient photovoltaic system

This paper presents the measures taken in the demonstration of the photovoltaic case study developed within the European project ‘Towards zero waste in industrial networks’ (Zerowin), integrating the D4R (Design for recycling, repair, refurbishment and reuse) criteria at both system and industrial network level. The demonstration is divided into three phases. The first phase concerns the development of a D4R photovoltaic concept, the second phase focused on the development of a specific component of photovoltaic systems and the third phase was the demonstration of the D4R design in two complete photovoltaic systems (grid-connected and stand-alone). This paper includes a description of the installed photovoltaic systems, including a brief summary at component level of the lithium ion battery system and the D4R power conditioning system developed for the pilot installations. Additionally, industrial symbioses within the network associated with the photovoltaic systems and the production model for the network are described

NlpI-Prc Proteolytic Complex Mediates Peptidoglycan Synthesis and Degradation via Regulation of Hydrolases and Synthases in <i>Escherichia coli</i>

Balancing peptidoglycan (PG) synthesis and degradation with precision is essential for bacterial growth, yet our comprehension of this intricate process remains limited. The NlpI-Prc proteolytic complex plays a crucial but poorly understood role in the regulation of multiple enzymes involved in PG metabolism. In this paper, through fluorescent D-amino acid 7-hydroxycoumarincarbonylamino-D-alanine (HADA) labeling and immunolabeling assays, we have demonstrated that the NlpI-Prc complex regulates the activity of PG transpeptidases and subcellular localization of PBP3 under certain growth conditions. PBP7 (a PG hydrolase) and MltD (a lytic transglycosylase) were confirmed to be negatively regulated by the NlpI-Prc complex by an in vivo degradation assay. The endopeptidases, MepS, MepM, and MepH, have consistently been demonstrated as redundantly essential “space makers” for nascent PG insertion. However, we observed that the absence of NlpI-Prc complex can alleviate the lethality of the mepS mepM mepH mutant. A function of PG lytic transglycosylases MltA and MltD as “space makers” was proposed through multiple gene deletions. These findings unveil novel roles for NlpI-Prc in the regulation of both PG synthesis and degradation, shedding light on the previously undiscovered function of lytic transglycosylases as “space makers” in PG expansion

Macroscopic limit cycle via pure noise-induced phase transition

Bistability generated via a pure noise-induced phase transition is reexamined from the view of bifurcations in macroscopic cumulant dynamics. It allows an analytical study of the phase diagram in more general cases than previous methods. In addition using this approach we investigate patially-extended systems with two degrees of freedom per site. For this system, the analytic solution of the stationary Fokker-Planck equation is not available and a standard mean field approach cannot be used to find noise induced phase transitions. A new approach based on cumulant dynamics predicts a noise-induced phase transition through a Hopf bifurcation leading to a macroscopic limit cycle motion, which is confirmed by numerical simulation.Comment: 8 pages, 8 figure

Out of Equilibrium Solutions in the XYXY-Hamiltonian Mean Field model

Out of equilibrium magnetised solutions of the $XY$-Hamiltonian Mean Field ($XY$-HMF) model are build using an ensemble of integrable uncoupled pendula. Using these solutions we display an out-of equilibrium phase transition using a specific reduced set of the magnetised solutions