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Search Results: 1 - 10 of 403119 matches for " Eli M. Noam "
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The Next Frontier for Openness: Wireless Communications
Eli M. Noam
Computer Science , 2001,
Abstract: For wireless communications, the FCC has fostered competition rather than openness. This has permitted the emergence of vertically integrated end-to-end providers, creating problems of reduced hardware innovation, software applications, user choice, and content access. To deal with these emerging issues and create multi-level forms of competition, one policy is likely to suffice: a Carterfone for wireless, coupled with more unlicensed spectrum.
Star formation rate in Holmberg IX dwarf galaxy
Serbian Astronomical Journal , 2011, DOI: 10.2298/saj1183071a
Abstract: In this paper we use previously determined Hα fluxes for dwarf galaxy Holmberg IX (Arbutina et al. 2009) to calculate star formation rate (SFR) in this galaxy. We discuss possible contaminations of Hα flux and, for the first time, we take into account optical emission from supernova remnants (SNRs) as a possible source of contamination of Hα flux. Derived SFR for Holmberg IX is 3:4 x 10-4M.yr-1. Our value is lower then in previous studies, due to luminous shock-heated source M&H 9-10, possible hypernova remnant, which we excluded from the total Hα flux in our calculation of SFR.
The detection rate of early UV emission from supernovae: A dedicated GALEX/PTF survey and calibrated theoretical estimates
Noam Ganot,Avishay Gal-Yam,Eran O. Ofek,Ilan Sagiv,Eli Waxman,Ofer Lapid,Shrinivas R. Kulkarni,Sagi Ben-Ami,Mansi M. Kasliwal,Doron Chelouche,Stephen Rafter,Ehud Behar,Ari Laor,Dovi Poznanski,Udi Nakar,Dan Maoz,Benny Trakhtenbrot,James D. Neill,Thomas A. Barlow,Christofer D. Martin,Suvi Gezari,Iair Arcavi,Joshua s. Bloom,Peter E. Nugent,Mark Sullivan
Physics , 2014,
Abstract: The radius and surface composition of an exploding massive star,as well as the explosion energy per unit mass, can be measured using early UV observations of core collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early UV emission from SNe. Six Type II SNe and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX NUV data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find that our observations are in good agreement with calculated rates assuming that red supergiants (RSGs) explode with fiducial radii of 500 solar, explosion energies of 10^51 erg, and ejecta masses of 10 solar masses. Exploding blue supergiants and Wolf-Rayet stars are poorly constrained. We describe how such observations can be used to derive the progenitor radius, surface composition and explosion energy per unit mass of such SN events, and we demonstrate why UV observations are critical for such measurements. We use the fiducial RSG parameters to estimate the detection rate of SNe during the shock-cooling phase (<1d after explosion) for several ground-based surveys (PTF, ZTF, and LSST). We show that the proposed wide-field UV explorer ULTRASAT mission, is expected to find >100 SNe per year (~0.5 SN per deg^2), independent of host galaxy extinction, down to an NUV detection limit of 21.5 mag AB. Our pilot GALEX/PTF project thus convincingly demonstrates that a dedicated, systematic SN survey at the NUV band is a compelling method to study how massive stars end their life.
Peri-Ocular Eye Patterning (POEP): More than Meets the Eye  [PDF]
Noam Josef
Open Journal of Animal Sciences (OJAS) , 2017, DOI: 10.4236/ojas.2017.73027
Abstract: Spatial body patterning is widely observed throughout the phylogenetic tree and is used for a variety of functions. Body colours in general and camouflaging patterns in particular have been extensively studied for their role in stealth and crypsis. Particular interest has focused on the diverse skin patterns surrounding animals’ eyes (Peri-Ocular Eye Patterning-POEP). These patterns have been suggested to aid in high brightness conditions, help camouflage an organism’s eyes or ornament and emphasize bright head colorations. In this work I demonstrate the apparent widespread use of POEP among various marine and terrestrial organisms (both vertebrates and invertebrates) and discuss the trait’s abundance, variations, and possible roles.
A Sub-Nyquist Radar Prototype: Hardware and Algorithms
Eliahu Baransky,Gal Itzhak,Idan Shmuel,Noam Wagner,Eli Shoshan,Yonina C. Eldar
Mathematics , 2012,
Abstract: Traditional radar sensing typically involves matched filtering between the received signal and the shape of the transmitted pulse. Under the confinement of classic sampling theorem this requires that the received signals must first be sampled at twice the baseband bandwidth, in order to avoid aliasing. The growing demands for target distinction capability and spatial resolution imply significant growth in the bandwidth of the transmitted pulse. Thus, correlation based radar systems require high sampling rates, and with the large amounts of data sampled also necessitate vast memory capacity. In addition, real-time processing of the data typically results in high power consumption. Recently, new approaches for radar sensing and detection were introduced, based on the Finite Rate of Innovation and Xampling frameworks. These techniques allow significant reduction in sampling rate, implying potential power savings, while maintaining the system's detection capabilities at high enough SNR. Here we present for the first time a design and implementation of a Xampling-based hardware prototype that allows sampling of radar signals at rates much lower than Nyquist. We demostrate by real-time analog experiments that our system is able to maintain reasonable detection capabilities, while sampling radar signals that require sampling at a rate of about 30MHz at a total rate of 1Mhz.
Role of Dynesys as Pedicle-Based Nonfusion Stabilization for Degenerative Disc Disorders
Neel Anand,Eli M. Baron
Advances in Orthopedics , 2012, DOI: 10.1155/2012/218385
Voices of Women - perceptions of health, illness and health care service during pregnancy in Northwest Russia and Northern Norway in 2000
Eli Heiberg m.fl.
Norsk Epidemiologi , 2009,
Abstract: -
Role of Dynesys as Pedicle-Based Nonfusion Stabilization for Degenerative Disc Disorders
Neel Anand,Eli M. Baron
Advances in Orthopedics , 2012, DOI: 10.1155/2012/218385
Abstract: Posterior nonfusion pedicle-screw-based stabilization remains a controversial area of spine surgery. To date, the Dynesys system remains the most widely implanted posterior nonfusion pedicle screw system. We review the history of Dynesys and discuss clinical outcome studies and biomechanical evaluations regarding the Dynesys system. Indications for surgery and controversies are discussed. Recommendations are made regarding technical implantation. 1. Introduction Posterior nonfusion pedicle-screw-based stabilization is a controversial area of spine surgery. In the last 15–20 years, numerous devices have appeared on the market only to fall out of favor with clinical trials. Various proposed indications exist ranging from discogenic pain to fusion alternatives in the case of possible instability. Additionally, these devices have been used in the setting of artificial discs, in a hybrid construct adjacent to a fusion, and even in the setting of degenerative scoliosis. Out of all of the devices available, the largest experience is with Dynesys. We review the history and literature regarding Dynesys. We also detail our experience with Dynesys in detail and discuss lessons learned in terms of the treatment of degenerative disc disease with these technologies. 2. Brief History The first commonly used posterior pedicle-screw-based nonfusion system was the Graf ligament. This was followed by the use of the Dynesys System. It has been postulated that pedicle-screw-based systems function as a tension band resulting in offloading of the disc possibly resulting in functional improvement [1–3]. Graf ligamentoplasty, introduced in the 1990s, was the first widely used pedicle-screw-based nonfusion stabilization procedure. In this procedure, braided polyester ligaments in the form of a loop were applied around pedicle screws under tension to lock an individual segment in extension [4]. In theory, this device shifted the load from the anterior part of the disc to the posterior annulus [5]. By offloading the painful anterior portion of the disc, this device theoretically may be useful in the treatment of back pain [4, 6]. Grevitt et al. [5] reviewed the outcome of 50 patients undergoing Graf ligamentoplasty. This was done primarily for degenerative disc disease. At an average followup of 24 months, they reported Oswestry Disability Indices (ODIs) scores improving from an average of 59% to 31%. Similar results were found by Gardner and Pande where they reported excellent results in 62% of patients with an average followup of 7.84 years [7]. Mean ODIs improved from 59% ± 10%
A linear thermohaline oscillator driven by stochastic atmospheric forcing
Stephen M. Griffies,Eli Tziperman
Physics , 1995, DOI: 10.1175/1520-0442(1995)008<2440:ALTODB>2.0.CO;2
Abstract: The interdecadal variability of a stochastically forced four-box model of the oceanic meridional thermohaline circulation (THC) is described and compared to the THC variability in the coupled ocean-atmosphere GCM of Delworth, Manabe, and Stouffer (1993). The box model is placed in a linearly stable thermally dominant mean state under mixed boundary conditions. A linear stability analysis of this state reveals one damped oscillatory THC mode in addition to purely damped modes. The variability of the model under a moderate amount of stochastic forcing, meant to emulate the random variability of the atmosphere affecting the coupled model's interdecadal THC variability, is studied. A linear interpretation, in which the damped oscillatory mode is of primary importance, is sufficient for understanding the mechanism accounting for the stochastically forced variability. Direct comparison of the variability in the box model and coupled GCM reveals common qualitative aspects. Such a comparison supports, although does not verify, the hypothesis that the coupled model's THC variability can be interpreted as the result of atmospheric weather exciting a linear damped oscillatory THC mode.
Heavy atom quantum diffraction by scattering from surfaces
Jeremy M. Moix,Eli Pollak
Physics , 2010, DOI: 10.1063/1.3528120
Abstract: Typically one expects that when a heavy particle collides with a surface, the scattered angular distribution will follow classical mechanics. The heavy mass assures that the de Broglie wavelength of the incident particle in the direction of the propagation of the particle (the parallel direction) will be much shorter than the characteristic lattice length of the surface, thus leading to a classical description. Recent work on molecular interferometry has shown that by increasing the perpendicular coherence length, one may observe interference of very heavy species passing through a grating. Here we show, using quantum mechanical simulations, that the same effect will lead to quantum diffraction of heavy particles colliding with a surface. We find that the effect is robust with respect to the incident energy, the angle of incidence and the mass of the particle. It may also be used to verify the quantum nature of the surface and its fluctuations at very low temperatures.
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