Arthropod Faunas of Monocultures and Polycultures in Reseeded Rangelands

Sap-feeding and predaceous arthropod faunas of forage bunchgrasses in reseeded rangeland vegetation were examined. Four major species of sap feeders were found; the major predators were spiders. Grass monoculture had very high densities of sap feeders compared with grass biculture, shrub-grass, tree-grass, and native areas; this was reflective of the large contribution from the mirids Irbisia brachycera Uhler and Conostethus americanus (Knight). They were present during the leaf stages of crested wheatgrass when it had its lowest carbohydrate root reserves. Homoptera and predator densities were not significantly related to the pattern of vegetation. The lowest number of sap-feeder species occurred in the grass monoculture, and sap-feeder faunas in this plot were dissimilar to those of all other plots. One-season dispersal experiments did not support the hypothesis that grass density caused the differences between arthropod faunas in different vegetation, whereas big sagebrush, common in reseeded pastures, repelled I. brachycera during short-term dispersal. The data indicate that reseeding to monocultures may result in high densities of Miridae during the leaf stages compared with moderate densities of Homoptera during the flower and seed stages in bicultures. The implications for pest management are discusse

Prior events predict cerebrovascular and coronary outcomes in the PROGRESS trial

<p><b>Background and Purpose:</b> The relationship between baseline and recurrent vascular events may be important in the targeting of secondary prevention strategies. We examined the relationship between initial event and various types of further vascular outcomes and associated effects of blood pressure (BP)–lowering.</p> <p><b>Methods:</b> Subsidiary analyses of the Perindopril Protection Against Recurrent Stroke Study (PROGRESS) trial, a randomized, placebo-controlled trial that established the benefits of BP–lowering in 6105 patients (mean age 64 years, 30% female) with cerebrovascular disease, randomly assigned to either active treatment (perindopril for all, plus indapamide in those with neither an indication for, nor a contraindication to, a diuretic) or placebo(s).</p> <p><b>Results:</b> Stroke subtypes and coronary events were associated with 1.5- to 6.6-fold greater risk of recurrence of the same event (hazard ratios, 1.51 to 6.64; P=0.1 for large artery infarction, P<0.0001 for other events). However, 46% to 92% of further vascular outcomes were not of the same type. Active treatment produced comparable reductions in the risk of vascular outcomes among patients with a broad range of vascular events at entry (relative risk reduction, 25%; P<0.0001 for ischemic stroke; 42%, P=0.0006 for hemorrhagic stroke; 17%, P=0.3 for coronary events; P homogeneity=0.4).</p> <p><b>Conclusions:</b> Patients with previous vascular events are at high risk of recurrences of the same event. However, because they are also at risk of other vascular outcomes, a broad range of secondary prevention strategies is necessary for their treatment. BP–lowering is likely to be one of the most effective and generalizable strategies across a variety of major vascular events including stroke and myocardial infarction.</p&gt

Random walk generated by random permutations of {1,2,3, ..., n+1}

We study properties of a non-Markovian random walk $X^{(n)}_l$, $l =0,1,2, >...,n$, evolving in discrete time $l$ on a one-dimensional lattice of integers, whose moves to the right or to the left are prescribed by the \text{rise-and-descent} sequences characterizing random permutations $\pi$ of $[n+1] = \{1,2,3, ...,n+1\}$. We determine exactly the probability of finding the end-point $X_n = X^{(n)}_n$ of the trajectory of such a permutation-generated random walk (PGRW) at site $X$, and show that in the limit $n \to \infty$ it converges to a normal distribution with a smaller, compared to the conventional P\'olya random walk, diffusion coefficient. We formulate, as well, an auxiliary stochastic process whose distribution is identic to the distribution of the intermediate points $X^{(n)}_l$, $l < n$, which enables us to obtain the probability measure of different excursions and to define the asymptotic distribution of the number of "turns" of the PGRW trajectories.Comment: text shortened, new results added, appearing in J. Phys.

Numerical Estimation of the Asymptotic Behaviour of Solid Partitions of an Integer

The number of solid partitions of a positive integer is an unsolved problem in combinatorial number theory. In this paper, solid partitions are studied numerically by the method of exact enumeration for integers up to 50 and by Monte Carlo simulations using Wang-Landau sampling method for integers up to 8000. It is shown that, for large n, ln[p(n)]/n^(3/4) = 1.79 \pm 0.01, where p(n) is the number of solid partitions of the integer n. This result strongly suggests that the MacMahon conjecture for solid partitions, though not exact, could still give the correct leading asymptotic behaviour.Comment: 6 pages, 4 figures, revtex

Exact expressions for correlations in the ground state of the dense O(1) loop model

Conjectures for analytical expressions for correlations in the dense O$(1)$ loop model on semi infinite square lattices are given. We have obtained these results for four types of boundary conditions. Periodic and reflecting boundary conditions have been considered before. We give many new conjectures for these two cases and review some of the existing results. We also consider boundaries on which loops can end. We call such boundaries ''open''. We have obtained expressions for correlations when both boundaries are open, and one is open and the other one is reflecting. Also, we formulate a conjecture relating the ground state of the model with open boundaries to Fully Packed Loop models on a finite square grid. We also review earlier obtained results about this relation for the three other types of boundary conditions. Finally, we construct a mapping between the ground state of the dense O$(1)$ loop model and the XXZ spin chain for the different types of boundary conditions.Comment: 25 pages, version accepted by JSTA

The Limiting Distribution of the Trace of a Random Plane Partition

We study the asymptotic behaviour of the trace (the sum of the diagonal parts) of a plane partition of the positive integer n, assuming that this parfition is chosen uniformly at random from the set of all such partitions.Comment: 19 page

Follow-up of blood-pressure lowering and glucose control in type 2 diabetes.

BACKGROUND In the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) factorial trial, the combination of perindopril and indapamide reduced mortality among patients with type 2 diabetes, but intensive glucose control, targeting a glycated hemoglobin level of less than 6.5%, did not. We now report results of the 6-year post-trial follow-up. METHODS We invited surviving participants, who had previously been assigned to perindopril–indapamide or placebo and to intensive or standard glucose control (with the glucose-control comparison extending for an additional 6 months), to participate in a post-trial follow-up evaluation. The primary end points were death from any cause and major macrovascular events. RESULTS The baseline characteristics were similar among the 11,140 patients who originally underwent randomization and the 8494 patients who participated in the post-trial follow-up for a median of 5.9 years (blood-pressure–lowering comparison) or 5.4 years (glucose-control comparison). Between-group differences in blood pressure and glycated hemoglobin levels during the trial were no longer evident by the first post-trial visit. The reductions in the risk of death from any cause and of death from cardiovascular causes that had been observed in the group receiving active blood-pressure–lowering treatment during the trial were attenuated but significant at the end of the post-trial follow-up; the hazard ratios were 0.91 (95% confidence interval [CI], 0.84 to 0.99; P=0.03) and 0.88 (95% CI, 0.77 to 0.99; P=0.04), respectively. No differences were observed during follow-up in the risk of death from any cause or major macrovascular events between the intensive-glucose-control group and the standard-glucose-control group; the hazard ratios were 1.00 (95% CI, 0.92 to 1.08) and 1.00 (95% CI, 0.92 to 1.08), respectively. CONCLUSIONS The benefits with respect to mortality that had been observed among patients originally assigned to blood-pressure–lowering therapy were attenuated but still evident at the end of follow-up. There was no evidence that intensive glucose control during the trial led to long-term benefits with respect to mortality or macrovascular events

Professor C. N. Yang and Statistical Mechanics

Professor Chen Ning Yang has made seminal and influential contributions in many different areas in theoretical physics. This talk focuses on his contributions in statistical mechanics, a field in which Professor Yang has held a continual interest for over sixty years. His Master's thesis was on a theory of binary alloys with multi-site interactions, some 30 years before others studied the problem. Likewise, his other works opened the door and led to subsequent developments in many areas of modern day statistical mechanics and mathematical physics. He made seminal contributions in a wide array of topics, ranging from the fundamental theory of phase transitions, the Ising model, Heisenberg spin chains, lattice models, and the Yang-Baxter equation, to the emergence of Yangian in quantum groups. These topics and their ramifications will be discussed in this talk.Comment: Talk given at Symposium in honor of Professor C. N. Yang's 85th birthday, Nanyang Technological University, Singapore, November 200