On the Factor Refinement Principle and its Implementation on Multicore Architectures

The factor refinement principle turns a partial factorization of integers (or polynomi­ als) into a more complete factorization represented by basis elements and exponents, with basis elements that are pairwise coprime. There are lots of applications of this refinement technique such as simplifying systems of polynomial inequations and, more generally, speeding up certain algebraic algorithms by eliminating redundant expressions that may occur during intermediate computations. Successive GCD computations and divisions are used to accomplish this task until all the basis elements are pairwise coprime. Moreover, square-free factorization (which is the first step of many factorization algorithms) is used to remove the repeated patterns from each input element. Differentiation, division and GCD calculation op­ erations are required to complete this pre-processing step. Both factor refinement and square-free factorization often rely on plain (quadratic) algorithms for multipli­ cation but can be substantially improved with asymptotically fast multiplication on sufficiently large input. In this work, we review the working principles and complexity estimates of the factor refinement, in case of plain arithmetic, as well as asymptotically fast arithmetic. Following this review process, we design, analyze and implement parallel adaptations of these factor refinement algorithms. We consider several algorithm optimization techniques such as data locality analysis, balancing subproblems, etc. to fully exploit modern multicore architectures. The Cilk++ implementation of our parallel algorithm based on the augment refinement principle of Bach, Driscoll and Shallit achieves linear speedup for input data of sufficiently large size

Posterior reversible encephalopathy syndrome (PRES) after bevacizumab therapy for metastatic colorectal cancer.

Posterior reversible encephalopathy syndrome (PRES) is an increasingly recognizable neuro-clinical syndrome. Clinical and neurological manifestations of PRES include hypertension, headache, encephalopathy, seizures, and symmetrical white matter changes on brain MRI. Most common precipitants of PRES are acute medical illness, hypertensive crisis, eclampsia, immunosuppressive therapy, and chemotherapy. Bevacizumab is a monoclonal antibody that halts angiogenesis by inhibiting vascular endothelial growth factor. It has gained widespread popularity in oncology world especially for metastatic and recurrent cancers due to its inherent ability to stop angiogenesis; a vital step for tumor growth. Bevacizumab has also been implicated as the cause of PRES due to dysregulation of the blood-brain barrier. We are reporting a case of PRES induced by Bevacizumab in a patient of colorectal cancer

High Performance Fault-Tolerant Solution of PDEs using the Sparse Grid Combination Technique

The data volume of Partial Differential Equation (PDE) based ultra-large-scale scientific simulations is increasing at a higher rate than that of the system’s processing power. To process the increased amount of simulation data within a reasonable amount of time, the evolution of computation is expected to reach the exascale level. One of several key challenges to overcome in these exascale systems is to handle the high rate of component failure arising due to having millions of cores working together with high power consumption and clock frequencies. Studies show that even the highly tuned widely used checkpointing technique is unable to handle the failures efficiently in exascale systems. The Sparse Grid Combination Technique (SGCT) is proved to be a cost-effective method for computing high-dimensional PDE based simulations with only small loss of accuracy, which can be easily modified to provide an Algorithm-Based Fault Tolerance (ABFT) for these applications. Additionally, the recently introduced User Level Failure Mitigation (ULFM) MPI library provides the ability to detect and identify application process failures, and reconstruct the failed processes. However, there is a gap of the research how these could be integrated together to develop fault-tolerant applications, and the range of issues that may arise in the process are yet to be revealed. My thesis is that with suitable infrastructural support an integration of ULFM MPI and a modified form of the SGCT can be used to create high performance robust PDE based applications. The key contributions of my thesis are: (1) An evaluation of the effectiveness of applying the modified version of the SGCT on three existing and complex applications (including a general advection solver) to make them highly fault-tolerant. (2) An evaluation of the capabilities of ULFM MPI to recover from a single or multiple real process/node failures for a range of complex applications computed with the modified form of the SGCT. (3) A detailed experimental evaluation of the fault-tolerant work including the time and space requirements, and parallelization on the non-SGCT dimensions. (4) An analysis of the result errors with respect to the number of failures. (5) An analysis of the ABFT and recovery overheads. (6) An in-depth comparison of the fault-tolerant SGCT based ABFT with traditional checkpointing on a non-fault-tolerant SGCT based application. (7) A detailed evaluation of the infrastructural support in terms of load balancing, pure- and hybrid-MPI, process layouts, processor affinity, and so on

Privacy of User Identities in Cellular Networks

This thesis looks into two privacy threats of cellular networks. For their operations, these networks have to deal with unique permanent user identities called International Mobile Subscriber Identity (IMSI). One of the privacy threats is posed by a device called IMSI catcher. An IMSI catcher can exploit various vulnerabilities. Some of these vulnerabilities are easier to exploit than others. This thesis looks into fixing the most easily exploitable vulnerability, which is in the procedure of identifying the subscriber. This vulnerability exists in all generations of cellular networks prior to 5G. The thesis discusses solutions to fix the vulnerability in several different contexts. One of the solutions proposes a generic approach, which can be applied to any generation of cellular networks, to fix the vulnerability. The generic approach uses temporary user identities, which are called pseudonyms, instead of using the permanent identity IMSI. The thesis also discusses another solution to fix the vulnerability, specifically in the identification procedure of 5G. The solution uses Identity-Based Encryption (IBE), and it is different from the one that has been standardised in 5G. Our IBE-based solution has some additional advantages that can be useful in future works. The thesis also includes a solution to fix the vulnerability in the identification procedure in earlier generations of cellular networks. The solution fixes the vulnerability when a user of a 5G network connects to those earlier generation networks. The solution is a hybridisation of the pseudonym-based generic solution and the standardised solution in 5G. The second of the two threats that this thesis deals with is related to the standards of a delegated authentication system, known as Authentication and Key Management for Applications (AKMA), which has been released in July 2020. The system enables application providers to authenticate their users by leveraging the authentication mechanism between the user and the user's cellular network. This thesis investigates what requirements AKMA should fulfil. The investigation puts a special focus on identifying privacy requirements. It finds two new privacy requirements, which are not yet considered in the standardisation process. The thesis also presents a privacy-preserving AKMA that can co-exist with a normal-mode AKMA.Väitöskirjassa tutkitaan kahta yksityisyyteen kohdistuvaa uhkaa mobiiliverkoissa. Näissä verkoissa käyttäjät tunnistetaan yksikäsitteisen pysyvän identiteetin perusteella. Hyökkääjä voi uhata käyttäjän yksityisyyttä sellaisen radiolähettimen avulla, joka naamioituu mobiiliverkon tukiasemaksi. Tällainen väärä tukiasema voi pyytää lähellä olevia mobiililaitteita kertomaan pysyvän identiteettinsä, jolloin hyökkääjä voi esimerkiksi selvittää, onko tietyn henkilön puhelin lähistöllä vai ei. Väitöskirjassa selvitetään, millaisilla ratkaisuilla tämän tyyppisiltä haavoittuvuuksilta voidaan välttyä. Viidennen sukupolven mobiiliteknologian standardiin on sisällytetty julkisen avaimen salaukseen perustuva suojaus käyttäjän pysyvälle identiteetille. Tällä ratkaisulla voidaan suojautua väärän tukiaseman uhkaa vastaan, mutta se toimii vain 5G-verkoissa. Yksi väitöskirjassa esitetyistä vaihtoehtoisista ratkaisuista soveltuu käytettäväksi myös vanhempien mobiiliteknologian sukupolvien yhteydessä. Ratkaisu perustuu pysyvän identiteetin korvaamiseen pseudonyymillä. Toinen esitetty ratkaisu käyttää identiteettiin pohjautuvaa salausta, ja sillä olisi tiettyjä etuja 5G-standardiin valittuun, julkisen avaimen salaukseen perustuvaan menetelmään verrattuna. Lisäksi väitöskirjassa esitetään 5G-standardiin valitun menetelmän ja pseudonyymeihin perustuvan menetelmän hybridi, joka mahdollistaisi suojauksen laajentamisen myös aiempiin mobiiliteknologian sukupolviin. Toinen väitöskirjassa tutkittu yksityisyyteen kohdistuva uhka liittyy 5G-standardin mukaiseen delegoidun tunnistautumisen järjestelmään. Tämä järjestelmä mahdollistaa käyttäjän vahvan tunnistautumisen automaattisesti mobiiliverkon avulla. Väitöskirjassa tutkitaan järjestelmälle asetettuja tietoturvavaatimuksia erityisesti yksityisyyden suojan näkökulmasta. Työssä on löydetty kaksi vaatimusta, joita ei ole toistaiseksi otettu huomioon standardeja kehitettäessä. Lisäksi työssä esitetään ratkaisu, jolla delegoidun tunnistautumisen järjestelmää voidaan laajentaa paremmin yksityisyyttä suojaavaksi

Performance and supply chain analysis of Binalebu-1 in some selected areas of Bangladesh

The study was conducted to find out the performance and supply chain of Binalebu-1 in four major Binalebu-1growing areas of Bangladesh, namely Cumilla, Mymensingh, Rangpur and Dhaka districts. Simple random sampling technique was followed for this study. The average cost of lemon production was estimated at Tk. 206127 per hectare of which about 68% was variable cost and 32% was fixed cost. Human labour cost was the lion share (32%) of total cost and it followed by irrigation cost (6.63%), Insecticide (2.64%) sapling (2.60%), and in the study areas. The average yield of Binalebu-1 was recorded 28.32 t/ha in all study areas while it was highest in 3rd year (30.24 t/ha) followed by 2nd year (28.17 t/ha) and 1st year (26.58 t/ha). The average gross return, gross margin and net return of lemon were found to be Tk 744517.62/ha, Tk 454521.67/ha, and Tk 538390.75/ha, respectively. Average BCR was found to be 2.71 on the basis of total cost. Supply chain was classified into four types: Channel 1: Accounts for 40 % which was ranked as I; Channel II: Accounts for 20 % which was Ranked as II; Channel III: Accounts for 18 % which was Ranked as III, Channel IV: Accounts for 12 % which was ranked as IV; Channel V: Accounts for 10 % which was Ranked as V. It was revealed that the value addition of the Faria, Bepari, Paiker, Arathdar, Retailer were Tk.135, Tk.95, Tk.55, Tk.39 and, Tk155 per quintal, respectively

Determinants of Drought Tolerant Rice Variety Adoption: Evidence from Rural farm Household in Northern Part of Bangladesh

The drought-tolerant rice variety Binadhan-19 study was conducted in five districts: Mymensingh, Ranpur, Pabna, Rajshahi and Chapainwabganj of Bangladesh. A total of 200 farmers were randomly selected (40 from each location) to collect the data with a pre-designed questionnaire. Tabular, descriptive statistics and Probit model were used to fulfil objectives. The estimated log-likelihood value of gender, farm size, yield, agricultural extension services have a statistically and significant positive effect on the adoption of the variety. The household characteristic related variables such as age, experience, annual income, human labour, duration of the variety have no statistically significant effect on the adoption of the variety. Marginal coefficients indicate that if male farmers increased by 100%, the probability of adopting the Binadhan-19 variety would increase at 38 times more likely to adopt the variety. If the farm size of Binadhan-19 increased by 100%, the probability of adopting the variety would be increased by 0.07%. A farmer who has access to agricultural extension service is about 39 times more likely to adopt the variety. Again, if the yield increased by 100%, adopting the varieties would increase by 0.08%. The marginal coefficients of locations and soil fertility are negatively significant, indicating that if these two variables increased by 100%, the probability of adopting the varieties would decrease by 0.06% and 30%, respectively

Persepsi pekerja terhadap strategi pembangunan kerjaya dalam organisasi: satu kajian di Johor Corporation, Johor Darul Takzim

Pembangunan kerjaya perlu dititikberatkan bagi pihak organisasi kerana ia dapat memberi peluang kepada para pekerja untuk berusaha keras membangunkan kerjaya dan memikirkan tentang kedudukan dan masa depan mereka dalam sesebuah organisasi. Bagi mengkaji pembangunan kerjaya, konsep pembangunan kerjaya amat penting untuk difahami terlebih dahulu. Pembangunan kerjaya merupakan suatu pendekatan formal yang digunakan oleh organisasi untuk membantu individu mendapatkan kemahiran dan pengalaman bagi menjayakan pekerjaan masa kini dan juga pada masa hadapan (Zafir dan Fazilah, 2003). Persepsi sering dikaitkan dengan pandangan seseorang individu. Persepsi setiap orang adalah berbeza mengikut pandangan masing-masing. Persepsi merupakan proses fizikal dan juga kognitif yang kompleks, aktif dan dinamik. Menurut Jaafar (1997), persepsi didefinisikan sebagai proses di mana individu memilih, menyusun dan menerima segala maklumat yang diperolehi melalui deria. Persepsi dapat melahirkan satu gambaran dan kefahaman yang berguna. Memandangkan pembangunan kerjaya dilihat sebagai salah satu aspek pengurusan sumber manusia yang penting, adalah perlu untuk mengkaji persepsi pekerja terhadap aspek strategi pembangunan kerjaya. Ia dapat mengkaji sejauh mana organisasi dan individu pekerja itu memberi perhatian terhadap pembangunan kerjaya pekerja berdasarkan tahap-tahap strategi pembangunan kerjaya yang ingin dikaji

In Vitro Screening for Antioxidant and Anticholinesterase Effects of Uvaria littoralis Blume.: A Nootropic Phytotherapeutic Remedy

Background: Oxidative stress is strongly linked in the development of numerous chronic and degenerative disorders. Medicinal plants with antioxidant and anticholinesterase activities exert a key role for the management of oxidative stress related disorders mainly Alzheimer's disease (AD). Therefore the purpose of this study was to assess antioxidant potentiality and anticholinesterase inhibitory activity of crude methanolic extract (CME), petroleum ether fraction (PEF), chloroform fraction (CLF), ethyl acetate fraction (EAF) and aqueous fraction (AQF) of Uvaria littoralis (U. littoralis) leaves. Methods: The antioxidant compounds namely total flavonoids contents (TFCs) and total proanthocyanidins contents (TPACCs) were determined for quantities constituent’s characterization. Antioxidant capacity of U. littoralis leaves were estimated by the iron reducing power (IRPA), 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and nitric oxide (NO) radical scavenging capacity. Anticholinesterase effects were estimated for acetylcholinesterase (AChE) and butyrylcholinestrase (BChE) activity. Results: The EAF of U. littoralis leaves showed the highest TFCs as compared to CLF, CME, PEF and AQF. TPACCs were also found highest in EAF. The highest absorbance for IRPA was found in EAF (2.220 nm) with respect to CME and other fractions at the highest concentration. The EAF showed best DPPH and NO radical scavenging activity with IC50 values of 31.63 and 55.47 μg/mL, respectively with regard to CME and remaining fractions. The PEF represents highest AChE inhibitory activity with IC50 values of 35.19 μg/mL and CLF showed highest BChE inhibitory activity with IC50 values of 32.49 μg/mL. Conclusions: The findings of the current study demonstrate the presence of antioxidant phytochemicals, likewise, turns out antioxidant and anticholinesterase potentiality of U. littoralis leaves which could be a prestigious candidate for the treatment of neurodegenerative diseases especially AD

Patient Satisfaction in Chamber Setting in Bangladesh measured by Patient-Doctor Relationship Questionnaire (PDRQ-9 Bangla)

Background: Assessment of patient satisfaction is crucial but there is significant lagging in this sector. Patient satisfaction is an important indicator of health care quality as well as a predictor of treatment adherence. The Good patient-doctor relationship is considered as an integral part of the patient satisfaction. In Bangladesh, this domain is yet to be explored in a large scale. Aim: It was aimed to look into the patient satisfaction level in chamber setting in Bangladesh measured using the patient-doctor relationship questionnaire (PDRQ-9 Bangla). Methods: PDRQ-9 is a short yet excellent tool for assessing the patient-doctor relationship. The data collection was done in private chamber setting by the PDRQ-9 and analyzed. Results: Though the result was not completely in line with the existing literature, the PDRQ-9 was found to be a useful and brief measurement tool in the context of the patient-doctor relationship. Conclusion: Large-scale research in this particular aspect of patient satisfaction in future may provide a more succinct resul