Nutrition and indoor cycling : A cross-sectional analysis of carbohydrate intake for online racing and training

Cycling is a sport characterised by high training load, and adequate nutrition is essential for training and race performance. With the increased popularity of indoor trainers, cyclists have a unique opportunity to practice and implement key nutritional strategies. This study aimed to assess carbohydrate (CHO) intake of cyclists training or racing in this unique scenario for optimising exercise nutrition. A mixed-methods approach consisting of a multiple-pass self-report food recall and questionnaire was used to determine total CHO intake pre, during and post-training or racing using a stationary trainer and compared with current guidelines for endurance exercise. Sub-analyses were also made for higher ability cyclists (>4 W/kg functional threshold power), races v. non-races and ‘key’ training sessions. Mean CHO intake pre and post-ride was 0·7 (SD 0·6) and 1·0 (SD 0·8) g kg/BM and 39·3 (SD 27·5) g/h during training. CHO intake was not different for races (pre/during/post, P = 0·31, 0·23, 0·18, respectively), ‘key sessions’ (P = 0·26, 0·89, 0·98) or higher ability cyclists (P = 0·26, 0·76, 0·45). The total proportion of cyclists who failed to meet CHO recommendations was higher than those who met guidelines (pre = 79 %, during = 86 %, post = 89 %). Cyclists training or racing indoors do not meet current CHO recommendations for cycling performance. Due to the short and frequently high-intensity nature of some sessions, opportunity for during exercise feeding may be limited or unnecessary

Radiatively-Driven Outflows and Avoidance of Common-Envelope Evolution in Close Binaries

Recent work on Cygnus X-2 suggests that neutron-star or black-hole binaries survive highly super-Eddington mass transfer rates without undergoing common-envelope evolution. We suggest here that the accretion flows in such cases are radiation pressure-dominated versions of the "ADIOS" picture proposed by Blandford and Begelman (1999), in which almost all the mass is expelled from large radii in the accretion disk. We estimate the maximum radius from which mass loss is likely to occur, and show that common-envelope evolution is probably avoided in any binary in which a main-sequence donor transfers mass on a thermal timescale to a neutron star or black hole, even though the mass transfer rate may reach values of 0.001 solar masses per year. This conclusion probably applies also to donors expanding across the Hertzsprung gap, provided that their envelopes are radiative. SS433 may be an example of a system in this state.Comment: 4 pages, submitted to Astrophysical Journal Letters, 26 March 199

What is on Tap? The Role of Spin in Compact Objects and Relativistic Jets

We examine the role of spin in launching jets from compact objects across the mass scale. Our work includes a total of 37 Seyferts, 11 stellar-mass black holes, and 13 neutron stars. We find that when the Seyfert reflection lines are modeled with Gaussian line features (a crude proxy for inner disk radius and therefore spin), only a slight inverse correlation is found between the Doppler-corrected radio luminosity at 5 GHz (a proxy for jet power) and line width. When the Seyfert reflection features are fit with relativistically-blurred disk reflection models that measure spin, there is a tentative positive correlation between the Doppler-corrected radio luminosity and the spin measurement. Further, when we include stellar-mass black holes in the sample, to examine the effects across the mass scale, we find a slightly stronger correlation with radio luminosity per unit mass and spin, at a marginal significance (2.3 sigma confidence level). Finally, when we include neutron stars, in order to probe lower spin values, we find a positive correlation (3.3 sigma confidence level) between radio luminosity per unit mass and spin. Although tentative, these results suggest that spin may have a role in determining the jet luminosity. In addition, we find a slightly more significant correlation (4.4 sigma confidence level) between radio luminosity per Bolometric luminosity and spin, using our entire sample of black holes and neutrons stars. Again, although tentative, these relations point to the possibility that the mass accretion rate, i.e. Bolometric luminosity, is also important in determining the jet luminosity, in addition to spin. Our analysis suggests that mass accretion rate and disk or coronal magnetic field strength may be the "throttle" in these compact systems, to which the Eddington limit and spin may set the maximum jet luminosity that can be achieved.Comment: 14 pages, 13 Figures, ApJ Accepte

Shoot yield drives phosphorus use efficiency in Brassica oleracea and correlates with root architecture traits

The environmental and financial costs of using inorganic phosphate fertilizers to maintain crop yield and quality are high. Breeding crops that acquire and use phosphorus (P) more efficiently could reduce these costs. The variation in shoot P concentration (shoot-P) and various measures of P use efficiency (PUE) were quantified among 355 Brassica oleracea L. accessions, 74 current commercial cultivars, and 90 doubled haploid (DH) mapping lines from a reference genetic mapping population. Accessions were grown at two or more external P concentrations in glasshouse experiments; commercial and DH accessions were also grown in replicated field experiments. Within the substantial species-wide diversity observed for shoot-P and various measures of PUE in B. oleracea, current commercial cultivars have greater PUE than would be expected by chance. This may be a consequence of breeding for increased yield, which is a significant component of most measures of PUE, or early establishment. Root development and architecture correlate with PUE; in particular, lateral root number, length, and growth rate. Significant quantitative trait loci associated with shoot-P and PUE occur on chromosomes C3 and C7. These data provide information to initiate breeding programmes to improve PUE in B. oleracea

New Wilson’s Phalarope Nesting Record from the Central Platte River Valley, Mormon Island, Hall County, Nebraska

The southeastern portion of the Wilson’s Phalarope’s (Phalaropus tricolor) breeding range encompasses parts of Nebraska (Colwell and Jehl 1994), including the Sandhills and northern Panhandle (Silcock and Jorgensen 2018). Additionally, there have been a number of breeding records from southcentral and southeastern Nebraska within the Rainwater Basin ecoregion since the mid-1990s (Mollhoff 2016, Silcock and Jorgensen 2018). However, there is very little evidence of regular breeding activity in the nearby Central Platte River Valley (CPRV), which spans from Chapman west to Overton, Nebraska, and is considered a globally important area for waterbirds (Johnsgard and Brown 2013, Silcock and Jorgensen 2018). Sutton and Arcilla (2018) documented two juvenile Wilson’s Phalaropes with two adults on 28 June 2017, confirming successful breeding in the CPRV on Mormon Island, Hall County, Nebraska. However, Sutton and Arcilla (2018) did not document an active nest and therefore lack a detailed description of the nesting habitat used by Wilson’s Phalaropes in this unique ecoregion. On 6 June 2019 we found a Wilson’s Phalarope nest while walking between avian point count stations on Mormon Island, 4.7 km northwest of Doniphan and 14.4 km southwest of Grand Island, Nebraska, on land owned and managed for the benefit of migratory birds by the Crane Trust (https://cranetrust.org/). The landscape is managed with rotational grazing and prescribed fire to simulate natural disturbance regimes (Fuhlendorf et al. 2009). Mormon Island contains the largest contiguous tract of wet meadow remaining in the CPRV (Currier and Henszey 1996, Brei and Bishop 2008). Mormon Island consists of about 1075 hectares (ha) or 2,656 acres (ac) of primarily relict and restored wet meadow and lowland tallgrass prairie habitat, and exists within a complex of 2,425 ha (5,992 ac) of land protected for conservation purposes along a 13 km (~8 mi.) stretch of the Platte River. The nest was found when an adult male Wilson’s Phalarope flushed directly off the nest from the ground at a distance of approximately 3 meters (m) from approaching observers

Molecular evidence for gender differences in the migratory behaviour of a small seabird

Molecular sexing revealed an unexpectedly strong female bias in the sex ratio of pre-breeding European Storm Petrels (Hydrobates pelagicus), attracted to playback of conspecific calls during their northwards migration past SW Europe. This bias was consistent across seven years, ranging from 80.8% to 89.7% female (mean annual sex ratio ± SD = 85.5% female ±4.1%). The sex ratio did not differ significantly from unity (i.e., 50% female) among (i) Storm Petrel chicks at a breeding colony in NW France, (ii) adults found dead on beaches in Southern Portugal, (iii) breeding birds attending nest burrows in the UK, captured by hand, and (iv) adults captured near a breeding colony in the UK using copies of the same sound recordings as used in Southern Europe, indicating that females are not inherently more strongly attracted to playback calls than males. A morphological discriminant function analysis failed to provide a good separation of the sexes, showing the importance of molecular sexing for this species. We found no sex difference in the seasonal or nocturnal timing of migration past Southern Europe, but there was a significant tendency for birds to be caught in sex-specific aggregations. The preponderance of females captured in Southern Europe suggests that the sexes may differ in migration route or in their colony-prospecting behaviour during migration, at sites far away from their natal colonies. Such differences in migration behaviour between males and females are poorly understood but have implications for the vulnerability of seabirds to pollution and environmental change at sea during the non-breeding season

Soil Microbial Networks Shift Across a High-Elevation Successional Gradient.

While it is well established that microbial composition and diversity shift along environmental gradients, how interactions among microbes change is poorly understood. Here, we tested how community structure and species interactions among diverse groups of soil microbes (bacteria, fungi, non-fungal eukaryotes) change across a fundamental ecological gradient, succession. Our study system is a high-elevation alpine ecosystem that exhibits variability in successional stage due to topography and harsh environmental conditions. We used hierarchical Bayesian joint distribution modeling to remove the influence of environmental covariates on species distributions and generated interaction networks using the residual species-to-species variance-covariance matrix. We hypothesized that as ecological succession proceeds, diversity will increase, species composition will change, and soil microbial networks will become more complex. As expected, we found that diversity of most taxonomic groups increased over succession, and species composition changed considerably. Interestingly, and contrary to our hypothesis, interaction networks became less complex over succession (fewer interactions per taxon). Interactions between photosynthetic microbes and any other organism became less frequent over the gradient, whereas interactions between plants or soil microfauna and any other organism were more abundant in late succession. Results demonstrate that patterns in diversity and composition do not necessarily relate to patterns in network complexity and suggest that network analyses provide new insight into the ecology of highly diverse, microscopic communities

The Evolutionary Status of SS433

We consider possible evolutionary models for SS 433. We assume that common-envelope evolution is avoided if radiation pressure is able to expel most of a super-Eddington accretion flow from a region smaller than the accretor's Roche lobe. This condition is satisfied, at least initially, for largely radiative donors with masses in the range 4-12 solar masses. For donors more massive than about 5 solar masses, moderate mass ratios q = M_2/M_1 > 1 are indicated, thus tending to favor black-hole accretors. For lower mass donors, evolutionary considerations do not distinguish between a neutron star or black hole accretor. In all cases the mass transfer (and mass loss) rates are much larger than the likely mass-loss rate in the precessing jets. Almost all of the transferred mass is expelled at radii considerably larger than the jet acceleration region, producing the "stationary" H-alpha line, the infrared luminosity, and accounting for the low X-ray luminosity.Comment: 13 pages, Astrophysical Journal Letters, accepte