Two phase detonation studies

An experimental study of the passage of a shock wave over a burning fuel drop is described. This includes high speed framing photographs of the interaction taken at 500,000 frames per second. A theoretical prediction of the ignition of a fuel drop by a shock wave is presented and the results compared with earlier experimental work. Experimental attempts to generate a detonation in a liquid fuel drop (kerosene)-liquid oxidizer drop (hydrogen peroxide)-inert gas-environment are described. An appendix is included which gives the analytical prediction of power requirements for the drop generator to produce certain size drops at a certain mass rate. A bibliography is also included which lists all of the publications resulting from this research grant

Machine learning -- based diffractive imaging with subwavelength resolution

Far-field characterization of small objects is severely constrained by the diffraction limit. Existing tools achieving sub-diffraction resolution often utilize point-by-point image reconstruction via scanning or labelling. Here, we present a new imaging technique capable of fast and accurate characterization of two-dimensional structures with at least wavelength/25 resolution, based on a single far-field intensity measurement. Experimentally, we realized this technique resolving the smallest-available to us 180-nm-scale features with 532-nm laser light. A comprehensive analysis of machine learning algorithms was performed to gain insight into the learning process and to understand the flow of subwavelength information through the system. Image parameterization, suitable for diffractive configurations and highly tolerant to random noise was developed. The proposed technique can be applied to new characterization tools with high spatial resolution, fast data acquisition, and artificial intelligence, such as high-speed nanoscale metrology and quality control, and can be further developed to high-resolution spectroscop

Ejaculate allocation by male sand martins, Riparia riparia

Males of many species allocate sperm to ejaculates strategically in response to variation in the risk and intensity of sperm competition. The notable exception is passerine birds, in which evidence for strategic allocation is absent. Here we report the results of a study testing for strategic ejaculate allocation in a passerine bird, the sand martin (Riparia riparia). Natural ejaculates were collected from males copulating with a model female. Ejaculates transferred in the presence of a rival male contained significantly more sperm than ejaculates transferred in the absence of a rival male. There was no evidence that this difference was due to the confounding effects of the year of ejaculate collection, the identity of the model female, the colony, the stage of season or the period of the day in which ejaculates were collected. A more detailed examination of the ejaculate patterns of individual males, achieved by the DNA profiling of ejaculates, provided additional evidence for strategic allocation of sperm

Effect of prophylactic corticosteroids on the incidence of reactions in newly diagnosed multibacillary leprosy patients [5]

To the editor: Leprosy reactions, including reversal re-actions and episodes of neuritis, are known to occur in leprosy patients most frequently in the first few months after starting multidrug therapy (MDT), especially in cases with multibacillary (MB) disease. Such reactions can lead to impairment of nerve function, and subsequent deformity and disability. That this can occur in leprosy patients who present without any nerve function impairment (NFI) at diagnosis is a discouraging phenomenon for both the patient and the doctor or health worker.It is an axiom of modern leprosy controlthat early case detection and treatment with MDT can prevent much NFI by halting the multiplication of the leprosy bacillus, and that this is the single most important activity in the prevention of NFI. [...]<br/

Effect of prophylactic corticosteroids on the incidence of reactions in newly diagnosed multibacillary leprosy patients [5]

To the editor: Leprosy reactions, including reversal re-actions and episodes of neuritis, are known to occur in leprosy patients most frequently in the first few months after starting multidrug therapy (MDT), especially in cases with multibacillary (MB) disease. Such reactions can lead to impairment of nerve function, and subsequent deformity and disability. That this can occur in leprosy patients who present without any nerve function impairment (NFI) at diagnosis is a discouraging phenomenon for both the patient and the doctor or health worker.It is an axiom of modern leprosy controlthat early case detection and treatment with MDT can prevent much NFI by halting the multiplication of the leprosy bacillus, and that this is the single most important activity in the prevention of NFI. [...]<br/

A stochastic model for the evolution of the web allowing link deletion

Recently several authors have proposed stochastic evolutionary models for the growth of the web graph and other networks that give rise to power-law distributions. These models are based on the notion of preferential attachment leading to the ``rich get richer'' phenomenon. We present a generalisation of the basic model by allowing deletion of individual links and show that it also gives rise to a power-law distribution. We derive the mean-field equations for this stochastic model and show that by examining a snapshot of the distribution at the steady state of the model, we are able to tell whether any link deletion has taken place and estimate the link deletion probability. Our model enables us to gain some insight into the distribution of inlinks in the web graph, in particular it suggests a power-law exponent of approximately 2.15 rather than the widely published exponent of 2.1

“Fix the system … the people who are in it are not the ones that are broken” A qualitative study exploring UK academic researchers’ views on support at work

Recent evidence suggests that it remains difficult for academic researchers to preserve global well-being when working in the UK higher education sector. Our study aimed to explore academic researchers' perspectives on how they feel their mental health and well-being could be better supported within the UK higher education system. Using a combination of semi-structured and narrative interviewing techniques, we gathered the perspectives of 26 researchers. Narrative and reflexive thematic analysis were then used on the data collected. Our findings highlight the need to tackle systemic issues such job insecurity and unrealistically high workloads, given the risk they can pose to researchers' mental health and well-being. Our findings also highlight the key influence of managers and supervisors in creating a supportive environment, and the importance of going beyond what support is offered. That is, it is vital to effectively promote any existing or emerging support systems, and to be proactive in offering this support. Given the diversity identified in researchers’ individual situations, it is important that support is flexible and takes into consideration individual requirements and preferences. Higher education authorities and institutions need to determine how they can foster a healthy, caring environment for researchers working in this sector going forwards

Sensitivity and specificity of methods of classification of leprosy without use of skin-smear examination

A 12-month cohort of 2664 new leprosy cases in Bangladesh has been analyzed to provide information about the sensitivity and specificity of two different methods of classifying leprosy into paucibacillary (PB) and multibacillary (MB), if the results of skin-smear examination are not taken into account. The two methods are: 1) a procedure based on counting skin lesions recommended by the World Health Organization (WHO) (&lt;6 skin lesions = PB, ≥6 skin lesions = MB); and 2) the 'Bangladesh method' (&lt;10 skin and nerve lesions = PB, ≥10 skin and nerve lesions = MB). In the latter system, any degree of nerve enlargement is taken to be a nerve lesion. The WHO method was found to be 89% sensitive and 88% specific at detecting smear-positive MB cases from among the cohort; the Bangladesh system, 92% sensitive and 88.6% specific. The WHO method did not detect 18 smear-positive cases as MN; the Bangladesh method left 13 smear-positive cases unclassified as MB. Several of these 'missed' (false-negative) cases had a high bacterial index. The WHO system of classifying leprosy cases as MB is simple to apply and has a reasonable balance between sensitivity and specificity. However, it must be recognized that the system will lead to a small but significant number of skin-smear-positive MB cases being treated with a PB treatment regimen.</p

Sensitivity and specificity of methods of classification of leprosy without use of skin-smear examination

A 12-month cohort of 2664 new leprosy cases in Bangladesh has been analyzed to provide information about the sensitivity and specificity of two different methods of classifying leprosy into paucibacillary (PB) and multibacillary (MB), if the results of skin-smear examination are not taken into account. The two methods are: 1) a procedure based on counting skin lesions recommended by the World Health Organization (WHO) (&lt;6 skin lesions = PB, ≥6 skin lesions = MB); and 2) the 'Bangladesh method' (&lt;10 skin and nerve lesions = PB, ≥10 skin and nerve lesions = MB). In the latter system, any degree of nerve enlargement is taken to be a nerve lesion. The WHO method was found to be 89% sensitive and 88% specific at detecting smear-positive MB cases from among the cohort; the Bangladesh system, 92% sensitive and 88.6% specific. The WHO method did not detect 18 smear-positive cases as MN; the Bangladesh method left 13 smear-positive cases unclassified as MB. Several of these 'missed' (false-negative) cases had a high bacterial index. The WHO system of classifying leprosy cases as MB is simple to apply and has a reasonable balance between sensitivity and specificity. However, it must be recognized that the system will lead to a small but significant number of skin-smear-positive MB cases being treated with a PB treatment regimen.</p

Detecting periodicity in experimental data using linear modeling techniques

Fourier spectral estimates and, to a lesser extent, the autocorrelation function are the primary tools to detect periodicities in experimental data in the physical and biological sciences. We propose a new method which is more reliable than traditional techniques, and is able to make clear identification of periodic behavior when traditional techniques do not. This technique is based on an information theoretic reduction of linear (autoregressive) models so that only the essential features of an autoregressive model are retained. These models we call reduced autoregressive models (RARM). The essential features of reduced autoregressive models include any periodicity present in the data. We provide theoretical and numerical evidence from both experimental and artificial data, to demonstrate that this technique will reliably detect periodicities if and only if they are present in the data. There are strong information theoretic arguments to support the statement that RARM detects periodicities if they are present. Surrogate data techniques are used to ensure the converse. Furthermore, our calculations demonstrate that RARM is more robust, more accurate, and more sensitive, than traditional spectral techniques.Comment: 10 pages (revtex) and 6 figures. To appear in Phys Rev E. Modified styl