We study the problem of obtaining lower bounds for polynomial calculus (PC) and polynomial calculus resolution (PCR) on proof degree, and hence by [Impagliazzo et al. '99] also on proof size. [Alekhnovich and Razborov'03] established that if the clause-variable incidence graph of a CNF formula F is a good enough expander, then proving that F is unsatisfiable requires high PC/PCR degree. We further

We exhibit families of 4-CNF formulas over n variables that have sums-of-squares (SOS) proofs of unsatisfiability of degree (a.k.a. rank) d but require SOS proofs of size nΩ(d) for values of d = d(n) from constant all the way up to nδ for some universal constant δ. This shows that the nO(d) running time obtained by using the Lasserre semidefinite programming relaxations to find degree-d SOS proofs

At a large tunnel project in Southern Sweden a number of geoelectrical and IP imaging were carried out. The tunnel is drilled through a horst with a complex geology which includes fractures, high water content and weathered zones. The measurements where carried out to compile a geologic model to use in the further planning of the project. The resistivity and IP complements each other very well sin

Introduction: Sudden cardiac death (SCD) and early onset cardiomyopathy (CM) in the young will always lead to suspicion of an underlying genetic disorder. Incited by the rapid advances in genetic testing for disease we have revisited families, which previously tested “gene-negative” for familial predominantly pediatric CM, in hopes of finding a causative gene variant. Methods: 10 different familie

In the absence of guidance from scientific evidence, a range of lymphedema prevention and management, guidelines were developed by relevant organizations around the world. These became publicly available, promoted and endorsed, particularly to women with breast cancer. The recommendations advised avoidance of any activity that could overload or restrict the lymphatic system and need for caution wh

Only some individuals with obesity develop liver fibrosis due to non-alcoholic fatty liver disease (NAFLD-fibrosis). We determined whether detailed assessment of lifestyle factors in addition to physical, biochemical and genetic factors helps in identification of these patients. A total of 100 patients with obesity (mean BMI 40.0 ± 0.6 kg/m2 ) referred for bariatric surgery at the Helsinki Univers

Processes in individual and mass production are governed by certain principles which need to be taken into account as early as the conceptual design phase. A comprehensive analysis of processes in tool production has shown that production also needs to be considered in remodeling or the introduction ofconcurrent engineering. The paper discusses the principles of the manufacturing process which aff

During the last decade, an active line of research in proof complexity has been into the space complexity of proofs and how space is related to other measures. By now these aspects of resolution are fairly well understood, but many open problems remain for the related but stronger polynomial calculus (PC/PCR) proof system. For instance, the space complexity of many standard "benchmark formulas" is

Pebble games were extensively studied in the 1970s and 1980s in a number of different contexts. The last decade has seen a revival of interest in pebble games coming from the field of proof complexity. Pebbling has proven to be a useful tool for studying resolution-based proof systems when comparing the strength of different subsystems, showing bounds on proof space, and establishing size-space tr

Grasslands are a prerequisite for rearing livestock, and livestock is the mainstay of people’s existence in drylands. As one Kenyan woman put it, “without grass there is no livestock, without livestock there is no life.” Based in the lowlands of Baringo County in Kenya’s Rift Valley, RAE (Rehabilitating Arid Environments) Ltd. has worked for 38 years to develop a successful socio-ecological model

This article reports work-in-progress of a parallel kinematic robot development for construction with main focus on the concept phase. We suppose the weight distribution of the proposed structure enables integration of robotic components into construction equipment while enabling tailoring of important characteristics such as accuracy, stiffness and workspace toward application needs.We describe c

The beneficial effects of protons are primarily based on reduction of low to intermediate radiation dose bath to normal tissue surrounding the radiotherapy target volume. Despite promise for reduced long-term toxicity, the percentage of cancer patients treated with proton therapy remains low. This is probably caused by technical improvements in planning and delivery of photon therapy, and by high

Investigating the Galactic center offers unique insights into the buildup and history of our Galaxy and is a stepping stone to understand galaxies in a larger context. It is reasonable to expect that the stars found in the Galactic center might have a different composition compared to stars found in the local neighborhood around the Sun. It is therefore quite exciting when recently there were repo