Efficient data mappings for parity-declustered data layouts

AbstractThe joint demands of high performance and fault tolerance in a large array of disks can be satisfied by a parity-declustered data layout. Such a data layout is generated by partitioning the data on the disks into stripes and choosing a part of each stripe to hold redundant information. Thus the data layout can be represented as a table of stripes. The data mapping problem is the problem of translating a data address into a disk identifier and an offset on that disk. Recent work has yielded mappings that compute disks and offsets directly from data addresses without the need to store tables. In this paper, we show that parity-declustered data layouts based on commutative rings yield mappings with improved computational efficiency and wider applicability

Molecular mechanisms involved in pulmonary arterial hypertension development

Pulmonary arterial hypertension (PAH) is an elevation in pulmonary arterial pressure, characterized by symptoms of dyspnea, chest pain, decrease in exercise tolerance-fatigue, syncope and, if untreated, PAH leads to right heart failure. In PAH, there is an imbalance between mediators of vasodilation and vasoconstriction (e.g. nitric oxide and prostacycline – potent vasodilators, platelet inhibitor and antimitogens are decreased in PAH, while thromboxane, vasoconstrictor and platelet activator is increased in PAH, resulting in smooth muscle hypertrophy of small vessels, adventitial and intimal proliferation, and plexiform vascular lesions with vascular thrombosis). Standard diagnostic procedures for PAH include physical examination, pulmonary function testing, radiographic imaging, transthoracic echocardiography, right heart catheterization. Current drugs include synthet c prostanoids (iloprost, epoprostenil, beraprost, treprostinil) – vasodilators and antiplatelet agents. Phosphodiesterase-5 inhibitors decrease the breakdown of cGMP, increasing its intracellular levels, leukotriene receptor antagonist, – zafirlukast, decreases pulmonary arterial and venous pressure. Endothelin receptor blockers, bosentan, decrease pulmonary vascular resistance and improve results of functional tests. Other treatments are: anticoagulants, calcium-channel blockers, positive airway pressure therapy for obstructive sleep apnea, or oxygen for hypoxemia, and surgery. In conclusion, although there are some promising drugs in therapy of PAH, there is a need to develop new ones, together with surgical approaches, in order to increase the survival of patients with PAH. Gene and cell therapy could be expected as future perspectives

Advancing global health through development and clinical trials partnerships: a randomized, placebo-controlled, double-blind assessment of safety, tolerability, and Immunogenicity of Plasmodium falciparum sporozoites vaccine for malaria in healthy Equatoguinean men

Equatorial Guinea (EG) has implemented a successful malaria control program on Bioko Island. A highly effective vaccine would be an ideal complement to this effort and could lead to halting transmission and eliminating malaria. Sanaria® PfSPZ Vaccine (Plasmodium falciparum sporozoite Vaccine) is being developed for this purpose. To begin the process of establishing the efficacy of and implementing a PfSPZ Vaccine mass vaccination program in EG, we decided to conduct a series of clinical trials of PfSPZ Vaccine on Bioko Island. Because no clinical trial had ever been conducted in EG, we first successfully established the ethical, regulatory, quality, and clinical foundation for conducting trials. We now report the safety, tolerability, and immunogenicity results of the first clinical trial in the history of the country. Thirty adult males were randomized in the ratio 2:1 to receive three doses of 2.7 × 105 PfSPZ of PfSPZ Vaccine (N = 20) or normal saline placebo (N = 10) by direct venous inoculation at 8-week intervals. The vaccine was safe and well tolerated. Seventy percent, 65%, and 45% of vaccinees developed antibodies to Plasmodium falciparum (Pf) circumsporozoite protein (PfCSP) by enzyme-linked immunosorbent assay, PfSPZ by automated immunofluorescence assay, and PfSPZ by inhibition of sporozoite invasion assay, respectively. Antibody responses were significantly lower than responses in U.S. adults who received the same dosage regimen, but not significantly different than responses in young adult Malians. Based on these results, a clinical trial enrolling 135 subjects aged 6 months to 65 years has been initiated in EG; it includes PfSPZ Vaccine and first assessment in Africa of PfSPZ-CVac. ClinicalTrials.gov identifier: NCT02418962

Worst-Case Performance of Cellular Channel Assignment Policies

this paper, we introduce two such metrics: the worst-case number of channels required to accommodate all possible configurations of N calls in a cell cluster, and the set of cell states that can be accommodated with M channels. We first measure two extreme policies, fixed channel allocation and maximum packing, under these metrics. We then prove a new lower bound, under the first metric, on any channel assignment policy. Next, we introduce three intermediate channel assignment policies, based on commonly used ideas of channel ordering, hybrid assignment, and partitioning. Finally, these policies are used to demonstrate the tradeoff between the performance and the complexity of a channel allocation policy. 1 Introductio

Balancing Load versus Decreasing Communication: Parameterizing the Tradeoff

Domain decomposition is an important step for parallel scientific applications, in particular finite element analyses. A good decomposition will minimize both the time spent on local computation and on interprocessor communication. It is often the case that these two goals cannot be satisfied simultaneously. In this paper, we use analytical and experimental results to illustrate the importance of considering the target architecture as well as the application when determining which factor to emphasize in a decomposition method. In particular, we derive a parameter j 0 that provides some guidelines as to which goal should be given primary focus. Our results yield two interesting facts: (1) allowing some load imbalance can provide some reduction in communication and total execution time and (2) as larger numbers of processors are applied to a problem, larger amounts of load imbalance are beneficial. Corresponding author: Eric J. Schwabe Department of ECE Northwestern University 2145 She..

Real-Time Emulations of Bounded-Degree Networks

this paper, we survey the state of the art in real-time network emulations. In particular, we consider emulation schemes whereby a host network of one type can mimic, in a step-by-step fashion, any computation that can be performed by a guest network of another type. An emulation is called real-time if sizes of the guest and the host are equal, to within a constant factor, and the time required by the host and the time used by the guest are also equal, to within a constant factor. We restrict our attention in this paper to bounded-degre

Improved Parity-Declustered Layouts for Disk Arrays

Recently, parity-declustered layouts have been studied as a tool for reducing the time needed to reconstruct a failed disk in a disk array [6, 11]. Construction of such layouts for large disk arrays generally involves the use of a balanced incomplete block design (BIBD), a type of subset system over the set of disks. This research has been somewhat hampered by the dearth of effective, easily implemented constructions of BIBDs on large sets, and by inefficiencies in some parity-distribution methods that create layouts that are larger than necessary. We make progress on these problems in several ways. In particular, we ffl Demonstrate new BIBD constructions that generalize some previous constructions and yield simpler BIBDs that are optimally small in some cases. ffl Show how relaxing some of the balance constraints on data layouts leads to constructions of approximately-balanced layouts that greatly increase the number of feasible layouts for large arrays. ffl Give a new method for d..

Flexible Usage of Redundancy in Disk Arrays

It is well--known that dedicating one disk's worth of space in a disk array to parity check information can allow the array to tolerate a single failure. More recently, two possible ways of increasing that benefit through the use of additional redundant information have been demonstrated: The additional redundancy can be used to allow the array to tolerate more than one disk failure without the loss of information (multiple--fault tolerance), or it can be used to speed up the reconstruction of a single failed disk and thus reduce the impact of on--line reconstruction on array performance (using a technique known as parity declustering). However, these two advantages could not be obtained simultaneously. In this paper, we demonstrate for the first time how to divide the benefits of extra space for redundant information arbitrarily between increased fault tolerance and accelerated reconstruction of failed disks. In addition, we give general lower bounds on the space overhead required to ..