1,041 research outputs found
CloudScope: diagnosing and managing performance interference in multi-tenant clouds
© 2015 IEEE.Virtual machine consolidation is attractive in cloud computing platforms for several reasons including reduced infrastructure costs, lower energy consumption and ease of management. However, the interference between co-resident workloads caused by virtualization can violate the service level objectives (SLOs) that the cloud platform guarantees. Existing solutions to minimize interference between virtual machines (VMs) are mostly based on comprehensive micro-benchmarks or online training which makes them computationally intensive. In this paper, we present CloudScope, a system for diagnosing interference for multi-tenant cloud systems in a lightweight way. CloudScope employs a discrete-time Markov Chain model for the online prediction of performance interference of co-resident VMs. It uses the results to optimally (re)assign VMs to physical machines and to optimize the hypervisor configuration, e.g. the CPU share it can use, for different workloads. We have implemented CloudScope on top of the Xen hypervisor and conducted experiments using a set of CPU, disk, and network intensive workloads and a real system (MapReduce). Our results show that CloudScope interference prediction achieves an average error of 9%. The interference-aware scheduler improves VM performance by up to 10% compared to the default scheduler. In addition, the hypervisor reconfiguration can improve network throughput by up to 30%
New insights into pedestrian flow through bottlenecks
Capacity estimation is an important tool for the design and dimensioning of
pedestrian facilities. The literature contains different procedures and
specifications which show considerable differences with respect to the
estimated flow values. Moreover do new experimental data indicate a stepwise
growing of the capacity with the width and thus challenge the validity of the
specific flow concept. To resolve these differences we have studied
experimentally the unidirectional pedestrian flow through bottlenecks under
laboratory conditions. The time development of quantities like individual
velocities, density and individual time gaps in bottlenecks of different width
is presented. The data show a linear growth of the flow with the width. The
comparison of the results with experimental data of other authors indicates
that the basic assumption of the capacity estimation for bottlenecks has to be
revised. In contradiction with most planning guidelines our main result is,
that a jam occurs even if the incoming flow does not overstep the capacity
defined by the maximum of the flow according to the fundamental diagram.Comment: Traffic flow, pedestrian traffic, crowd dynamics, capacity of
bottlenecks (16 pages, 8 figures); (+ 3 new figures and minor revisions
The HARPS search for southern extra-solar planets I. HD330075 b: a new 'hot Jupiter'
We report on the first extra-solar planet discovered with the brand new HARPS
instrument. The planet is a typical 'hot Jupiter' with m2sini = 0.62 MJup and
an orbital period of 3.39 days, but from the photometric follow-up of its
parent star HD330075 we can exclude the presence of a transit. The induced
radial-velocity variations exceed 100 m/s in semi-amplitude and are easily
detected by state-of-the-art spectro-velocimeters. Nevertheless, the faint
magnitude of the parent star (V = 9.36) benefits from the efficient instrument:
With HARPS less than 10 observing nights and 3 hours of total integration time
were needed to discover the planet and characterize its orbit. The orbital
parameters determined from the observations made during the first HARPS run in
July 2003 have been confirmed by 7 additional observations carried out in
February 2004. The bisector analysis and a photometric follow-up give no hint
for activity-induced radial-velocity variations, indicating that the velocity
curve is best explained by the presence of a low-mass companion to the star. In
this paper we present a set of 21 measurements of excellent quality with
weighted rms as low as 2.0 m/s. These measurements lead to a well defined orbit
and consequently to the precise orbital parameters determination of the
extra-solar planet HD330075b.Comment: 5 pages, 2 figures, accepted for publication by Astronomy and
Astrophysics, see also http://obswww.unige.ch/~udry/planet/planet.htm
Sexual motivation is reflected by stimulus-dependent motor cortex excitability
Sexual behavior involves motivational processes. Findings from both animal models and neuroimaging in humans suggest that the recruitment of neural motor networks is an integral part of the sexual response. However, no study so far has directly linked sexual motivation to physiologically measurable changes in cerebral motor systems in humans. Using transcranial magnetic stimulation in hetero- and homosexual men, we here show that sexual motivation modulates cortical excitability. More specifically, our results demonstrate that visual sexual stimuli corresponding with one's sexual orientation, compared with non-corresponding visual sexual stimuli, increase the excitability of the motor cortex. The reflection of sexual motivation in motor cortex excitability provides evidence for motor preparation processes in sexual behavior in humans. Moreover, such interrelationship links theoretical models and previous neuroimaging findings of sexual behavio
Physikalische Parameter extrakorporaler StoĂwellen
Prerequisites for the successful investigation of the mechanism of action of ESWT (extracorporeal shockwave therapy) and the establishment of treatment standards, are the ability to measure, and a knowledge of, the physical parameters involved. The most accurate measurements are obtained with laser hydrophones. Various parameters (amplitude, rise time, pulse width, pressure pulse decay, rarification phase) of a typical shock wave can thus be determined. These can then be used to calculate energy flux density, focal extent, focal volume and as well as focal energy, effective energy in a defined area, and effective biological energy. These parameters can be utilized to work out a theoretical treatment protocol
Costs analysis of a population level rabies control programme in Tamil Nadu, India
The study aimed to determine costs to the state government of implementing different interventions for controlling rabies among the entire human and animal populations of Tamil Nadu. This built upon an earlier assessment of Tamil Naduâs efforts to control rabies. Anti-rabies vaccines were made available at all health facilities. Costs were estimated for five different combinations of animal and human interventions using an activity-based costing approach from the provider perspective. Disease and population data were sourced from the state surveillance data, human census and livestock census. Program costs were extrapolated from official documents. All capital costs were depreciated to estimate annualized costs. All costs were inflated to 2012 Rupees. Sensitivity analysis was conducted across all major cost centres to assess their relative impact on program costs. It was found that the annual costs of providing Anti-rabies vaccine alone and in combination with Immunoglobulins was \$0.7 million (Rs 36 million) and \$2.2 million (Rs 119 million), respectively. For animal sector interventions, the annualised costs of rolling out surgical sterilisation-immunization, injectable immunization and oral immunizations were estimated to be \$ 44 million (Rs 2,350 million), \$23 million (Rs 1,230 million) and \$ 11 million (Rs 590 million), respectively. Dog bite incidence, health systems coverage and cost of rabies biologicals were found to be important drivers of costs for human interventions. For the animal sector interventions, the size of dog catching team, dog population and vaccine costs were found to be driving the costs. Rabies control in Tamil Nadu seems a costly proposition the way it is currently structured. Policy makers in Tamil Nadu and other similar settings should consider the long-term financial sustainability before embarking upon a state or nation-wide rabies control programme
Neural distinctiveness of fatigue and low sleep quality in multiple sclerosis
Background and purpose
Fatigue and low sleep quality in multiple sclerosis (MS) are closely related symptoms. Here, the associations between the brain's functional connectivity (FC) and fatigue and low sleep quality were investigated to determine the degree of neural distinctiveness of these symptoms.
Method
A hundred and four patients with relapsingâremitting MS (age 38.9â±â10.2âyears, 66 females) completed the Modified Fatigue Impact Scale and the Pittsburgh Sleep Quality Index and underwent resting-state functional magnetic resonance imaging. FC was analyzed using independent-component analysis in sensorimotor, default-mode, fronto-parietal and basal-ganglia networks. Multiple linear regression models allowed us to test the association between FC and fatigue and sleep quality whilst controlling for one another as well as for demographic, disease-related and imaging variables.
Results
Higher fatigue correlated with lower sleep quality (r = 0.54, pâ<â0.0001). Higher fatigue was associated with lower FC of the precentral gyrus in the sensorimotor network, the precuneus in the posterior default-mode network and the superior frontal gyrus in the left fronto-parietal network, independently of sleep quality. Lower sleep quality was associated with lower FC of the left intraparietal sulcus in the left fronto-parietal network, independently of fatigue. Specific associations were found between fatigue and the sensorimotor network's global FC and between low sleep quality and the left fronto-parietal network's global FC.
Conclusion
Despite the high correlation between fatigue and low sleep quality in the clinical picture, our findings clearly indicate that, on the neural level, fatigue and low sleep quality in MS are associated with decreased FC in distinct functional brain networks
- âŠ