777 research outputs found
Neutrino Oscillations in a Supersymmetric SO(10) Model with Type-III See-Saw Mechanism
The neutrino oscillations are studied in the framework of the minimal
supersymmetric SO(10) model with Type-III see-saw mechanism by additionally
introducing a number of SO(10) singlet neutrinos. The light Majorana neutrino
mass matrix is given by a combination of those of the singlet neutrinos and the
active neutrinos. The minimal SO(10) model gives an unambiguous Dirac
neutrino mass matrix, which enables us to predict the masses and the other
parameters for the singlet neutrinos. These predicted masses take the values
accessible and testable by near future collider experiments under the
reasonable assumptions. More comprehensive calculations on these parameters are
also given.Comment: 14 pages, 5 figures; the version to appear in JHE
Topological signature of deterministic chaos in short nonstationary signals from an optical parametric oscillator
Although deterministic chaos has been predicted to occur in the triply
resonant optical parametric oscillator (TROPO) fifteen years ago, experimental
evidence of chaotic behavior in this system has been lacking so far, in marked
contrast with most nonlinear systems, where chaos has been actively tracked and
found. This situation is probably linked to the high sensitivity of the TROPO
to perturbations, which adversely affects stationary operation at high power.
We report the experimental observation in this system of a burst of irregular
behavior of duration 80 microseconds. Although the system is highly
nonstationary over this time interval, a topological analysis allows us to
extract a clearcut signature of deterministic chaos from a time series segment
of only 9 base cycles (3 microseconds). This result suggests that
nonstationarity is not necessarily an obstacle to the characterization of
chaos
Criminal Justice Reform as HIV and TB Prevention in African Prisons
Katherine Todrys and Joseph Amon argue for criminal justice system reforms in sub-Saharan Africa to reduce HIV and TB transmission in prisons and to guarantee detainees' human rights and health
Changes in Cell Morphology Are Coordinated with Cell Growth through the TORC1 Pathway
SummaryBackgroundGrowth rate is determined not only by extracellular cues such as nutrient availability but also by intracellular processes. Changes in cell morphology in budding yeast, mediated by polarization of the actin cytoskeleton, have been shown to reduce cell growth.ResultsHere we demonstrate that polarization of the actin cytoskeleton inhibits the highly conserved Target of Rapamycin Complex 1 (TORC1) pathway. This downregulation is suppressed by inactivation of the TORC1 pathway regulatory Iml1 complex, which also regulates TORC1 during nitrogen starvation. We further demonstrate that attenuation of growth is important for cell recovery after conditions of prolonged polarized growth.ConclusionsOur results indicate that extended periods of polarized growth inhibit protein synthesis, mass accumulation, and the increase in cell size at least in part through inhibiting the TORC1 pathway. We speculate that this mechanism serves to coordinate the ability of cells to increase in size with their biosynthetic capacity
Cooperative oscillation of non-degenerate transverse modes in an optical system: multimode operation in parametric oscillators
We show experimentally that parametric interaction can induce a cooperative
oscillation of non simultaneously resonant transverse modes in an optical
parametric oscillator. More generally, this effect is expected to occur in any
spatially extended system subjected to boundary conditions where nonlinear wave
mixing of two nonresonant spatial modes can generate a resonant oscillation
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Multimedia delivery in the future internet
The term “Networked Media” implies that all kinds of media including text, image, 3D graphics, audio
and video are produced, distributed, shared, managed and consumed on-line through various networks,
like the Internet, Fiber, WiFi, WiMAX, GPRS, 3G and so on, in a convergent manner [1]. This white
paper is the contribution of the Media Delivery Platform (MDP) cluster and aims to cover the Networked
challenges of the Networked Media in the transition to the Future of the Internet.
Internet has evolved and changed the way we work and live. End users of the Internet have been confronted
with a bewildering range of media, services and applications and of technological innovations concerning
media formats, wireless networks, terminal types and capabilities. And there is little evidence that the pace
of this innovation is slowing. Today, over one billion of users access the Internet on regular basis, more
than 100 million users have downloaded at least one (multi)media file and over 47 millions of them do so
regularly, searching in more than 160 Exabytes1 of content. In the near future these numbers are expected
to exponentially rise. It is expected that the Internet content will be increased by at least a factor of 6, rising
to more than 990 Exabytes before 2012, fuelled mainly by the users themselves. Moreover, it is envisaged
that in a near- to mid-term future, the Internet will provide the means to share and distribute (new)
multimedia content and services with superior quality and striking flexibility, in a trusted and personalized
way, improving citizens’ quality of life, working conditions, edutainment and safety.
In this evolving environment, new transport protocols, new multimedia encoding schemes, cross-layer inthe
network adaptation, machine-to-machine communication (including RFIDs), rich 3D content as well as
community networks and the use of peer-to-peer (P2P) overlays are expected to generate new models of
interaction and cooperation, and be able to support enhanced perceived quality-of-experience (PQoE) and
innovative applications “on the move”, like virtual collaboration environments, personalised services/
media, virtual sport groups, on-line gaming, edutainment. In this context, the interaction with content
combined with interactive/multimedia search capabilities across distributed repositories, opportunistic P2P
networks and the dynamic adaptation to the characteristics of diverse mobile terminals are expected to
contribute towards such a vision.
Based on work that has taken place in a number of EC co-funded projects, in Framework Program 6 (FP6)
and Framework Program 7 (FP7), a group of experts and technology visionaries have voluntarily
contributed in this white paper aiming to describe the status, the state-of-the art, the challenges and the way
ahead in the area of Content Aware media delivery platforms
Rain-Fed Farming System at a Crossroads in Semi-Arid Areas of Tanzania: What Roles do Climate Variability and Change Play?
Positive changes, like adopting drought resistant crop varieties, in the rain-fed farming system (RFFS) in response to climate variability and change enhance system’s ability to support people’s living as opposed to negative changes, like lack of pastures, which put the system at risk of failure in supporting the living. Using participatory rural appraisal (PRA) and household survey, this paper examined the roles of climate variability and change in triggering changes in RFFS. Specifically, the paper: (i) assessed dominant crop and livestock farming system; (ii) assessed the change element of crop and livestock production systems; and (iii) examined factors for the changes in RFFS. A random sample of 388 households was used. Qualitative data analysis was done through content analysis. Binary logistic regression was used to assess factors that explain changes on RFFS. The results showed that dominant crops were different in each village. Secondly, some changes in crop varieties and in livestock grazing arrangements were noted in response to climate variability and change. Unlike the hypothesis (P>0.05), the results demonstrated that warming (ß = -10.61, Wald = 36.26, P ? 0.001) showed highest significant impact on likelihood of adopting new crop varieties relative to other factors. Similarly, drought (ß = 2.16, Wald = 6.82, P ? 0.009) showed highest impact on the likelihood of changing a grazing place. Yet, the changes were constrained by factors like natural resources protective policies, failure of crop varieties to withstand warming and drought, and poor land use management. Therefore, the RFFS was at a crossroads with implications on system sustainability and livelihoods. The government and private interventions should support farmers and agro-pastoralists to manage risks related to the changes in RFFS in response to climate variability and change. Keywords: Climate change, agro-pastoralism, livelihoods, semi-arid, Tanzani
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Dynamic cooling strategy based on individual animal response mitigated heat stress in dairy cows
Technological progress enables individual cow's temperatures to be measured in real time, using a bolus sensor inserted into the rumen (reticulorumen). However, current cooling systems often work at a constant schedule based on the ambient temperature and not on monitoring the animal itself. This study hypothesized that tailoring the cooling management to the cow's thermal reaction can mitigate heat stress. We propose a dynamic cooling system based on in vivo temperature sensors (boluses). Thus, cooling can be activated as needed and is thus most efficacious. A total of 30 lactating cows were randomly assigned to one of two groups; the groups received two different evaporative cooling regimes. A control group received cooling sessions on a preset time-based schedule, the method commonly used in farms; and an experimental group, which received the sensor-based (SB) cooling regime. Sensor-based was changed weekly according to the cow's reaction, as reflected in the changes in body temperatures from the previous week, as measured by reticulorumen boluses. The two treatment groups of cows had similar milk yields (44.7 kg/d), but those in the experimental group had higher milk fat (3.65 vs 3.43%), higher milk protein (3.23 vs 3.13%), higher energy corrected milk (ECM, 42.84 vs 41.48 kg/d), higher fat corrected milk 4%; (42.76 vs 41.34 kg/d), and shorter heat stress duration (5.03 vs 9.46 h/day) comparing to the control. Dry matter intake was higher in the experimental group. Daily visits to the feed trough were less frequent, with each visit lasting longer. The sensor-based cooling regime may be an effective tool to detect and ease heat stress in high-producing dairy cows during transitional seasons when heat load can become severe in arid and semi-arid zones
Killing the umpire: cooperative defects in mitotic checkpoint and BRCA2 genes on the road to transformation
Recent findings from mouse models of BRCA2 genetic lesions have provided intriguing insights and important questions concerning modes of tumor development in familial breast and ovarian cancers. Fibroblasts from mice homozygous for the BRCA2(Tr) allele grow poorly and display an array of chromosomal abnormalities that are consistent with a role for BRCA2 in DNA repair. This growth defect can be overcome and cellular transformation promoted by the expression of defective, dominant negative alleles of p53 and of the mitotic checkpoint gene Bub1, both of which are known to induce chromosome instability. These findings are mirrored in the genetic lesions sustained in tumors found in the rare BRCA2(Tr/Tr)mice that survive to adulthood, which include defects in p53 as well as the mitotic checkpoint proteins Bub1 and Mad3L. Together, these data hint that tumors in these mice evolve from an unusually intense selective pressure to remove DNA damage checkpoints, which in turn might be facilitated by chromosomal abolition of mitotic checkpoints and the consequent increase in shuffling of genetic information. How these genetic lesions co-operate to yield transformed cells and how these data relate to BRCA1 and BRCA2 defects in the human population are important questions raised by this work
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