\u3ci\u3eAnthidium Oblongatum\u3c/i\u3e (Apoidea: Megachilidae) Confirmed as a Michigan Resident, with Notes on Other Michigan \u3ci\u3eAnthidium\u3c/i\u3e Species

The Palearctic wool-carder bee, Anthidium oblongatum (Illiger) is newly documented in Michigan, with vouchers from Kent, Washtenaw, and Wayne Counties. Additional Michigan records are provided for Anthidium manicatum (L.) and the native Anthidium psoraleae Robertson

Resonance magneto-resistance in double barrier structure with spin-valve

The conductance and tunnel magneto-resistance (TMR) of the double barrier magnetic tunnel junction with spin-valve sandwich (F/P/F) inserted between two insulating barrier, are theoretically investigated. It is shown, that resonant tunnelling, due to the quantum well states of the electron confined between two barriers, sharply depends on the mutual orientation of the magnetizations of ferromagnetic layers F. The calculated optimistic value of TMR exceeds 2000% .Comment: 3 pages, 4 figure

Detecting Electronic States at Stacking Faults in Magnetic Thin Films by Tunneling Spectroscopy

Co islands grown on Cu(111) with a stacking fault at the interface present a conductance in the empty electronic states larger than the Co islands that follow the stacking sequence of the Cu substrate. Electrons can be more easily injected into these faulted interfaces, providing a way to enhance transmission in future spintronic devices. The electronic states associated to the stacking fault are visualized by tunneling spectroscopy and its origin is identified by band structure calculations.Comment: 4 pages, 4 figures; to be published in Phys. Rev. Lett (2000

Epitaxial Co2Cr0.6Fe0.4Al thin films and magnetic tunneling junctions

Epitaxial thin films of the theoretically predicted half metal Co2Cr0.6Fe0.4Al were deposited by dc magnetron sputtering on different substrates and buffer layers. The samples were characterized by x-ray and electron beam diffraction (RHEED) demonstrating the B2 order of the Heusler compound with only a small partition of disorder on the Co sites. Magnetic tunneling junctions with Co2Cr0.6Fe0.4Al electrode, AlOx barrier and Co counter electrode were prepared. From the Julliere model a spin polarisation of Co2Cr0.6Fe0.4Al of 54% at T=4K is deduced. The relation between the annealing temperature of the Heusler electrodes and the magnitude of the tunneling magnetoresistance effect was investigated and the results are discussed in the framework of morphology and surface order based of in situ STM and RHEED investigations.Comment: accepted by J. Phys. D: Appl. Phy

Spin injection and spin accumulation in all-metal mesoscopic spin valves

We study the electrical injection and detection of spin accumulation in lateral ferromagnetic metal-nonmagnetic metal-ferromagnetic metal (F/N/F) spin valve devices with transparent interfaces. Different ferromagnetic metals, permalloy (Py), cobalt (Co) and nickel (Ni), are used as electrical spin injectors and detectors. For the nonmagnetic metal both aluminium (Al) and copper (Cu) are used. Our multi-terminal geometry allows us to experimentally separate the spin valve effect from other magneto resistance signals such as the anomalous magneto resistance (AMR) and Hall effects. We find that the AMR contribution of the ferromagnetic contacts can dominate the amplitude of the spin valve effect, making it impossible to observe the spin valve effect in a 'conventional' measurement geometry. In a 'non local' spin valve measurement we are able to completely isolate the spin valve signal and observe clear spin accumulation signals at T=4.2 K as well as at room temperature (RT). For aluminum we obtain spin relaxation lengths (lambda_{sf}) of 1.2 mu m and 600 nm at T=4.2 K and RT respectively, whereas for copper we obtain 1.0 mu m and 350 nm. The spin relaxation times tau_{sf} in Al and Cu are compared with theory and results obtained from giant magneto resistance (GMR), conduction electron spin resonance (CESR), anti-weak localization and superconducting tunneling experiments. The spin valve signals generated by the Py electrodes (alpha_F lambda_F=0.5 [1.2] nm at RT [T=4.2 K]) are larger than the Co electrodes (alpha_F lambda_F=0.3 [0.7] nm at RT [T=4.2 K]), whereas for Ni (alpha_F lambda_F<0.3 nm at RT and T=4.2 K) no spin signal is observed. These values are compared to the results obtained from GMR experiments.Comment: 16 pages, 12 figures, submitted to PR

Social physique anxiety and physical activity in early adolescent girls : the influence of maturation and physical activity motives

This study considered the influence of maturation on social physique anxiety (SPA), the relationship between SPA and current and future physical activity (PA) levels and the influence of motives for physical activity on this relationship in early adolescent girls (n=162; mean age=11.80±0.33 years). Participants completed the Pubertal Development Scale, the modified Social Physique Anxiety Scale and the Motives for Physical Activity Scale at baseline and the Physical Activity Questionnaire for Older Children at baseline and 6 months later. The girls became less active across the 6 months and girls in the early stages of maturation had significantly lower SPA than the girls in the middle and late stages of maturation. SPA was not related to current or future physical activity in the sample as a whole. Cluster analysis identified four groups with different motive profiles and the High Appearance and Fitness group demonstrated a moderate negative relationship between SPA and PA at phase 1, whereas the other groups did not. These findings indicate that SPA may increase with maturation and the relationship between SPA and PA is dependent on reasons for being active. For girls who are motivated to be active primarily by body-related reasons SPA is likely to lead to lower levels of PA

Quasiparticle dynamics in ferromagnetic compounds of the Co-Fe and Ni-Fe systems

We report a theoretical study of the quasiparticle lifetime and the quasiparticle mean free path caused by inelastic electron-electron scattering in ferromagnetic compounds of the Co-Fe and Ni-Fe systems. The study is based on spin-polarized calculations, which are performed within the $GW$ approximation for equiatomic and Co- and Ni-rich compounds, as well as for their constituents. We mainly focus on the spin asymmetry of the quasiparticle properties, which leads to the spin-filtering effect experimentally observed in spin-dependent transport of hot electrons and holes in the systems under study. By comparing with available experimental data on the attenuation length, we estimate the contribution of the inelastic mean free path to the latter.Comment: 10 pages, 10 figure

Fit to Play? Health-Related Fitness Levels of Youth Athletes: A Pilot Study

A recent National Strength and Conditioning Association position statement suggests that many youth are not prepared for the physical demands of sport. The purpose of this study was to compare health-related fitness (HRF) of youth athletes with normative findings from the general population. We recruited 136 athletes (63 male and 73 female athletes) aged 11-19 (16.01 ± 1.35) years and collected HRF (body composition, cardiorespiratory endurance, musculoskeletal strength and endurance). Results were categorized based on FITNESSGRAM® standards and compared with Canadian youth general population normative data. Most male athletes were classified as "needs improvement" for cardiorespiratory and muscular endurance, and body mass index (BMI). Conversely, most female athletes were at or above the "healthy fitness zone" for all measures. Male athletes at both age groups (11-14, 15-19; p < 0.001) and female athletes aged 11-14 (p < 0.05) demonstrated lower cardiorespiratory endurance compared with Canadian general population. Female athletes (both age groups) demonstrated greater muscular strength, and male athletes (age, 15-19 years) demonstrated lower BMI than the Canadian general population. The results are concerning as male athletes demonstrated poorer HRF compared with the general population. Although most female athletes were within healthy ranges, a portion of them were still at risk. Considering the demands sport places on the body, evaluating HRF is paramount for performance and injury prevention but more importantly for overall health. Youth sport and strength coaches should evaluate and aim to enhance HRF, as participation in sport does not guarantee adequate HRF. Promoting long-term athletic development and life-long health should be a priority in youth

Functional Movement Screen(TM) in Youth Sport Participants: Evaluating the Proficiency Barrier for Injury

Background & Purpose: The number of youth participating in sport increases yearly; however, the evaluation of youths’ movement ability and preparedness for sport remains inadequate or neglected. The Functional Movement Screen (FMS™) is an assessment of an individual’s movement quality that has been utilized to evaluate risk of injury in collegiate and professional sport; however, there is minimal support regarding the predictive value of the screen in youth sport. The purpose of this study was to evaluate the mean and distribution of FMS™ performance in sport participants age 11-18, and to evaluate the existence of a composite FMS™ score proficiency barrier to predict injury risk. Study Design: Prospective cohort study. Methods: One hundred, thirty-six participants (63 male, 73 female) age 11 to 18 years (16.01 + 1.35) were recruited from local schools and sport organizations. The FMS™ was administered prior to each participant’s competitive season and scored by researchers who demonstrated reliability in assessments derived from the screen (κw = 0.70 to 1). Injury data were collected by the participants’ Athletic Trainer over one season. An injury was defined as any physical insult or harm resulting from sports participation that required an evaluation from a health professional with time modified or time lost from sport participation. Results: Females scored significantly higher than males for mean FMS™ composite score (t=14.40; m=12.62; p < 0.001), and on individual measures including: the hurdle step (t=1.91; m=1.65; p < 0.001), shoulder mobility (t=2.68; m=2.02; p < 0.001), active straight leg raise (t=2.32; m=1.87; p < 0.001), and the rotary stability components (t=1.91; m=1.65; p < 0.05). Two FMS™ composite scores (score <14 and <15) significantly increased the odds of injury (OR=2.955). When adjusting for sport, there was no score relating to increased odds of injury. Conclusion: Dysfunctional movement as identified by the FMS™ may be related to increased odds of injury during the competitive season in youth athletes. Consideration of an individual’s movement within the context of their sport is necessary, as each sport and individual have unique characteristics. Addressing movement dysfunction may aid in injury reduction and potentially improve sport performance. Level of Evidence: 1b. Key Words: Functional movement screen, injury prevention, movement system, movement quality, youth spor