Parametric FEM simulation of composite barrier FTJs under external bias at room temperature

A study on a parametrized model of a composite barrier FTJ (three-interface system, with a non-polar dielectric layer) under an external bias voltage and at room temperature, using FEM-based simulations, was performed. The approach involves the Thomas-Fermi model assuming incomplete screening of polarization charges for building the energy barrier profile, and numerically simulates the electron transport through the barrier by bias-voltage-dependent tunneling, using Tsu-Esaki formulation. That naturally include the temperature dependent contributions to the total current density. The TER coefficient and current densities are computed considering variation of a large set of parameters that describe the composite barrier FTJ system in realistic physical range of values with respect to a reference (prototypical) system. In this study, the parametric simulations were performed starting from selected data reported on the SRO/STO/BTO/SRO heterostructure. The most important results of our work can be stated as follows: i) The FEM simulations prove to be reliable approach when we are interested in the prediction of FTJ characteristics at temperatures close to 300 K, and ii) We show that several configurations with large TER values may be predicted, but at the expense of very low current densities in the ON state. We suggest that the results may be useful for assessing the FTJ performances at ambient temperature, as well as to design preoptimized FTJs by using different combinations of materials to comply with a set of properties of a specific model

739 observed NEAs and new 2-4m survey statistics within the EURONEAR network

We report follow-up observations of 477 program Near-Earth Asteroids (NEAs) using nine telescopes of the EURONEAR network having apertures between 0.3 and 4.2 m. Adding these NEAs to our previous results we now count 739 program NEAs followed-up by the EURONEAR network since 2006. The targets were selected using EURONEAR planning tools focusing on high priority objects. Analyzing the resulting orbital improvements suggests astrometric follow-up is most important days to weeks after discovery, with recovery at a new opposition also valuable. Additionally we observed 40 survey fields spanning three nights covering 11 sq. degrees near opposition, using the Wide Field Camera on the 2.5m Isaac Newton Telescope (INT), resulting in 104 discovered main belt asteroids (MBAs) and another 626 unknown one-night objects. These fields, plus program NEA fields from the INT and from the wide field MOSAIC II camera on the Blanco 4m telescope, generated around 12,000 observations of 2,000 minor planets (mostly MBAs) observed in 34 square degrees. We identify Near Earth Object (NEO) candidates among the unknown (single night) objects using three selection criteria. Testing these criteria on the (known) program NEAs shows the best selection methods are our epsilon-miu model which checks solar elongation and sky motion and the MPC's NEO rating tool. Our new data show that on average 0.5 NEO candidates per square degree should be observable in a 2m-class survey (in agreement with past results), while an average of 2.7 NEO candidates per square degree should be observable in a 4m-class survey (although our Blanco statistics were affected by clouds). At opposition just over 100 MBAs (1.6 unknown to every 1 known) per square degree are detectable to R=22 in a 2m survey based on the INT data, while our two best ecliptic Blanco fields away from opposition lead to 135 MBAs (2 unknown to every 1 known) to R=23.Comment: Published in Planetary and Space Sciences (Sep 2013

Cistita necrotică - dificultăţi diagnostice şi terapeutice

Abstract Necrotic cystitis, also called incrustation cystitis, raises etiopathological and therapeutical problems, with relapse of the necrosis after removal of pathological tissue. Between 01.01.1999 and 31.12.2005 there have been 55 patients institutionalized in our Clinic, presenting lower urinary tract symptoms (LUTS). Instrumental investigations have demonstrated the thickening of the bladder wall, more frequently in the trigonum area. Ultrasound examination and cystography couldn’t exclude an infiltrative bladder tumor. Cystoscopy which showed necrotic bladder tissue, with calcareous incrustations, followed by the resection of the pathologic tissue. In 45 cases the histopathological result was necrotic cystitis and in 10 cases infiltrative urothelial bladder tumor or epidermoid metaplasia. In order to clarify the etiology of the necrosis an investigation protocol have been used, consisting of laboratory tests for autoimmune diseases, vascular or local causes that initiate the necrosis (previous surgery in the area, endoscopic interventions). In 5 cases with autoimmune disease, the treatment was transurethral resection and plasmapheresis. The evolution was favorable in 4 cases. Failure: 1 patient. In 12 cases the cause of the necrosis appears to be a diabetic vasculitis, judging by the deep necrosis, dispersed over several small areas. The posttherapeutic evolution depends on the correct treatment of diabetes. In 10 patients with previous endoscopic surgery, the necrosis has been induced by inadequate electrical currents or mechanical lesions. In 18 patients the causing factor remained unknown. The limited necrosis of the bladder can be caused by autoimmune diseases, vascular diseases (diabetes) and endo-urethral maneuvers. The endoscopic resection of the necrotic bladder wall to the healthy, well vascularised tissue beneath is an important therapeutic procedure. The treatment of the causing factors (autoimmune, vascular) will consolidate the healing. Not knowing the other causes will lead to failure, and repeated endoscopic treatment will result in short term ameliorations. Introducere. Cistita necrotică, denumită în literatură şi “cistita de incrustaţie”, ridică probleme de etiopatogenie, prezentând dificultăţi terapeutice, cu recidiva necrozei după îndepărtarea ţesuturilor patologice. Materiale şi metode. Între 01.01.1999-31.12.2005 au fost internaţi în clinica noastră 55 de pacienţi cu fenomene urinare joase de tip iritativ. Investigaţiile paraclinice au pus în evidenţă peretele vezical îngroşat, situaţie frecventă în trigon. Ecografia şi cistografia nu puteau exclude aspectul unei tumori vezicale infiltrative.Cistoscopia a evidenţiat un ţesut vezical necrozat, cu incrustaţii calcare, fiind urmată de rezecţia ţesutului patologic. La 45 de pacienţi rezultatul histopatologic a fost de cistită necrotică, iar la 10 bolnavi s-a depistat tumoră vezicală urotelială infiltrativă sau metaplazie epidermoidă. Pentru a elucida etiopatogenia necrozei, s-a aplicat un protocol de investigare care include teste de laborator pentru depistarea unui proces autoimun, a unor cauze vasculare sau a unor cauze locale de declanşare a necrozei (intervenţii în antecedente, manevre endoscopice, etc.). Rezultate şi discuţii. La 5 bolnavi cu proces autoimun, tratamentul a constat din rezecţie transuretrală şi din plasmafereză. Evoluţie favorabilă, cu vindecare - la 4 bolnavi. Eşec: 1 pacientă. La 12 bolnavi cauza necrozei este sugerată a fi o vasculită diabetică, după aspectul profund al necrozei în puncte dispersate, evoluţia postterapeutică este influenţată de tratamentul corect al diabetului. La 10 pacienţi cu manevre chirurgicale endoscopice în antecedente, inducţia procesului necrotic a fost provocat de curenţi electrici inadecuaţi sau de leziuni mecanice. La 18 bolnavi cauza a fost necunoscută. Concluzii. Necroza limitată a vezicii urinare poate avea cauze autoimune, vasculare (diabet), manevre endouretrale. Rezecţia endoscopică a peretelui vezical necrozat până în ţesut bine vascularizat este un gest terapeutic important. Tratamentul cauzal (autoimun, vascular, etc.) consolidează vindecarea. Necunoaşterea şi a altor cauze duce la eşec, iar tratamentul endoscopic repetat - la ameliorări pasagere

Rapid progression of prostate cancer in men with a BRCA2 mutation.

Men with BRCA2 mutations have been found to be at increased risk of developing prostate cancer. There is a recent report that BRCA2 carriers with prostate cancer have poorer survival than noncarrier prostate cancer patients. In this study, we compared survival of men with a BRCA2 mutation and prostate cancer with that of men with a BRCA1 mutation and prostate cancer. We obtained the age at diagnosis, age at death or current age from 182 men with prostate cancer from families with a BRCA2 mutation and from 119 men with prostate cancer from families with a BRCA1 mutation. The median survival from diagnosis was 4.0 years for men with a BRCA2 mutation vs 8.0 years for men with a BRCA1 mutation, and the difference was highly significant (P<0.01). It may be important to develop targeted chemotherapies to treat prostate cancer in men with a BRCA2 mutation

EURONEAR - Recovery, Follow-up and Discovery of NEAs and MBAs using Large Field 1-2m Telescopes

We report on the follow-up and recovery of 100 program NEAs, PHAs and VIs using the ESO/MPG 2.2m, Swope 1m and INT 2.5m telescopes equipped with large field cameras. The 127 fields observed during 11 nights covered 29 square degrees. Using these data, we present the incidental survey work which includes 558 known MBAs and 628 unknown moving objects mostly consistent with MBAs from which 58 objects became official discoveries. We planned the runs using six criteria and four servers which focus mostly on faint and poorly observed objects in need of confirmation, follow-up and recovery. We followed 62 faint NEAs within one month after discovery and we recovered 10 faint NEAs having big uncertainties at their second or later opposition. Using the INT we eliminated 4 PHA candidates and VIs. We observed in total 1,286 moving objects and we reported more than 10,000 positions. All data were reduced by the members of our network in a team effort, and reported promptly to the MPC. The positions of the program NEAs were published in 27 MPC and MPEC references and used to improve their orbits. The O-C residuals for known MBAs and program NEAs are smallest for the ESO/MPG and Swope and about four times larger for the INT whose field is more distorted. The incidental survey allowed us to study statistics of the MBA and NEA populations observable today with 1--2m facilities. We calculate preliminary orbits for all unknown objects, classifying them as official discoveries, later identifications and unknown outstanding objects. The orbital elements a, e, i calculated by FIND_ORB software for the official discoveries and later identified objects are very similar with the published elements which take into account longer observational arcs; thus preliminary orbits were used in statistics for the whole unknown dataset. (CONTINUED)Comment: Accepted in Planetary and Space Science (Aug 2011

Evolution of apoptosis-like programmed cell death in unicellular protozoan parasites

Apoptosis-like programmed cell death (PCD) has recently been described in multiple taxa of unicellular protists, including the protozoan parasites Plasmodium, Trypanosoma and Leishmania. Apoptosis-like PCD in protozoan parasites shares a number of morphological features with programmed cell death in multicellular organisms. However, both the evolutionary explanations and mechanisms involved in parasite PCD are poorly understood. Explaining why unicellular organisms appear to undergo 'suicide' is a challenge for evolutionary biology and uncovering death executors and pathways is a challenge for molecular and cell biology. Bioinformatics has the potential to integrate these approaches by revealing homologies in the PCD machinery of diverse taxa and evaluating their evolutionary trajectories. As the molecular mechanisms of apoptosis in model organisms are well characterised, and recent data suggest similar mechanisms operate in protozoan parasites, key questions can now be addressed. These questions include: which elements of apoptosis machinery appear to be shared between protozoan parasites and multicellular taxa and, have these mechanisms arisen through convergent or divergent evolution? We use bioinformatics to address these questions and our analyses suggest that apoptosis mechanisms in protozoan parasites and other taxa have diverged during their evolution, that some apoptosis factors are shared across taxa whilst others have been replaced by proteins with similar biochemical activities

Rapid Transition towards the Division of Labor via Evolution of Developmental Plasticity

A crucial step in several major evolutionary transitions is the division of labor between components of the emerging higher-level evolutionary unit. Examples include the separation of germ and soma in simple multicellular organisms, appearance of multiple cell types and organs in more complex organisms, and emergence of casts in eusocial insects. How the division of labor was achieved in the face of selfishness of lower-level units is controversial. I present a simple mathematical model describing the evolutionary emergence of the division of labor via developmental plasticity starting with a colony of undifferentiated cells and ending with completely differentiated multicellular organisms. I explore how the plausibility and the dynamics of the division of labor depend on its fitness advantage, mutation rate, costs of developmental plasticity, and the colony size. The model shows that the transition to differentiated multicellularity, which has happened many times in the history of life, can be achieved relatively easily. My approach is expandable in a number of directions including the emergence of multiple cell types, complex organs, or casts of eusocial insects

Limited duration of vaccine poliovirus and other enterovirus excretion among human immunodeficiency virus infected children in Kenya

<p>Abstract</p> <p>Background</p> <p>Immunodeficient persons with persistent vaccine-related poliovirus infection may serve as a potential reservoir for reintroduction of polioviruses after wild poliovirus eradication, posing a risk of their further circulation in inadequately immunized populations.</p> <p>Methods</p> <p>To estimate the potential for vaccine-related poliovirus persistence among HIV-infected persons, we studied poliovirus excretion following vaccination among children at an orphanage in Kenya. For 12 months after national immunization days, we collected serial stool specimens from orphanage residents aged <5 years at enrollment and recorded their HIV status and demographic, clinical, immunological, and immunization data. To detect and characterize isolated polioviruses and non-polio enteroviruses (NPEV), we used viral culture, typing and intratypic differentiation of isolates by PCR, ELISA, and nucleic acid sequencing. Long-term persistence was defined as shedding for ≥ 6 months.</p> <p>Results</p> <p>Twenty-four children (15 HIV-infected, 9 HIV-uninfected) were enrolled, and 255 specimens (170 from HIV-infected, 85 from HIV-uninfected) were collected. All HIV-infected children had mildly or moderately symptomatic HIV-disease and moderate-to-severe immunosuppression. Fifteen participants shed vaccine-related polioviruses, and 22 shed NPEV at some point during the study period. Of 46 poliovirus-positive specimens, 31 were from HIV-infected, and 15 from HIV-uninfected children. No participant shed polioviruses for ≥ 6 months. Genomic sequencing of poliovirus isolates did not reveal any genetic evidence of long-term shedding. There was no long-term shedding of NPEV.</p> <p>Conclusion</p> <p>The results indicate that mildly to moderately symptomatic HIV-infected children retain the ability to clear enteroviruses, including vaccine-related poliovirus. Larger studies are needed to confirm and generalize these findings.</p

Evolution of reproductive development in the volvocine algae

The evolution of multicellularity, the separation of germline cells from sterile somatic cells, and the generation of a male–female dichotomy are certainly among the greatest innovations of eukaryotes. Remarkably, phylogenetic analysis suggests that the shift from simple to complex, differentiated multicellularity was not a unique progression in the evolution of life, but in fact a quite frequent event. The spheroidal green alga Volvox and its close relatives, the volvocine algae, span the full range of organizational complexity, from unicellular and colonial genera to multicellular genera with a full germ–soma division of labor and male–female dichotomy; thus, these algae are ideal model organisms for addressing fundamental issues related to the transition to multicellularity and for discovering universal rules that characterize this transition. Of all living species, Volvox carteri represents the simplest version of an immortal germline producing specialized somatic cells. This cellular specialization involved the emergence of mortality and the production of the first dead ancestors in the evolution of this lineage. Volvocine algae therefore exemplify the evolution of cellular cooperation from cellular autonomy. They also serve as a prime example of the evolution of complex traits by a few successive, small steps. Thus, we learn from volvocine algae that the evolutionary transition to complex, multicellular life is probably much easier to achieve than is commonly believed

Luminous efficiency based on FRIPON meteors and limitations of ablation models

Context. In meteor physics, the luminous efficiency τ is used to convert the meteor's magnitude to the corresponding meteoroid's mass. However, a lack of sufficiently accurate verification methods or adequate laboratory tests mean that discussions around this parameter are a subject of controversy. Aims: In this work, we aim to use meteor data obtained by the Fireball Recovery and InterPlanetary Observation to calculate the luminous efficiencies of the recorded meteors. We also show the limitations of the methods presented herein. Methods: Deceleration-based formulas were used to calculate the masses of the pre-atmospheric meteoroids. These can in turn be compared to the meteor brightnesses to assess the luminous efficiencies of the recorded objects. Fragmentation of the meteoroids is not considered within this model. Good measurements of the meteor deceleration are required. Results: We find τ-values, as well as the shape change coefficients, of 294 meteors and fireballs with determined masses in the range of 10^−6 / -100 kg. The derived τ-values have a median of τ_median = 2.17%. Most of them are of the order of 0.1-10%. We present how our values are obtained, compare them with data reported in the literature, and discuss several methods. A dependence of τ on the pre-atmospheric velocity of the meteor, ve, is noticeable with a relation of τ = 0.0023⋅ve^2.3. Furthermore, a dependence of τ on the initial meteoroid mass, Me, is found with negative linear behaviour in log-log space: τ = 0.48⋅Me/−0.47. Conclusions: The higher luminous efficiency of fast meteors could be explained by the higher amount of energy released. Fast meteoroids produce additional emission lines that radiate more efficiently in specific wavelengths due to the appearance of the so-called second component of higher temperature. Furthermore, the negative dependence of τ on Me implies that the radiation of smaller meteoroids is more efficient. The results of this study also show the limitations of the ablation-based model for the determination of the luminous efficiency