A new puzzle for random interaction

We continue a series of numerical experiments on many-body systems with random two-body interactions, by examining correlations in ratios in excitation energies of yrast $J$ = 0, 2, 4, 6, 8 states. Previous studies, limited only to $J$ = 0,2,4 states, had shown strong correlations in boson systems but not fermion systems. By including $J \ge 6$ states and considering different scatter plots, strong and realistic correlations appear in both boson and fermion systems. Such correlations are a challenge to explanations of random interactions.Comment: 4 pages, 4 figure

Molecular diversity of arbuscular mycorrhizal fungi in onion roots from organic and conventional farming systems in the Netherlands

Diversity and colonization levels of naturally occurring arbuscular mycorrhizal fungi (AMF) in onion roots were studied to compare organic and conventional farming systems in the Netherlands. In 2004, 20 onion fields were sampled in a balanced survey between farming systems and between two regions, namely, Zeeland and Flevoland. In 2005, nine conventional and ten organic fields were additionally surveyed in Flevoland. AMF phylotypes were identified by rDNA sequencing. All plants were colonized, with 60% for arbuscular colonization and 84% for hyphal colonization as grand means. In Zeeland, onion roots from organic fields had higher fractional colonization levels than those from conventional fields. Onion yields in conventional farming were positively correlated with colonization level. Overall, 14 AMF phylotypes were identified. The number of phylotypes per field ranged from one to six. Two phylotypes associated with the Glomus mosseae-coronatum and the G. caledonium-geosporum species complexes were the most abundant, whereas other phylotypes were infrequently found. Organic and conventional farming systems had similar number of phylotypes per field and Shannon diversity indices. A few organic and conventional fields had larger number of phylotypes, including phylotypes associated with the genera Glomus-B, Archaeospora, and Paraglomus. This suggests that farming systems as such did not influence AMF diversity, but rather specific environmental conditions or agricultural practice

Using Radium isotopes to evaluate the mixing timeline and relative age of waters in a leaky coastal lagoon

The Ria Formosa wetland system is classified as a leaky coastal lagoon and covers approximately 100 km2 of the South of Portugal, with roughly 50% being intertidal. Its hinterland is set in an arid region and on a coastal plain subject to intensive agriculture since the 50’s. In spite of high exchange coefficients with the coastal ocean (50 and 75% at neap and spring tides, respectively) and the annual total potential freshwater discharge from the hinterland a fraction of the daily tidal prism, worrying signs of eutrophication have been detected during the past couple of decades. These include fish- and clam-kill episodes, increased occurrence of nuisance algal blooms and substitution of native sea grass communities by macroalgae. Notwithstanding its critical importance for the evaluation of pollutant exposure period, the literature includes a wide range of estimates for the ‘residence time’ of waters within the lagoon (16 hours to 11 days, with an the apparent consensus falling within the 1-2 day interval) and this point is a clear obstacle for a correct environmental risk assessment, including management of the system. This lack of clarity is due in our view to two main factors: i) the lack of proper physical definition of the term ‘residence time’, with its consequent misuse and misapplication in context, a misconception that is unfortunately too common within the environmental community, and different concepts in the application of transport time scales ii) the geomorphological and hydraulic complexity of the system.. As part of ongoing research evaluating the role of Submarine Groundwater Discharge (SGD) as a loading vector for nutrients (especially Nitrate) into the lagoon, we use the radium quartet in combination with remote sensing and isotope mixing models to develop and discuss a mixing timeline for the system, We conclude that the average, whole-system residence time of waters within the lagoon is at least 4 days

Comparing phenomenological recipes with a microscopic model for the electric amplitude in strangeness photoproduction

Corrections to the Born approximation in photo-induced strangeness production off a proton are calculated in a semi-realistic microscopic model. The vertex corrections and internal contributions to the amplitude of the $\gamma p \to K^+ \Lambda$ reaction are included on the one-loop level. Different gauge-invariant phenomenological prescriptions for the modification of the Born contribution via the introduction of form factors and contact terms are discussed. In particular, it is shown that the popular minimal-substitution method of Ohta corresponds to a special limit of the more realistic approach.Comment: 10 pages, 6 figures in the tex

Infarct tissue characterization in implantable cardioverter-defibrillator recipients for primary versus secondary prevention following myocardial infarction: a study with contrast-enhancement cardiovascular magnetic resonance imaging

Knowledge about potential differences in infarct tissue characteristics between patients with prior life-threatening ventricular arrhythmia versus patients receiving prophylactic implantable cardioverter-defibrillator (ICD) might help to improve the current risk stratification in myocardial infarction (MI) patients who are considered for ICD implantation. In a consecutive series of (ICD) recipients for primary and secondary prevention following MI, we used contrast-enhanced (CE) cardiovascular magnetic resonance (CMR) imaging to evaluate differences in infarct tissue characteristics. Cine-CMR measurements included left ventricular end-diastolic and end-systolic volumes (EDV, ESV), left ventricular ejection fraction (LVEF), wall motion score index (WMSI), and mass. CE-CMR images were analyzed for core, peri, and total infarct size, infarct localization (according to coronary artery territory), and transmural extent. In this study, 95 ICD recipients were included. In the primary prevention group (n = 66), LVEF was lower (23 ± 9 % vs. 31 ± 14 %; P < 0.01), ESV and WMSI were higher (223 ± 75 ml vs. 184 ± 97 ml, P = 0.04, and 1.89 ± 0.52 vs. 1.47 ± 0.68; P < 0.01), and anterior infarct localization was more frequent (P = 0.02) than in the secondary prevention group (n = 29). There were no differences in infarct tissue characteristics between patients treated for primary versus secondary prevention (P > 0.6 for all). During 21 ± 9 months of follow-up, 3 (5 %) patients in the primary prevention group and 9 (31 %) in the secondary prevention group experienced appropriate ICD therapy for treatment of ventricular arrhythmia (P < 0.01). There was no difference in infarct tissue characteristics between recipients of ICD for primary versus secondary prevention, while the secondary prevention group showed a higher frequency of applied ICD therapy for ventricular arrhythmia.\u

A Letter of A. C. Van Raalte to Philip Phelps

A letter of A. C. Van Raalte to Philip Phelps, pressing with urgency the need to keep raising money for Hope College: We must keep to work: constantly to work for years to come with force and perseverance, else we will make bad work. We must have buildings.https://digitalcommons.hope.edu/vrp_1860s/1527/thumbnail.jp