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Search Results: 1 - 10 of 429706 matches for " F. S.;Wrobel "
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Solution of hyperbolic bioheat transfer problems by numerical green's functions: the ExGA-linear θ method
Loureiro, F. S.;Wrobel, L. C.;Mansur, W. J.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2012, DOI: 10.1590/S1678-58782012000400006
Abstract: this paper presents a time-domain formulation called explicit green's approach (exga) linear θ method for the solution of the bioheat equation. starting from the hyperbolic bioheat equation, which includes the parabolic one as a special case, the linear method is incorporated into the standard exga time marching scheme. the numerical green's function is firstly computed in the laplace transform domain and then back-transformed to the time domain through the stehfest inversion algorithm. the proposed formulation has the properties of stabilizing the results and suppressing numerical oscillations that appear in the presence of discontinuous solutions as assessed through the analysis of some bioheat transfer problems.
He and Ne ages of large presolar silicon carbide grains: Solving the recoil problem
U. Ott,P. R. Heck,F. Gyngard,R. Wieler,F. Wrobel,S. Amari,E. Zinner
Physics , 2009, DOI: 10.1071/AS08039
Abstract: Knowledge about the age of presolar grains provides important insights into Galactic chemical evolution and the dynamics of grain formation and destruction processes in the Galaxy. Determination from the abundance of cosmic ray interaction products is straightforward, but in the past has suffered from uncertainties in correcting for recoil losses of spallation products. The problem is less serious in a class of large (tens of micrometer) grains. We describe the correction procedure and summarise results for He and Ne ages of presolar SiC "Jumbo" grains that range from close to zero to ~850 Myr, with the majority being less than 200 Myr. We also discuss the possibility of extending our approach to the majority of smaller SiC grains and explore possible contributions from trapping of cosmic rays.
James S. Wrobel,Samuel Marclay,Bijan Najafi
Journal of Sports Science and Medicine , 2012,
Abstract: Golfers have better balance than their age-matched counterparts; however, it is uncertain if this persists during the swing as a function of skill level. The purpose of the study was to investigate dynamic postural control (center of mass (COM) motion) measured during different phases of the swing in golfers of varying proficiency. Eighteen healthy golfers were grouped by handicap: novice (no handicap, n = 7), intermediate (handicap 15-19, n = 7), and advanced (handicap 9-14, n = 4). Indoor testing was performed hitting 3 tee shots using a common driver. A five-camera (60 Hz) motion analysis system (9 markers) was used to extract kinematics data. There were no significant group differences in gender, age, or BMI. Advanced players had lower COM displacement with respect to address at the time of maximum arm speed (p = 0. 001) compared to intermediate (57%, p = 0.014) and novice (73%, p = 0.023). These changes persisted after COM distance and time normalization. Advanced golfers had improved COM linearity during the downswing (p < 0.001) compared to intermediate (30%, p = 0.029) and novice (51%, p < 0.001). Advanced players had decreased COM displacement at the time of maximum arm speed and a more linear COM path during the early downswing. Further study should focus on these changes during ball launch conditions
Clinical factors associated with a conservative gait pattern in older male veterans with diabetes
James S Wrobel, Ryan T Crews, John E Connolly
Journal of Foot and Ankle Research , 2009, DOI: 10.1186/1757-1146-2-11
Abstract: Male veterans (mean age = 67 years; SD = 9.8; range 37–86) with diabetes (n = 152) participated in this study from July 2000 to May 2001 at the Veterans Affairs Medical Center, White River Junction, VT. Various demographic, clinical, static mobility, and plantar pressure measures were collected. Conservative gait pattern was defined by visual gait analysis as failure to demonstrate a heel-to-toe gait during the propulsive phase of gait.Patients with the conservative gait pattern had lower walking speed and decreased stride length compared to normal gait. (0.68 m/s v. 0.91 m/s, p < 0.001; 1.04 m v. 1.24 m, p < 0.001) Age, monofilament insensitivity, and Romberg's sign were significantly higher; and ankle dorsiflexion was significantly lower in the conservative gait pattern group. In the multivariate analysis, walking speed, age, ankle dorsiflexion, and callus were retained in the final model describing 36% of the variance. With the inclusion of ankle dorsiflexion in the model, monofilament insensitivity was no longer an independent predictor.Our multivariate investigation of conservative gait in diabetes patients suggests that walking speed, advanced age, limited ankle dorsiflexion, and callus describe this condition more so than clinical measures of neuropathy.Gait alteration in patients with diabetes has been described [1-3]. Patients with diabetes and peripheral neuropathy (DMPN) exhibit gait instability [4,5]. While this may appear trivial to the treating clinician, unsteadiness in gait demonstrated the strongest association with depressive symptoms in a study by Vileikyte and colleagues [6]. Chamberlin and colleagues identified fearful walkers from a Modified Falls Efficacy Scale. They found fearful walkers demonstrated a slower walking speed, shorter stride length, and longer double support time than walkers not identified as fearful [7]. Courtemanche and colleagues observed similar findings in DMPN patients. They found prolonged reaction times leading the auth
Radio Continuum Evidence for Outflow and Absorption in the Seyfert 1 Galaxy Markarian 231
J. S. Ulvestad,J. M. Wrobel,C. L. Carilli
Physics , 1999, DOI: 10.1086/307111
Abstract: The VLBA and the VLA have been used to image the continuum radio emission from Mrk 231, a Seyfert 1 galaxy and the brightest infrared galaxy in the local universe. The smallest scales reveal a double source less than 2 pc in extent. The components of this central source have minimum brightness temperatures of 10^9 to 10^{10} K, spectral turnovers between 2 and 10 GHz, and appear to define the galaxy nucleus plus the inner regions of a jet. The components may be free-free absorbed or synchtrotron self-absorbed. On larger scales, the images confirm a previously known north-south triple source extending 40 pc and elongated perpendicular to a 350-pc starburst disk. Both lobes show evidence for free-free absorption near 2 GHz, probably due to ionized gas with a density of 1-2 X 10^3 cm^{-3} in the innermost parts of the starburst disk. The absorbing gas may be ionized by the active nucleus or by local regions of enhanced star formation. The elongation of the 40-pc triple differs by 65 deg from that of the 2-pc source. The different symmetry axes on different scales imply strong curvature in the inner part of the radio jet. The radio continuum from the 350-pc disk has a spectral index near -0.4 above 1.4 GHz and is plausibly energized by a massive burst of star formation. On VLA scales, asymmetric and diffuse emission extends for more than 25 kpc. This emission has a steep spectrum, linear polarization exceeding 50% at some locations, and shares the symmetry axis of the 40-pc triple. The diffuse radio source is probably generated by energy deposition from a slow-moving nuclear jet, which conceivably could help energize the off-nuclear starburst as well.
A Sub-kpc Disk in MRK 231
C. L. Carilli,J. M. Wrobel,J. S. Ulvestad
Physics , 1997,
Abstract: We present imaging of the HI 21cm absorption line system seen toward the nuclear regions of Mrk 231 at z = 0.04217, and imaging of the radio continuum emission at 1.4 GHz, on scales ranging from a few parsecs to a few hundred parsecs. These data indicate the existence of a sub-kpc gas disk in Mrk 231, as seen in HI 21cm absorption and in radio continuum emission. The radio continuum morphology is consistent with a disk of maximum radius of 440 mas, at an inclination angle of 45deg, with a major axis oriented east-west. The HI 21cm absorption shows an east-west gradient in position and velocity of about +/-110 km/s out to radii of 100 mas. We identify this HI and radio continuum disk as the inner part of the molecular disk seen on a factor three larger scale. The physical conditions for the thermal and non-thermal gas in the sub-kpc disk of Mrk 231 are similar to those proposed for compact nuclear starburst galaxies, and in particular to the conditions proposed for the sub-kpc gas disk in Arp 220. From the neutral hydrogen velocity field we derive a gravitational mass enclosed within a 50 pc radius of 3x10**8 solar masses. We derive a massive star formation rate in the disk of 60 solar masses per year. We also present a search for HI 21cm absorption associated with the optical broad absorption line systems toward Mrk 231. We do not detect HI 21cm absorption associated with any of the optical BAL systems. These negative results require that the neutral atomic gas in the BAL clouds be fairly warm (T > 50 K), unless the NaI abundance is higher than solar, or the dust-to-gas ratio is higher than Galactic, or the observed extinction toward the nucleus of Mrk 231 is not due to the BAL gas.
AGN Feedback Driven Molecular Outflow in NGC 1266
K. Alatalo,K. E. Nyland,G. Graves,S. Deustua,J. Wrobel,L. M. Young,T. A. Davis,M. Bureau,E. Bayet,L. Blitz,M. Bois,F. Bournaud,M. Cappellari,R. L. Davies,P. T. de Zeeuw,E. Emsellem,S. Khochfar,D. Krajnovic,H. Kuntschner,S. Martin,R. M. McDermid,R. Morganti,T. Naab,T. Oosterloo,M. Sarzi,N. Scott,P. Serra,A. Weijmans
Physics , 2012, DOI: 10.1017/S1743921312019485
Abstract: NGC 1266 is a nearby field galaxy observed as part of the ATLAS3D survey (Cappellari et al. 2011). NGC 1266 has been shown to host a compact (< 200 pc) molecular disk and a mass-loaded molecular outflow driven by the AGN (Alatalo et al. 2011). Very Long Basline Array (VLBA) observations at 1.65 GHz revealed a compact (diameter < 1.2 pc), high bright- ness temperature continuum source most consistent with a low-level AGN origin. The VLBA continuum source is positioned at the center of the molecular disk and may be responsible for the expulsion of molecular gas in NGC 1266. Thus, the candidate AGN-driven molecular outflow in NGC 1266 supports the picture in which AGNs do play a significant role in the quenching of star formation and ultimately the evolution of the red sequence of galaxies.
Dale Towshend, The Orders of Gothic; Foucault, Lacan, and the Subject of Gothic Writing, 1764-1820
Claire Wrobel
Revue d’études Benthamiennes , 2010,
Abstract: Dans The Orders of Gothic, Dale Townshend propose une lecture conjointe de trois corpus : les écrits de Foucault, ceux de Lacan et la littérature gothique produite au Royaume Uni entre 1764 et 1820. 1764 correspond à la parution du Castle of Otranto de Horace Walpole, sous-titré A Gothick Story et qui contient un certain nombre de traits récurrents dans ces romans de la terreur, que l’on a également appelés romans noirs. Townshend s’intéresse donc au gothique canonique, celui qui s’achève...
Gothique, réforme et Panoptique
Claire Wrobel
Revue d’études Benthamiennes , 2010, DOI: 10.4000/etudes-benthamiennes.214
Abstract: IntroductionJamais construit, jamais occupé, le Panoptique de Bentham demeure une architecture virtuelle qu’il est possible d’interpréter, de rêver ou de cauchemarder avec peut-être plus de liberté que si elle s’était incarnée dans la pierre. Si d’un c té, des recherches récentes ont permis de préciser l’évolution historique de ce projet dans la pensée de Bentham, dans d’autres domaines, le Panoptique est un paradigme utilisé pour lire la littérature anglo-saxonne de la fin du XVIIIe sièc...
Reflection Scan: an Off-Path Attack on TCP
Jan Wrobel
Computer Science , 2012,
Abstract: The paper demonstrates how traffic load of a shared packet queue can be exploited as a side channel through which protected information leaks to an off-path attacker. The attacker sends to a victim a sequence of identical spoofed segments. The victim responds to each segment in the sequence (the sequence is reflected by the victim) if the segments satisfy a certain condition tested by the attacker. The responses do not reach the attacker directly, but induce extra load on a routing queue shared between the victim and the attacker. Increased processing time of packets traversing the queue reveal that the tested condition was true. The paper concentrates on the TCP, but the approach is generic and can be effective against other protocols that allow to construct requests which are conditionally answered by the victim. A proof of concept was created to assess applicability of the method in real-life scenarios.
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