On the Decidability of Reachability in Linear Time-Invariant Systems

We consider the decidability of state-to-state reachability in linear time-invariant control systems over discrete time. We analyse this problem with respect to the allowable control sets, which in general are assumed to be defined by boolean combinations of linear inequalities. Decidability of the version of the reachability problem in which control sets are affine subspaces of $\mathbb{R}^n$ is a fundamental result in control theory. Our first result is that reachability is undecidable if the set of controls is a finite union of affine subspaces. We also consider versions of the reachability problem in which (i)~the set of controls consists of a single affine subspace together with the origin and (ii)~the set of controls is a convex polytope. In these two cases we respectively show that the reachability problem is as hard as Skolem's Problem and the Positivity Problem for linear recurrence sequences (whose decidability has been open for several decades). Our main contribution is to show decidability of a version of the reachability problem in which control sets are convex polytopes, under certain spectral assumptions on the transition matrix

Safety of anti-TNF agents in patients with compensated cirrhosis: a case-control study

Background: There is limited data on the use of anti-TNF agents in patients with concomitant cirrhosis. The aim of this study is to assess the safety of anti-TNF agents in patients with compensated cirrhosis who used these medications for the treatment of an underlying rheumatologic condition or IBD. Methods: Multicenter, retrospective, matched, case-control study. A one to three case-control match was performed. Adults who received anti-TNF therapy were matched to three adults with cirrhosis who did not receive anti-TNF therapy. Patients were matched for etiology of cirrhosis, MELD-Na and age. Primary outcome was the development of hepatic decompensation. Secondary outcomes included development of infectious complications, hepatocellular carcinoma (HCC), extra-hepatic malignancy, and mortality. Results: Eighty patients with cirrhosis who received anti-TNF agents were matched with 240 controls. Median age was 57.2 years. Median MELD-Na for the anti-TNF cohort was seven and median MELD-Na for the controls was eight. The most common etiology of cirrhosis was NAFLD. Anti-TNF therapy did not increase risk of decompensation (HR: 0.91, 95% CI: 0.64–1.30, p = 0.61) nor influence the time to development of a decompensating event. Anti-TNF therapy did not increase the risk of hepatic mortality or need for liver transplantation (HR: 1.18, 95% CI: 0.55–2.53, p = 0.67). Anti-TNF therapy was not associated with an increased risk of serious infection (HR: 1.21, 95% CI: 0.68–2.17, p = 0.52), HCC (OR: 0.45, 95% CI: 0.13–1.57, p = 0.21), or extra-hepatic malignancy (OR: 0.82, 95% CI: 0.29–2.30, p = 0.71). Conclusions: Anti-TNF agents in patients with compensated cirrhosis does not influence the risk of decompensation, serious infections, transplant free survival, or malignancy

Editorial

The 11th International Symposium on Operational Research (SOR’11) was organized by Slovenian Society INFORMATIKA – Section for Operational Research (SDI-SOR) in Dolenjske Toplice, Slovenia, during the week of 28 – 30 September 2011. At SOR’11 it was decided to publish a Special Issue of Business Systems Research Journal (SI of BSRJ) on innovative approaches to OR methodology and its applications in business, micro and macro-economics, management, finance, social sciences, energy, environment, transport and other areas. The call for papers for SI of BSRJ was open, and it was directed to the participants of SOR’11 as well as to other researchers and practitioners from the field of OR. We have received 9 submissions for this special issue, some of them being extended journal versions of short conference papers from proceedings (Zadnik Stirn et al., 2011). Each submission was first reviewed by the Guest Editors, and the papers were then blind reviewed by two experts

Post-partum milk progesterone profiles in SahiwalxFriesian cows on different energy intake.

Progesterone (P4) concentration in 21 SahiwalxFriesian cows kept on three energy levels (n=7) were determined thrice weekly for 120 days after first calving using a simple direct radioimmunoassay in fat-free milk. Based on post-partum P4 profiles, resumption of ovarian activity (Mean ± S.D.) commenced at 32.9 ± 19.2, 22.4 ± 14.3 and 25.6 ± 8.8 days post-partum for low, medium and high energy groups, respectively. Using P4 levels of ≥ 1 ng/ml as a criterion for corpus luteum activity, first ovulation occured at 37.7 ± 18.0, 26.6 ± 15.7 and 25.3 ± 8.3 days post-partum, respectively. Although intervals to resumption of ovarian activity and to first ovulation were longer in the low energy group, these differences were not significant (P < 0.05). First observed oestrus was noted at 28.0 ± 21.6, 32.7 ± 9.8 and 25.4 ± 6.0 days post-partum for low, medium and high energy groups, with 13.6, 29.6 and 14.3% incidence of undetected oestrus, respectively. From P4 profiles, mean cycle length before conception of the three groups were 19.9 ± 4.1, 19.3 ± 3.8 and 20.9 ± 3.6 days, while the intervals from calving to conception were 74.3 ± 14.9, 79.1 ± 17.3 and 88.3 ± 30.4 days, respectively. A higher incidence of repeat breeding was observed in the high energy group although mean intervals to conception were not significantly different

Gender Differences and Consumer Videogame Engagement

This paper intends to examine the gender differences on the engagement states of consumer videogame engagement through comparing the male group vs. female group. To meet this objective, the authors aim to utilize the causal-comparative study to analyse the gender differences on consumer videogame engagement. Data were collected from a sample of 235 teen videogame consumers whose aged were between 16-19years and studying in the private and public universities. Out of 235, the only 219 teen videogame consumers were valid and able to further use for data analysis. Using SPSS 22.0, we examined the valid data through independent t-test and also calculated the effect size for the significant hypotheses. The study findings reported that male teen videogame consumers are significantly different from female teen videogame consumers on the three engagement states of consumer videogame engagement such as cognitive, affective, and behavioural engagement. This paper is first among the videogame studies that has investigated the gender differences on the engagement states of consumer videogame engagement

Gender Differences and Consumer Videogame Engagement

This paper intends to examine the gender differences on the engagement states of consumer videogame engagement through comparing the male group vs. female group. To meet this objective, the authors aim to utilize the causal-comparative study to analyse the gender differences on consumer videogame engagement. Data were collected from a sample of 235 teen videogame consumers whose aged were between 16-19years and studying in the private and public universities. Out of 235, the only 219 teen videogame consumers were valid and able to further use for data analysis. Using SPSS 22.0, we examined the valid data through independent t-test and also calculated the effect size for the significant hypotheses. The study findings reported that male teen videogame consumers are significantly different from female teen videogame consumers on the three engagement states of consumer videogame engagement such as cognitive, affective, and behavioural engagement. This paper is first among the videogame studies that has investigated the gender differences on the engagement states of consumer videogame engagement