The Asymptotic Complexity of Coded-BKW with Sieving Using Increasing Reduction Factors

The Learning with Errors problem (LWE) is one of the main candidates for post-quantum cryptography. At Asiacrypt 2017, coded-BKW with sieving, an algorithm combining the Blum-Kalai-Wasserman algorithm (BKW) with lattice sieving techniques, was proposed. In this paper, we improve that algorithm by using different reduction factors in different steps of the sieving part of the algorithm. In the Regev setting, where $q = n^2$ and $\sigma = n^{1.5}/(\sqrt{2\pi}\log_2^2 n)$, the asymptotic complexity is $2^{0.8917n}$, improving the previously best complexity of $2^{{0.8927n}}$. When a quantum computer is assumed or the number of samples is limited, we get a similar level of improvement.Comment: Longer version of a paper to be presented at ISIT 2019. Updated after comments from the peer-review process. Includes an appendix with a proof of Theorem

Livsmedelskontroll i Östhammars kommun: vad skulle göra företagen nöjdare?

Livsmedelskontroll är en viktig del i arbetet för att öka livsmedelsföretagens efterlevnad av lagstiftning och förhindra att konsumenter blir sjuka. Relationen och kommunikationen med livsmedelsföretagen kan ha betydelse för kontrollens effektivitet, varför det är viktigt att känna till hur livsmedelskontrollen uppfattas från företagens perspektiv. Denna studie syftar till att ta fram förbättringsförslag för att öka nöjdheten hos livsmedelsföretagen i Östhammars kommun. Detta undersöks genom semistrukturerade intervjuer i två kommuner. Den jämförande kommunen är Älvkarleby kommun, i vilken företagen har en högre upplevd nöjdhet enligt Sveriges Kommuner och Regioners undersökning, Insikt. Totalt intervjuades fem representanter för livsmedelsföretag i varje studerad kommun. Analys av material gjordes med tematisk analys. Resultatet visar att det finns skillnader i hur livsmedelsföretagen upplever kontrollen mellan kommunerna samt inom Östhammars kommun. Kommunikation och bemötande från inspektörerna under kontrollen uppfattas som bra i båda kommuner. I Östhammar finns brister i tillgängligheten och för båda kommunerna uttrycks önskemål om mer information från kommunen. I Östhammar är upplevelsen av kontrollen mer varierad än i Älvkarleby. Följande förbättringsförslag togs fram för Östhammars kommun: - Öka tillgängligheten genom att tillhandahålla kontaktuppgifter efter utförd inspektion. - Öka informationsflödet till livsmedelsföretagen, exempelvis genom webbsida, informationsbroschyr eller mejlutskick. Informera om vart information finns. - Kontinuerlig kompetensutveckling för inspektörer i kommunikation/samtalsmetodik.Food safety control is an important part of increasing compliance with legislation and reduce foodborne illness. The relationship and communication with food companies may affect the outcome of the control, which is why it is important to examine food safety control from their perspective. This study aims to produce improvement proposals to increase the satisfaction of the food companies in the municipality of Östhammar. This was investigated through semi-structured interviews in two municipalities. The compared municipality is Älvkarleby, in which the companies have a higher perceived satisfaction according to Sveriges Kommuner och Regioner’s survey, Insikt. A total of five representatives of food companies in each studied municipality were interviewed and analysis was done with thematic analysis. The results show that there are differences in how the food companies experience the control between the municipalities. There are also differences in experience within the municipality of Östhammar. Communication and attitude from the inspectors are perceived as good in both municipalities. In Östhammar there is potential for improvement in availability and for both municipalities food companies express a need for more information from the municipality. In Östhammar, the control is perceived to vary to a greater degree than in Älvkarleby. The following improvement proposals was complied for the municipality of Östhammar: - Increase availability by providing contact details after an inspection has been carried out. - Increase the flow of information to the food companies, for example through a website, information brochure or e-mail. Inform about where food companies can find neccesary information. - Continuous training for inspectors in communication/conversation methodology

Acute gastrointestinal graft-versus-host disease in allogeneic hematopoietic stem cell transplanted children and adolescents : clinical aspects of histopathological evaluation and risk factors

Background Acute graft-versus-host disease (aGVHD), following allogeneic hematopoietic stem cell transplantation (HSCT), is a potentially life-threating condition. Gastrointestinal involvement of aGVHD (GI-aGVHD) affects approximately every fourth transplanted child. The diagnosis of GI-aGVHD is primarily symptom-based. However, symptoms associated with GI-aGVHD are nonspecific; thus, histopathological confirmation of the diagnosis, is recommended. The overall objectives of this thesis were: i) to evaluate the influence of two different conditioning regimens on the incidence of GI-aGVHD, and ii) to evaluate clinical aspects of the currently recommended diagnostic approach to GI-aGVHD, i.e., endoscopy-guided histopathological assessment, applied to pediatric HSCT patients. Patients and methods Four retrospective cohort studies were included in this thesis. Paper I enrolled all children with HSCT performed during 2000–2010 at Karolinska University Hospital Huddinge who also had underlying diagnoses of juvenile myelomonocytic leukemia (JMML) or myelodysplastic syndrome (MDS). The children were conditioned with busulfan (Bu) and cyclophosphamide (Cy), with or without addition of melphalan (Mel). Paper IIIV included all children who underwent HSCT at any of the four HSCT centers in Sweden between 2000 and 2012 and with endoscopy-guided histopathological assessment performed to confirm symptom-based GI-aGVHD within one-year post-HSCT. In paper III-IV a retrospective, blinded, histopathological assessment (RIHA) was carried out based on the National Institutes of Health (NIH) 2014 criteria for histopathology-based GI-GVHD. Paper IV only included those with at least a biopsy sampling from the rectosigmoid area and the area proximal to the left colonic flexure. Results Paper 1: Twenty-five children were enrolled. Forty-seven percent (8/17) of the children that received addition of Mel to the BuCy conditioning, versus none (0/8) in the BuCy group, developed GI-aGVHD (stages 2-4) (p<0.05). Paper II: Based on 68 children with 91 endoscopic occasions, treatment changes in response to histopathology reports occurred in 48% (44/91). Paper III: Seventy children with 92 endoscopic occasions were assessed. Histopathologybased GI-GVHD diagnosis was established in 67 of 92 (73%) endoscopic occasions in the RIHA and in 50 of 92 (54%) in the clinical standard histopathological assessment (p=0.014). The risk of a subsequent re-endoscopy within one-year post-HSCT was higher in endoscopic occasions with GI-GVHD solely detected in RIHA versus non-GI-GVHD in both assessments (p=0.005). Paper IV: Forty-four children with 51 endoscopic occasions were analyzed. Biopsies from the rectosigmoid area had 85% sensitivity for RIHA-based GI-GVHD diagnosis. The corresponding figure for combined biopsy sampling from both rectosigmoid area and upper gastrointestinal tract was 97% and was similarly high compared with biopsies collected from complete lower endoscopy. Conclusions I) Addition of Mel to the BuCy conditioning increased the incidence of symptom-based GI-aGVHD in children with JMML and MDS. II) Endoscopy-guided histopathological assessment was found to influence the treatment decisions and should therefore be considered in children with GI-aGVHD. III) In children with symptom-based GI-aGVHD, without confirmation of the diagnosis by clinical standard histopathological assessment, a second histopathological assessment based on the NIH 2014 criteria should be considered before performing a re-endoscopy. IV) Sigmoidoscopy combined with upper endoscopy, colonoscopy/ileocolonoscopy, or full upper and lower endoscopy should be considered as preferred choices for the endoscopic procedure in children with clinically suspected GI-aGVHD

Memory Optimization in the JastAdd Metacompiler

JastAdd is a tool for generating programming language compilers. These compilers generally use more memory than other compilers for the same language. In this thesis we have categorized the memory use of two JastAdd-generated compilers, to identify opportunities to reduce their memory use. We present several optimizations for reducing the memory use of these compilers. These include changes to the runtime representation of the AST and memoization in the code generated by JastAdd. We have implemented the optimizations in JastAdd and benchmarked their performance with respect to memory use and execution time. We see an overall reduction of the optimizable memory use for the two compilers of approximately 5% and 24%.Detta arbete undersöker och utvärderar nya metoder för att minska minnesanvänd- ningen i kompilatorer genererade med metakompilatorsystemet JastAdd

Lactic acid bacteria fermentations in oat-based suspensions

This thesis deals with the fermentation characteristics of lactic acid bacteria (LAB) in oat-based suspensions, with formulation work of fermented products based on oat and with nutritional studies of these products. Changes in structure in terms of viscosity and ropiness were studied when exopolysaccharide (EPS)-producing LAB strains, namely, Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772, Lactobacillus brevis G-77 and Pediococcus damnosus 2.6 were grown in these oat-based suspensions. Differences in structure were seen after growth of EPS-producing bacteria, resulting in higher viscosity and ropiness in these products. The formulation work of fermented products was carried out by using commercial yoghurt cultures with and without the presence of an EPS-producing strain. The products developed were found to have sensory acceptance and good bacterial survival during storage. The bacterial survival of three probiotic strains, Lactobacillus reuteri ATCC 55730, Lactobacillus acidophilus DSM 20079 and Bifidobacterium bifidum DSM 20456, was also studied in different oat-based suspensions with and without the influence of a yoghurt culture during 30 days of storage. The highest survival was seen for the Lactobacillus reuteri strain. The co-fermentation in the presence of a yoghurt culture gave a lower pH in the final products and decreased the survival rates for all strains. The nutritional effects of fermented, oat-based products were investigated by using germfree and conventional rats and by performing a clinical study on 56 healthy subjects. Physiological parameters such as changes in serum cholesterol, faecal excretion of cholesterol, and amount of faecal short chain fatty acids (SCFA) were studied. In addition, changes in the faecal flora were investigated in the human subjects. No changes in the serum cholesterol levels or faecal excretion of cholesterol were seen in the rat models when the animals were fed on different, fermented oat-based products. A diffeent feacal SCFA pattern was seen in the conventional rats fed on the oat-based diets than in the group fed on rice. A lipid lowering effect was seen in the human subjects eating a fermented, ropy, oat-based product for five weeks, which gave a dietary intake of 3.5 g native beta-glucans from oat per day. An increase in total bacterial count and Bifidobacterium subsp. was also seen in faecal samples from these subjects. In conclusion, there is a potential for the development of fermented, non-dairy, oat-based products with a "ropy" structure containing soluble fibres of both native and microbial origin and with the lipid lowering effect that is generally associated with an intake of oat

Is there any space for compact housing in sustainable development? – Insights from Sweden

The Earth’s population is steadily increasing and there is a fast growing urbanization as people move from rural areas to cities. Lack of housing is a big issue in many cities. At the same time, dwellings are growing in size demanding more land and natural resources, a development which is not sustainable in the long run. That is problematic as it occupies land and requires natural resources, which is not necessarily sustainable. The aim of this study was to examine the prerequisites for compact housing in Sweden and whether it is a widespread phenomenon or not. Case studies were carried out in three ‘sustainable’ housing and city planning projects (BoKompakt, Hållbarheten and Brunnshög) and in-depth interviews conducted with responsible actors. The impact of the building regulations was also identified as an important issue and therefore Boverket, the Swedish Housing Authority, was included in the investigation. The case studies show that it is more common to implement aspects like sustainable materials and energy efficiency rather than downsizing the dwellings in sustainable housing projects. When compact housing is considered it is mainly due to economical rather than ecological reasons. One obstacle for compact housing are the strict building regulations, BBR, and the requirements of accessibility. So far, the regulations have only been questioned for student housing. The conclusion is that compact housing is not especially widespread in Sweden but as the prerequisites are getting more supportive, it could hopefully spread more.Finns det utrymme för kompakta bostäder i en hållbar stadsutveckling? Allt fler människor flyttar till städer. Det påverkar användningen av olika naturresurser men ökar också konkurrensen om mark – en resurs som inte är oändlig – då fler bosätter sig inom städernas begränsade områden. Trots att den genomsnittliga familjen minskat i storlek har bostäder å andra sidan blivit allt större. För att kunna uppnå en hållbar utveckling måste alla dra sitt strå till stacken. Hur vi bor är inget undantag eftersom det är svårt att bortse från att våra bostäder på olika sätt är resurskrävande. I den här studien har tre olika projekt som profilerat sig ”hållbara” undersökts. Hållbarheten, ett experimentellt flerbostadshus i Malmö där hyresgästerna kan mäta och kontrollera sin energiförbrukning; Brunnshög, en planerad stadsdel i Lund som ska fungera som en europeisk modell för hållbar stadsutveckling samt BoKompakt, studentbostäder med väldigt kompakta boytor i Lund. Syftet har varit att ur ett svenskt perspektiv undersöka hur förutsättningarna för kompakta bostäder ser ut och att försöka få en bild av hur vanliga de är inom hållbart bostadsbyggande. Studien visar att det ofta är annat än mindre bostadsytor som huvudsaklingen prioriteras vid den här typen av byggprojekt, t ex miljövänliga byggmaterial och energieffektivisering. Den visar också att kompaktbostaden inte är en särskilt spridd företeelse. Boverket, den myndighet som tillhandahåller de svenska byggreglerna, har också inkluderats i studien eftersom det har varit av intresse att undersöka hur regler inverkar på möjligheterna att bygga mer kompakt. Det har länge varit svårt att utmana byggreglerna men det allt större behovet av bostäder har gjort att Boverket börjat se över regelverket och infört lättnader som möjliggör mindre studentbostäder. Detta motiveras med att studentbostaden är en tillfällig bostadslösning. Andra grupper än studenter berörs därför än så länge inte av lättnaderna i reglerna. Vidare har studien visat att ekonomisk hållbarhet går före den ekologiska hållbarheten men det händer att båda går att kombinera, t ex i form av experiment som BoKompakt, där lägre hyra (ekonomisk hållbarhet) har kombinerats med kompakta ytor (ekologisk hållbarhet). Förutsättningarna för kompakta bostäder kommer med största sannolikhet att förbättras i takt med att reglerna ändras och det kan också betyda att denna typ av bostäder blir vanligare

Gradient Methods for Large-Scale and Distributed Linear Quadratic Control

This thesis considers methods for synthesis of linear quadratic controllers for large-scale, interconnected systems. Conventional methods that solve the linear quadratic control problem are only applicable to systems with moderate size, due to the rapid increase in both computational time and memory requirements as the system size increases. The methods presented in this thesis show a much slower increase in these requirements when faced with system matrices with a sparse structure. Hence, they are useful for control design for systems of large order, since they usually have sparse systems matrices. An equally important feature of the methods is that the controllers are restricted to have a distributed nature, meaning that they respect a potential interconnection structure of the system. The controllers considered in the thesis have the same structure as the centralized LQG solution, that is, they are consisting of a state predictor and feedback from the estimated states. Strategies for determining the feedback matrix and predictor matrix separately, are suggested. The strategies use gradient directions of the cost function to iteratively approach a locally optimal solution in either problem. A scheme to determine bounds on the degree of suboptimality of the partial solution in every iteration, is presented. It is also shown that these bounds can be combined to give a bound on the degree of suboptimality of the full output feedback controller. Another method that treats the synthesis of the feedback matrix and predictor matrix simultaneously is also presented. The functionality of the developed methods is illustrated by an application, where the methods are used to compute controllers for a large deformable mirror, found in a telescope to compensate for atmospheric disturbances. The model of the mirror is obtained by discretizing a partial differential equation. This gives a linear, sparse representation of the mirror with a very large state space, which is suitable for the methods presented in the thesis. The performance of the controllers is evaluated using performance measures from the adaptive optics community

Quantifying neurodegeneration from medical images with machine learning and graph theory

Neurodegeneration (or brain atrophy) is part of the pathological cascade of Alzheimer’s disease (AD) and is strongly associated with cognitive decline. In clinics, atrophy is measured through visual assessments of specific brain regions on medical images according to established rating scales. In this thesis, we developed a model based on recurrent convolutional neural networks (AVRA: Automatic visual ratings of atrophy) that could predict scores from magnetic resonance images (MRI) according to commonly used clinical rating scales, namely: Scheltens’ scale for medial temporal atrophy (MTA), Pasquier’s frontal subscale of global cortical atrophy (GCA-F), and Koedam’s posterior atrophy (PA) scale. AVRA was trained on over 2000 images rated by a single neuroradiologist and demonstrated similar inter-rater agreement levels on all three scales to what has reported between two "human raters" in previous studies. We further applied different versions of AVRA, trained systematically on data with different levels of heterogeneity, in external data from multiple European memory clinics. We observed a general performance drop in the out-of-distribution (OOD) data compared to test sets sampled from the same cohort as the training data. By training AVRA on data from multiple sources, we show that the performance in external cohorts generally increased. AVRA demonstrated a notably low agreement in one memory clinic, despite good quality images, which suggests that it may be challenging to assess how well a machine learning model generalizes to OOD data. For additional validation of our model, we compared AVRA’s MTA ratings to two external radiologists’ and the volumes of the hippocampi and inferior lateral ventricles. The images came from a longitudinal cohort that comprised individuals with subjective cognitive decline (SCD) and mild cognitive impairment (MCI) followed up over six years. AVRA showed substantial agreement to one of the radiologists, and lower rating agreement to the other. The two radiologists also showed low agreement between each other. All sets of ratings were strongly associated with the subcortical volumes, suggesting that all three raters were reliable. We further observed that individuals with SCD and (probably) underlying AD pathology had a faster MTA progression than MCI patients with non-AD biomarker profile. Finally, we evaluated a method to quantify patterns of atrophy through the use of graph theory. We compared structural gray matter networks between groups of healthy controls and AD patients, con- structed from different subsamples and with different network construc- tion methods. Our experiments suggested that structural gray matter networks may not be very stable. Our networks required more than 150 subjects/group to show convergence in the included network properties, which is a greater sample size than used in the majority of the studies applying these methods. The different graph construction methods did not yield consistent differences between the control and AD networks, which may explain why findings have been inconsistent across previous studies. To conclude, we demonstrated that a machine learning model can successfully learn to mimic a radiologist’s assessment of atrophy without intra-rater variability. The challenge going forward is to assert model consistency across clinics, scanners and image quality—nuisances that humans are better at ignoring than deep learning models