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Search Results: 1 - 10 of 297559 matches for " J. Broderick "
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The Scientist as an Advocate: When and When Not  [PDF]
Michael J. Wade, Urs Broderick Furrer
Journal of Environmental Protection (JEP) , 2018, DOI: 10.4236/jep.2018.95030
Abstract: As most of us fundamentally know, there are times a scientist should and should not act as an advocate. As an individual, advocating for environmental preservation is almost required as a member of the world’s scholarly scientific community. However, when that same scientist is asked to offer opinion testimony as an expert witness within the parameters of a lawsuit filed within their particular legal system, there is no room for advocacy. Because it appears that the line an expert scientist must not cross is becoming ever more blurred, we intend to discuss when a scientist should and should not act as an advocate and the reasons that the line between advocate and impartial expert exists. In a legal setting such as a trial or an arbitration hearing, scientists are required to be qualified as an “expert” on the technical subject being considered by the trier of fact before rendering any opinions. Indeed, scientists, unlike all other witnesses, are permitted to present opinions regarding otherwise admissible evidence after being accepted by the Judge as a qualified expert in the field to which he or she intends to testify. However, while the scientist is permitted to present his or her opinions, the scientist is not permitted to advocate for a position or for their interpretation of the evidence presented in a courtroom trial or an arbitration hearing. Rather, those roles are reserved for the parties’ attorneys. Rather, it is the role of the scientist to solely offer opinions with respect to the evidence or facts which are the subject of the dispute. In doing so, the scientist is expected to act as disinterested scholar or teacher faithfully interpreting the data whatever it may reveal. In the eyes of established legal systems, such as the United States (U.S.) or United Kingdom (U.K.), were a scientist to attempt to become an advocate, rather than a scholar and teacher, that scientist’s opinions would no longer be based on fact but, rather, the interests of his or her client, thus damaging the scientist’s credibility. In doing so, the expert could potentially cause irreparable harm to his or her client’s case and his or her reputation.
Fast and Flexible Selection with a Single Switch
Tamara Broderick,David J. C. MacKay
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0007481
Abstract: Selection methods that require only a single-switch input, such as a button click or blink, are potentially useful for individuals with motor impairments, mobile technology users, and individuals wishing to transmit information securely. We present a single-switch selection method, “Nomon,” that is general and efficient. Existing single-switch selection methods require selectable options to be arranged in ways that limit potential applications. By contrast, traditional operating systems, web browsers, and free-form applications (such as drawing) place options at arbitrary points on the screen. Nomon, however, has the flexibility to select any point on a screen. Nomon adapts automatically to an individual's clicking ability; it allows a person who clicks precisely to make a selection quickly and allows a person who clicks imprecisely more time to make a selection without error. Nomon reaps gains in information rate by allowing the specification of beliefs (priors) about option selection probabilities and by avoiding tree-based selection schemes in favor of direct (posterior) inference. We have developed both a Nomon-based writing application and a drawing application. To evaluate Nomon's performance, we compared the writing application with a popular existing method for single-switch writing (row-column scanning). Novice users wrote 35% faster with the Nomon interface than with the scanning interface. An experienced user (author TB, with 10 hours practice) wrote at speeds of 9.3 words per minute with Nomon, using 1.2 clicks per character and making no errors in the final text.
The Equation of State of Neutron-Star Matter in Strong Magnetic Fields
A. Broderick,M. Prakash,J. M. Lattimer
Physics , 2000, DOI: 10.1086/309010
Abstract: We study the effects of very strong magnetic fields on the equation of state (EOS) in multicomponent, interacting matter by developing a covariant description for the inclusion of the anomalous magnetic moments of nucleons. For the description of neutron star matter, we employ a field-theoretical approach which permits the study of several models which differ in their behavior at high density. Effects of Landau quantization in ultra-strong magnetic fields ($B>10^{14}$ Gauss) lead to a reduction in the electron chemical potential and a substantial increase in the proton fraction. We find the generic result for $B>10^{18}$ Gauss that the softening of the EOS caused by Landau quantization is overwhelmed by stiffening due to the incorporation of the anomalous magnetic moments of the nucleons. In addition, the neutrons become completely spin polarized. The inclusion of ultra-strong magnetic fields leads to a dramatic increase in the proton fraction, with consequences for the direct Urca process and neutron star cooling. The magnetization of the matter never appears to become very large, as the value of $|H/B|$ never deviates from unity by more than a few percent. Our findings have implications for the structure of neutron stars in the presence of large frozen-in magnetic fields.
Is there really a dichotomy in AGN jet power?
J. W. Broderick,R. P. Fender
Physics , 2011, DOI: 10.1111/j.1365-2966.2011.19060.x
Abstract: To gain new insights into the radio-loud/radio-quiet dichotomy reported for active galactic nuclei, we examine radio loudness as a function of Eddington ratio for a previously published sample of 199 AGN from five different populations. After initially considering radio loudnesses derived using total radio luminosities, we repeat the investigation using core radio luminosities only, applying a previously established mass correction for these core luminosities. In both cases, for Eddington ratios < 1 per cent, Fanaroff-Riley type I and broad-line radio galaxies are on average more radio-loud than Seyfert and low-ionization nuclear emission-line region galaxies. However, the distribution of radio loudnesses for the mass-corrected, core-only sample is much narrower than that of the clearly bimodal total radio loudness distribution. The advantages and disadvantages of using core- or lobe-dominated radio luminosity as a measure of instantaneous jet power are discussed. We furthermore compare the core and total radio luminosities for the entire sample, as well as illustrating the importance of the mass term by comparing the AGN with a sample of black hole X-ray binaries. We conclude that if the mass-corrected core radio luminosity is a good measure of jet power, then black hole spin may have considerably less impact on jet power than previously reported, or that our sample does not include the extremes of spin. If the spread in jet power is small then we suggest that characteristics of the ambient environment and/or the radio source age could be equally as important in producing a radio-loud/radio-quiet dichotomy seen in total radio luminosity.
Electronic stimulators for surface neural prosthesis
Broderick Barry J.,Breen Paul P.,ólaighin Gearóid
Journal of Automatic Control , 2008, DOI: 10.2298/jac0802025b
Abstract: This paper presents the technological advancements in neural prosthesis devices using Functional Electrical Stimulation (FES). FES refers to the restoration of motor functions lost due to spinal cord injury (SCI), stroke, head injury, or diseases such as Cerebral Palsy or Multiple Sclerosis by eliciting muscular contractions through the use of a neuromuscular electrical stimulator device. The field has developed considerably since its inception, with the miniaturisation of circuity, the development of programmable and adaptable stimulators and the enhancement of sensors used to trigger the application of stimulation to suit a variety of FES applications. This paper discusses general FES system design requirements in the context of existing commercial and research FES devices, focusing on surface stimulators for the upper and lower limbs. These devices have demonstrated feasible standing and stepping in a clinical setting with paraplegic patients, improvements in dropped foot syndrome with hemiplegic patients and aided in the restoration of grasping function in patients with upper limb motor dysfunction.
Observation of soliton explosions in a passively mode-locked fiber laser
Antoine F. J. Runge,Neil G. R. Broderick,Miro Erkintalo
Physics , 2014,
Abstract: Soliton explosions are among the most exotic dissipative phenomena studied in mode-locked lasers. In this regime, a dissipative soliton circulating in the laser cavity experiences an abrupt structural collapse, but within a few roundtrips returns to its original quasi-stable state. In this work we report on the first observation of such events in a fiber laser. Specifically, we identify clear explosion signatures in measurements of shot-to-shot spectra of an Yb-doped mode-locked fiber laser that is operating in a transition regime between stable and noise-like emission. The comparatively long, all-normal-dispersion cavity used in our experiments also permits direct time-domain measurements, and we show that the explosions manifest themselves as abrupt temporal shifts in the output pulse train. Our experimental results are in good agreement with realistic numerical simulations based on an iterative cavity map.
Effects of Strong Magnetic Fields in Strange Baryonic Matter
A. E. Broderick,M. Prakash,J. M. Lattimer
Physics , 2001, DOI: 10.1016/S0370-2693(01)01514-3
Abstract: We investigate the effects of very strong magnetic fields upon the equation of state of dense bayonic matter in which hyperons are present. In the presence of a magnetic field, the equation of state above nuclear density is significantly affected both by Landau quantization and magnetic moment interactions, but only for field strengths $B>5\times10^{18}$ G. The former tends to soften the EOS and increase proton and lepton abundances, while the latter produces an overall stiffening of the EOS. Each results in a supression of hyperons relative to the field-free case. The structure of a neutron star is, however, primarily determined by the magnetic field stress. We utilize existing general relativistic magneto-hydrostatic calculations to demonstrate that maximum average fields within a stable neutron are limited to values $B\le 1-3 \times10^{18}$ G. This is not large enough to significantly influence particle compositions or the matter pressure, unless fluctuations dominate the average field strengths in the interior or configurations with significantly larger field gradients are considered.
Dynamics of soliton explosions in passively mode-locked fiber lasers
Antoine F. J. Runge,Neil G. R. Broderick,Miro Erkintalo
Physics , 2015,
Abstract: A soliton explosion is an instability whereby a dissipative soliton undergoes a sudden structural collapse, but remarkably returns back to its original shape after a short transient. We recently reported the first experimental observation of this effect in a fiber laser (A. F. J. Runge et al., Optica 2, 36 (2015)). Here, we expand on our initial work, presenting a more detailed experimental and numerical study of the characteristics and dynamics of soliton explosions in passively mode-locked fiber lasers. Specifically, we explore different cavity configurations and gain levels, observing and characterizing explosion events using spectral and temporal real-time single-shot techniques. Our results highlight that the explosion characteristics observed in experiments depend critically on the position in the cavity where the output coupler is located. Furthermore, we find that the frequency at which explosions occur can be controlled by adjusting the pump power. We also identify a new kind of ``partial'' explosion, where strong spectral interference fringes appear on the pulse spectra, but a full collapse is avoided. Finally, we perform numerical simulations based on a realistic iterative cavity map, and obtain results that are in good agreement with experimental measurements. Careful analysis of the simulation results provide strong credence to the interpretation that soliton explosions can be linked to a multi-pulsing instability.
Localizing Sagittarius A* and M87 on Microarcsecond Scales with Millimeter VLBI
Avery E. Broderick,Abraham Loeb,Mark J. Reid
Physics , 2011, DOI: 10.1088/0004-637X/735/1/57
Abstract: With the advent of the Event Horizon Telescope (EHT), a millimeter/sub-millimeter very-long baseline interferometer (VLBI), it has become possible to image a handful of black holes with sub-horizon resolutions. However, these images do not translate into microarcsecond absolute positions due to the lack of absolute phase information when an external phase reference is not used. Due to the short atmospheric coherence time at these wavelengths, nodding between the source and phase reference is impractical. However, here we suggest an alternative scheme which makes use of the fact that many of the VLBI stations within the EHT are arrays in their own right. With this we show that it should be possible to absolutely position the supermassive black holes at the centers of the Milky Way (Sgr A*) and M87 relative to nearby objects with precisions of roughly 1 microarcsecond. This is sufficient to detect the perturbations to Sgr A*'s position resulting from interactions with the stars and stellar-mass black holes in the Galactic cusp on year timescales, and severely constrain the astrophysically relevant parameter space for an orbiting intermediate mass black hole, implicated in some mechanisms for producing the young massive stars in the Galactic center. For M87, it allows the registering of millimeter images, in which the black hole may be identified by its silhouette against nearby emission, and existing larger scale radio images, eliminating present ambiguities in the nature of the radio core and inclination, opening angle, and source of the radio jet.
Potassium and Manganese Fertilization and the Effects on Millet Seed Yield, Seed Quality, and Forage Potential of Residual Stalks  [PDF]
Maru Kipleting Kering, Cyril Broderick
Agricultural Sciences (AS) , 2018, DOI: 10.4236/as.2018.97061
Abstract: Millets are important natural grain source for wild and game birds and the domesticated varieties are good sources of grain for human and livestock nutrition as well as summer forage. Unlike sorghum, millet seed has less anti-nutrient factors and is a better choice for animal feed formulations. Pearl millet is an example of such millets and has both forage- and grain-type varieties. However, opportunities exist for dual use of millet for grain and residue for forage. In this study two millets: Pennisetum glaucum (L.) R. Br. (Pearl millet var. TifGrain 102) and Panicum ramosum (L.) (Browntop millet) were evaluated for their response to potassium (K) and manganese (Mn) fertilizer. The experiment was a randomized complete block with treatments in a split-split arrangement. Potassium and Mn were supplied as K fertilizer (0-0-60) and manganese sulfate (MnSO4·2H2O), respectively. Potassium and Mn fertilizer rates and their interaction with each other and variety had no effect on determined parameters. TifGrain 102 grain yield averaged at 5900 kg·ha-1 was significantly greater than 4680 kg·ha-1 obtained for Browntop millet. While grain oil contents were similar, Browntop grain had greater contents of crude proteins. And except for K, Browntop seed had greater contents of all determined macro-and micronutrients. Residual stalks of Browntop had greater forage crude protein, total digestible nutrient (TDN) and lower acid detergent fiber (ADF). Browntop residual material had greater quantities of estimated net energy for growth (NEG), lactation (NEL), maintenance (NME). While TifGrain 102 residual stalks had greater contents of P and K, it had significantly lower contents of Ca, Mg and S compared to Browntop. Overall, while these two millets have shown good potential for dual use, Browntop may offer a better choice for high quality seed and residual stalks for forage.
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