EFFECTS OF PERENNIAL FORAGE COMPOSITION AND HARVEST INTENSITY ON THE WEED SEEDBANK COMMUNITY

Most arable weeds arise from a resident soil seedbank and are typically controlled with tillage and herbicides, each of which pose sustainability challenges to growers and consumers. However, agronomic management practices that reduce weed seed input to the seedbank and that accelerate mortality of seeds already in the soil could reduce the need for more conventional weed control. Previous research and farmer practice has demonstrated that rotation of annual crops with several years of perennial forage can reduce weed abundance and the need for chemical weed control. In perennial forage systems, crop species and harvest intensity may have important effects on seedbank composition due to the multiple stress and mortality factors these systems impose on weeds, including facilitation of strong crop-weed competitive interactions, periodic defoliation of crop (and weed) canopies, and potentially crop species-specific associations with soil faunal and microbial communities that cause seed damage and mortality. Unfortunately, we know little about the influence of agronomic practices such as forage crop species selection or harvest frequency and harvest height on weed population dynamics or the specific mechanisms that regulate weed seed survival in the soil in perennial forage systems. We used a three-year factorial field experiment established in 2018 that included four mixtures of perennial forage legumes, each grown with orchardgrass, Dactylis glomerata L., two harvest height treatments (5 and 10 cm residual forage height), and two harvest frequency treatments (three and five harvests per year) to investigate how perennial forage composition and management act as community assembly filters on the composition and abundance of the weed seedbank. The composition and abundance of the weed seedbank was quantified at the end of the third year of the study using the direct germination method in a heated greenhouse. While overall seedbank density did not differ across treatments, seedbank community composition was influenced by the interactive effects of both harvest height and harvest frequency. More intensely harvested plots (shorter stubble remaining) favored weed seed bank communities more heavily dominated by weed species with specific functional traits: mat-forming weeds that set seed close to the soil surface were favored in short stubble harvest regimes, possibly due to their ability to grow and reproduce while evading defoliation. Conversely, the harvest regime in less intensely harvested plots enabled a more generalist weed community. In order to determine whether weed seed decay mechanisms might vary across the treatments, we conducted a weed seed burial experiment with seeds of a common weed, velvetleaf (Abutilon theophrasti Medik.). Seeds were buried in each experimental unit to simulate seed shed and incorporation in the soil and were extracted in the following spring. Seed death over the burial period was not different in more intensely harvested plots compared to less intensely harvested plots. This suggests that when considering how forage canopy management practices mediate seed mortality, seed decay may be of lesser importance compared to other mechanisms of seedbank decline such as fatal germination and seed predation. An indicator plant material was buried to gain a secondary measurement of cellulose decay in the system without the complex effects of seed dormancy and viability. In red clover and white clover biculture plots, cellulose decay was greater in more frequent harvest treatments when compared to less frequent. Lastly, both the decay of velvetleaf seeds and of indicator cellulose were significant predictors of seedbank community composition, demonstrating that microbial activity acts as a biological filter on weed seedbank community assembly

Research Report: Radicchio Cultivar Performance in New Hampshire

Radicchio (Cichorium intybus var. latifolium) is grown widely throughout Europe, especially northern Italy. In addition to having interesting color and flavor profiles, they are rich in phenolics and other bioactive compounds. While increasingly popular as a niche vegetable in the region, there is little research-based information to guide growers. The New England growing climate is very different from that of major production regions, and it presents unique challenges. There is tremendous phenotypic variation among and within groups and cultivars. The availability of varieties to commercial growers in the U.S. has expanded greatly, but there remains a need for reliable regionally relevant information about performance of these varieties. In 2022 and 2023, we evaluated over 30 varieties in a replicated trial. We also planted three varieties at four different dates to evaluate the effects of planting date on harvest maturity and marketable yields. In the current research report, we describe the results of these experiments

Field-induced polarisation of Dirac valleys in bismuth

Electrons are offered a valley degree of freedom in presence of particular lattice structures. Manipulating valley degeneracy is the subject matter of an emerging field of investigation, mostly focused on charge transport in graphene. In bulk bismuth, electrons are known to present a threefold valley degeneracy and a Dirac dispersion in each valley. Here we show that because of their huge in-plane mass anisotropy, a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. According to our measurements, charge conductivity by carriers of a single valley can exceed four-fifth of the total conductivity in a wide range of temperature and magnetic field. At high temperature and low magnetic field, the three valleys are interchangeable and the three-fold symmetry of the underlying lattice is respected. As the temperature lowers and/or the magnetic field increases, this symmetry is spontaneously lost. The latter may be an experimental manifestation of the recently proposed valley-nematic Fermi liquid state.Comment: 14 pages + 5 pages of supplementary information; a slightly modified version will appear as an article in Nature physic

Gravitational waves from cosmological compact binaries

We consider gravitational waves emitted by various populations of compact binaries at cosmological distances. We use population synthesis models to characterize the properties of double neutron stars, double black holes and double white dwarf binaries as well as white dwarf-neutron star, white dwarf-black hole and black hole-neutron star systems. We use the observationally determined cosmic star formation history to reconstruct the redshift distribution of these sources and their merging rate evolution. The gravitational signals emitted by each source during its early-inspiral phase add randomly to produce a stochastic background in the low frequency band with spectral strain amplitude between 10^{-18} Hz^{-1/2} and 5 10^{-17} Hz^{-1/2} at frequencies in the interval [5 10^{-6}-5 10^{-5}] Hz. The overall signal which, at frequencies above 10^{-4}Hz, is largely dominated by double white dwarf systems, might be detectable with LISA in the frequency range [1-10] mHz and acts like a confusion limited noise component which might limit the LISA sensitivity at frequencies above 1 mHz.Comment: 14 pages, 14 figures, uses mn.sty, submitted to MNRA

“Medically unexplained” symptoms and symptom disorders in primary care: prognosis-based recognition and classification

Background: Many patients consult their GP because they experience bodily symptoms. In a substantial proportion of cases, the clinical picture does not meet the existing diagnostic criteria for diseases or disorders. This may be because symptoms are recent and evolving or because symptoms are persistent but, either by their character or the negative results of clinical investigation cannot be attributed to disease: so-called “medically unexplained symptoms” (MUS). MUS are inconsistently recognised, diagnosed and managed in primary care. The specialist classification systems for MUS pose several problems in a primary care setting. The systems generally require great certainty about presence or absence of physical disease, they tend to be mind-body dualistic, and they view symptoms from a narrow specialty determined perspective. We need a new classification of MUS in primary care; a classification that better supports clinical decision-making, creates clearer communication and provides scientific underpinning of research to ensure effective interventions. Discussion: We propose a classification of symptoms that places greater emphasis on prognostic factors. Prognosis-based classification aims to categorise the patient’s risk of ongoing symptoms, complications, increased healthcare use or disability because of the symptoms. Current evidence suggests several factors which may be used: symptom characteristics such as: number, multi-system pattern, frequency, severity. Other factors are: concurrent mental disorders, psychological features and demographic data. We discuss how these characteristics may be used to classify symptoms into three groups: self-limiting symptoms, recurrent and persistent symptoms, and symptom disorders. The middle group is especially relevant in primary care; as these patients generally have reduced quality of life but often go unrecognised and are at risk of iatrogenic harm. The presented characteristics do not contain immediately obvious cut-points, and the assessment of prognosis depends on a combination of several factors. Conclusion: Three criteria (multiple symptoms, multiple systems, multiple times) may support the classification into good, intermediate and poor prognosis when dealing with symptoms in primary care. The proposed new classification specifically targets the patient population in primary care and may provide a rational framework for decision-making in clinical practice and for epidemiologic and clinical research of symptoms

Cosmic Physics: The High Energy Frontier

Cosmic rays have been observed up to energies $10^8$ times larger than those of the best particle accelerators. Studies of astrophysical particles (hadrons, neutrinos and photons) at their highest observed energies have implications for fundamental physics as well as astrophysics. Thus, the cosmic high energy frontier is the nexus to new particle physics. This overview discusses recent advances being made in the physics and astrophysics of cosmic rays and cosmic gamma-rays at the highest observed energies as well as the related physics and astrophysics of very high energy cosmic neutrinos. These topics touch on questions of grand unification, violation of Lorentz invariance, as well as Planck scale physics and quantum gravity.Comment: Topical Review Paper to be published in the Journal of Physics G, 50 page

Systematic review of measurement properties of questionnaires measuring somatization in primary care patients

Objective The aim of this review is to critically appraise the evidence on measurement properties of self-report questionnaires measuring somatization in adult primary care patients and to provide recommendations about which questionnaires are most useful for this purpose. Methods We assessed the methodological quality of included studies using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist. To draw overall conclusions about the quality of the questionnaires, we conducted an evidence synthesis using predefined criteria for judging the measurement properties. Results We found 24 articles on 9 questionnaires. Studies on the Patient Health Questionnaire-15 (PHQ-15) and the Four-Dimensional Symptom Questionnaire (4DSQ) somatization subscale prevailed and covered the broadest range of measurement properties. These questionnaires had the best internal consistency, test-retest reliability, structural validity, and construct validity. The PHQ-15 also had good criterion validity, whereas the 4DSQ somatization subscale was validated in several languages. The Bodily Distress Syndrome (BDS) checklist had good internal consistency and structural validity. Some evidence was found for good construct validity and criterion validity of the Physical Symptom Checklist (PSC-51) and good construct validity of the Symptom Check-List (SCL-90-R) somatization subscale. However, these three questionnaires were only studied in a small number of primary care studies. Conclusion Based on our findings, we recommend the use of either the PHQ-15 or 4DSQ somatization subscale for somatization in primary care. Other questionnaires, such as the BDS checklist, PSC-51 and the SCL-90-R somatization subscale show promising results but have not been studied extensively in primary care. © 2017 Elsevier Inc

Predictors of persistent medically unexplained physical symptoms: findings from a general population study

Objective: To explore the course persistency of Medically Unexplained Symptoms (MUS) and its prognostics factors in the general adult population. Knowledge of prognostic factors of MUS may indicate possible avenues for intervention development. Methods: Data were derived from the Netherlands Mental Health Survey and Incidence Study-2 (NEMESIS-2), a nationally representative face-to-face cohort study among the Dutch general population aged 18-64 years. We selected subjects with MUS at baseline and who participated at follow-up (N=324) and reassessed those subjects for having MUS at three year follow-up. Logistic regression analyses were used to determine risk factors for persistency of MUS. Results: 36.4% of the subjects had persistent MUS at follow-up. In logistic regression analyses adjusted for sex and age, persistency of MUS was predicted by the number of comorbid chronic medical disorder(s), lower education, female sex, not having a paid job, parental psychopathology as well as lower functioning. In the logistic regression analysis in which all significant variables adjusted for sex and age were entered simultaneously, three variables predicted persistent MUS: parental psychopathology, the number of comorbid chronic medical disorder(s) and physical functioning, with odds ratios of 2.01 (1.20-3.38), 1.19 (1.01-1.40) and 0.99 (0.97-1.00), respectively. Conclusion: In the adult general population, MUS were persistent in over one third of the subjects with MUS at baseline. Persistency was uniquely significantly predicted by parental psychopathology, number of comorbid chronic medical disorders and physical functioning. These findings warrant further research into early intervention and treatment options for persons with an increased risk of persistent MUS

Identity and Characteristics of Feathers Used in Tree Swallow Nest Lining Across Habitat Types

Nest construction is a critical component of parental investment in most birds, and can have important fitness consequences. Tree Swallows (Tachycineta bicolor) are secondary cavity nesters that build their nests using dry grasses and a feather lining. It has been proposed that these feathers are a limiting resource which enhance reproductive success of Swallow pairs. However, there is little information about the identity and characteristics of the feathers that this species relies on for reproduction. Our goal was to characterize the feathers used as nesting materials by Tree Swallows within a 60 mile radius of Richmond, Indiana. We monitored 41 nest boxes and collected feathers to determine the number, sizes, colors, and types of feathers present. Feathers were identified using three complementary methods: microscopy, DNA barcoding, and comparison to museum specimens. Our results indicate that on average Tree Swallows use 77.34 ± 12.08 (SE) feathers in their nests. We found that the most common feather type, size range, and color, were contour (95.14%), 5-10 cm (62.66%), and brown (50.50%), respectively. We found significant differences between the number of feathers used across different habitats. We also identified a greater diversity of feathers than was previously recorded. In addition to using feathers from the orders Anseriformes, Galliformes, Cathartiformes, and Strigiformes as reported in previous literature, Tree Swallows in our study site used feathers from 6 other orders (Columbiformes, Gruiformes, Pelecaniformes, Accipitriformes, Piciformes, and Passeriformes). This is the first time this information has been reported for Tree Swallows