Increased sprint performance with false step in collegiate athletes trained to forward step.

The ability to achieve rapid acceleration is a crucial asset for athletes. An emergent tactic to achieve this advantage has been the performance of a backward step when beginning a sprinting action. This action has even gained the moniker 'false step', implying its lack of utility. Thus, a significant debate has developed among coaches regarding the value of this phenomenon. This study examined the false step through a comparison with a forward step condition, where participants were only allowed to step forward to initiate a sprint. Comparisons were made between velocity products as well as mechanical antecedents during the first milliseconds of sprint initiation. Participants were 30 healthy college-aged student-athletes, who were asked to perform three false step and forward step sprint trials. Timing gates and 3D modelling were used to examine velocities and mechanical variables during these trials. Overall, results demonstrated that the false step was significantly (p < 0.001) faster (0.23s; 9.44%) over a ten-metre sprint. Additionally, angular variables of the ankles during sprint initiation were found to be significantly different between false and forward step conditions. Findings suggest that the false step may be beneficial for athletes and is an advantageous technique for achieving a rapid change in velocity.

The challenges of modeling and forecasting the spread of COVID-19.

The coronavirus disease 2019 (COVID-19) pandemic has placed epidemic modeling at the forefront of worldwide public policy making. Nonetheless, modeling and forecasting the spread of COVID-19 remains a challenge. Here, we detail three regional-scale models for forecasting and assessing the course of the pandemic. This work demonstrates the utility of parsimonious models for early-time data and provides an accessible framework for generating policy-relevant insights into its course. We show how these models can be connected to each other and to time series data for a particular region. Capable of measuring and forecasting the impacts of social distancing, these models highlight the dangers of relaxing nonpharmaceutical public health interventions in the absence of a vaccine or antiviral therapies.

Impact of social distancing during COVID-19 pandemic on crime in Los Angeles and Indianapolis.

Governments have implemented social distancing measures to address the ongoing COVID-19 pandemic. The measures include instructions that individuals maintain social distance when in public, school closures, limitations on gatherings and business operations, and instructions to remain at home. Social distancing may have an impact on the volume and distribution of crime. Crimes such as residential burglary may decrease as a byproduct of increased guardianship over personal space and property. Crimes such as domestic violence may increase because of extended periods of contact between potential offenders and victims. Understanding the impact of social distancing on crime is critical for ensuring the safety of police and government capacity to deal with the evolving crisis. Understanding how social distancing policies impact crime may also provide insights into whether people are complying with public health measures. Examination of the most recently available data from both Los Angeles, CA, and Indianapolis, IN, shows that social distancing has had a statistically significant impact on a few specific crime types. However, the overall effect is notably less than might be expected given the scale of the disruption to social and economic life.

Test-retest reliability of TRIMP in collegiate ice hockey players.

The utility of the heart rate derived variable TRaining IMPulse (TRIMP) for assessing internal training load in ice hockey players is not clear. Having a reliable measure of internal training load during on-ice training sessions would help coaches program exercise training. This study determined the reliability of TRIMP during on-ice training sessions in ice hockey players. Twelve Division I collegiate male ice hockey players (aged 18-23 years) had their heart rate (HR) data recorded during two on-ice practice sessions separated by two weeks. TRIMP and other descriptive HR variables were compared between sessions. TRIMP demonstrated moderate reliability during on-ice sessions. Systematic error, quantified as standardized change in means was negligible (-0.19); random error quantified as the percent typical error (%TE) was moderate (12.2%); and, test-retest correlation was very strong (0.75). TRIMP is suitable for quantifying training load during intermittent work in hockey athletes. The results from our study can be used to determine the threshold for meaningful change in TRIMP, which may aid in informing decisions by coaches and strength training staff regarding on-ice training session difficulty and composition.

Relationships between the second to fourth digit ratio (2D:4D) and game-related statistics in semi-professional female basketball players.

OBJECTIVE: Digit ratio (2D:4D) is a negative correlate of sports performance, although this relationship may be weak in open-skill sports such as basketball. The primary aim was to quantify relationships between 2D:4D and game-related statistics in semi-professional female basketball players. The secondary aim was to quantify the differences in mean 2D:4Ds between players based on their position in the starting lineup. METHODS: Using a cross-sectional design, 64 female basketball players who competed in the South Australian Premier League were measured in-season for height, mass, and 2D:4D, with game-related statistics collected end-season. Partial correlations (adjusted for age and body mass index) were used to quantify relationships between right and left 2D:4Ds and game-related statistics. Unpaired t-tests were used to quantify differences in mean 2D:4Ds between starting and reserve players. RESULTS: 2D:4D was a substantial negative correlate of blocks, rebounds, and field-goal percentage; meaning, females with lower 2D:4Ds were generally better defensively as they recorded more blocks and rebounds, and were more efficient scorers, irrespective of their age and body size. Mean 2D:4D differed by position in the starting lineup, as females with lower 2D:4Ds were more likely to be in the starting lineup. CONCLUSIONS: This study found evidence that 2D:4D was a correlate of performance in an open-skill sport. Female players with lower digit ratios tended to perform better in several aspects of basketball, especially defensively, and were more likely to be starters, suggesting they are the best players on the team in their positions. These results probably reflect the organizational benefits of prenatal testosterone.

Modelling radicalization: how small violent fringe sects develop into large indoctrinated societies.

We model radicalization in a society consisting of two competing religious, ethnic or political groups. Each of the 'sects' is divided into moderate and radical factions, with intra-group transitions occurring either spontaneously or through indoctrination. We also include the possibility of one group violently attacking the other. The intra-group transition rates of one group are modelled to explicitly depend on the actions and characteristics of the other, including violent episodes, effectively coupling the dynamics of the two sects. We use a game theoretic framework and assume that radical factions may tune 'strategic' parameters to optimize given utility functions aimed at maximizing their ranks while minimizing the damage inflicted by their rivals. Constraints include limited overall resources that must be optimally allocated between indoctrination and external attacks on the other group. Various scenarios are considered, from symmetric sects whose behaviours mirror each other, to totally asymmetric ones where one sect may have a larger population or a superior resource availability. We discuss under what conditions sects preferentially employ indoctrination or violence, and how allowing sects to readjust their strategies allows for small, violent sects to grow into large, indoctrinated communities.

The Effects of Caffeine on Vertical Jump Height and Execution in Collegiate Athletes.

Bloms, LP, Fitzgerald, JS, Short, MW, and Whitehead, JR. The effects of caffeine on vertical jump height and execution in collegiate athletes. J Strength Cond Res 30(7): 1855-1861, 2016-Caffeine ingestion elicits a variety of physiological effects that may be beneficial to maximal-intensity exercise performance, although its effectiveness and physical mechanism of action enhancing ballistic task performance are unclear. The purpose of this study was to examine the effects of caffeine ingestion on vertical jump height and jump execution in Division I collegiate athletes. The study used a single-blind, randomized, crossover design. Athletes (n = 25) consumed either caffeine (5 mg·kg) or placebo. After a 60-minute waiting period, athletes performed 3 squat jumps (SJ) and 3 countermovement jumps (CMJ) while standing on a force platform. Jump height and execution variables were calculated from mechanography data. In comparison with placebo, caffeine increased SJ height (32.8 ± 6.2 vs. 34.5 ± 6.7 cm; p = 0.001) and CMJ height (36.4 ± 6.9 vs. 37.9 ± 7.4 cm; p = 0.001). Peak force (p = 0.032) and average rate of force development (p = 0.037) were increased during the CMJ in the caffeine trail compared with the control. Time to half peak force was the only execution variable improved with caffeine (p = 0.019) during the SJ. It seems that caffeine affects both height and execution of jumping. Our data indicate that the physical mechanism of jump enhancement is increased peak force production or rate of force development during jumping depending on technique. The physical mechanism of jump enhancement suggests that the ergogenic effects of caffeine may transfer to other ballistic tasks involving the lower-body musculature in collegiate athletes.

Transplantation of umbilical cord and bone marrow-derived mesenchymal stem cells in a patient with relapsing-remitting multiple sclerosis.

There is currently great interest in the use of mesenchymal stem cells as a therapy for multiple sclerosis with potential to both ameliorate inflammatory processes as well as improve regeneration and repair. Although most clinical studies have used autologous bone marrow-derived mesenchymal stem cells, other sources such as allogeneic umbilical cord-derived cells may provide a more accessible and practical supply of cells for transplantation. In this case report we present the treatment of aggressive multiple sclerosis with multiple allogenic human umbilical cord-derived mesenchymal stem cell and autologous bone marrow-derived mesenchymal stem cells over a 4 y period. The treatments were tolerated well with no significant adverse events. Clinical and radiological disease appeared to be suppressed following the treatments and support the expansion of mesenchymal stem cell transplantation into clinical trials as a potential novel therapy for patients with aggressive multiple sclerosis.

Criminal defectors lead to the emergence of cooperation in an experimental, adversarial game.

While the evolution of cooperation has been widely studied, little attention has been devoted to adversarial settings wherein one actor can directly harm another. Recent theoretical work addresses this issue, introducing an adversarial game in which the emergence of cooperation is heavily reliant on the presence of "Informants," actors who defect at first-order by harming others, but who cooperate at second-order by punishing other defectors. We experimentally study this adversarial environment in the laboratory with human subjects to test whether Informants are indeed critical for the emergence of cooperation. We find in these experiments that, even more so than predicted by theory, Informants are crucial for the emergence and sustenance of a high cooperation state. A key lesson is that successfully reaching and maintaining a low defection society may require the cultivation of criminals who will also aid in the punishment of others.

Neural differentiation of patient specific iPS cells as a novel approach to study the pathophysiology of multiple sclerosis.

The recent introduction of technologies capable of reprogramming human somatic cells into induced pluripotent stem (iPS) cells offers a unique opportunity to study many aspects of neurodegenerative diseases in vitro that could ultimately lead to novel drug development and testing. Here, we report for the first time that human dermal fibroblasts from a patient with relapsing-remitting Multiple Sclerosis (MS) were reprogrammed to pluripotency by retroviral transduction using defined factors (OCT4, SOX2, KLF4, and c-MYC). The MSiPS cell lines resembled human embryonic stem (hES) cell-like colonies in morphology and gene expression and exhibited silencing of the retroviral transgenes after four passages. MSiPS cells formed embryoid bodies that expressed markers of all three germ layers by immunostaining and Reverse Transcriptase (RT)-PCR. The injection of undifferentiated iPS cell colonies into immunodeficient mice formed teratomas, thereby demonstrating pluripotency. The MSiPS cells were successfully differentiated into mature astrocytes, oligodendrocytes and neurons with normal karyotypes. Although MSiPS-derived neurons displayed some differences in their electrophysiological characteristics as compared to the control cell line, they exhibit properties of functional neurons, with robust resting membrane potentials, large fast tetrodotoxin-sensitive action potentials and voltage-gated sodium currents. This study provides for the first time proof of concept that disease cell lines derived from skin cells obtained from an MS patient can be generated and successfully differentiated into mature neural lineages. This represents an important step in a novel approach for the study of MS pathophysiology and potential drug discovery.

Quantitative and phenotypic analysis of bone marrow-derived cells in the intact and inflamed central nervous system.

Bone marrow has been proposed as a possible source of cells capable of replacing injured neural cells in diseases such as Multiple Sclerosis (MS). Previous studies have reported conflicting results regarding the transformation of bone marrow cells into neural cells in vivo. This study is a detailed analysis of the fate of bone marrow derived cells (BMDC) in the CNS of C57Bl/6 mice with and without experimental autoimmune encephalomyelitis using flow cytometry to identify GFP-labeled BMDC that lacked the pan-hematopoietic marker, CD45 and co-expressed neural markers polysialic acid-neural cell adhesion molecule or A2B5. A small number of BMDC displaying neural markers and lacking CD45 expression was identified within both the non-inflamed and inflamed CNS. However, the majority of BMDC exhibited a hematopoietic phenotype.

A novel unbiased proteomic approach to detect the reactivity of cerebrospinal fluid in neurological diseases.

Neurodegenerative diseases, such as multiple sclerosis represent global health issues. Accordingly, there is an urgent need to understand the pathogenesis of this and other central nervous system disorders, so that more effective therapeutics can be developed. Cerebrospinal fluid is a potential source of important reporter molecules released from various cell types as a result of central nervous system pathology. Here, we report the development of an unbiased approach for the detection of reactive cerebrospinal fluid molecules and target brain proteins from patients with multiple sclerosis. To help identify molecules that may serve as clinical biomarkers for multiple sclerosis, we have biotinylated proteins present in the cerebrospinal fluid and tested their reactivity against brain homogenate as well as myelin and myelin-axolemmal complexes. Proteins were separated by two-dimensional gel electrophoresis, blotted onto membranes and probed separately with biotinylated unprocessed cerebrospinal fluid samples. Protein spots that reacted to two or more multiple sclerosis-cerebrospinal fluids were further analyzed by matrix assisted laser desorption ionization-time-of-flight time-of-flight mass spectrometry. In addition to previously reported proteins found in multiple sclerosis cerebrospinal fluid, such as αß crystallin, enolase, and 14-3-3-protein, we have identified several additional molecules involved in mitochondrial and energy metabolism, myelin gene expression and/or cytoskeletal organization. These include aspartate aminotransferase, cyclophilin-A, quaking protein, collapsin response mediator protein-2, ubiquitin carboxy-terminal hydrolase L1, and cofilin. To further validate these findings, the cellular expression pattern of collapsin response mediator protein-2 and ubiquitin carboxy-terminal hydrolase L1 were investigated in human chronic-active MS lesions by immunohistochemistry. The observation that in multiple sclerosis lesions phosphorylated collapsin response mediator protein-2 was increased, whereas Ubiquitin carboxy-terminal hydrolase L1 was down-regulated, not only highlights the importance of these molecules in the pathology of this disease, but also illustrates the use of our approach in attempting to decipher the complex pathological processes leading to multiple sclerosis and other neurodegenerative diseases.

A consensus statement addressing mesenchymal stem cell transplantation for multiple sclerosis: it's time!

Multiple sclerosis is a neurodegenerative disease of the central nervous system that is characterized by inflammation, demyelination with associated accumulation of myelin debris, oligodendrocyte and axonal loss. Current therapeutic interventions for multiple sclerosis predominantly modulate the immune system and reduce the inflammatory insult by general, non-specific mechanisms but have little effect on the neurodegenerative component of the disease. Predictably, the overall long-term impact of treatment is limited since the neurodegenerative component of the disease, which can be the dominant process in some patients, determines permanent disability. Mesenchymal stem cells, which are endowed with potent immune regulatory and neuroprotective properties, have recently emerged as promising cellular vehicles for the treatment of MS. Preclinical evaluation in experimental models of MS have shown that MSCs are efficacious in suppressing clinical disease. Mechanisms that may underlie these effects predominantly involve the secretion of immunomodulatory and neurotrophic growth factors, which collectively act to limit CNS inflammation, stimulate neurogenesis, protect axons and promote remyelination. As a logical progression to clinical utility, the safety of these cells have been initially assessed in hematological, cardiac and inflammatory diseases. Importantly, transplantation with autologous or allogeneic MSCs has been well tolerated by patients with few significant adverse effects. On the basis of these results, new, multicentre clinical trials have been launched to assess the safety and efficacy of MSCs for inflammatory MS. It thus comes as no surprise that the coalescence of an international group of experts have convened to generate a consensus guide for the transplantation of autologous bone marrow-derived MSC which, in time, may set the foundation for the next generation of therapies for the treatment of MS patients.

Dissipation and displacement of hotspots in reaction-diffusion models of crime.

The mechanisms driving the nucleation, spread, and dissipation of crime hotspots are poorly understood. As a consequence, the ability of law enforcement agencies to use mapped crime patterns to design crime prevention strategies is severely hampered. We also lack robust expectations about how different policing interventions should impact crime. Here we present a mathematical framework based on reaction-diffusion partial differential equations for studying the dynamics of crime hotspots. The system of equations is based on empirical evidence for how offenders move and mix with potential victims or targets. Analysis shows that crime hotspots form when the enhanced risk of repeat crimes diffuses locally, but not so far as to bind distant crime together. Crime hotspots may form as either supercritical or subcritical bifurcations, the latter the result of large spikes in crime that override linearly stable, uniform crime distributions. Our mathematical methods show that subcritical crime hotspots may be permanently eradicated with police suppression, whereas supercritical hotspots are displaced following a characteristic spatial pattern. Our results thus provide a mechanistic explanation for recent failures to observe crime displacement in experimental field tests of hotspot policing.

Flows driven by flagella of multicellular organisms enhance long-range molecular transport.

Evolution from unicellular organisms to larger multicellular ones requires matching their needs to the rate of exchange of molecular nutrients with the environment. This logistic problem poses a severe constraint on development. For organisms whose body plan is a spherical shell, such as the volvocine green algae, the current (molecules per second) of needed nutrients grows quadratically with radius, whereas the rate at which diffusion alone exchanges molecules grows linearly, leading to a bottleneck radius beyond which the diffusive current cannot meet metabolic demands. By using Volvox carteri, we examine the role that advection of fluid by the coordinated beating of surface-mounted flagella plays in enhancing nutrient uptake and show that it generates a boundary layer of concentration of the diffusing solute. That concentration gradient produces an exchange rate that is quadratic in the radius, as required, thus circumventing the bottleneck and facilitating evolutionary transitions to multicellularity and germ-soma differentiation in the volvocalean green algae.

Stalactite growth as a free-boundary problem: a geometric law and its platonic ideal.

The chemical mechanisms underlying the growth of cave formations such as stalactites are well known, yet no theory has yet been proposed which successfully accounts for the dynamic evolution of their shapes. Here we consider the interplay of thin-film fluid dynamics, calcium carbonate chemistry, and CO2 transport in the cave to show that stalactites evolve according to a novel local geometric growth law which exhibits extreme amplification at the tip as a consequence of the locally-varying fluid layer thickness. Studies of this model show that a broad class of initial conditions is attracted to an ideal shape which is strikingly close to a statistical average of natural stalactites.

Coaches' assessment of their coaching efficacy compared to athletes' perceptions.

This study compared coaches' assessments of their own coaching efficacy with their athletes' perceptions of the coaches' efficacy. Coaching efficacy was measured with the Coaching Efficacy Scale. Participants were 9 football coaches and 76 football players from the same team. Analysis indicated coaches were confident in their coaching abilities (range 6.5 to 9.0 on a 9-point scale). For 7 of the 9 coaches the coaches' ratings of themselves were higher than the athletes' ratings. For the other 2 coaches, athletes' ratings of coaches' efficacy were higher than the coaches' ratings of themselves. All coaches' ratings fell within the 95% confidence interval based on the athletes' ratings of the coaches' efficacy. Results are discussed in terms of the interplay between athletes and coaches efficacy beliefs and its influence on behavior.