Intermittent Connectivity for Exploration in Communication-Constrained Multi-Agent Systems

Motivated by exploration of communication-constrained underground environments using robot teams, we study the problem of planning for intermittent connectivity in multi-agent systems. We propose a novel concept of information-consistency to handle situations where the plan is not initially known by all agents, and suggest an integer linear program for synthesizing information-consistent plans that also achieve auxiliary goals. Furthermore, inspired by network flow problems we propose a novel way to pose connectivity constraints that scales much better than previous methods. In the second part of the paper we apply these results in an exploration setting, and propose a clustering method that separates a large exploration problem into smaller problems that can be solved independently. We demonstrate how the resulting exploration algorithm is able to coordinate a team of ten agents to explore a large environment

Adapting pediatric obesity care to better suit adolescent patients: Design of a treatment platform and results compared with standard care in the national patient quality register.

BACKGROUND: Obesity constitutes a critical risk for adolescent health. This study aimed at identifying youth-friendly components of obesity treatment. METHODS: In this feasibility study, an adolescent obesity treatment platform was implemented at two Pediatric outpatient clinics in Sweden. Body mass index (BMI), BMI z-score, and the category of obesity (International Obesity Task Force) were compared before and after the intervention and with data on standard care from the Swedish Childhood Obesity Treatment Register. RESULTS: The study included 99 participants (49 females) aged 13-18 years from 1 September 2014, to 31 December 2016. A pediatric nurse met the participants on average 6.5 times in the average inclusion period of 15 months. Physical activity sessions attracted 63 participants. Acceptance Commitment Therapy and In Real Life groups attracted 24 participants. At inclusion, 62 participants had obesity and 37 severe obesity, and 71/99 (72%) remained in the same category. The mean BMI increased from 32.0 to 33.4 kg/m2 (p < 0.01), but 56/94 (60%) participants lowered their BMI or increased less than 1 kg/m2 and 73% stayed to the end of the study. Participants who were new to treatment and participants coming for more than eight visits to the nurse did not increase in BMI. BMI did not change for the 221 out of 641 register patients who had two recordings of BMI in the study period. CONCLUSIONS: The platform was successful in increasing retention, and 60% of participants lowered or maintained their BMI. Still, seven out of ten adolescents with obesity or severe obesity remained in the same weight category

A randomized controlled trial comparing intensive non-surgical treatment with bariatric surgery in adolescents aged 13-16 years (AMOS2): Rationale, study design, and patient recruitment.

BACKGROUND: Previous non-randomized studies show similar outcomes in adolescents and adults after bariatric surgery. We describe the study protocol, recruitment, and selected baseline data of patients in a randomized multi-center study, the Adolescent Morbid Obesity Surgery 2 (AMOS2). METHODS: Three clinics in Sweden collaborated in designing the study and recruitment of patients from August 1, 2014 to June 30, 2017. Patients were selected among adolescents 13-16 years of age attending third-level obesity care for at least one year. Patients were randomized 1:1 to bariatric surgery (predominantly Roux-en-Y gastric bypass) or intensive non-surgical treatment starting with an eight-week low-calorie-diet. RESULTS: Fifty adolescents (37 girls) were randomized, 25 (19 girls) to bariatric surgery. Mean age was 15.7 years (range 13.3-16.9), weight 122.6 kg (range 95-183.3), Body Mass Index (BMI) 42.6 kg/m2 (range 35.7-54.9) and BMI-SDS 3.45 (range 2.9-4.1). One patient had type 2 diabetes mellitus, and 12/45 (27%) had elevated liver enzymes. There were no significant differences between the groups. For the 39 eligible patients who were offered but declined inclusion, BMI was not different from included patients. However, patients who declined were younger, 15.2 years (p = 0.021). A sex difference was also noted with more of eligible girls, 37/53 (69.8%), than boys, 13/36 (36.1%), wanting to participate in the study (p = 0.002). CONCLUSIONS: This clinical trial, randomizing adolescents with severe obesity to bariatric surgery or intensive non-surgical treatment, aims at informing about whether it is beneficial to undergo bariatric surgery in early adolescence. It will also enlighten the outcome of comprehensive non-surgical treatment. The study was registered at www.clinicalTrials.gov number NCT02378259

Searching For Dark Matter with Plasma Haloscopes

We summarise the recent progress of the Axion Longitudinal Plasma HAloscope (ALPHA) Consortium, a new experimental collaboration to build a plasma haloscope to search for axions and dark photons. The plasma haloscope is a novel method for the detection of the resonant conversion of light dark matter to photons. ALPHA will be sensitive to QCD axions over almost a decade of parameter space, potentially discovering dark matter and resolving the Strong CP problem. Unlike traditional cavity haloscopes, which are generally limited in volume by the Compton wavelength of the dark matter, plasma haloscopes use a wire metamaterial to create a tuneable artificial plasma frequency, decoupling the wavelength of light from the Compton wavelength and allowing for much stronger signals. We develop the theoretical foundations of plasma haloscopes and discuss recent experimental progress. Finally, we outline a baseline design for ALPHA and show that a full-scale experiment could discover QCD axions over almost a decade of parameter space.Comment: Endorsers: Jens Dilling, Michael Febbraro, Stefan Knirck, and Claire Marvinney. 26 pages, 17 figures, version accepted in Physical Review

Distribuerad Bayesisk Optimering i Multi-Agent System

A variety of engineering problems require extremely resource consuming system performance optimization with an inaccessible system model, some examples include tuning the hyper-parameters in a complex machine learning model, simulation-based aerodynamic design and power system optimization. Bayesian optimization is an approach to solve black-box optimization problems when sample efficiency is of high priority. By parallelizing evaluations, the presence of multiple computing agents can be utilized to solve the optimization problem more efficiently. This thesis address the multi-agent black-box evaluation-expensive optimization problem by enabling distributed Bayesian optimization. Parallel methods proposed in previous research are extended to the distributed setting and a novel approach called Diversity Regularization is developed. Furthermore, motivated by applications in robotics systems such as source seeking, the evaluation-transition trade-off is addressed through regularization. Finally, empirical regret analysis to compare the presented methods on benchmark functions is performed.Många ingenjörsproblem kräver extremt resurskrävande optimering av systemprestanda utan tillgång till en model av systemet, till exempel att ställa in hyperparametrarna i en komplex maskininlärningsmodel, simuleringsbaserad aerodynamiskdesign och optimering av elnät. Bayesisk optimering är en metod föroptimering av svartlådsfunktioner när samplingseffektivitet har hög prioritet. Genom att parallellisera funktionsutvärderingar kan närvaron av flera agenter användas för att lösa optimeringsproblemet mer effektivt. Denna avhandling behandlar optimering av resurskrävande svartlådsfunktioner med flera agenter genom att möjliggöra distribuerad Bayesisk optimering. Parallella metoderföreslagna i tidigare forskning omformuleras till den distribuerade problemformuleringen och e n ny metod som kallas Diversity Regularization presenteras. Dessutom, motiverat av tillämpningar i robotiksystem som källsökning, behandlasavvägningen mellan utvärderingskostnaden och förflyttningskostnaden genom regularisering. Slutligen utförs empirisk analys för att jämföra de presenterade metoderna på referensfunktioner.  

Immune moldulatory effects of intravenous immunoglobulin in vitro and after allogeneic bone marrow transplantation

Intravenous immunoglobulin (IVIG) has been used in patients with immunodeficienciesand various autoimmune diseases. Its immune modulatory effect is well documented.In allogeneic bone marrow transplantation (BMT) IVIG has been used to reduce theincidence of infections and graft-versus-host-disease (GVHD). To investigate furtherthe immune-modulatory effects of IVIG, we have studied now its effects on nonspecific(mitogenic) and specific Iymphocyte responses as well as immunoglobulin (Ig) -producingcells. There was a significant dose-dependent inhibition by IVIG of various mitogenic responsesby peripheral blood Iymphocytes (PBL). Inhibition was the same when stimulating differentT-lymphocyte subsets. The specific Iymphocyte response in mixed Iymphocyte cultures(MLC) and to Staphylococcus aureus protein A (SPA) were also inhibited by IVIG. Whencomparing 12 commercial IVIG preparauons (2.5 g/l), inhibition varied from 0% to66%. IgG preparations made from single donors proved more effective than commercialIVIG in inhibiting phytohemagglutinin stimulation. The use of cytomegalovirus (CMV)hyper-Ig compared to IVIG did not result in increased inhibition of the Iymphocyteresponse to herpes virus antigen, but CMV negative Ig resulted in less inhibition.IgG- and IgM-production from PBL and bone marrow cells, measured as plaque-formingcells (PFC) were also inhibited in a dose-dependent fashion by IVIG. Cells were stimulatedby SPA, lipopolysaccharide from E. coli (LPS) or with CMV Antigen (Ag). The inhibitionof spleen-PFC varied depending on the stimuli. We compared equimolar concentrationsof IgG, IgG-F(ab' )2 and IgG-Fc to determine the part of the IgG molecule which mediatedthe inhibitory effect. Lymphocyte responses were inhibited by F(ab')2 fragments,but only by one of two Fc preparations tested. A comparison of 4 brands of IVIG fragmentsshowed that IgG and F(ab' )2 preparauons inhibited IgG and IgM production of LPS-stimulatedspleen cells, but no significant inhibition was obtained with any of the purifiedFc products. In an analysis of serum levels of various cytokines in sibling BMT recipients,we found a correlation between IVIG treatment and decreased serum levels of i) sIL-2r,IL-3, IL-4, IL-6 and IL-10 in patients without complications and ii) IL-lra and TNF-alevels in patients with acute GVHD. In two clinical studies, we evaluated the effects of prophylactic IVIG treatmentafter BMT (0.5 g/kg once weekly until day 90). The 1st study included 98 HLA-identicalsibling transplant recipients and the 2nd 107 recipients of marrow from matched unrelateddonors (MUD). No beneficial effects of IVIG treatment on GVHD, various bacterial,fungal and viral infections or other transplant related complications were detectedin either of the two studies. Of all 208 pauents, only one IVIG-treated patient and4 of the controls had CMV pneumonia. The overall survival rates in the two studieswere similar, with an actuarial two-year survival of 59% in the IVIG group and 57%in the controls. The median follow-up (June, 1997) was 4.4 years and 4.2 years inthe two groups respectively. Forty-two IVIG-treated patients (45%) and 50 controlshave died (45%). Relapse caused the death of 15 treated patients and 16 controls.Fewer IVIG treated pauents died of bacterial infections (2 vs. 11, P=0.03) and moreof the them, died of VOD (7 vs 0, P=0.03). Conclusions: IVIG clearly inhibits cell-mediated T and B cell responsesin vitro. The inhibition seems to be mediated by the F(ab')2 part of the IgG molecule.Immune modulatory effects by IVIG may be beneficial in BMT recipients, but our retrospectivestudy on prophylactic use after HLA identical sibling BMT did not confirm earlierresults about infections and GVHD. Nor did we detect any beneficial effects of treatmentin MUD-transplant reapients. We question the use of prophylactic high-dose IVIG ona regular basis in BMT recipients. Key words: IVIG, IgG, F(ab')2, Fc, immune modulation, T cell responses, Bcell responses, cytokines, bone marrow transplantation, infections, CMV, graft-versus-hostdisease ISBN 91-628-2636-