SMT-based Model Checking for Recursive Programs

We present an SMT-based symbolic model checking algorithm for safety verification of recursive programs. The algorithm is modular and analyzes procedures individually. Unlike other SMT-based approaches, it maintains both "over-" and "under-approximations" of procedure summaries. Under-approximations are used to analyze procedure calls without inlining. Over-approximations are used to block infeasible counterexamples and detect convergence to a proof. We show that for programs and properties over a decidable theory, the algorithm is guaranteed to find a counterexample, if one exists. However, efficiency depends on an oracle for quantifier elimination (QE). For Boolean Programs, the algorithm is a polynomial decision procedure, matching the worst-case bounds of the best BDD-based algorithms. For Linear Arithmetic (integers and rationals), we give an efficient instantiation of the algorithm by applying QE "lazily". We use existing interpolation techniques to over-approximate QE and introduce "Model Based Projection" to under-approximate QE. Empirical evaluation on SV-COMP benchmarks shows that our algorithm improves significantly on the state-of-the-art.Comment: originally published as part of the proceedings of CAV 2014; fixed typos, better wording at some place

Urinary tract infection in men

Uri nary tract in fec tion in men Ab stract. Ob jec tive: To ex plore the prev alence and mi cro bi ol ogy of uri nary tract in fection (UTI) in symp tom atic men in a pri mary care set ting and to de ter mine the ap pro pri ateness of pa tient man age ment of these con ditions by the gen eral prac ti tio ners. Meth ods: A cross-sec tional sur vey was car ried out matching doc u men ta tion of symp toms and man agement with urine cul ture and re sults of sus cep tibil ity tests. All pa tients pre sent ing with symptoms typ i cal for a UTI in 36 teach ing gen eral prac tices in the area of Göttingen, Ger many, were el i gi ble for en rol ment in the study. 15% (n = 90) of all pa tients were adult men. Gen eral prac ti tio ners (GPs) were in structed to man age pa tients as usual. Pa tient char ac ter is tics, dipstick tests and treat ment were matched with results of urine cul tures and sus cep ti bil ity testing. Re sults: Men pre sent ing with symp toms in dic a tive of UTI were pre dom i nantly el derly (me dian age 61 years) and 41% had ad di tional risk fac tors. An ti bi ot ics were pre scribed for 36%, but these were not well-tar geted. Urine cul ture re vealed UTI in 60%, of which half had low col ony counts (23% of all pa tients) or multi ple bac te rial growth (7%); 40% had ster ile urine. Dip stick tests proved un help ful: leu kocytes and ni trite had sen si tiv i ties of 54% and 38%, specificities of 55% and 84%, pos i tive pre dic tive val ues of 65% and 78% and neg ative pre dic tive val ues of 44% and 46%, re spectively. Re sis tance lev els were 53% for amoxicillin and cefaclor, 28% for cefixim, 22% for ciprofloxacin, 34% for both trimethoprim as in di vid ual sub stance and the com bi na tion with sulfamethoxazole (cotrimoxazole) and 25% for ni tro fu ran toin. Con clusion: Men with symp toms in dic a tive of a UTI should not be treated em pir i cally. A urine culture and antibiogram should be ob tained before a treat ment de ci sion is made. A low-count UTI was com mon and should not be con sidered nor mal

Epigenetic deregulation of multiple S100 gene family members by differential hypomethylation and hypermethylation events in medulloblastoma

Deregulated expression of genes encoding members of the S100 family of calcium-binding proteins has been associated with the malignant progression of multiple tumour types. Using a pharmacological expression reactivation approach, we screened 16 S100 genes for evidence of epigenetic regulation in medulloblastoma, the most common malignant brain tumour of childhood. Four family members (S100A2, S100A4, S100A6 and S100A10) demonstrated evidence of upregulated expression in multiple medulloblastoma cell lines, following treatment with the DNA methyltransferase inhibitor, 5′-aza-2′-deoxycytidine. Subsequent analysis revealed methylation of critical CpG sites located within these four genes in an extended cell line panel. Assessment of these genes in the non-neoplastic cerebellum (from which medulloblastomas develop) revealed strong somatic methylation affecting S100A2 and S100A4, whereas S100A6 and S100A10 were unmethylated. Assessed against these normal tissue-specific methylation states, S100A6 and S100A10 demonstrated tumour-specific hypermethylation in medulloblastoma primary tumours (5 out of 40 and 4 out of 35, respectively, both 12%) and cell lines (both 7 out of 9, 78%), which was associated with their transcriptional silencing. Moreover, S100A6 hypermethylation was significantly associated with the aggressive large cell/anaplastic morphophenotype (P=0.026). In contrast, pro-metastatic S100A4 displayed evidence of hypomethylation relative to the normal cerebellum in a significant proportion primary tumours (7 out of 41, 17%) and cell lines (3 out of 9, 33%), which was associated with its elevated expression. In summary, these data characterise complex patterns of somatic methylation affecting S100 genes in the normal cerebellum and demonstrate their disruption causing epigenetic deregulation of multiple S100 family members in medulloblastoma development. Epigenetic events affecting S100 genes have potential clinical utility and merit further investigation as molecular biomarkers for this disease

Improved Upper Limit on the Neutrino Mass from a Direct Kinematic Method by KATRIN.

We report on the neutrino mass measurement result from the first four-week science run of the Karlsruhe Tritium Neutrino experiment KATRIN in spring 2019. Beta-decay electrons from a high-purity gaseous molecular tritium source are energy analyzed by a high-resolution MAC-E filter. A fit of the integrated electron spectrum over a narrow interval around the kinematic end point at 18.57 keV gives an effective neutrino mass square value of (-1.0_{-1.1}^{+0.9})  eV^{2}. From this, we derive an upper limit of 1.1 eV (90% confidence level) on the absolute mass scale of neutrinos. This value coincides with the KATRIN sensitivity. It improves upon previous mass limits from kinematic measurements by almost a factor of 2 and provides model-independent input to cosmological studies of structure formation

Commissioning of the vacuum system of the KATRIN Main Spectrometer

The KATRIN experiment will probe the neutrino mass by measuring the beta-electron energy spectrum near the endpoint of tritium beta-decay. An integral energy analysis will be performed by an electro-static spectrometer (Main Spectrometer), an ultra-high vacuum vessel with a length of 23.2 m, a volume of 1240 m^3, and a complex inner electrode system with about 120000 individual parts. The strong magnetic field that guides the beta-electrons is provided by super-conducting solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum gauges had to be considered. A system consisting of 6 turbo-molecular pumps and 3 km of non-evaporable getter strips has been deployed and was tested during the commissioning of the spectrometer. In this paper the configuration, the commissioning with bake-out at 300{\deg}C, and the performance of this system are presented in detail. The vacuum system has to maintain a pressure in the 10^{-11} mbar range. It is demonstrated that the performance of the system is already close to these stringent functional requirements for the KATRIN experiment, which will start at the end of 2016.Comment: submitted for publication in JINST, 39 pages, 15 figure