An experimental comparison of cache-oblivious and cache-conscious programs

Cache-oblivious algorithms have been advanced as a way of circumventing some of the difficulties of optimizing applica-tions to take advantage of the memory hierarchy of mod-ern microprocessors. These algorithms are based on the divide-and-conquer paradigm – each division step creates sub-problems of smaller size, and when the working set of a sub-problem fits in some level of the memory hierarchy, the computations in that sub-problem can be executed without suffering capacity misses at that level. In this way, divide-and-conquer algorithms adapt automatically to all levels of the memory hierarchy; in fact, for problems like matrix mul-tiplication, matrix transpose, and FFT, these recursive al-gorithms are optimal to within constant factors for some theoretical models of the memory hierarchy. An important question is the following: how well do care-fully tuned cache-oblivious programs perform compared to carefully tuned cache-conscious programs for the same prob-lem? Is there a price for obliviousness, and if so, how much performance do we lose? Somewhat surprisingly, there are few studies in the literature that have addressed this ques-tion. This paper reports the results of such a study in the domain of dense linear algebra. Our main finding is that in this domain, even highly optimized cache-oblivious pro-grams perform significantly worse than corresponding cache-conscious programs. We provide insights into why this is so, and suggest research directions for making cache-oblivious algorithms more competitive

Model-Based Inference and Classification of Immunologic Control Mechanisms from TKI Cessation and Dose Reduction in Patients with CML

Recent clinicalfindings in patients with chronic myeloid leukemia (CML) suggest that the risk of molecular recurrence after stopping tyrosine kinase inhibitor (TKI) treatment substantially depends on an individual's leukemia-specific immune response. However, it is still not possible to prospectively identify patients that will remain in treatment-free remission (TFR). Here, we used an ordinary differential equation model for CML, which explicitly includes an antileukemic immunologic effect, and applied it to 21 patients with CML for whom BCR-ABL1/ABL1 time courses had been quantified before and after TKI cessation. Immunologic control was conceptually necessary to explain TFR as observed in about half of the patients. Fitting the model simulations to data, we identified patient-specific parameters and classified patients into three different groups according to their predicted immune system configuration ("immunologic landscapes"). While one class of patients required complete CML eradication to achieve TFR, other patients were able to control residual leukemia levels after treatment cessation. Amongthem were a third class of patients that maintained TFR only if an optimal balance between leukemia abundance and immunologic activation was achieved before treatment cessation. Model simulations further suggested that changes in the BCR-ABL1 dynamics resulting from TKI dose reduction convey information about the patient-specific immune system and allow prediction of outcome after treatment cessation. This inference of individual immunologic configurations based on treatment alterations can also be applied to other cancer types in which the endogenous immune system supports maintenance therapy, long-term disease control, or even cure. Significance: This mathematical modeling approach provides strong evidence that different immunologic configurations in patients with CML determine their response to therapy cessation and that dose reductions can help to prospectively infer different risk groups.Peer reviewe

Land, history or modernization? Explaining ethnic fractionalization

Ethnic fractionalization (EF) is frequently used as an explanatory tool in models of economic development, civil war and public goods provision. However, if EF is endogenous to political and economic change, its utility for further research diminishes. This turns out not to be the case. This paper provides the first comprehensive model of EF as a dependent variable. It contributes new data on the founding date of the largest ethnic group in each state. It builds political and international variables into the analysis alongside historical and geoclimatic parameters. It extends previous work by testing models of politically relevant EF. In addition, this research interprets model results in light of competing theories of nationalism and political change. Results show that cross-national variation in EF is largely exogenous to modern politico-economic change. However, the data are inconclusive with respect to competing geoclimatic, historical institutional and modernist theories of ethnogenesis

Proactive Obfuscation

Proactive obfuscation is a new method for creating server replicas that are likely to have fewer shared vulnerabilities. It uses semantics-preserving code transformations to generate diverse executables, periodically restarting servers with these fresh versions. The periodic restarts help bound the number of compromised replicas that a service ever concurrently runs, and therefore proactive obfuscation makes an adversary's job harder. Proactive obfuscation was used in implementing two prototypes: a distributed firewall based on state-machine replication and a distributed storage service based on quorum systems. Costs intrinsic to supporting proactive obfuscation were quantified by measuring the performance of these prototypes.Supported in part by AFOSR grant F9550-06-0019, National Science Foundation Grants 0430161 and CCF-0424422 (TRUST), and Microsoft Corporation

Multi-Verifier Signatures

Multi-verifier signatures generalize traditional digital signatures to a secret-key setting. Just like digital signatures, these signatures are both transferable and secure under arbitrary (unbounded) adaptive chosen-message attacks. In contrast to digital signature schemes, however, we exhibit practical constructions of multi-verifier signature schemes that are provably secure and are based only on pseudorandom functions in the plain model without any random oracles

Viegla galvas smadzeņu trauma (smadzeņu satricinājums)

MedicīnaVeselības aprūpeMedicineHealth CareKonteksts – viegla galvas smadzeņu trauma ir viena no biežāk gūtajām traumām ceļu satiksmes un sporta negadījumos, kā arī gūstot arodtraumas. Tomēr ekspertu viedokļi par konkrētiem aspektiem attiecībā uz klasifikāciju, diagnostiku un ārstēšanas metodēm ir atšķirīgi. Atšķirīgas definīcijas, klasifikācijas un līdzīgu patoloģisku procesu definēšana rada grūtības salīdzināt pētījumus datubāzē “UpToDate. Šajā darbā ir apkopoti ne tikai jaunākie viedokļi un rekomendācijas, bet arī sniegts ieskats par turpmāk nepieciešamajiem pētījumiem. Metodes – Literatūras apskats. Informācijas meklēšana PubMed datu bāzē laika posmā no 2020. gada oktobra līdz 2021. gada oktobrim par vieglām galvas smadzeņu traumām pieaugušo populācijā, to definēšanu, epidemioloģiju, diagnostikas pasākumiem, ieskaitot punktu sistēmu, biomarķierus un vizuālo diagnostiku (DT, MR radioloģiskie izmeklējumi), kā pasākumus, kas jāievēro pilnībā atlabstot pēc galvas traumas (return to play protocols). Tika iekļauti raksti angļu un vācu valodās. Lai identificētu citus iespējamos avotus, tika pārbaudītas arī atsauces no jau atklātajiem literatūras datiem. Kopā izmantotas 56 atsauces. Papildu informācijas izpētei un ekspertu atzinumiem tika izmantota uz pierādījumiem balstīta medicīnas datubāze “UpToDate” Mērķis – Pārskatīt pašreizējos pētījumus par vieglām galvas smadzeņu traumām un to ārstēšanu, analizēt iemeslus dažādām pieejām pētnieku, ārstu un ekspertu vidū. Diagnostikas un aprūpes trūkumu konstatēšana, potenciālu uzlabojumu iespējas un jaunu diagnostikas pasākumu perspektīvas. Secinājums – Pašreizējā zināšanu un diagnostikas instrumentu izvēle joprojām ir ierobežota, var tikt veikti uzlabojumi attiecībā uz sabiedrības informētību, atpazīšanas un diagnostikas pasākumiem, pacientu kontroli dinamikā pēc atlabšanas, izvairīšanos no nevajadzīgu radioloģisko izmeklējumu veikšanas, samazinātu jonizējošā starojuma iedarbību un optimizētu izmaksu efektivitāti, neriskējot ar iespējamiem trūkumiem pacientu drošības jomā.Background/Objectives. – Mild traumatic brain injury is a subtype of one of the most frequent sustained injuries in road accidents, as well as sports and occupational traumas. However, expert opinions differ on certain aspects in relation to classification, diagnostic approaches, and management of this injury. The different definitions, classifications and naming of similar pathogenic processes makes it challenging to compare UpToDate research. Not only did I compile the most recent opinions and recommendations, but also can this paper give an idea about further research necessity. Methods. – Literature review. Search of PubMed database during the period of October 2020 to October 2021 on Mild Traumatic Brain Injury in adult population, its definition, epidemiology, diagnostic measures, including score systems, biomarkers, and imaging techniques (Terms CT, MRI, Radiological investigations), as well as return to play protocols. English and German language articles were included. References from the detected reports were checked to identify other reports. In total 56 sources were used. Additional research by usage of evidence-based medicine database “UpToDate” for additional information research and expert opinions. Aim. – To review the current level of research on diagnostics and management of mild traumatic brain injury, analyze its controversiality among researchers, physicians, and experts. Detection of shortcomings of diagnostics and care, potential for improvement and outlook for new diagnostic measures. Conclusion. – The current state of knowledge and choice of diagnostic tools is still limited, improvements can be made concerning the spread of awareness in society, detection and diagnostic measures, follow-up of patients, avoidance of unnecessary imaging, decrease exposure to ionizing radiation, and optimize cost-efficiency without risking shortcomings for patient safety

Dynamic Searchable Symmetric Encryption

Searchable symmetric encryption (SSE) allows a client to encrypt its data in such a way that this data can still be searched. The most immediate application of SSE is to cloud storage, where it enables a client to securely outsource its data to an untrusted cloud provider without sacrificing the ability to search over it. SSE has been the focus of active research and a multitude of schemes that achieve various levels of security and efficiency have been proposed. Any practical SSE scheme, however, should (at a minimum) satisfy the following properties: sublinear search time, security against adaptive chosenkeyword attacks, compact indexes and the ability to add and delete files efficiently. Unfortunately, none of the previously-known SSE constructions achieve all these properties at the same time. This severely limits the practical value of SSE and decreases its chance of deployment in real-world cloud storage systems. To address this, we propose the first SSE scheme to satisfy all the properties outlined above. Our construction extends the inverted index approach (Curtmola et al., CCS 2006) in several non-trivial ways and introduces new techniques for the design of SSE. In addition, we implement our scheme and conduct a performance evaluation, showing that our approach is highly efficient and ready for deployment.