Magnetic field in a young circumbinary disk

We use polarization observations of a circumbinary disk to investigate how the polarization properties change at distinct frequency bands. Our goal is to discern the main mechanism responsible for the polarization through comparison between our observations and model predictions. We used ALMA to perform full polarization observations at 97.5 GHz, 233 GHz and 343.5 GHz. The target is the Class I object BHB07-11, which is the youngest object in the Barnard 59 protocluster. Complementary VLA observations at 34.5 GHz revealed a binary system within the disk. We detect an extended and structured polarization pattern remarkably consistent among all three bands. The distribution of polarized intensity resembles a horseshoe shape with polarization angles following this morphology. From the spectral index between bands 3 and 7, we derive a dust opacity index $\beta \sim 1$ consistent with maximum grain sizes larger than expected to produce self-scattering polarization in each band. The polarization morphology do not match predictions from self-scattering. On the other hand, marginal correspondence is seen between our maps and predictions from radiation field assuming the brightest binary component as main radiation source. Molecular line data from BHB07-11 indicates disk rotation. We produced synthetic polarization maps from a rotating magnetized disk model assuming combined poloidal and toroidal magnetic field components. The magnetic field vectors (i. e., the polarization vectors rotated by 90\degr) are better represented by a model with poloidal magnetic field strength about 3 times the toroidal one. The similarity of our polarization patterns among the three bands provides a strong evidence against self-scattering and radiation fields. On the other hand, our data are reasonably well reproduced by a model of disk with toroidal magnetic field components slightly smaller than poloidal ones.Comment: 8 pages, 8 figures, accepted for publication in Astronomy & Astrophysic

Obesity, energy balance and spermatogenesis

Obesity has grown to pandemic proportions. It affects an increasing number of children, adolescents and young adults exposed to the silent comorbidities of this disorder for a longer period. Infertility has arisen as one important comorbidity associated with the energy dysfunction promoted by obesity. Spermatogenesis is a highly regulated process that is determined by specific energetic requirements. The reproductive potential of males relies on hormonal-dependent and -independent stimuli that control sperm quality. There are conflicting data concerning the impact of male overweight and obesity on sperm quality, as well as on the possible paternal-induced epigenetic trait inheritance of obesity. In addition, it remains a matter of debate whether massive weight loss induced by lifestyle interventions, drugs or bariatric surgery may or may not benefit obese men seeking fatherhood. Herein, we propose to discuss how energy balance may modulate hormonal signalling and sperm quality in overweight and obese men. We also discuss some molecular mechanisms that mediate obesity-related dysfunction in male reproductive system and how paternal obesity may lead to trait inheritance. Finally, we will discuss how lifestyle modifications and sustained weight loss, particularly the loss achieved by bariatric surgery, may revert some of the deleterious effects of obesity in men and their offspring.info:eu-repo/semantics/publishedVersio

Nonextensive statistical mechanics applied to protein folding problem: kinetics aspects

A reduced (stereo-chemical) model is employed to study kinetic aspects of globular protein folding process, by Monte Carlo simulation. Nonextensive statistical approach is used: transition probability p i j between configurations i &#8594; j is given by p i j =[1 +(1 - q)&#916;Gi j/kB T ]1/(1-q), where q is the nonextensive (Tsallis) parameter. The system model consists of a chain of 27 beads immerse in its solvent; the beads represent the sequence of amino acids along the chain by means of a 10-letter stereo-chemical alphabet; a syntax (rule) to design the amino acid sequence for any given 3D structure is embedded in the model. The study focuses mainly kinetic aspects of the folding problem related with the protein folding time, represented in this work by the concept of first passage time (FPT). Many distinct proteins, whose native structures are represented here by compact self avoiding (CSA) configurations, were employed in our analysis, although our results are presented exclusively for one representative protein, for which a rich statistics was achieved. Our results reveal that there is a specific combinations of value for the nonextensive parameter q and temperature T, which gives the smallest estimated folding characteristic time (t). Additionally, for q = 1.1, (t) stays almost invariable in the range 0.9 < T < 1.3, slightly oscillating about its average value <img border=0 width=32 height=32 src="../../../../../../../img/revistas/bjp/v39n2a/a16txt01.gif" align=absmiddle > or = 27 ±&#963;, where &#963; = 2 is the standard deviation. This behavior is explained by comparing the distribution of the folding times for the Boltzmann statistics (q &#8594; 1), with respect to the nonextensive statistics for q = 1.1, which shows that the effect of the nonextensive parameter q is to cut off the larger folding times present in the original (q &#8594; 1) distribution. The distribution of natural logarithm of the folding times for Boltzmann statistics is a triple peaked Gaussian, while, for q = 1.1 (Tsallis), it is a double peaked Gaussian, suggesting that a log-normal process with two characteristic times replaced the original process with three characteristic times. Finally we comment on the physical meaning of the present results, as well its significance in the near future works

Freezing time emulating new and faster devices with virtual machines

Recent proposals of emerging data storage devices make it necessary to reevaluate all levels of the storage hierarchy to optimize the software stack performance. However, these new devices are not always widely available and therefore early experiments may be impossible. Emulators aim at mimicking as close as possible the behavior of a component, nonetheless, emulating new and fast storage devices is a challenging task due to time perception. In this work, we propose an approach to emulate storage devices using virtual machines (VMs) allowing the evaluation of a new device within a real system. We use a technique called freezing time, which pauses a VM to manipulate its clock and hide the real I/O completion time. Our approach is implemented at the hypervisor level and it is transparent to the guest operating system or application. We evaluate the technique under a real system using regular magnetic disks to emulate faster storage devices. Our method presented a latency error of 6.5% compared to a real device. Moreover, decoupled experiment between two laboratories, at the Barcelona Super Computing Center (BSC) in Spain, and the Center of Computer Science and Free Software (C3SL) in Brazil, demonstrated that our approach is reproducible and promising to allow the virtual evaluation of next-gen storage devices.This work was partially supported by the Spanish Ministry of Science and Innovation under the TIN2015-65316 Grant, the Generalitat de Catalunya under contract 2014-SGR-1051, the Serrapilheira Institute (Grant number Serra-1709-16621), as well as the European Union’s Horizon 2020 Research and Innovation Programme, under Grant Agreement no. 671951 (NEXTGenIO) for the extensions added after the MASCOTS paper.Peer ReviewedPostprint (author's final draft

Generation of precision-cut slice cultures of human placenta.

We present a protocol to generate an advanced ex vivo model of human placenta. We use a vibrating tissue slicer to obtain precision-cut slices representative of the entire thickness of human placenta. This approach delivers standardized cultures with a preserved microstructure and cellular composition comparable to the native tissue. We applied this system to study SARS-CoV-2 infection at the maternal-fetal interface. Moreover, this system can be used to investigate the basic functions of the human placenta in health and disease. For complete details on the use and execution of this protocol, please refer to Fahmi et al. (2021)

Freezing Time: a new approach for emulating fast storage devices using VM

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Recently we are seeing a considerable effort from both academy and industry in proposing new technologies for storage devices. Often these devices are not readily available for evaluation and methods to allow performing their tests just from their performance parameters are an important tool for system administrators. Simulators are a traditional approach for carrying out such evaluations, however, they are more suitable for evaluating the storage device as an isolate component, mostly due to time constraints. In this paper, we propose an approach based on virtual machine technology that is capable of emulate storage devices transparently for the operating system allowing evaluation of simulating devices within a real system using any synthetic or real workload. To emulate devices in real environments it is necessary to use the currently available devices as a storage medium which creates a difficulty when the device to be emulated is faster than this storage medium. To circumvent this limitation we introduce a new technique called Freezing Time, which takes advantage of virtual machine pausing mechanism to manipulate the virtual machine clock and hide the real I/O completion time. Our approach can be implemented just requiring the hypervisor to be modified, providing a high degree of compatibility and flexibility since it is not necessary to modify neither the operating system nor the application. We evaluate our tool under a real system using old magnetic disks to emulate faster storage devices. Experiments using our technique presented an average latency error of 6.08% for read operations and 6.78% for write operations when comparing a real to device.This work was partially supported by the Spanish Ministry of Science and Innovation under the TIN2015–65316 grant, the Generalitat de Catalunya under contract 2014–SGR–1051.Peer ReviewedPostprint (author's final draft

Spontaneous symmetry breaking in amnestically induced persistence

We investigate a recently proposed non-Markovian random walk model characterized by loss of memories of the recent past and amnestically induced persistence. We report numerical and analytical results showing the complete phase diagram, consisting of 4 phases, for this system: (i) classical nonpersistence, (ii) classical persistence (iii) log-periodic nonpersistence and (iv) log-periodic persistence driven by negative feedback. The first two phases possess continuous scale invariance symmetry, however log-periodicity breaks this symmetry. Instead, log-periodic motion satisfies discrete scale invariance symmetry, with complex rather than real fractal dimensions. We find for log-periodic persistence evidence not only of statistical but also of geometric self-similarity.Comment: 4 pages, 2 color fig

Lifestyle, metabolic disorders and male hypogonadism - a one-way ticket?

Hypogonadism is more frequent among men with common metabolic diseases, notably obesity and type 2 diabetes. Indeed, endocrine disruption caused by metabolic diseases can trigger the onset of hypogonadism, although the underlying molecular mechanisms are not entirely understood. Metabolic diseases are closely related to unhealthy lifestyle choices, such as dietary habits and sedentarism. Therefore, hypogonadism is part of a pathological triad gathering unhealthy lifestyle, metabolic disease and genetic background. Additionally, hypogonadism harbors the potential to aggravate underlying metabolic disorders, further sustaining the mechanisms leading to disease. To what extent does lifestyle intervention in men suffering from these metabolic disorders can prevent, improve or reverse hypogonadism, is still controversial. Moreover, recent evidence suggests that the metabolic status of the father is related to the risk of inter and transgenerational inheritance of hypogonadism. In this review, we will address the proposed mechanisms of disease, as well as currently available interventions for hypogonadism.publishe

Amnestically induced persistence in random walks

We study how the Hurst exponent $\alpha$ depends on the fraction $f$ of the total time $t$ remembered by non-Markovian random walkers that recall only the distant past. We find that otherwise nonpersistent random walkers switch to persistent behavior when inflicted with significant memory loss. Such memory losses induce the probability density function of the walker's position to undergo a transition from Gaussian to non-Gaussian. We interpret these findings of persistence in terms of a breakdown of self-regulation mechanisms and discuss their possible relevance to some of the burdensome behavioral and psychological symptoms of Alzheimer's disease and other dementias.Comment: 4 pages, 3 figs, subm. to Phys. Rev. Let