10,709 research outputs found
Acceleration and Particle Field Interactions of Cosmic Rays I: Formalism
The acceleration of ultra high energy cosmic rays is conjectured to occur
through various interactions with the electromagnetic fields in different
astrophysical objects, like magnetic matter clumps, besides the well-known
shock and stochastic Fermi mechanisms. It is apparent that the latter are not
depending on the particle's charge, quantitatively. Based on this model, a
considerable portion of the dynamics, that derives a charged particle parallel
to a magnetic field and under the influence of a force
, is assumed to be composed of an acceleration by a non-magnetic
force and a gyromotion along direction,
plus drifts in the direction of . The model and its
formalism are introduced. Various examples for drift motions and accelerating
forces are suggested. The formalism is given in a non-relativistic version.
Obviously, the translation into the relativistic version is standard. In a
forthcoming work, a quantitative estimation of the energy gained by charged
cosmic rays in various astrophysical objects will be evaluated.Comment: 9 pages, 2 EPS figure
Correlation of the Hippocampal theta rhythm to changes in hypothalamic temperature
Warming and cooling the preoptic anterior hypothalamic area in awake, loosely restrained rabbits was found to evoke theta rhythm. This is consistent with previous studies indicating that theta rhythm is a nonspecific response evoked by stimulation of several sensory modalities. Several studies have correlated theta rhythm with alertness. A neural pathway involving the hypothalamus, the hippocampus, the septal area, and the reticular formation is proposed. Thus, a role of this pathway may be to alert the animal to changes in its body temperature
Correlation of hippocampal theta rhythm with changes in cutaneous temperature
A possible role for the hippocampus in alerting an animal to changes in cutaneous temperature was examined. Following local warming or cooling of the ears of unanesthetized, loosely restrained rabbits, theta waves (4-7 Hz EEG waves) were recorded from electrodes straddling the hippocampus. The onset of the hippocampal theta rhythm was correlated with changes in cutaneous temperature, an observation consistent with studies indicating that the theta rhythm is a nonspecific response evoked by stimulation of several sensory modalities. Additional data from cats and rabbits were correlated with specific neurons within the hippocampus, namely pyramidal cells. Post stimulus time histograms obtained by excitation of the dorsal fornix were interpreted in terms of excitatory and inhibitory inputs to pyramidal cells. Thus, the theta rhythm, which appears to be evoked by changes in cutaneous temperature, can be related to a specific type of hippocampal neuron which is in turn connected with other areas of the brain involved in temperature regulation
Generation of Entangled Photon Holes using Quantum Interference
In addition to photon pairs entangled in polarization or other variables,
quantum mechanics also allows optical beams that are entangled through the
absence of the photons themselves. These correlated absences, or ``entangled
photon holes'', can lead to counter-intuitive nonlocal effects analogous to
those of the more familiar entangled photon pairs. Here we report an
experimental observation of photon holes generated using quantum interference
effects to suppress the probability that two photons in a weak laser pulse will
separate at an optical beam splitter.Comment: 4 pages, color figures, submitted to Phys. Rev.
Measuring the Impact of Higher Education in Promoting Sustainable Development Goals: Analysis of the Arab universities’ performance
Sustainability's global importance has amplified the role of universities in achieving the UN Sustainable Development Goals (SDGs) through research, education, and community engagement. Aim: This study aims to provide valuable insights into the role of Arab universities in promoting sustainability within the context of global higher education. Approach and methods: This study analyzes the performance of 200 universities from 15 Arab countries in the THE IMPACT Rankings. Their performance was compared to 135 universities from three of the leading world-class higher education systems: Canada, UK, and USA. Results: A global demand for sustainable development, Arab universities face challenges in improving their contributions to the SDGs and sustainability rankings. Despite the impressive growth in the participation of Arab universities in THE IMPACT Rankings yet lags in quality and impact of Arab universities contributions towards SDGs. Conclusion: The policy implications underscore the importance of institutional commitment to sustainability in Arab universities, urging the alignment of policies, funding, and curriculum with the United Nations Sustainable Development Goals (SDGs). Arab universities need to bridge performance gaps, promote green initiatives, and contribute effectively to the achievement of SDGs while recognizing the diverse socio-economic context and priorities of the Arab region.Globalne znaczenie zrównoważonego rozwoju spotęgowało rolę uniwersytetów w realizacji Celów Zrównoważonego Rozwoju (SDG) ONZ poprzez badania, edukację i zaangażowanie społeczności. Cel: Celem tego badania jest dostarczenie cennych spostrzeżeń dotyczących roli uniwersytetów arabskich w promowaniu zrównoważonego rozwoju w kontekście globalnego szkolnictwa wyższego. Podejście i metody: Badanie to analizuje wyniki 200 uniwersytetów z 15 krajów arabskich w rankingach THE IMPACT. Ich wyniki porównano z 135 uniwersytetami z trzech czołowych światowych systemów szkolnictwa wyższego: Kanady, Wielkiej Brytanii i USA. Wyniki: W obliczu globalnego zapotrzebowania na zrównoważony rozwój, uniwersytety arabskie napotykają wyzwania w poprawie swojego wkładu w SDG i rankingi zrównoważoności. Pomimo imponującego wzrostu udziału uniwersytetów arabskich w rankingach THE IMPACT, jest jeszcze wiele do zrobienia w zakresie jakości i wpływu ich wkładu w SDG. Wnioski: Implikacje polityczne podkreślają znaczenie zobowiązania instytucjonalnego do zrównoważonego rozwoju w uniwersytetach arabskich, nawołując do dostosowania polityk, finansowania i programów nauczania do Celów Zrównoważonego Rozwoju (SDG) ONZ. Uniwersytety arabskie muszą zniwelować luki w wynikach, promować inicjatywy zielone i efektywnie przyczyniać się do osiągnięcia SDG, uwzględniając różnorodny kontekst społeczno-ekonomiczny i priorytety regionu arabskiego.
 
Management of erectile dysfunction post-radical prostatectomy
© 2015 Saleh et al.Radical prostatectomy is a commonly performed procedure for the treatment of localized prostate cancer. One of the long-term complications is erectile dysfunction. There is little consensus on the optimal management; however, it is agreed that treatment must be prompt to prevent fibrosis and increase oxygenation of penile tissue. It is vital that patient expectations are discussed, a realistic time frame of treatment provided, and treatment started as close to the prostatectomy as possible. Current treatment regimens rely on phosphodiesterase 5 inhibitors as a first-line therapy, with vacuum erection devices and intraurethral suppositories of alprostadil as possible treatment combination options. With nonresponders to these therapies, intracavernosal injections are resorted to. As a final measure, patients undergo the highly invasive penile prosthesis implantation. There is no uniform, objective treatment program for erectile dysfunction post-radical prostatectomy. Management plans are based on poorly conducted and often underpowered studies in combination with physician and patient preferences. They involve the aforementioned drugs and treatment methods in different sequences and doses. Prospective treatments include dietary supplements and gene therapy, which have shown promise with there proposed mechanisms of improving erectile function but are yet to be applied successfully in human patients
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