Spinal motoneuron firing properties mature from rostral to caudal during postnatal development of the mouse

Altricial mammals are born with immature nervous systems comprised of circuits that do not yet have the neuronal properties and connectivity required to produce future behaviours. During the critical period of postnatal development, neuronal properties are tuned to participate in functional circuits. In rodents, cervical motoneurons are born prior to lumbar motoneurons, and spinal cord development follows a sequential rostro‐caudal pattern. Here we asked whether birth order is reflected in the postnatal development of electrophysiological properties. We show that motoneurons of both regions have similar properties at birth and follow the same developmental profile, with maximal firing increasing and excitability decreasing into the third postnatal week. However, these maturative processes occur in cervical motoneurons prior to lumbar motoneurons, correlating with the maturation of premotor descending and local spinal systems. These results suggest that motoneuron properties do not mature by cell autonomous mechanisms alone, but also depend on developing premotor circuits

Sinus Histiocytosis with Massive Lymphadenopathy

Two cases of a recently described entity, 'sinus histiocytosis with massive lymphadenopathy,' occurring in Black males, are reported. Prominent cervical adenopathy was the main presenting feature in both. Histologically, these nodes were characterised by pronounced proliferation of sinus histiocytes which showed phagocytosis of blood cells, predominantly Iymphocytes. One of the patients has been followed up for 9 years and has remained clinically well despite persistence of the adenopathy. The importance of recognition of this condition is stressed in order to obviate unnecessarily radical therapy for a mistaken diagnosis of malignancy.S. Afr. Med. J., 48, 451 (1974

Passive cooling technology for photovoltaic panels for domestic houses

The efficiency of photovoltaic panels decreases as the panels' temperature increases, which results in deduction of electricity generation. In order to reduce this effect, different cooling methods were proposed and investigated. This paper reviews the previous work on cooling PV cells and concludes that the cost-effectiveness, design feasibility and minimal energy consumption are the important design consideration for cooling systems. Based on these considerations, this paper reports a passive cooling method that utilizes rainwater as cooling media and a gas expansion device to distribute the rainwater. The gas is thermally expanded from receiving solar radiation as such the amount of water it pushes to flow over the PV cells is proportional with the solar radiation it received. The paper reports a design and simulation of such a system for a domestic house application. In the paper, a relationship of the gas chamber size, solar radiation and gas expansion volume was established for evaluation with respect to the variation of gas temperature and the amount of rainwater used for cooling. A heat transfer model was used to evaluate the performance of the cells by cooling with this passive device. The results show that on a design day, the passive cooling system reduces the temperature of the cells and increases electrical efficiency of the PV panel by 8.3%. The payback period of this system is <14 years

Descending Systems Direct Development of Key Spinal Motor Circuits

The formation of mature spinal motor circuits is dependent on both activity-dependent and independent mechanisms during postnatal development. During this time, reorganization and refinement of spinal sensorimotor circuits occurs as supraspinal projections are integrated. However, specific features of postnatal spinal circuit development remain poorly understood. This study provides the first detailed characterization of rat spinal sensorimotor circuit development in the presence and absence of descending systems. We show that the development of proprioceptive afferent input to motoneurons (MNs) and Renshaw cells (RCs) is disrupted by thoracic spinal cord transection at postnatal day 5 (P5TX). P5TX also led to malformation of GABApre neuron axo–axonic contacts on Ia afferents and of the recurrent inhibitory circuit between MNs and RCs. Using a novel in situ perfused preparation for studying motor control, we show that malformation of these spinal circuits leads to hyperexcitability of the monosynaptic reflex. Our results demonstrate that removing descending input severely disrupts the development of spinal circuits and identifies key mechanisms contributing to motor dysfunction in conditions such as cerebral palsy and spinal cord injury

Space-efficient Feature Maps for String Alignment Kernels

String kernels are attractive data analysis tools for analyzing string data. Among them, alignment kernels are known for their high prediction accuracies in string classifications when tested in combination with SVM in various applications. However, alignment kernels have a crucial drawback in that they scale poorly due to their quadratic computation complexity in the number of input strings, which limits large-scale applications in practice. We address this need by presenting the first approximation for string alignment kernels, which we call space-efficient feature maps for edit distance with moves (SFMEDM), by leveraging a metric embedding named edit sensitive parsing (ESP) and feature maps (FMs) of random Fourier features (RFFs) for large-scale string analyses. The original FMs for RFFs consume a huge amount of memory proportional to the dimension d of input vectors and the dimension D of output vectors, which prohibits its large-scale applications. We present novel space-efficient feature maps (SFMs) of RFFs for a space reduction from O(dD) of the original FMs to O(d) of SFMs with a theoretical guarantee with respect to concentration bounds. We experimentally test SFMEDM on its ability to learn SVM for large-scale string classifications with various massive string data, and we demonstrate the superior performance of SFMEDM with respect to prediction accuracy, scalability and computation efficiency.Comment: Full version for ICDM'19 pape

Sacrococcygeal germ-cell tumours - the Red Cross War Memorial Children's hospital experience, 1980 - 1996

Objective. To document the experience of Red Cross War Memorial Children's Hospital in the treatment of sacrococcygeal germ-eell tumours.Patients. Twenty-seven patients with sacrococcygeal germ-cell tumours were treated in our hospital from 1980 to 1996.Design. A retrospective review of these patients' records was undertaken.Results. There were 19 female and 8 male patients. Seventeen (63%) presented in the neonatal period, 13 on the first day of life. Complete surgical resection of the tumour was achieved in all patients with mature or immature teratomas (20 patients) and in 2 neonates with malignant tumours. The first of these 2 neonates, with a malignant teratoma, was not given chemotherapy and remains well 10 years later. The second, with a yolk-sac tumour, also received no initial chemotherapy. He relapsed at the age of 9 months and was successfully treated with repeat excision and chemotherapy. All 5 patients first diagnosed after the age of 1 year had malignant tumours. These patients had incomplete surgical resection (3) or biopsy only (2), and 3 were successfully treated with chemotherapy. One patient relapsed with yolksac tumour after initial complete resection cif a mature teratoma. She was successfully treated with repeat surgery and chemotherapy

Angular adaptivity with spherical harmonics for Boltzmann transport

This paper describes an angular adaptivity algorithm for Boltzmann transport applications which uses Pn and filtered Pn expansions, allowing for different expansion orders across space/energy. Our spatial discretisation is specifically designed to use less memory than competing DG schemes and also gives us direct access to the amount of stabilisation applied at each node. For filtered Pn expansions, we then use our adaptive process in combination with this net amount of stabilisation to compute a spatially dependent filter strength that does not depend on a priori spatial information. This applies heavy filtering only where discontinuities are present, allowing the filtered Pn expansion to retain high-order convergence where possible. Regular and goal-based error metrics are shown and both the adapted Pn and adapted filtered Pn methods show significant reductions in DOFs and runtime. The adapted filtered Pn with our spatially dependent filter shows close to fixed iteration counts and up to high-order is even competitive with P0 discretisations in problems with heavy advection.Comment: arXiv admin note: text overlap with arXiv:1901.0492

Scalable angular adaptivity for Boltzmann transport

This paper describes an angular adaptivity algorithm for Boltzmann transport applications which for the first time shows evidence of $\mathcal{O}(n)$ scaling in both runtime and memory usage, where $n$ is the number of adapted angles. This adaptivity uses Haar wavelets, which perform structured $h$-adaptivity built on top of a hierarchical P$_0$ FEM discretisation of a 2D angular domain, allowing different anisotropic angular resolution to be applied across space/energy. Fixed angular refinement, along with regular and goal-based error metrics are shown in three example problems taken from neutronics/radiative transfer applications. We use a spatial discretisation designed to use less memory than competing alternatives in general applications and gives us the flexibility to use a matrix-free multgrid method as our iterative method. This relies on scalable matrix-vector products using Fast Wavelet Transforms and allows the use of traditional sweep algorithms if desired

In the face of threat: neural and endocrine correlates of impaired facial emotion recognition in cocaine dependence.

The ability to recognize facial expressions of emotion in others is a cornerstone of human interaction. Selective impairments in the recognition of facial expressions of fear have frequently been reported in chronic cocaine users, but the nature of these impairments remains poorly understood. We used the multivariate method of partial least squares and structural magnetic resonance imaging to identify gray matter brain networks that underlie facial affect processing in both cocaine-dependent (n = 29) and healthy male volunteers (n = 29). We hypothesized that disruptions in neuroendocrine function in cocaine-dependent individuals would explain their impairments in fear recognition by modulating the relationship with the underlying gray matter networks. We found that cocaine-dependent individuals not only exhibited significant impairments in the recognition of fear, but also for facial expressions of anger. Although recognition accuracy of threatening expressions co-varied in all participants with distinctive gray matter networks implicated in fear and anger processing, in cocaine users it was less well predicted by these networks than in controls. The weaker brain-behavior relationships for threat processing were also mediated by distinctly different factors. Fear recognition impairments were influenced by variations in intelligence levels, whereas anger recognition impairments were associated with comorbid opiate dependence and related reduction in testosterone levels. We also observed an inverse relationship between testosterone levels and the duration of crack and opiate use. Our data provide novel insight into the neurobiological basis of abnormal threat processing in cocaine dependence, which may shed light on new opportunities facilitating the psychosocial integration of these patients.This work was funded by a research grant from the Medical Research Council (G0701497) and supported by the infrastructure of the Behavioural and Clinical Neuroscience Institute (which is supported by a joint award from the Medical Research Council and the Wellcome Trust). This study was jointly sponsored by the Cambridge University Hospitals NHS Foundation Trust and the University of Cambridge. KD Ersche, CC Hagan, and PS Jones are supported by the Medical Research Council, and DG Smith by the Cambridge Overseas Trust.This is the final version of the article. It first appeared from NPG via http://dx.doi.org/10.1038/tp.2015.5