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There have been sporadic reports of babies born after post-humous conception since the technology became available 50 years ago. Most commonly, a young man has an illness which threatens his [...], It is possible to retrieve viable sperm from a dying man or from a recently dead body. This sperm can be frozen for later use by his wife or partner to produce his genetic offspring. But the technical feasibility alone does not morally justify such an endeavour. Posthumous semen retrieval raises questions about consent, the respectful treatment of the dead body, and the welfare of the child to be. We present two cases, discuss these three issues, and conclude that such requests should generally not be honoured unless there is convincing evidence that the dead man would want his widow to carry and bear his child. Even with consent, the welfare of the potential child must be considered.

The Diviner Lunar Radiometer Experiment on the Lunar Reconnaissance Orbiter has been acquiring visible and infrared radiance measurements of the Moon for nearly 10 years. These data have been compiled into polar stereographic maps of temperatures poleward of 80° latitude at fixed local times and fixed subsolar longitudes to provide an overview of diurnal temperatures of the polar regions. The data have been divided into winter and summer seasons, defined by the times of year when the subsolar latitude is above or below the equator, to characterize the variations in seasonal temperatures that result from the 1.54° angle between the Moon's spin pole and the ecliptic plane. Since the illumination in the polar regions is perpetually at grazing angles, topography plays a dominate role in surface temperatures. Consequently, the surface and near‐surface thermal environment can vary in complex ways with time of day and season, which produces areas that are seasonally shadowed for prolonged periods and that are much more extensive than the permanently shadowed regions (PSRs). We find that surfaces below 110 K capable of cold trapping water over 1 Gyr increases by factors of 2.8 and 4.3 in the winter for the south and north polar regions, respectively, with seasonal residence times of adsorbed water molecules occurring at higher temperatures and thus larger areas. The Diviner instrument on the Lunar Reconnaissance Orbiter has been providing temperature measurements of the lunar surface for nearly 10 years. These observations have been compiled into polar maps of the summer and winter seasonal temperatures. Illumination in the polar regions is perpetually at grazing angles, and therefore topography plays a large role in surface temperatures which can vary in complex ways with time of day and season. The areas that are cold enough to trap water during the winter season are significantly larger than the cold, permanently shadowed regions. Nearly 10 years of Diviner data is compiled into summer and winter season temperature maps of the polar regions of the MoonSurface temperatures can vary in complex ways with time of day and seasonSeasonal shadowing increases in the south and north by factors 2.8 and 4.3, respectively, in winter which may influence volatile transport

The heat flow and physical properties package measured soil thermal conductivity at the landing site in the 0.03–0.37 m depth range. Six measurements spanning solar longitudes from 8.0° to 210.0° were made and atmospheric pressure at the site was simultaneously measured using InSight's Pressure Sensor. We find that soil thermal conductivity strongly correlates with atmospheric pressure. This trend is compatible with predictions of the pressure dependence of thermal conductivity for unconsolidated soils under martian atmospheric conditions, indicating that heat transport through the pore filling gas is a major contributor to the total heat transport. Therefore, any cementation or induration of the soil sampled by the experiments must be minimal and soil surrounding the mole at depths below the duricrust is likely unconsolidated. Thermal conductivity data presented here are the first direct evidence that the atmosphere interacts with the top most meter of material on Mars. A soil's ability to transport heat is a fundamental parameter that holds information on quantities like soil bulk porosity, composition, grain size, and the state of cementation or induration. In the soil, heat is transported through grain‐to‐grain contacts as well as through the pore filling CO2gas. The heat flow and physical properties package (HP3) of the InSight Mars mission measured soil thermal conductivity at the landing site repeatedly over the course of a martian year. As atmospheric pressure changes between seasons due to the redistribution of CO2across the planet, we found that soil thermal conductivity also changes. Thermal conductivity increased for increased atmospheric pressure, a behavior typical for unconsolidated material. This implies that the amount of cement or induration of the sampled soil must be minimal. We measured thermal conductivity of the martian soil and found that its conductivity strongly correlates with atmospheric pressureWe conclude that heat conduction through the pore‐filling gas is significant and that cementation of the soil must be minimalOur data show that the atmosphere directly interacts with the top most meter of material on Mars We measured thermal conductivity of the martian soil and found that its conductivity strongly correlates with atmospheric pressure We conclude that heat conduction through the pore‐filling gas is significant and that cementation of the soil must be minimal Our data show that the atmosphere directly interacts with the top most meter of material on Mars

The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission will perform the first Martian in situ heat flow measurement by deploying the Heat Flow and Physical Properties Package (HP3) onto the Martian surface. In order to estimate the heat flow coming from the planetary interior, HP3will measure the local subsurface thermal gradient as well as the local thermal conductivity to a depth of up to 5 m. From these measurements, local heat flow can be determined, but this will in general differ from the heat flow emanating from the planetary interior due to atmosphere‐induced perturbations. Here we quantify heat flow perturbation induced by dust loading of the Martian atmosphere using dust opacity data obtained by the Mars Exploration Rover Opportunity. Dust opacity data span the time period between Mars year (MY) 27 and MY 32, thus incorporating the global dust storm event of MY 28 as a signal. We consider two end‐member cases for the regolith thermal conductivity and find that the background planetary heat flow is superposed by atmosphere‐induced perturbations of less than 1.5 mW m−2at depths below 2 m if regolith thermal conductivity is low and around 0.025 W m−1K−1on average. If thermal conductivity is high and around 0.05 W m−1K−1on average, perturbations are less than 2.5 mW m−2at depths below 3 m. Overall, the influence of interannual variability on subsurface heat flow is found to be moderate following a global dust storm. Considerably smaller perturbations are introduced by regional dust storms, which are of shorter duration and smaller magnitude. We use a 5 Mars years time series of the Martian atmospheric dust opacity data to quantify the magnitude of the heat flow perturbationsNumerical simulations show minor and moderate pertubation of the heat flow caused by local and global dust storm, respectivelyThe heat pulse introduced by global dust storms travels up to a depth of 3 m and can only be observed in the Mars year following the storm

The Mars Environmental Dynamics Analyzer (MEDA) on board Perseverance includes first‐of‐its‐kind sensors measuring the incident and reflected solar flux, the downwelling atmospheric IR flux, and the upwelling IR flux emitted by the surface. We use these measurements for the first 350 sols of the Mars 2020 mission (Ls∼ 6°–174° in Martian Year 36) to determine the surface radiative budget on Mars and to calculate the broadband albedo (0.3–3 μm) as a function of the illumination and viewing geometry. Together with MEDA measurements of ground temperature, we calculate the thermal inertia for homogeneous terrains without the need for numerical thermal models. We found that (a) the observed downwelling atmospheric IR flux is significantly lower than the model predictions. This is likely caused by the strong diurnal variation in aerosol opacity measured by MEDA, which is not accounted for by numerical models. (b) The albedo presents a marked non‐Lambertian behavior, with lowest values near noon and highest values corresponding to low phase angles (i.e., Sun behind the observer). (c) Thermal inertia values ranged between 180 (sand dune) and 605 (bedrock‐dominated material) SI units. (d) Averages of albedo and thermal inertia (spatial resolution of ∼3–4 m2) along Perseverance's traverse are in very good agreement with collocated retrievals of thermal inertia from Thermal Emission Imaging System (spatial resolution of 100 m per pixel) and of bolometric albedo in the 0.25–2.9 μm range from (spatial resolution of ∼300 km2). The results presented here are important to validate model predictions and provide ground‐truth to orbital measurements. We analyzed first‐of‐its‐kind measurements from the weather station on board NASA's Perseverance rover. These include the incident solar radiation and the amount that is reflected by the surface, as well as the thermal atmospheric forcing (greenhouse effect) and the thermal heat released by the surface. These measurements comprise the radiant energy budget, which is fundamental to understanding Mars' weather through its impact on temperatures. From the solar measurements, we obtained the surface reflectance for a variety of illuminating and viewing geometries. We found that the thermal atmospheric forcing is weaker than expected from models, likely because of the strong diurnal variation in atmospheric aerosols observed by the rover, which is not accounted for by models. We also found that the surface reflectance is not uniform from all directions, but that it decreases when the Sun is highest in the sky (near noon) and increases when the Sun is directly behind the observer (sunset and sunrise), and thus the shadows cast by their roughness elements (e.g., pores and pits) are minimized. Because models neither consider diurnal variations in atmospheric aerosols nor in the surface reflectance, the results presented here are important to validate model predictions for future human exploration. Mars Environmental Monitoring Station (MEDA) allows the first in situ determination of the surface radiative budget on Mars, providing key constraints on numerical modelsMEDA allows the direct determination of thermal inertia and albedo, providing ground‐truth to satellite retrievalsAlbedo shows a strong non‐Lambertian behavior, with minimum values at noon and higher values toward sunrise and sunset Mars Environmental Monitoring Station (MEDA) allows the first in situ determination of the surface radiative budget on Mars, providing key constraints on numerical models MEDA allows the direct determination of thermal inertia and albedo, providing ground‐truth to satellite retrievals Albedo shows a strong non‐Lambertian behavior, with minimum values at noon and higher values toward sunrise and sunset

Polar hydrogen deposits on the Moon provide evidence that its spin axis has shifted; analysis of the locations of these deposits and of the lunar figure suggests that the shift occurred as a result of changes in the Moon’s moments of inertia caused by a low-density thermal anomaly beneath the Procellarum region.

The authors present new ethical constructs and design considerations for a clinical trial of compatible pair participation in kidney exchange.

Lunar water is redistributed by various processes. Topographic diffusion affects the transport of water and contributes to its preservation in subsurface layers. Here, we analyze 16 complex craters (∼3.2 – ∼4.2 Ga) larger than 20 km in diameter near the lunar south pole to quantify their degradation states. The results show that the diffusive rates of late Imbrian craters are similar to those of similarly aged simple craters, while Nectarian and pre‐Nectarian craters are degraded less efficiently. Within a complex crater, the mass accumulation by topographic diffusion and ejecta blankets from other complex craters preserves water, ranging up to 1 wt% on average. However, impact mixing and internal heat further limit the stability of ancient water to subsurface regions with ages younger than 3.9 Ga and at depth from a few meters to 10s of meters. Water in lunar shadowed regions is redistributed by various processes. When small craters form on a large crater's wall, its topography gradually erodes. Surface materials and deposited water move downhill, leading to a mixture of these materials and accumulations on the complex crater's floor. Here, we analyze 16 complex craters older than 3.2 Ga and larger than 20 km in diameter near the lunar south pole to investigate how fast these complex craters are topographically eroded. The results show that the speeds of topographic degradation of craters with an age of ∼3.2 Ga are comparable to those of similarly aged simple craters, while older craters experience significant degradation but are diffused inefficiently. On a complex crater, water may be stored in accumulated mass by topographic diffusion and large ejecta blankets for a long time. Such accumulated regions may host water, ranging up to 1 wt%. However, impact mixing and internal heat compete against the water supply and storage, limiting the water existence in subsurface layers at 10s of meters but a few meters below the surface and younger than 3.9 Ga. Topographic degradation of 16 complex craters near the lunar south pole significantly varies with surface age and crater sizeMass wasting by topographic diffusion and ejecta blanketing mixes water with regolith, giving a water mass fraction of up to 1 wt%Impact mixing and internal heat limit the existence of unaffected ancient water at 10s of meters in depth and younger than 3.9 Ga Topographic degradation of 16 complex craters near the lunar south pole significantly varies with surface age and crater size Mass wasting by topographic diffusion and ejecta blanketing mixes water with regolith, giving a water mass fraction of up to 1 wt% Impact mixing and internal heat limit the existence of unaffected ancient water at 10s of meters in depth and younger than 3.9 Ga

Kidneys from nondirected donors (NDDs) have historically been allocated directly to the deceased donor wait list (DDWL). Recently, however, NDDs have participated in kidney exchange (KE) procedures, including KE 'chains', which have received considerable media attention. This increasing application of KE chains with NDD participation has occurred with limited ethical analysis and without ethical guidelines. This article aims to provide a rigorous ethical evaluation of NDDs and chain KEs. NDDs and bridge donors (BDs) (i.e. living donors who link KE procedures within KE chains) raise several ethical concerns including coercion, privacy, confidentiality, exploitation and commercialization. In addition, although NDD participation in KE procedures may increase transplant numbers, it may also reduce NDD kidney allocation to the DDWL, and disadvantage vulnerable populations, particularly O blood group candidates. Open KE chains (also termed 'never-ending' chains) result in a permanent diversion of NDD kidneys from the DDWL. The concept of limited KE chains is discussed as an ethically preferable means for protecting NDDs and BDs from coercion and minimizing 'backing out', whereas 'honor systems' are rejected because they are coercive and override autonomy. Recent occurrences of BDs backing out argue for adoption of ethically based protective measures for NDD participation in KE.

We propose a new model for living organ donation that would invite elective laparoscopic cholecystectomy patients to become volunteer, unrelated living kidney donors. Such donors would be surgical patients first and living donors second, in contrast to the current system, which ‘creates’ a surgical patient by operating on a healthy individual. Elective surgery patients have accepted the risks of anesthesia and surgery for their own surgical needs but would face additional surgical risks when a donor nephrectomy is combined with their cholecystectomy procedure. Because these two procedures have never been performed together, the precise level of additional risk entailed in such a combined approach is unknown and will require further study. However, considering the large number of elective cholecystectomies performed each year in the United States, if as few as 5% of elective cholecystectomy patients agreed to also serve as living kidney donors, the number of living kidney donors would increase substantially. If this proposal is accepted by a minority of patients and surgeons, and proves safe and effective in a protocol study, it could be applied to other elective abdominal surgery procedures and used to obtain other abdominal donor organs (e.g. liver and intestinal segments) for transplantation.

The distribution of impact craters on the ejecta of Giordano Bruno, a recent (<10 Ma) 22‐km diameter crater within the lunar highlands, exhibits substantial variations. We surveyed craters D≥ 10 m across a 1,323 km2area of Giordano Bruno's ejecta and compared the distribution of craters with variations in thermophysical properties derived from the Lunar Reconnaissance Orbiter Diviner instrument. We used Diviner‐derived rock abundance and nighttime regolith temperatures along with thermal model‐predicted surface temperatures for a diversity of terrains to identify and isolate areas of the ejecta based on thermophysical properties such as bulk density and thermal conductivity. We found that thermophysical properties of the ejecta vary considerably both laterally and vertically, and consistently differ from typical regolith, indicating the presence of higher thermal inertia materials. Crater‐size frequencies are significantly lower in areas with terrain properties exhibiting higher: rock abundance, nighttime temperatures, and/or modeled thermal inertia. This discrepancy in crater distribution increases for craters smaller than ∼25 m. These thermophysical variations indicate changes in the mechanical properties of the target materials. We suggest that these variations—specifically, terrain‐dependent crater scaling variations and impactor‐scale heterogeneities in material properties such as the presence or absence of large boulders—may influence crater diameters or inhibit crater production altogether in Giordano Bruno's ejecta; furthermore, these factors are size‐dependent. Our understanding of the lunar chronology relies heavily on comparing crater counts on the ejecta of impact craters with laboratory dating methods of samples returned by the Apollo and Luna missions. However, discrepancies in crater populations on crater ejecta blankets have been observed and may present a source of uncertainty in the modeling of the lunar chronology. In this study, we show that variations in the distribution of craters on the ejecta of crater Giordano Bruno correspond with variations in terrain properties. Nighttime temperatures are sensitive to variations in density and thermal conductivity. We identified the variations in these properties using Diviner nighttime temperature observations and show that these properties correlate with variations in crater frequencies. Our results strongly support the idea that target properties are likely influencing the production of craters and therefore must be accounted for when estimating crater count‐derived absolute ages. The distribution of craters on Giordano Bruno varies with thermophysical propertiesThermal modeling of the ejecta shows lateral and vertical variations in thermal propertiesVariations in target properties influence the production of craters on the ejecta, resulting in variable absolute model age estimates The distribution of craters on Giordano Bruno varies with thermophysical properties Thermal modeling of the ejecta shows lateral and vertical variations in thermal properties Variations in target properties influence the production of craters on the ejecta, resulting in variable absolute model age estimates

Although some of the coldest surface temperatures in the entire Solar System are found near the poles of our own Moon, the thermophysical properties of lunar regolith at these ultracold temperatures (i.e., below ∼150 K) are not well understood. Standard lunar thermal models generally match the surface temperatures observed by global orbital remote sensing data but are inconsistent with infrared data collected from ultracold polar terrain. We build upon previous theoretical work on the low‐temperature physics of lunar regolith to introduce a global thermal conductivity model consistent with the temperature trends observed by the Diviner Lunar Radiometer Experiment (Diviner). This updated thermophysical model primarily affects nighttime surface temperatures, subsurface temperatures at high latitudes, and permanently shadowed regions (PSRs). An additional outcome of this thermophysical model is the ability to accommodate the surface temperature trends observed by Diviner both in warm low latitudes and cold high latitudes. Subsurface temperatures in near‐polar craters are ∼5–10 K warmer than previous thermal models, and cooler nighttime surface temperatures are observed globally. Model results of PSRs reveal larger surface temperature amplitudes (as observed by Diviner) and steeper geothermal gradients. A comprehensive understanding of lunar regolith's low‐temperature thermal behavior is an essential step in modeling the potential location and quantity of cold trapped volatiles in the lunar south pole. Here, we hope to provide theoretical support and motivation for more complete low‐temperature thermal conductivity laboratory measurements. A theory for describing the low‐temperature thermal properties of lunar soil is developed and applied to the top outer layer of the Moon. We compare model results with global surface temperature data collected by the Diviner Lunar Radiometer Experiment (Diviner) onboard the Lunar Reconnaissance Orbiter (LRO). The new thermal model differs from previous standard models in several ways. The model produces cooler nighttime surface temperatures at low and high latitudes, and we observe warmer subsurface temperatures with increasing latitude. Additionally, the updated model provides larger surface temperature amplitudes in polar terrain, specifically in shadowed near‐polar craters. Overall, a novel outcome of this new model is the ability to accommodate surface temperature trends observed by Diviner both at low and high latitudes, and the ability to predict warmer subsurface temperatures in very cold polar regions. By updating the low‐temperature thermal properties of lunar soil, we hope to better understand the stability of important organic volatiles, such as water ice, in the polar regions of the Moon. We develop a low‐temperature thermal conductivity model of lunar regolith that agrees with in situ and orbital remote sensing dataA temperature‐dependent solid conduction term accommodates the large surface temperature amplitudes observed in low‐temperature regionsAverage subsurface temperatures in near‐polar terrain may be ∼5–10 K warmer than previous thermal model calculations We develop a low‐temperature thermal conductivity model of lunar regolith that agrees with in situ and orbital remote sensing data A temperature‐dependent solid conduction term accommodates the large surface temperature amplitudes observed in low‐temperature regions Average subsurface temperatures in near‐polar terrain may be ∼5–10 K warmer than previous thermal model calculations

1. In the metathoracic ganglion of the locust some neurones can effect changes in the membrane potential of identified post‐synaptic motor neurones without themselves spiking. 2. These 'non‐spiking' neurones have processes only within the metathoracic ganglion, and therefore are local intraganglionic interneurones. 3. The absence of spikes in the interneurones reflects their normal physiological state and is not due to the experimental conditions. 4. When the interneurones are depolarized by the injection of current pulses lasting several hundred milliseconds, post‐synaptic motor neurones are either depolarized, or hyperpolarized, for the duration of the pulse. 5. The magnitude of the change in post‐synaptic voltage is graded according to the amount of presynaptic current. 6. A number of physiological tests indicate that the graded effects upon motor neurones are mediated by chemical synaptic transmission. For example, an evoked hyperpolarization of a motor neurone can be reversed in polarity by simultaneously hyperpolarizing the motor neurone with injected current. 7. At their resting potential some interneurones tonically release sufficient transmitter to have a measurable post‐synaptic effect. The injection of depolarizing and hyperpolarizing currents into these interneurones effects opposite changes in post‐synaptic potential. 8. Other interneurones must be depolarized from resting potential before a post‐synaptic effect is observed, and hyperpolarizing currents have no post‐synaptic effect. In these interneurones it is estimated that a depolarization of only 2 mV is sufficient to effect the release of transmitter. 9. The membrane potentials of non‐spiking interneurones can fluctuate by as much as 15 mV during active movements of the hind legs and individual p.s.p.s as large as 5 mV can be recorded. Therefore, summed p.s.p.s or even single ones are expected to be the electrophysiological signals effecting transmitter release from these interneurones.

This study was designed to determine the extent to which differences in criteria for dialysis patient selection and availability of financial resources cause the wide variation in acceptance rates for dialysis in Canada, the United Kingdom, and the United States. We also sought to determine whether there is agreement among nephrologists in the three countries on which patients should not be offered dialysis. We used a cross-sectional survey of all members of the Canadian Society of Nephrology and the Renal Association of Great Britain, and a randomized sample of 800 members of the American Society of Nephrology. Five case vignettes were presented asking for yes/no decisions on offering or not offering dialysis, together with ranking of factors considered important. We also inquired about dialysis resources and physician demographics. We compared responses by country. More nephrologists from the United Kingdom returned responses (83%) than Canadian (53%) or American (36%) nephrologists. American nephrologists offered dialysis more than Canadian or British nephrologists (three of five cases; P < 0.04 to P < 0.001) and ranked patient/family wishes (three of five cases; P < 0.057 to P < 0.0001) and fear of lawsuit (P < 0.04 to P = 0.0012) higher than British or Canadian nephrologists. Canadian and British nephrologists reported their perception of patients' quality of life as a reason to provide (P = 0.0019) or not provide (P = 0.068 to P = 0.0026) dialysis more often than their American counterparts. Despite these differences, nephrologists from each country did not differ by more than 30% on any decision and ranked factors almost identically. Ten percent and 12% of Canadian and British nephrologists, respectively, but only 2% of American nephrologists, reported refusing dialysis due to lack of resources (P < 0.0001). We conclude that the wide variation in dialysis acceptance rates in the three countries is somewhat influenced by differences in patient selection criteria and withholding of dialysis by nephrologists based on financial constraints, but that other factors, such as differences in rates of patient nonreferral for dialysis, contribute more significantly to the variation. Generally agreed on practice guidelines for dialysis patient selection appear possible. (Am J Kidney Dis 1998 Jan;31(1):12-8)

The receptive fields of spiking local interneurons in the locust were defined by making intracellular recordings from them while stimulating mechanoreceptors on the surface of a hindleg. All the interneurons tested have their cell bodies near the ventral midline, in the so-called "midline" group. Those described here receive inputs only from external mechanoreceptors; others receive inputs from internal proprioceptors alone or from receptors of both kinds. The receptors on the surface of a hindleg that contribute to the receptive field of an interneuron may be clustered together in a discrete area or be distributed in separate regions that provide either excitation or inhibition. An interneuron may have a receptive field that is wholly excitatory or one with both excitatory and inhibitory regions. Excitatory but not inhibitory effects are mediated by direct connections between afferents and interneurons. The longitudinal boundaries of most receptive fields occur along one of the major axes of the leg. For example, hairs on the anterior half of a leg can be excitatory, while hairs on the posterior half are inhibitory; or those on the dorsal half are excitatory, and those on the ventral half are inhibitory. The proximal-distal boundaries of a receptive field often correspond to the articulations between the segments of a leg, although they may also occur within a segment of a leg where there are no other obvious anatomical discontinuities. The receptive fields of these interneurons often overlap, and an individual afferent from a hair excites more than one interneuron. In this way a particular region on the surface of a hindleg may be mapped onto as many as 12 interneurons. The size of a receptive field is not correlated with its position along the proximal-distal axis of the leg, but the smallest fields occur on the distal tibia or span the femorotibial joint.

1. The modulatory actions of an identified octopaminergic neurone (DUMETi) that projects to the extensor‐tibiae muscle of the locust hind leg depend upon the frequency of stimulation of the slow motoneurone (SETi) to this muscle. 2. At low frequencies of SETi stimulation (1Hz and below) the predominant modulatory effects are increases in the amplitude and relaxation rate of twitch tension. At higher frequencies, where twitches summate but tetanus is incomplete (up to 20 Hz), the reduction of maintained tension becomes considerably more important. 3. Both octopamine application and DUMETi stimulation reduce the amount of catch tension displayed by the extensor muscle when SETi is fired in a variety of different stimulus patterns. The extensor‐tibiae muscle is itself ‘pattern sensitive’ since is shows a ‘positive spacing effect’ when SETi is stimulated at an average frequency of 1 Hz. 4. It is suggested that a primary function of DUMETi is to change the response of the muscle from one that favours maintenance of posture to one that favours rapid changes in joint position or force, such as might occur during locomotion.

A population of spiking local interneurons in the metathoracic ganglion of the locust is vigorously excited by particular sensory stimuli from the hindlegs and participates in local postural reflexes. We examined the inputs from singly innervated mechanoreceptors (hairs and campaniform sensilla) to these spiking local interneurons, to nonspiking local interneurons, and to motor neurons that are also elements of local reflex pathways. Recordings were made intracellularly from the interneurons and motor neurons and extracellularly from afferent fibers. The physiological evidence is consistent with the spiking local interneurons being excited by direct, chemically mediated synaptic inputs from the afferents. Each afferent spike is followed at a constant latency by an excitatory postsynaptic potential (EPSP) in a spiking local interneuron, even at instantaneous frequencies as high as 300 Hz. The estimated synaptic delay is 1.5 ms, similar to that measured at other presumed monosynaptic connections within the same ganglion. Cobalt stains of individual interneurons, and of the central projections of afferent fibers show that both branch within the same ventral region of neuropil. Afferents from several hairs and campaniform sensilla converge on an individual spiking local interneuron. One interneuron is shown to receive inputs from at least seven hairs and four campaniform sensilla, but these represent only a tiny fraction of the total number of such sensilla on a hindleg. Practical limitations to the number of sensilla that can be tested for each interneuron means that the degree of convergence is likely to be considerably underestimated. We found no evidence that nonspiking local interneurons or motor neurons receive direct inputs from the afferents tested. Neurons of both types are, however, affected by stimulation of individual hairs, and the resulting pattern of postsynaptic potentials (PSPs) is similar to the pattern of spikes evoked in the spiking local interneurons. We infer from the evidence presented here and elsewhere (10, 11) that the spiking local interneurons are involved in at least two types of pathways for local interactions: 1) sensory neuron-spiking local interneuron-motor neuron, and 2) sensory neuron-spiking local interneuron-nonspiking local interneuron-motor neuron. We conclude that the spiking local interneurons are major elements in the primary integration of inputs from external receptors on the hindlegs.

We conducted this study to better inform amyotrophic lateral sclerosis (ALS) patients about home ventilation and to assist them in decision-making. We gathered data on the prevalence of ALS patients on home ventilation in northern Illinois and the percentage who chose it, and we asked identified subjects, their families, and physicians for their attitudes toward home ventilation. Fewer than 10 of ALS patients had chosen home ventilation, and fewer than 5 were still on it. Seventeen patients (90) were glad to have chosen home ventilation and would choose it again. Family caregivers reported major burdens, and only half would choose it for themselves. The mean yearly cost of home ventilation was 153,252. Home ventilation is effective for ALS patients and desired by the small number who undergo it, but it imposes significant burdens on families.

HLA-typing, gene analysis, anti-islet cell antibody testing and metabolic studies can identify people at high risk for developing Type 1 (insulin-dependent) diabetes mellitus prior to the onset of clinical disease. The positive predictive value of these tests is high in first degree relatives of patients with Type 1 diabetes, but six times less so in the general population, where disease incidence is much lower but where 90% of new cases occur. Multiple testing improves sensitivity but decreases specificity. Intervention strategies are being designed with the aim of delaying or preventing progression to clinical disease. The more invasive the intervention, the greater is the specificity required. The practical and ethical implications of identifying high risk of diabetes in healthy individuals are complex and require further research, but some lessons can be learned from the experience of other disease prediction programmes.

As their name implies, local interneurones arborize within anatomically restricted regions of a nervous system, and the connections that they make establish local circuits. In arthropods, they may arborize wholly within a segmental ganglion, or within a specialized region of the brain. Local interneurones can be divided into two physiological types: spiking and nonspiking. In segmental ganglia, spiking local interneurones are largely responsible for the local processing of primary sensory inputs, whereas non-spiking ones play a major role in the control and coordination of motor neurone activity at the segmental level. By contrast, in the brain, primary visual inputs are processed mainly by non-spiking interneurones. Local interactions between neurones may occur in three ways: by the graded release of transmitter, by the presynaptic modulation of spike-evoked PSPs and by the ‘conventional’ mechanism where spike frequency is translated across a synapse as the summed amplitude of discrete spikeevoked PSPs. Although graded synaptic transmission is the only mechanism so far described for the local interactions of non-spiking interneurones, it is not limited to them. It may occur also in non-spiking neurones specialized to transmit graded signals over long distances, or in local, intraganglionic regions of motor neurones or long interneurones. The ability of spiking neurones to exert graded effects may depend upon input and output synapses being intermingled on their fine branches, at sites relatively distant from the region of spike initiation. Since these synapses are widely distributed over the neurones, local intraganglionic interactions can be seen as the summed effect of many, yet more restricted local interactions. Restricted local interactions also may occur within parts of non-spiking interneurones, but this is a conjecture, based on modelling studies, and upon considerable EM evidence for serial and reciprocal synapses in most other types of arthropod neurones.

We use the Martian surface temperature response to Phobos transits observed next to the InSight lander in Elysium Planitia to constrain the thermal properties of the uppermost layer of regolith. Modeled transit lightcurves validated by solar panel current measurements are used to modify the boundary conditions of a 1D heat conduction model. We test several model parameter sets, varying the thickness and thermal conductivity of the top layer to explore the range of parameters that match the observed temperature response within its uncertainty both during the eclipse as well as the full diurnal cycle. The measurements indicate a thermal inertia (TI) of 103−16+22Jm−2K−1s−1/2in the uppermost layer of 0.2–4 mm, significantly smaller than the TI of 200Jm−2K−1s−1/2derived from the diurnal temperature curve. This could be explained by larger particles, higher density, or some or slightly higher amount of cementation in the lower layers. The Mars moon Phobos passed in front of the Sun from the perspective of the InSight lander on several occasions. The Mars surface temperatures measured by the lander became slightly colder during these transits due to the lower amount of sunlight the surface received at this time. The transits only last 20–35 s and therefore only the very top layer, about 0.3–0.8 mm, of the ground has time to cool significantly. The top layer cools and heats up faster than we expected based on the temperature changes of the day‐night cycle, which affects about 4 cm of the ground. Based on this observation we conclude that the material in the top mm of the ground is different from that below. A possible explanation would be an increase of density with depth, a larger fraction of smaller particles such as dust at the top, or a layer where particles are slightly cemented together beginning at 0.2–4 mm below the surface. The Martian surface temperature response to Phobos transits at the InSight landing site is interpretedThe thermal inertia of the uppermost layer of soil is 103−16+22Jm−2K−1s−1/2The thermal conductivity or density of the top 0.2–4 mm is significantly less than that of the top 4 cm The Martian surface temperature response to Phobos transits at the InSight landing site is interpreted The thermal inertia of the uppermost layer of soil is 103−16+22Jm−2K−1s−1/2 The thermal conductivity or density of the top 0.2–4 mm is significantly less than that of the top 4 cm

The heat flow and physical properties package (HP3) of the InSight Mars mission is an instrument package designed to determine the martian planetary heat flow. To this end, the package was designed to emplace sensors into the martian subsurface and measure the thermal conductivity as well as the geothermal gradient in the 0–5 m depth range. After emplacing the probe to a tip depth of 0.37 m, a first reliable measurement of the average soil thermal conductivity in the 0.03–0.37 m depth range was performed. Using the HP3mole as a modified line heat source, we determined a soil thermal conductivity of 0.039 ± 0.002 W m−1K−1, consistent with the results of orbital and in‐situ thermal inertia estimates. This low thermal conductivity implies that 85%–95% of all particles are smaller than 104–173 μm and suggests that soil cementation is minimal, contrary to the considerable degree of cementation suggested by image data. Rather, cementing agents like salts could be distributed in the form of grain coatings instead. Soil densities compatible with the measurements are 1211−113+149kg m−3, indicating soil porosities of 63−9+4%. The heat flow and physical properties package (HP3) of the InSight Mars mission is an instrument package that was designed to measure soil temperature as well as the soil's ability to transport heat, the so called thermal conductivity. After the probe was inserted to a depth of 0.37 m a first measurement of the soil's thermal conductivity was performed. The soil was found to be a poor thermal conductor with average conductivity close to 0.039 W m−1K−1. As thermal transport properties in sands are related to grain size, the latter can be estimated based on the performed measurement. We find that particles must be smaller than about 150 μm, corresponding to fine sand that may be intermixed with dust. Further, salts in the soil can act as cementing agents, which connect individual sand grains and thus increase the strength of grain‐to‐grain contacts and therefore thermal conductivity. However, given the low thermal conductivity determined here, the amount of such cement must be minimal, contrary to what is suggested by image data. Finally, we find that the soil must have significant porosity of about 60% to be compatible with our measurements. The Heat Flow and Physical Properties Package (HP3) measured the average thermal conductivity of the martian soilAverage soil thermal conductivity in the 0.03–0.37 m depth range is 0.039 ± 0.002 W m−1K−1This implies that 85%–95% of all particles are smaller than 104–173 μm The Heat Flow and Physical Properties Package (HP3) measured the average thermal conductivity of the martian soil Average soil thermal conductivity in the 0.03–0.37 m depth range is 0.039 ± 0.002 W m−1K−1 This implies that 85%–95% of all particles are smaller than 104–173 μm

The finding by the OSIRIS‐REx (Origins, Spectral Interpretation, Resource Identification, and Security‐Regolith Explorer) mission that its target (101955) Bennu is an active asteroid has raised questions as to whether the observed particle ejection events are driven by temperature. To investigate sublimation of water ice and rock thermal fracture as possible temperature‐driven causes, we modeled the global temperatures of Bennu and searched for correlations with the identified ejection points on the asteroid surface. We computed temperatures with the Advanced Thermophysical Model and the 75‐cm‐resolution global shape model of Bennu derived by the OSIRIS‐REx mission. We find that ~1,856 m2of Bennu's polar regions have orbit‐averaged temperatures that are sufficiently cold to enable water ice, if buried within the top few meters of the surface, to remain stable over geological timescales. Millimeter thick layers of surface water ice are also stable over ~103‐year timescales within polar centimeter‐scale cold traps. However, we do not find evidence of conditions enabling ice stability in the warmer equatorial regions, where ejection events have been observed, implying that sublimation of water ice is not the cause of particle ejection. Conversely, rock thermal fracture remains a possible mechanism of particle ejection. We find high amplitudes of diurnal temperature variation, a proxy for the efficacy of thermal fracturing, at all latitudes on Bennu due to its extreme ruggedness. Therefore, if rock thermal fracture is the mechanism, particles could be ejected from any latitude, which is consistent with the continued observations of particle ejection by OSIRIS‐REx. The OSIRIS‐REx mission discovered that particles are being ejected periodically from the surface of near‐Earth asteroid Bennu. Some hypotheses for the process (es) driving these ejection events relate to temperature. These include sublimation of volatile substances such as water (like in a comet) and thermal fracturing (cracking of rocks driven by day‐night temperature changes). To evaluate these hypotheses, we performed numerical simulations of temperatures across the surface of Bennu over its orbit. Temperatures on the majority of the surface, including at the ejection sites, are too warm for water ice to be present, even if covered by dust. We therefore conclude that sublimation of water ice is not responsible for the particle ejections. Nevertheless, portions of the polar regions are cold enough that subsurface water ice could exist. Small (centimeter‐scale) cold traps near the poles could store surface water ice for up to ~1,000 years. We find that thermal fracturing is a viable mechanism to explain the particle ejections because Bennu exhibits large day‐night differences in temperature. These large temperature differences occur even at high latitudes on the sunward facing sides of boulders. This widespread viability of thermal fracturing is consistent with the observation of particles ejecting from various latitudes on Bennu. Modeled temperatures indicate that water ice sublimation is not the process ejecting particles from the surface of BennuSubsurface water ice however could be stable in small regions near the polesThe diurnal temperature curve has a large amplitude at all latitudes, which supports thermal fracturing as a cause of the ejection events

MANY neurones, particularly in sensory systems of both vertebrates and invertebrates, do not produce action potentials1–3. In motor pathways within the central nervous system of arthropods there are interneurones whose slow changes in membrane potential can affect the frequency of action potentials in motoneurones4–6. Some of these interneurones normally produce spikes6, but others apparently do not4,5. We have studied the properties of synaptic transmission between these non-spiking interneurones and motoneurones in the locust, Schistocera gregaria, in the course of investigating the integrative mechanisms underlying the generation of motor patterns7.