18,295 research outputs found
Energy-aware dynamic pricing model for cloud environments
Energy consumption is a critical operational cost for Cloud providers. However, as commercial providers typically use fixed pricing schemes that are oblivious about the energy costs of running virtual machines, clients are not charged according to their actual energy impact. Some works have proposed energy-aware cost models that are able to capture each clientâs real energy usage. However, those models cannot be naturally used for pricing Cloud services, as the energy cost is calculated after the termination of the service, and it depends on decisions taken by the provider, such as the actual placement of the clientâs virtual machines. For those reasons, a client cannot estimate in advance how much it will pay. This paper presents a pricing model for virtualized Cloud providers that dynamically derives the energy costs per allocation unit and per work unit for each time period. They account for the energy costs of the providerâs static and dynamic energy consumption by sharing out them according to the virtual resource allocation and the real resource usage of running virtual machines for the corresponding time period. Newly arrived clients during that period can use these costs as a baseline to calculate their expenses in advance as a function of the number of requested allocation and work units. Our results show that providers can get comparable revenue to traditional pricing schemes, while offering to the clients more proportional prices than fixed-price models.Peer ReviewedPostprint (author's final draft
Developing Self-Awareness in Counseling Professionals
This paper identifies the importance of multicultural competency in counselors; (2) defines culture and self-identity to include subculture, constellation of privilege and/or the intersectionality of marginalization that occurs in every person; (3) identifies worldview as culturally defined and influenced, not a single issue; (4) acknowledges the importance for internship experience as a monitored hands-on experience for CITs to gain practice and supervision; (5) encourages counselors to identify their intersections to increase their awareness of intersectionality in a similar investigative practice and supervision environment; (6) succinctly summarizes and categorizes select identity models for developing multicultural competencies in counseling professionals; (7) identifies the need to shift competency model inward to develop self-competency and awareness; (8) Brief introduction of possible results of applying a self-awareness model adapted from cultural competent frameworks to CITs
Matrices commuting with a given normal tropical matrix
Consider the space of square normal matrices over
, i.e., and .
Endow with the tropical sum and multiplication .
Fix a real matrix and consider the set of matrices
in which commute with . We prove that is a finite
union of alcoved polytopes; in particular, is a finite union of
convex sets. The set of such that is
also a finite union of alcoved polytopes. The same is true for the set
of such that .
A topology is given to . Then, the set is a
neighborhood of the identity matrix . If is strictly normal, then
is a neighborhood of the zero matrix. In one case, is
a neighborhood of . We give an upper bound for the dimension of
. We explore the relationship between the polyhedral complexes
, and , when and commute. Two matrices,
denoted and , arise from , in connection with
. The geometric meaning of them is given in detail, for one example.
We produce examples of matrices which commute, in any dimension.Comment: Journal versio
Exploring the fate of cattle herds with inconclusive reactors to the tuberculin skin test
Bovine tuberculosis (TB) is an important animal health issue in many parts of the world. In England and Wales, the primary test to detect infected animals is the single intradermal comparative cervical tuberculin test, which compares immunological responses to bovine and avian tuberculins. Inconclusive test reactors (IRs) are animals that demonstrate a positive reaction to the bovine tuberculin only marginally greater than the avian reaction, so are not classified as reactors and immediately removed. In the absence of reactors in the herd, IRs are isolated, placed under movement restrictions and re-tested after 60 days. Other animals in these herds at the time of the IR result are not usually subject to movement restrictions. This could affect efforts to control TB if undetected infected cattle move out of those herds before the next TB test. To improve our understanding of the importance of IRs, this study aimed to assess whether median survival time and the hazard of a subsequent TB incident differs in herds with only IRs detected compared with negative-testing herds. Survival analysis and extended Cox regression were used, with herds entering the study on the date of the first whole herd test in 2012. An additional analysis was performed using an alternative entry date to try to remove the impact of IR retesting and is presented in the Supplementary Material. Survival analysis showed that the median survival time among IR only herds was half that observed for clear herds (2.1 years and 4.2 years respectively; p < 0.001). Extended Cox regression analysis showed that IR-only herds had 2.7 times the hazard of a subsequent incident compared with negative-testing herds in year one (hazard ratio: 2.69; 95% CI: 2.54, 2.84; p < 0.001), and that this difference in the hazard reduced by 63% per year. After 2.7 years the difference had disappeared. The supplementary analysis supported these findings showing that IR only herds still had a greater hazard of a subsequent incident after the IR re-test, but that the effect was reduced. This emphasizes the importance of careful decision making around the management of IR animals and indicates that re-testing alone may not be sufficient to reduce the risk posed by IR only herds in England and Wales
Challenges for Superstring Cosmology
We consider whether current notions about superstring theory below the Planck
scale are compatible with cosmology. We find that the anticipated form for the
dilaton interaction creates a serious roadblock for inflation and makes it
unlikely that the universe ever reaches a state with zero cosmological constant
and time-independent gravitational constant.Comment: 14 pages, 2 figures available as eps files on reques
Self interacting Brans Dicke cosmology and Quintessence
Recent cosmological observations reveal that we are living in a flat
accelerated expanding universe. In this work we have investigated the nature of
the potential compatible with the power law expansion of the universe in a self
interacting Brans Dicke cosmology with a perfect fluid background and have
analyzed whether this potential supports the accelerated expansion. It is found
that positive power law potential is relevant in this scenario and can drive
accelerated expansion for negative Brans Dicke coupling parameter . The
evolution of the density perturbation is also analyzed in this scenerio and is
seen that the model allows growing modes for negative .Comment: 8pages, 5 figures, PRD style, some changes are made, figures added,
reference added. To be published in Int. J. Mod. Phys.
Extended Inflation from Strings
We study the possibility of extended inflation in the effective theory of
gravity from strings compactified to four dimensions and find that it strongly
depends on the mechanism of supersymmetry breaking. We consider a general class
of string--inspired models which are good candidates for successful extended
inflation. In particular, the --problem of ordinary extended inflation
is automatically solved by the production of only very small bubbles until the
end of inflation. We find that the inflaton field could belong either to the
untwisted or to the twisted massless sectors of the string spectrum, depending
on the supersymmetry breaking superpotential.Comment: 18p
Anxiety: An Evolutionary Approach
Anxiety disorders are among the most common mental illnesses, with huge attendant suffering. Current treatments are not universally effective, suggesting that a deeper understanding of the causes of anxiety is needed. To understand anxiety disorders better, it is first necessary to understand the normal anxiety response. This entails considering its evolutionary function as well as the mechanisms underlying it. We argue that the function of the human anxiety response, and homologues in other species, is to prepare the individual to detect and deal with threats. We use a signal detection framework to show that the threshold for expressing the anxiety response ought to vary with the probability of threats occurring, and the individual's vulnerability to them if they do occur. These predictions are consistent with major patterns in the epidemiology of anxiety. Implications for research and treatment are discussed
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