Lee-yang zeros and the complexity of the ferromagnetic ising model on bounded-degree graphs

We study the computational complexity of approximating the partition function of the ferromagnetic Ising model in the Lee-Yang circle of zeros given by |λ| = 1, where λ is the external field of the model. Complex-valued parameters for the Ising model are relevant for quantum circuit computations and phase transitions in statistical physics, but have also been key in the recent deterministic approximation scheme for all |λ| ≠ 1 by Liu, Sinclair, and Srivastava. Here, we focus on the unresolved complexity picture on the unit circle, and on the tantalising question of what happens in the circular arc around λ = 1, where on one hand the classical algorithm of Jerrum and Sinclair gives a randomised approximation scheme on the real axis suggesting tractability, and on the other hand the presence of Lee-Yang zeros alludes to computational hardness. Our main result establishes a sharp computational transition at the point λ = 1; in fact, our techniques apply more generally to the whole unit circle |λ| = 1. We show #P-hardness for approximating the partition function on graphs of maximum degree Δ when b, the edge-interaction parameter, is in the interval [EQUATION] and λ is a non-real on the unit circle. This result contrasts with known approximation algorithms when |λ| ≠ 1 or [EQUATION], and shows that the Lee-Yang circle of zeros is computationally intractable, even on bounded-degree graphs. Our inapproximability result is based on constructing rooted tree gadgets via a detailed understanding of the underlying dynamical systems, which are further parameterised by the degree of the root. The ferromagnetic Ising model has radically different behaviour than previously considered anti-ferromagnetic models, and showing our #P-hardness results in the whole Lee-Yang circle requires a new high-level strategy to construct the gadgets. To this end, we devise an elaborate inductive procedure to construct the required gadgets by taking into account the dependence between the degree of the root of the tree and the magnitude of the derivative at the fixpoint of the corresponding dynamical system

The African Hospitalist Fellowship

The African Paediatric Fellowship Programme is rolling out a training course for newly qualified paediatricians to equip them with the leadership skills to function in complex general paediatric settings. The care of children in Africa carries its own unique demands, from the layering effects of multiple conditions through to establishing and sustaining services under severe resource constraints. This novel training concept aims to strengthen confidence and knowledge in areas that are not priorities during standard general paediatric training. The skills gained are considered of great relevance in assisting general paediatricians to achieve their full potential in their careers

Infected epidermal cyst of the clitoris in an infant

Clitoral enlargement in the pediatric population is a rare condition, usually related to problems of sexual differentiation, but malignant and benign clitoral lesions have also been described. We report the case of a newborn infant, investigated at birth for an intersex disorder because of clitoromegaly. Hormonal screening was normal and ultrasound (US) did not show a pelvic or abdominal mass. Three weeks later, the lesion was larger, tense and erythematous. An abscess was suspected. A drainage was then performed, and the bacteriological culture revealed the presence of Staphylococci aurei. A magnetic resonance imaging (MRI) performed to exclude a tumor of the soft tissue was normal. A diagnosis of infected epidermal cyst was confirmed by the pathology. Two months later, the external genital aspect was normal and the child asymptomatic

Predictive factors at birth of the severity of gastroschisis.

To establish children born with gastroschisis (GS). We performed a retrospective study covering the period from January 2000 to December 2007. The following variables were analyzed for each child: Weight, sex, apgar, perforations, atresia, volvulus, bowel lenght, subjective description of perivisceritis, duration of parenteral nutrition, first nasogastric milk feeding, total milk feeding, necrotizing enterocolitis, average period of hospitalization and mortality. For statistical analysis, descriptive data are reported as mean ± standard deviation and median (range). The non parametric test of Mann-Whitney was used. The threshold for statistical significance was P < 0.05 (Two-Tailed). Sixty-eight cases of GS were studied. We found nine cases of perforations, eight of volvulus, 12 of atresia and 49 children with subjective description of perivisceritis (72%). The mortality rate was 12% (eight deaths). Average duration of total parenteral nutrition was 56.7 d (8-950; median: 22), with five cases of necrotizing enterocolitis. Average length of hospitalization for 60 of our patients was 54.7 d (2-370; median: 25.5). The presence of intestinal atresia was the only factor correlated with prolonged parenteral nutrition, delayed total oral milk feeding and longer hospitalization. In our study, intestinal atresia was our predictive factor of the severity of GS

Real-time marker-less multi-person 3D pose estimation in RGB-Depth camera networks

This paper proposes a novel system to estimate and track the 3D poses of multiple persons in calibrated RGB-Depth camera networks. The multi-view 3D pose of each person is computed by a central node which receives the single-view outcomes from each camera of the network. Each single-view outcome is computed by using a CNN for 2D pose estimation and extending the resulting skeletons to 3D by means of the sensor depth. The proposed system is marker-less, multi-person, independent of background and does not make any assumption on people appearance and initial pose. The system provides real-time outcomes, thus being perfectly suited for applications requiring user interaction. Experimental results show the effectiveness of this work with respect to a baseline multi-view approach in different scenarios. To foster research and applications based on this work, we released the source code in OpenPTrack, an open source project for RGB-D people tracking.Comment: Submitted to the 2018 IEEE International Conference on Robotics and Automatio

Soluble Guanylate Cyclase Generation of cGMP Regulates Migration of MGE Neurons

Here we have provided evidence that nitric oxide-cyclic GMP (NO-cGMP) signaling regulates neurite length and migration of immature neurons derived from the medial ganglionic eminence (MGE). Dlx1/2(-/-) and Lhx6(-/-) mouse mutants, which exhibit MGE interneuron migration defects, have reduced expression of the gene encoding the alpha subunit of a soluble guanylate cyclase (Gucy1A3). Furthermore, Dlx1/2(-/-) mouse mutants have reduced expression of NO synthase 1 (NOS1). Gucy1A3(-/-) mice have a transient reduction in cortical interneuron number. Pharmacological inhibition of soluble guanylate cyclase and NOS activity rapidly induces neurite retraction of MGE cells in vitro and in slice culture and robustly inhibits cell migration from the MGE and caudal ganglionic eminence. We provide evidence that these cellular phenotypes are mediated by activation of the Rho signaling pathway and inhibition of myosin light chain phosphatase activity

An adapted triage tool (ETAT) at Red Cross War Memorial Children’s Hospital Medical Emergency Unit, Cape Town: An evaluation

Objective. To evaluate the efficacy of an adapted Emergency Triage Assessment and Treatment (ETAT) tool at a children’s hospital. Design. A two-armed descriptive study. Setting. Red Cross War Memorial Children’s Hospital, Cape Town, South Africa. Methods. Triage data on 1 309 children from October 2007 and July 2009 were analysed. The number of children in each triage category (red (emergency), orange (urgent or priority) and green (non-urgent)) and their disposal were evaluated. Results. 1. The October 2007 series: 902 children aged 5 days - 15 years were evaluated. Their median age was 20 (interquartile range (IQR) 7 - 50) months, and 58.8% (n=530) were triaged green, 37.5% (n=338) orange and 3.8% (n=34) red. Over 90% of children in the green category were discharged (478/530), while 32.5% of children triaged orange (110/338) and 52.9% of children triaged red (18/34) were admitted. There was a significant increase in admission rate for each triage colour change from green through orange to red after adjustment for age category (risk ratio (RR) 2.6; 95% confidence interval (CI) 2.2 - 3.1). 2. The July 2009 cohort: 407 children with a median age of 22 months (IQR 7 - 53 months) were enrolled. Twelve children (2.9%) were triaged red, 187 (45.9%) orange and 208 (51.1%) green. A quarter (101/407) of the children triaged were admitted: 91.7% (11/12) from the red category and 36.9% (69/187) from the orange category were admitted, while 89.9% of children in the green category (187/208) were discharged. After adjusting for age category, admissions increased by more than 300% for every change in triage acuity (RR 3.2; 95% CI 2.5 - 4.1). Conclusions. The adapted ETAT process may serve as a reliable triage tool for busy paediatric medical emergency units in resource-constrained countries and could be evaluated further in community emergency settings

An adapted triage tool (ETAT) at Red Cross War Memorial Children’s Hospital Medical Emergency Unit, Cape Town: An evaluation

Objective. To evaluate the efficacy of an adapted Emergency Triage Assessment and Treatment (ETAT) tool at a children’s hospital. Design. A two-armed descriptive study. Setting. Red Cross War Memorial Children’s Hospital, Cape Town, South Africa. Methods. Triage data on 1 309 children from October 2007 and July 2009 were analysed. The number of children in each triage category (red (emergency), orange (urgent or priority) and green (non-urgent)) and their disposal were evaluated. Results. 1. The October 2007 series: 902 children aged 5 days - 15 years were evaluated. Their median age was 20 (interquartile range (IQR) 7 - 50) months, and 58.8% (n=530) were triaged green, 37.5% (n=338) orange and 3.8% (n=34) red. Over 90% of children in the green category were discharged (478/530), while 32.5% of children triaged orange (110/338) and 52.9% of children triaged red (18/34) were admitted. There was a significant increase in admission rate for each triage colour change from green through orange to red after adjustment for age category (risk ratio (RR) 2.6; 95% confidence interval (CI) 2.2 - 3.1). 2. The July 2009 cohort: 407 children with a median age of 22 months (IQR 7 - 53 months) were enrolled. Twelve children (2.9%) were triaged red, 187 (45.9%) orange and 208 (51.1%) green. A quarter (101/407) of the children triaged were admitted: 91.7% (11/12) from the red category and 36.9% (69/187) from the orange category were admitted, while 89.9% of children in the green category (187/208) were discharged. After adjusting for age category, admissions increased by more than 300% for every change in triage acuity (RR 3.2; 95% CI 2.5 - 4.1). Conclusions. The adapted ETAT process may serve as a reliable triage tool for busy paediatric medical emergency units in resource-constrained countries and could be evaluated further in community emergency settings