Field Theory Expansions of String Theory Amplitudes.

Motivated by quantum field theory (QFT) considerations, we present new representations of the Euler-Beta function and tree-level string theory amplitudes using a new two-channel, local, crossing symmetric dispersion relation. Unlike standard series representations, the new ones are analytic everywhere except at the poles, sum over poles in all channels, and include contact interactions, in the spirit of QFT. This enables us to consider mass-level truncation, which preserves all the features of the original amplitudes. By starting with such expansions for generalized Euler-Beta functions and demanding QFT-like features, we single out the open superstring amplitude. We demonstrate the difficulty in deforming away from the string amplitude and show that a class of such deformations can be potentially interesting when there is level truncation. Our considerations also lead to new QFT-inspired, parametric representations of the Zeta function and π, which show fast convergence.

Musculoskeletal and Esthetic Complications after Neonatal Thoracotomy: Revisited.

Aim: The aim is to study the complications of neonatal thoracotomy and its preventive measures. Methods: We retrospectively reviewed 53 neonates who underwent thoracotomy from January 2017 to December 2019 for a period of 3 years. Patient demographic data, primary disease for which they underwent thoracotomy, postoperative complications (immediate and delayed) during follow-up were documented. Results: During 3-year period, 53 neonates underwent thoracotomy for various surgical pathologies. The indications were esophageal atresia with tracheoesophageal fistula (n = 49), eventration of diaphragm (n = 3), congenital lobar emphysema of left upper lobe of lung (n = 1). Most of them were right posterolateral thoracotomies (n = 48, 90.56%) and left posterolateral thoracotomy was done in only 5 cases (9.43%). Associated anomalies were seen in 22 cases, such as cardiac (n = 19), renal (n = 4) and gastrointestinal (n = 5). Associated comorbidities seen in 14 cases; preterm (n = 4), low birth weight (n = 13), delayed presentation (n = 6). Early postoperative complications such as pneumonia (34%, n = 18) and wound infection (11.3%, n = 6) were noted. Delayed complications include musculoskeletal abnormalities (n = 19, 35.8%) and esthetic complications such as asymmetry of chest (5.6%). Conclusion: Neonatal thoracotomy is associated with complications such as pneumonia, wound infections, and musculoskeletal abnormalities such as asymmetry of chest and scoliosis. These can be prevented by adequate postoperative pain relief, muscle-sparing thoracotomies, avoiding tight closures, and nerve injuries. Long-term follow-up is required because these complications may manifest later on also. Early detection and institution of physiotherapy may help.

Reentrant melting of lanes of rough circular disks.

We consider binary suspension of rough, circular particles in two dimensions under athermal conditions. The suspension is subject to a time-independent external drive in response to which half of the particles are pulled along the field direction, whereas the other half is pushed in the opposite direction. Simulating the system with different magnitude of external drive in steady state, we obtain oppositely moving macroscopic lanes only for a moderate range of external drive. Below as well as above the range we obtain states with no lane. Hence we find that the no-lane state reenters along the axis of the external drive in the nonequilibrium phase diagram corresponding to the laning transition, with varying roughness of individual particles and external drive. Interparticle friction (contact dissipation) due to the roughness of the individual particle is the main player behind the reentrance of the no-lane state at high external drives.

Orbital magnetism of an active particle in viscoelastic suspension.

We consider an active (self-propelling) particle in a viscoelastic fluid. The particle is charged and constrained to move in a two-dimensional harmonic trap. Its dynamics is coupled to a constant magnetic field applied perpendicular to its plane of motion via Lorentz force. Due to the finite activity, the generalized fluctuation-dissipation relation (GFDR) breaks down, driving the system away from equilibrium. While breaking GFDR, we have shown that the system can have finite classical orbital magnetism only when the dynamics of the system contains finite inertia. The orbital magnetic moment has been calculated exactly. Remarkably, we find that when the elastic dissipation timescale of the medium is larger (smaller) than the persistence timescale of the self-propelling particle, it is diamagnetic (paramagnetic). Therefore, for a given strength of the magnetic field, the system undergoes a transition from diamagnetic to paramagnetic state (and vice versa) simply by tuning the timescales of underlying physical processes, such as active fluctuations and viscoelastic dissipation. Interestingly, we also find that the magnetic moment, which vanishes at equilibrium, behaves nonmonotonically with respect to increasing persistence of self-propulsion, which drives the system out of equilibrium.

Delayed presentation of anorectal malformations in a tertiary care hospital in India.

AIM: To study delayed presentation of ARMs, management and its effect on surgical and functional complications. METHODS: It is a retrospective study from March 2015 to March 2020. All the patients satisfying the criteria of delayed ARMs, i.e., presenting 7 days after birth were included. Information regarding type of ARM, mode of presentation, time of presentation, associated anomalies, management strategy, postoperative complications and functional outcome was noted. Minimum follow-up period was 6 months. RESULTS: Out of 102 patients with ARM, 44 patients presented late. Among the 44 patients, 9 were males and 35 were females. Associated comorbidities observed are low birth weight (n = 9) and preterm (n = 13). Associated anomalies observed were cardiac (n = 18), renal (n = 8), other gastrointestinal (n = 5) and skeletal (n = 1). (1) Male: rectourethral fistula-2 (staged repair), anal stenosis-3 (anoplasty) and anocutaneous fistula-4 (anoplasty). (2) Female: vestibular fistula: 15 (6 primary definitive surgery + 9 staged repair), ectopic anus: 3 (staged repair), anal stenosis: 2 (anoplasty), urogenital sinus: 4 (staged repair), H-type ARM: 8 (staged repair) and persistent cloaca: 3 (staged repair). Primary repair was done in 15 patients (34%), and staged repair was done in 29 patients (65.9%). Anoplasty was done in 9 patients, ASARP (modified tsuchida's procedure) in 8 patients and PSARP in 27 patients. Postoperative complications observed were constipation (n = 21, 47.7%), fecal incontinence (n = 12, 27.27%) with perianal excoriation in 2 patients, anal stenosis (n = 3, 6.8%) and rectal mucosal prolapse (n = 2, 4.5%) CONCLUSION: Delayed presentation of ARMs is not uncommon and is more common in females. Management is almost similar to those who present early. Those who present with chronic constipation and megarectum require staged repair. Complications were more frequent with delayed presentation. Hence, every newborn should have careful examination of perineum and screened for ARM to avoid possible morbidity and mortality.

Stochastic heat engine using an active particle.

The topic of microscopic heat engine has undergone intensive research in recent years. Microscopic heat engines can exploit thermal as well as active fluctuations to extract thermodynamic work. We investigate the properties of a microscopic Stirling's engine that uses an active (self-propelling) particle as a working substance, in contact with two thermal baths. It is shown that the presence of activity leads to an enhanced performance of the engine. The efficiency can be improved by increasing the activity strength for all cycle time, including the nonquasistatic regime. We verify that the analytical results agree very well with our simulations. The variation of efficiency with the temperature difference between the two thermal baths has also been explored. The optimum region of operation of the engine has been deduced, by using its efficient power (product of efficiency and power) as a quantifier. Finally, a simple model is provided that emulates the behavior of a flywheel driven by this engine.

Tuning the self-organization of confined active particles by the steepness of the trap.

We consider the collective dynamics of self-propelling particles in two dimensions. They can align themselves according to the direction of propulsion of their neighbours, together with small rotational fluctuations. They also interact with each other via soft, isotropic, repulsive potentials. The particles are confined in a circular trap. The steepness of the trap is tuneable. The average packing fraction of the particles is low. When the trap is steep, particles flock along its boundary. They form a polar cluster that spreads over the boundary. The cluster is not spatially ordered. We show that when the steepness is decreased beyond a threshold value, the cluster becomes round and compact and eventually spatial order (hexagonal) emerges in addition to the pre-established polar order. We investigate the kinetics of such ordering. We find that while rotating around the centre of the trap along its circular boundary, the cluster needs to roll around its centre of mass to be spatially ordered. We have studied the stability of the order when the trap is suddenly switched off. We find that for the particles with velocity alignment interaction, the decay of the spatial order is much slower than the particles without the alignment interaction.

Correction: BMPER Promotes Epithelial-Mesenchymal Transition in the Developing Cardiac Cushions.

[This corrects the article DOI: 10.1371/journal.pone.0139209.].

Active particle condensation by non-reciprocal and time-delayed interactions.

We consider the flocking of self-propelling agents in two dimensions, each of which communicates with its neighbors within a limited vision-cone. Also, the communication occurs with some time-delay. The communication among the agents are modeled by Vicsek rules. In this study we explore the combined effect of non-reciprocal interaction (induced by limited vision-cone) among the agents and the presence of delay in the interactions on the dynamical pattern formation within the flock. We find that under these two influences, without any position-based attractive interactions or confining boundaries, the agents can spontaneously condense into "drops". Though the agents are in motion within the drop, the drop as a whole is pinned in space. We find that this novel state of the flock has a well-defined order and it is stabilized by the noise present in the system.

Ambiguous genitalia-A social dilemma in Bangladesh: A case report.

INTRODUCTION: Ambiguous Genitalia is a form of birth defect in which sex of the newborn cannot be readily distinguishable because of atypical appearance of the external genitalia. CASE REPORT-CLINICAL FINDINGS: The patient, an 8 months old baby, was identified as a female baby since birth; but, some senior members of their neighborhood raised confusion regarding sex differentiation of the child. On examination, there was enlarged clitoris or micropenis, bifid scrotum or labioscrotal fold, and separate presence of urethral and vaginal orifices. Right testis was found in the middle of right inguinal canal and left testis was found near the deep inguinal ring. CASE REPORT-DIAGNOSIS, THERAPEUTIC INTERVENTION AND OUTCOME: The ultrasonogram showed a rudimentary uterus measuring 26.7×7.27mm with no ovary and the right testis was found in the mid inguinal canal while the left testis was in the deep inguinal ring. Diagnostic endoscopic procedure showed normal appearing testes in deep inguinal ring, about 2cm vaginal remnant with normal urethra and bladder. Hormonal study revealed low serum testosterone with normal DHT and high oestradiol while the karyotyping revealed 46XY. After 3 months of hormonal treatment, multiple surgical interventions were taken to correctly determine the sex of the child. Later on the patient was discharged with follow up advices. CONCLUSION: 'Ambiguous genitalia' is considered as a taboo in Bangladesh; hence, the social awareness regarding this curable disorder is a timely need in Bangladesh.

Determining Physical Properties of the Cell Cortex.

Actin and myosin assemble into a thin layer of a highly dynamic network underneath the membrane of eukaryotic cells. This network generates the forces that drive cell- and tissue-scale morphogenetic processes. The effective material properties of this active network determine large-scale deformations and other morphogenetic events. For example, the characteristic time of stress relaxation (the Maxwell time τM) in the actomyosin sets the timescale of large-scale deformation of the cortex. Similarly, the characteristic length of stress propagation (the hydrodynamic length λ) sets the length scale of slow deformations, and a large hydrodynamic length is a prerequisite for long-ranged cortical flows. Here we introduce a method to determine physical parameters of the actomyosin cortical layer in vivo directly from laser ablation experiments. For this we investigate the cortical response to laser ablation in the one-cell-stage Caenorhabditis elegans embryo and in the gastrulating zebrafish embryo. These responses can be interpreted using a coarse-grained physical description of the cortex in terms of a two-dimensional thin film of an active viscoelastic gel. To determine the Maxwell time τM, the hydrodynamic length λ, the ratio of active stress Î¶Δµ, and per-area friction γ, we evaluated the response to laser ablation in two different ways: by quantifying flow and density fields as a function of space and time, and by determining the time evolution of the shape of the ablated region. Importantly, both methods provide best-fit physical parameters that are in close agreement with each other and that are similar to previous estimates in the two systems. Our method provides an accurate and robust means for measuring physical parameters of the actomyosin cortical layer. It can be useful for investigations of actomyosin mechanics at the cellular-scale, but also for providing insights into the active mechanics processes that govern tissue-scale morphogenesis.

Dynamical density functional theory for microswimmers.

Dynamical density functional theory (DDFT) has been successfully derived and applied to describe on one hand passive colloidal suspensions, including hydrodynamic interactions between individual particles. On the other hand, active "dry" crowds of self-propelled particles have been characterized using DDFT. Here, we go one essential step further and combine these two approaches. We establish a DDFT for active microswimmer suspensions. For this purpose, simple minimal model microswimmers are introduced. These microswimmers self-propel by setting the surrounding fluid into motion. They hydrodynamically interact with each other through their actively self-induced fluid flows and via the common "passive" hydrodynamic interactions. An effective soft steric repulsion is also taken into account. We derive the DDFT starting from common statistical approaches. Our DDFT is then tested and applied by characterizing a suspension of microswimmers, the motion of which is restricted to a plane within a three-dimensional bulk fluid. Moreover, the swimmers are confined by a radially symmetric trapping potential. In certain parameter ranges, we find rotational symmetry breaking in combination with the formation of a "hydrodynamic pumping state," which has previously been observed in the literature as a result of particle-based simulations. An additional instability of this pumping state is revealed.

BMPER Promotes Epithelial-Mesenchymal Transition in the Developing Cardiac Cushions.

Formation of the cardiac valves is an essential component of cardiovascular development. Consistent with the role of the bone morphogenetic protein (BMP) signaling pathway in cardiac valve formation, embryos that are deficient for the BMP regulator BMPER (BMP-binding endothelial regulator) display the cardiac valve anomaly mitral valve prolapse. However, how BMPER deficiency leads to this defect is unknown. Based on its expression pattern in the developing cardiac cushions, we hypothesized that BMPER regulates BMP2-mediated signaling, leading to fine-tuned epithelial-mesenchymal transition (EMT) and extracellular matrix deposition. In the BMPER-/- embryo, EMT is dysregulated in the atrioventricular and outflow tract cushions compared with their wild-type counterparts, as indicated by a significant increase of Sox9-positive cells during cushion formation. However, proliferation is not impaired in the developing BMPER-/- valves. In vitro data show that BMPER directly binds BMP2. In cultured endothelial cells, BMPER blocks BMP2-induced Smad activation in a dose-dependent manner. In addition, BMP2 increases the Sox9 protein level, and this increase is inhibited by co-treatment with BMPER. Consistently, in the BMPER-/- embryos, semi-quantitative analysis of Smad activation shows that the canonical BMP pathway is significantly more active in the atrioventricular cushions during EMT. These results indicate that BMPER negatively regulates BMP-induced Smad and Sox9 activity during valve development. Together, these results identify BMPER as a regulator of BMP2-induced cardiac valve development and will contribute to our understanding of valvular defects.

Phylogeny and synonymous codon usage pattern of Papaya ringspot virus coat protein gene in the sub-Himalayan region of north-east India.

Sub-Himalayan West Bengal is favorable for the production of several fruits and vegetables. Papaya is one of the common plants cultivated in the area. Most of the papaya plants of the area are susceptible to Papaya ringspot virus (PRSV). Coat protein genes of 6 PRSV isolates of the area were sequenced following RT-PCR. Phylogenetic study of the PRSV isolates showed about 80%-90% similarity with Cuban isolates. The codon usage pattern of our isolates was also analyzed, along with several other isolates. PRSV isolates of our study showed a preference for 8 putative optimal codons. Correspondence analysis of the genes of different isolates along the first 2 major axes were done, as the first 2 axes contributed more in shaping codon usage pattern. In the phylogenetic tree constructed by the neighbour-joining method, our isolates clustered together with the east Indian, north Indian, and Bangladeshi isolates. The diversity and codon usage pattern of the PRSV isolates of different regions were studied, and it was observed that the codon usage pattern of PRSV isolates is probably influenced by translational selection along with mutational bias.

Rapidly Fatal Silicosis Among Jewellery Workers Attending a District Medical College of West Bengal, India.

BACKGROUND: Silicosis is a slowly progressive chronic occupational lung disease, developed after a prolong period of exposure to high concentration of silica dust. METHODS: In this longitudinal study, we enrolled old and new silicosis patients (n=19; 8 jewellery polishers, 11 from other occupations) seen at our Pulmonary Medicine Department from June 2009 to December 2012 to document the course of illness as per their occupational exposure. RESULTS: Six of the eight jewellery polishing workers had developed silicosis within five years of exposure, while six of the 11 other workers with other occupational exposure had developed silicosis after exposure of 10 years or more. Mean duration of exposure was significantly less among jewellery polishing workers compared to other workers (3.4 +/- 1.7 versus 9.3 +/- 4.1; p=0.001). Mean duration of illness (months) (14.9 +/- 5.8 versus 28.5 +/- 16.5; p=0.040) were significantly less among the jewellery polishing workers compared to other workers. At the end of the study period, all eight jewellery polishing workers with silicosis had died while four of the 11 patients with other occupational exposure had died. CONCLUSION: Silicosis among jewellery polishing workers was found to be more severe and progressive compared to silicosis due to other occupational exposures, in our study.

Bilateral pleural effusion with APLA positivity in a case of rhupus syndrome.

Rhupus syndrome is a rare syndrome characterized by overlap of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Our patient was a diagnosed case of RA and developed SLE 2 years after. She was a middle-aged woman, presented with bilateral pleural effusion with exacerbation of skin and joint symptoms of SLE. We diagnosed the case as tubercular pleural effusion by positive Mycobacterium tuberculosis in bactec 460 culture. She had also anti-phospholipid antibody positivity without any symptoms and signs of thrombosis.

Single-particle stochastic heat engine.

We have performed an extensive analysis of a single-particle stochastic heat engine constructed by manipulating a Brownian particle in a time-dependent harmonic potential. The cycle consists of two isothermal steps at different temperatures and two adiabatic steps similar to that of a Carnot engine. The engine shows qualitative differences in inertial and overdamped regimes. All the thermodynamic quantities, including efficiency, exhibit strong fluctuations in a time periodic steady state. The fluctuations of stochastic efficiency dominate over the mean values even in the quasistatic regime. Interestingly, our system acts as an engine provided the temperature difference between the two reservoirs is greater than a finite critical value which in turn depends on the cycle time and other system parameters. This is supported by our analytical results carried out in the quasistatic regime. Our system works more reliably as an engine for large cycle times. By studying various model systems, we observe that the operational characteristics are model dependent. Our results clearly rule out any universal relation between efficiency at maximum power and temperature of the baths. We have also verified fluctuation relations for heat engines in time periodic steady state.

Extracting work from a single heat bath: a case study of a Brownian particle under an external magnetic field in the presence of information.

Work can be extracted from a single bath beyond the limit set by the second law of thermodynamics by performing measurement on the system and utilizing the acquired information. This imposes an upper bound on extracted work and maintains a generalized (i.e., with information) second law. As an example, we studied a Brownian particle confined in a two-dimensional harmonic trap in the presence of a magnetic field, whose position coordinates are measured with finite precision. Two separate cases are investigated in this study: (A) moving the center of the potential and (B) varying the stiffness of the potential. Optimal protocols that extremize the work in a finite-time process are explicitly calculated for these two cases. For case A, we show that even though the optimal protocols depend on magnetic field, surprisingly, extracted work is independent of the field. For case B, both the optimal protocol and the extracted work depend on the magnetic field. However, the presence of a magnetic field always reduces the extraction of work for the latter case.

Beyond the "coffee ring": re-entrant ordering in an evaporation-driven self-assembly in a colloidal suspension on a substrate.

We study the phenomenon of evaporation-driven self-assembly of a colloid suspension of silica microspheres in the interior region and away from the rim of the droplet on a glass plate. In view of the importance of achieving a large-area, monolayer assembly, we first realize a suitable choice of experimental conditions, minimizing the influence of many other competing phenomena that usually complicate the understanding of fundamental concepts of such self-assembly processes in the interior region of a drying droplet. Under these simplifying conditions to bring out essential aspects, our experiments unveil an interesting competition between ordering and compaction in such drying systems in analogy to an impending glass transition. We establish a re-entrant behavior in the order-disorder phase diagram as a function of the particle density, such that there is an optimal range of the particle density to realize the long-range ordering. The results are explained with the help of simulations and phenomenological theory.

Colloidal particles in a drying suspension: a phase field crystal approach.

Using a phase field crystal model we study the structure and dynamics of a drop of colloidal suspension during evaporation of the solvent. We model an experimental system where contact line pinning of the drop on the substrate is non-existent. Under such carefully controlled conditions, evaporation of the drop produces an ordered or disordered arrangement of the colloidal residue depending only on the initial average density of solute and the drying rate. We obtain a non-equilibrium phase boundary showing amorphous and crystalline phases of single component and binary mixtures of colloidal particles in the density-drying rate plane. While single-component colloids order in the two-dimensional triangular lattice, a symmetric binary mixture of mutually repulsive particles can be ordered into three triangular sub-lattices in two dimensions. Two of them are occupied by the two species of particles with the third sub-lattice vacant.