MRI findings associated with anterior cruciate ligament tears in National Football League athletes

BACKGROUND: Anterior cruciate ligament (ACL) tears are a high-frequency injury requiring a lengthy recovery in professional American football players. Concomitant pathology associated with ACL tears as identified on magnetic resonance imaging (MRI) is not well understood in these athletes. PURPOSE: To describe the MRI findings of concomitant injuries associated with ACL tears among athletes in the National Football League (NFL). STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Of 314 ACL injuries in NFL athletes from 2015 through 2019, 191 complete MRI scans from the time of primary ACL injury were identified and reviewed by 2 fellowship-trained musculoskeletal radiologists. Data were collected on ACL tear type and location, as well as presence and location of bone bruises, meniscal tears, articular cartilage pathology, and concomitant ligament pathology. Mechanism data from video review were linked with imaging data to assess association between injury mechanism (contact vs noncontact) and presence of concomitant pathology. RESULTS: Bone bruises were evident in 94.8% of ACL tears in this cohort, most often in the lateral tibial plateau (81%). Meniscal, additional ligamentous, and/or cartilage injury was present in 89% of these knees. Meniscal tears were present in 70% of knees, lateral (59%) more than medial (41%). Additional ligamentous injury was present in 71% of all MRI scans, more often a grade 1/2 sprain (67%) rather than a grade 3 tear (33%), and most often involving the medial collateral ligament (MCL) (57%) and least often the posterior cruciate ligament (10%). Chondral damage was evident in 49% of all MRI scans, with ≥1 full-thickness defect in 25% of all MRI scans, most often lateral. Most (79%) ACL tears did not involve direct contact to the injured lower extremity. Direct contact injuries (21%) were more likely to have a concomitant MCL tear and/or medial patellofemoral ligament injury and less likely to have a medial meniscal tear. CONCLUSION: ACL tears were rarely isolated injuries in this cohort of professional American football athletes. Bone bruises were almost always present, and additional meniscal, ligamentous, and chondral injuries were also common. MRI findings varied by injury mechanism

Now you see it, now you don't - the circumstellar disk in the GRO J1008--57 system

Multiwavelength observations are reported here of the Be/X-ray binary pulsar system GRO J1008-57. Over ten years worth of data are gathered together to show that the periodic X-ray outbursts are dependant on both the binary motion and the size of the circumstellar disk. In the first instance an accurate orbital solution is determined from pulse periods, and in the second case the strength and shape of the Halpha emission line is shown to be a valuable indicator of disk size and its behaviour. Furthermore, the shape of the emission line permits a direct determination of the disk size which is in good agreement with theoretical estimates. A detailed study of the pulse period variations during outbursts determined the binary period to be 247.8, in good agreement with the period determined from the recurrence of the outbursts.Comment: Accepted for publication in MNRA

When lack of control enhances closeness to others : the case of unemployment and economic threat

When personal control is threatened, people often turn to their own group and show negativity towards others. In three studies, we tested an alternative prediction that the salient lack of personal control (vs. control) experienced in the context of unemployment can lead to connectedness and more positive perception of similar others (e.g., members of groups affected by unemployment or the economic crisis). In two European countries, we found experimental (Study 1: Poland) and correlational (Study 2: Spain) evidence that a lowered sense of control of unemployed people was related to more favorable intergroup evaluations. Furthermore, when lack of control related to unemployment threat was experimentally induced, participants perceived a Greek outgroup more positively, and this effect was mediated by identification with and similarity to this group (Study 3). We discuss the role of the shared experience of collective uncontrollability in promoting positive intergroup relation

Constraining compactness and magnetic field geometry of X-ray pulsars from the statistics of their pulse profiles

The light curves observed from X-ray pulsars and magnetars reflect the radiation emission pattern, the geometry of the magnetic field, and the neutron star compactness. We study the statistics of X-ray pulse profiles in order to constrain the neutron star compactness and the magnetic field geometry. We collect the data for 124 X-ray pulsars, which are mainly in high-mass X-ray binary systems, and classify their pulse profiles according to the number of observed peaks seen during one spin period, dividing them into two classes, single- and double-peaked. We find that the pulsars are distributed about equally between both groups. We also compute the probabilities predicted by the theoretical models of two antipodal point-like spots that emit radiation according to the pencil-like emission patterns. These are then compared to the observed fraction of pulsars in the two classes. Assuming a blackbody emission pattern, it is possible to constrain the neutron star compactness if the magnetic dipole has arbitrary inclinations to the pulsar rotational axis. More realistic pencil-beam patterns predict that 79% of the pulsars are double-peaked independently of their compactness. The theoretical predictions can be made consistent with the data if the magnetic dipole inclination to the rotational axis has an upper limit of 40+/-4 deg. We also discuss the effect of limited sensitivity of the X-ray instruments to detect weak pulses, which lowers the number of detected double-peaked profiles and makes the theoretical predictions to be consistent with the data even if the magnetic dipole does have random inclinations. This shows that the statistics of pulse profiles does not allow us to constrain the neutron star compactness. In contrast to the previous claims by Bulik et al. (2003), the data also do not require the magnetic inclination to be confined in a narrow interval.Comment: 14 pages, 10 figures, Astronomy and Astrophysics, in pres

Application-Layer Connector Synthesis

International audienceThe heterogeneity characterizing the systems populating the Ubiquitous Computing environment prevents their seamless interoperability. Heterogeneous protocols may be willing to cooperate in order to reach some common goal even though they meet dynamically and do not have a priori knowledge of each other. Despite numerous e orts have been done in the literature, the automated and run-time interoperability is still an open challenge for such environment. We consider interoperability as the ability for two Networked Systems (NSs) to communicate and correctly coordinate to achieve their goal(s). In this chapter we report the main outcomes of our past and recent research on automatically achieving protocol interoperability via connector synthesis. We consider application-layer connectors by referring to two conceptually distinct notions of connector: coordinator and mediator. The former is used when the NSs to be connected are already able to communicate but they need to be speci cally coordinated in order to reach their goal(s). The latter goes a step forward representing a solution for both achieving correct coordination and enabling communication between highly heterogeneous NSs. In the past, most of the works in the literature described e orts to the automatic synthesis of coordinators while, in recent years the focus moved also to the automatic synthesis of mediators. Within the Connect project, by considering our past experience on automatic coordinator synthesis as a baseline, we propose a formal theory of mediators and a related method for automatically eliciting a way for the protocols to interoperate. The solution we propose is the automated synthesis of emerging mediating connectors (i.e., mediators for short)

Observations of Accreting Pulsars

We summarize five years of continuous monitoring of accretion-powered pulsars with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory. Our 20-70 keV observations have determined or refined the orbital parameters of 13 binaries, discovered 5 new transient accreting pulsars, measured the pulsed flux history during outbursts of 12 transients (GRO J1744-28, 4U 0115+634, GRO J1750-27, GS 0834-430, 2S 1417-624, GRO J1948+32, EXO 2030+375, GRO J1008-57, A 0535+26, GRO J2058+42, 4U 1145-619 and A 1118-616), and also measured the accretion torque history of during outbursts of 6 of those transients whose orbital parameters were also known. We have also continuously measured the pulsed flux and spin frequency for eight persistently accreting pulsars (Her X-1, Cen X-3, Vela X-1, OAO 1657-415, GX 301-2, 4U 1626-67, 4U 1538-52, and GX 1+4). Because of their continuity and uniformity over a long baseline, BATSE observations have provided new insights into the long-term behavior of accreting magnetic stars. We have found that all accreting pulsars show stochastic variations in their spin frequencies and luminosities, including those displaying secular spin-up or spin-down on long time scales, blurring the conventional distinction between disk-fed and wind-fed binaries. Pulsed flux and accretion torque are strongly correlated in outbursts of transient accreting pulsars, but uncorrelated, or even anticorrelated, in persistent sources.Comment: LaTeX, psfig, 90 pages, 42 figures. To appear in Dec. 1997 ApJS, Vol 113, #

A Theory of Mediators for Eternal Connectors

International audienceOn the fly synthesis of mediators is a revolutionary approach to the seamless networking of today's and future digital systems that increasingly need be connected. The resulting emergent mediators (or Connectors) adapt the interaction protocols run by the connected systems to let them communicate. However, although the mediator concept has been studied and used quite extensively to cope with many heterogeneity dimensions, a remaining key challenge is to support on-the-fly synthesis of mediators. Towards this end, this paper introduces a theory of mediators for the ubiquitous networking environment. The proposed formal model: (i) precisely characterizes the problem of interoperability between networked systems, and (ii) paves the way for automated reasoning about protocol matching (interoperability) and related mediator synthesis

Simulation and experimental study of proton bunch self-modulation in plasma with linear density gradients

We present numerical simulations and experimental results of the self-modulation of a long proton bunch in a plasma with linear density gradients along the beam path. Simulation results agree with the experimental results reported [F. Braunmller, T. Nechaeva et al. (AWAKE Collaboration), Phys. Rev. Lett. 125, 264801 (2020)PRLTAO0031-900710.1103/PhysRevLett.125.264801]: with negative gradients, the charge of the modulated bunch is lower than with positive gradients. In addition, the bunch modulation frequency varies with gradient. Simulation results show that dephasing of the wakefields with respect to the relativistic protons along the plasma is the main cause for the loss of charge. The study of the modulation frequency reveals details about the evolution of the self-modulation process along the plasma. In particular for negative gradients, the modulation frequency across time-resolved images of the bunch indicates the position along the plasma where protons leave the wakefields. Simulations and experimental results are in excellent agreement

Development of the self-modulation instability of a relativistic proton bunch in plasma

Self-modulation is a beam–plasma instability that is useful to drive large-amplitude wakefields with bunches much longer than the plasma skin depth. We present experimental results showing that, when increasing the ratio between the initial transverse size of the bunch and the plasma skin depth, the instability occurs later along the bunch, or not at all, over a fixed plasma length because the amplitude of the initial wakefields decreases. We show cases for which self-modulation does not develop, and we introduce a simple model discussing the conditions for which it would not occur after any plasma length. Changing bunch size and plasma electron density also changes the growth rate of the instability. We discuss the impact of these results on the design of a particle accelerator based on the self-modulation instability seeded by a relativistic ionization front, such as the future upgrade of the Advanced WAKefield Experiment

A Puzzling Paucity of Double Peaked X-ray Pulsars

Accretion powered pulsars exhibit a variety of lightcurves. In this paper we propose to classify the observed lightcurves as single or double pulsed.We analyze the lightcurves of 86 accretion powered pulsars and assign them to these classes. We present three datasets: first in which the classification can be easily done, second for which the classification is more difficult and not certain, and third for which we were unable to classify the pulsar because of lack of published data. We analyze a simple model in which the angles between the magnetic and rotation axis $\beta$, and between the rotation axis and the line of sight $\theta$ are random, and show that it is inconsistent with the data. We also present a model in whichthe angle between the magnetic axis and rotation axis is restricted and compare it with the data. This leads to an upper limit on the angle $\beta < 40^\circ$. We conclude that there must be a mechanism that leads to alignment of the magnetic and spin axis in X-ray pulsars.Comment: submitted to A&