Leading-twist Single-transverse-spin asymmetries: Drell-Yan and Deep-Inelastic Scattering

Recently, Brodsky, Hwang and Schmidt have proposed a new mechanism that gives a transverse spin symmetry at leading twist in semi-inclusive deep-inelastic scattering. I show that the new mechanism is compatible with factorization and is due to an transverse-spin asymmetry in the k_T distribution of quarks in a hadron (the "Sivers asymmetry"). An earlier proof that the Sivers asymmetry vanishes because of time-reversal invariance is invalidated by the path-ordered exponential of the gluon field in the operator definition of parton densities. Instead, the time-reversal argument shows that the Sivers asymmetry is reversed in sign in hadron-induced hard processes (e.g., Drell-Yan), thereby violating naive universality of parton densities. Previous phenomenology with time-reversal-odd parton densities is therefore validated.Comment: 12 pages latex. V.2: references corrected. V.3: references added, misprints correcte

Wearable robotic exoskeleton for overground gait training in sub-acute and chronic hemiparetic stroke patients: preliminary results

BACKGROUND: Recovery of therapeutic or functional ambulatory capacity in post-stroke patients is a primary goal of rehabilitation. Wearable powered exoskeletons allow patients with gait dysfunctions to perform over-ground gait training, even immediately after the acute event.AIM: To investigate the feasibility and the clinical effects of an over-ground walking training with a wearable powered exoskeleton in sub-acute and chronic stroke patients.DESIGN: Prospective, pilot pre-post, open label, non-randomized experimental study.SETTING: A single neurological rehabilitation center for inpatients and outpatients.POPULATION: Twenty-three post-stroke patients were enrolled: 12 sub-acute (mean age: 43.8\ub113.3 years, 5 male and 7 female, 7 right hemiparesis and 5 left hemiparesis) and 11 chronic (mean age: 55.5\ub115.9 years, 7 male and 4 female, 4 right hemiparesis and 7 left hemiparesis) patients.METHODS: Patients underwent 12 sessions (60 min/session, 3 times/week) of walking rehabilitation training using Ekso\u2122, a wearable bionic suit that enables individuals with lower extremity disabilities and minimal forearm strength to stand up, sit down and walk over a flat hard surface with a full weight-bearing reciprocal gait. Clinical evaluations were performed at the beginning of the training period (t0), after 6 sessions (t1) and after 12 sessions (t2) and were based on the Ashworth scale, Motricity Index, Trunk Control Test, Functional Ambulation Scale, 10-Meter Walking Test, 6-Minute Walking Test, and Walking Handicap Scale. Wilcoxon's test (P<0.05) was used to detect significant changes.RESULTS: Statistically significant improvements were observed at the three assessment periods for both groups in Motricity Index, Functional Ambulation Scale, 10-meter walking test, and 6-minute walking test. Sub-acute patients achieved statistically significant improvement in Trunk Control Test and Walking Handicap Scale at t0-t2. Sub-acute and chronic patient did not achieve significant improvement in Ashworth scale at t0-t2.CONCLUSIONS: Twelve sessions of over-ground gait training using a powered wearable robotic exoskeleton improved ambulatory functions in sub-acute and chronic post-stroke patients. Large, randomized multicenter studies are needed to confirm these preliminary data.CLINICAL REHABILITATION IMPACT: To plan a completely new individual tailored robotic rehabilitation strategy after stroke, including task-oriented over-ground gait training

EEG Fractal Analysis Reflects Brain Impairment after Stroke

Stroke is the commonest cause of disability. Novel treatments require an improved understanding of the underlying mechanisms of recovery. Fractal approaches have demonstrated that a single metric can describe the complexity of seemingly random fluctuations of physiological signals. We hypothesize that fractal algorithms applied to electroencephalographic (EEG) signals may track brain impairment after stroke. Sixteen stroke survivors were studied in the hyperacute (<48 h) and in the acute phase (∼1 week after stroke), and 35 stroke survivors during the early subacute phase (from 8 days to 32 days and after ∼2 months after stroke): We compared resting-state EEG fractal changes using fractal measures (i.e., Higuchi Index, Tortuosity) with 11 healthy controls. Both Higuchi index and Tortuosity values were significantly lower after a stroke throughout the acute and early subacute stage compared to healthy subjects, reflecting a brain activity which is significantly less complex. These indices may be promising metrics to track behavioral changes in the very early stage after stroke. Our findings might contribute to the neurorehabilitation quest in identifying reliable biomarkers for a better tailoring of rehabilitation pathways

First isolation of mycobacterium bovis from buffalo of the north east of Argentina

Fil: Guanziroli Stefani, M. C. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias; Argentina.Fil: Cicuta, M. E. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias; Argentina.Fil: Zumárraga, M. Instituto Nacional de Tecnología Agropecuaria. Instituto de Biotecnología; Argentina.Fil: Romano, M. I. Instituto Nacional de Tecnología Agropecuaria. Instituto de Biotecnología; Argentina.Para detectar búfalos infectados con Mycobacterium bovis se realizaron pruebas tuberculínicas intradérmicas a 402 búfalos de raza Murrah del nordeste argentino. Cuatro animales resultaron positivos y seis sospechosos a la prueba ano–caudal simple, de los cuales cinco fueron positivos a la prueba cervical comparada. Se realizó necropsia a una hembra de 9 años que había reaccionado positivamente a ambas pruebas, en la que se observó sólo un ganglio retromamario afectado con necrosis caseosa. A partir del mismo se aisló M. bovis espoligotipo 34, que es el más frecuente en los aislamientos provenientes del ganado bovino de la zona. Se destaca la ubicación del linfonódulo afectado para tenerla en cuenta en las necropsias de la especie bubalina.In order to detect buffalos infected with Mycobacterium bovis, 402 animals of Murrah breed were tested by means of intradermal tuberculin. Four resulted positive and six suspicious to the caudal fold simple test; from these, five were positive to comparative cervical test. One nine years–old positive female was necropsied. The only granulomatous lesion found was in one retromammary lymph–node. From this, M. bovis spoligotype 34 was isolated. This genetic type is the predominant in cows of this region. We emphasize the localization of this lesion, which is not usually found in cattle

Primer aislamiento de Mycobacterium bovis de búfalo del nordeste argentino

Para detectar búfalos infectados con Mycobacterium bovis se realizaron pruebas tuberculínicas intradérmicas a 402 búfalos de raza Murrah del nordeste argentino. Cuatro animales resultaron positivos y seis sospechosos a la prueba ano–caudal simple, de los cuales cinco fueron positivos a la prueba cervical comparada. Se realizó necropsia a una hembra de 9 años que había reaccionado positivamente a ambas pruebas, en la que se observó sólo un ganglio retromamario afectado con necrosis caseosa. A partir del mismo se aisló M. bovis espoligotipo 34, que es el más frecuente en los aislamientos provenientes del ganado bovino de la zona. Se destaca la ubicación del linfonódulo afectado para tenerla en cuenta en las necropsias de la especie bubalina

Intrinsic transverse momentum and the polarized Drell-Yan process

In this paper we study the cross section at leading order in $1/Q$ for polarized Drell-Yan scattering at measured lepton-pair transverse momentum $Q_T$. We find that for a hadron with spin $1/2$ the quark content at leading order is described by six distribution functions for each flavor, which depend on both the lightcone momentum fraction $x$, and the quark transverse momentum \bbox{k}_T^2. These functions are illustrated for a free-quark ensemble. The cross sections for both longitudinal and transverse polarizations are expressed in terms of convolution integrals over the distribution functions.Comment: 25 pages, REVTEX 3.0 (3 figures included in separate LATEX file using feynman.tex), NIKHEF-94-P1 (Revised version

Transverse Momentum Distributions for Heavy Quark Pairs

We study the transverse momentum distribution for a $pair$ of heavy quarks produced in hadron-hadron interactions. Predictions for the large transverse momentum region are based on exact order $\alpha_s^3$ QCD perturbation theory. For the small transverse momentum region, we use techniques for all orders resummation of leading logarithmic contributions associated with initial state soft gluon radiation. The combination provides the transverse momentum distribution of heavy quark pairs for all transverse momenta. Explicit results are presented for $b\bar b$ pair production at the Fermilab Tevatron collider and for $c\bar c$ pair production at fixed target energies.Comment: LaTeX (27 pages text, 8 figures not included, but available on request

An impairment-specific hip exoskeleton assistance for gait training in subjects with acquired brain injury: a feasibility study

This study was designed to investigate the feasibility and the potential effects on walking performance of a short gait training with a novel impairment-specific hip assistance (iHA) through a bilateral active pelvis orthosis (APO) in patients with acquired brain injury (ABI). Fourteen subjects capable of independent gait and exhibiting mild-to-moderate gait deficits, due to an ABI, were enrolled. Subjects presenting deficit in hip flexion and/or extension were included and divided into two groups based on the presence (group A, n = 6) or absence (group B, n = 8) of knee hyperextension during stance phase of walking. Two iHA-based profiles were developed for the groups. The protocol included two overground gait training sessions using APO, and two evaluation sessions, pre and post training. Primary outcomes were pre vs. post-training walking distance and steady-state speed in the 6-min walking test. Secondary outcomes were self-selected speed, joint kinematics and kinetics, gait symmetry and forward propulsion, assessed through 3D gait analysis. Following the training, study participants significantly increased the walked distance and average steady-state speed in the 6-min walking tests, both when walking with and without the APO. The increased walked distance surpassed the minimal clinically important difference for groups A and B, (respectively, 42 and 57&nbsp;m &gt; 34&nbsp;m). In group A, five out of six subjects had decreased knee hyperextension at the post-training session (on average the peak of the knee extension angle was reduced by 36%). Knee flexion during swing phase increased, by 16% and 31%, for A and B groups respectively. Two-day gait training with APO providing iHA was effective and safe in improving walking performance and knee kinematics in ABI survivors. These preliminary findings suggest that this strategy may be viable for subject-specific post-ABI gait rehabilitation