The Aboveground and Belowground Growth Characteristics of Juvenile Conifers in the Southwestern United States

Juvenile tree survival will play an important role in the persistence of coniferous forests and woodlands in the southwestern United States (SWUS). Vulnerability to climatic and environmental stress declines as trees grow, such that larger, more deeply rooted juveniles are less likely to experience mortality. It is unclear how juvenile conifers partition the aboveground and belowground components of early growth, if growth differs between species and ecosystem types, and what environmental factors influence juvenile carbon allocation above- or belowground. We developed a novel data set for four juvenile conifer groups (junipers, piñon pines, ponderosa pines, firs; 1121 juveniles sampled, 221 destructively) in three height classes ( \u3c 150 mm, 150–300 mm, and 300+ mm), across 25 SWUS sites. We compared growth characteristics across groups and height classes and related differences to climatic and environmental factors. As tree height increased from \u3c 150 mm to 300+ mm, belowground growth increased, root:shoot ratio declined, and specific leaf area declined for all conifers except firs. Maximum rooting depth was shallower than previous estimates ( \u3c ˜400 mm). Lower elevation juveniles were frequently located in sheltered microsites that provided high shading, whereas mid- and higher elevation juveniles were frequently unsheltered. Across all forest and woodland sites, herbaceous cover was positively correlated with aboveground growth. At study locations comprised of multiple sites, differences in aboveground growth were best explained by ecosystem type (piñon pine-juniper woodland, ponderosa pine forest, mixed-conifer forest) and local environmental variation. Our results indicate generally more belowground early growth and more aboveground later growth, but specific allocation patterns varied among ecosystem (greater proportional shoot growth at lower and mid-elevations compared with higher elevations). Juvenile conifers had similar magnitudes of proportional growth across conifer groups, displaying limited capacity to acclimate growth to differences in climate that control ecosystem type. If juvenile conifers also do not acclimate physiologically to their environment, our findings suggest that local environmental variation will play a primary role in regulating forest and woodland persistence and modify the effects of climate change in the SWUS

The sensitivity of carbon exchanges in Great Plains grasslands to precipitation variability

In the Great Plains, grassland carbon dynamics differ across broad gradients of precipitation and temperature, yet finer-scale variation in these variables may also affect grassland processes. Despite the importance of grasslands, there is little information on how fine-scale relationships compare between them regionally. We compared grassland C exchanges, energy partitioning and precipitation variability in eight sites in the eastern and western Great Plains using eddy covariance and meteorological data. During our study, both eastern and western grasslands varied between an average net carbon sink and a net source. Eastern grasslands had a moderate vapor pressure deficit (VPD = 0.95 kPa) and high growing season gross primary productivity (GPP = 1010 ± 218 g C m−2 yr−1). Western grasslands had a growing season with higher VPD (1.43 kPa) and lower GPP (360 ± 127 g C m−2 yr−1). Western grasslands were sensitive to precipitation at daily timescales, whereas eastern grasslands were sensitive at monthly and seasonal timescales. Our results support the expectation that C exchanges in these grasslands differ as a result of varying precipitation regimes. Because eastern grasslands are less influenced by short-term variability in rainfall than western grasslands, the effects of precipitation change are likely to be more predictable in eastern grasslands because the timescales of variability that must be resolved are relatively longer. We postulate increasing regional heterogeneity in grassland C exchanges in the Great Plains in coming decades.Konza Prairie Biological Station. Grant Number: DEB-0823341U.S. Department of Energy. Grant Number: DE-AC02-05CH11231U.S. Department of Agriculture. Grant Number: 2014-67003-22070DOE-NIGEC. Grant Number: 26-6223-7230-002Natural Sciences and Engineering Research Council of Canada Discovery. Grant Number: RGPIN-2014-05882Sevilleta LTERNAS

Solitary coherent structures in viscoelastic shear flow: computation and mechanism

Starting from stationary bifurcations in Couette-Dean flow, we compute nontrivial stationary solutions in inertialess viscoelastic circular Couette flow. These solutions are strongly localized vortex pairs, exist at arbitrarily large wavelengths, and show hysteresis in the Weissenberg number, similar to experimentally observed ``diwhirl'' patterns. Based on the computed velocity and stress fields, we elucidate a heuristic, fully nonlinear mechanism for these flows. We propose that these localized, fully nonlinear structures comprise fundamental building blocks for complex spatiotemporal dynamics in the flow of elastic liquids.Comment: 5 pages text and 4 figures. Submitted to Physical Review Letter

Coronavirus Occurrence and Transmission Over 8 Years in the HIVE Cohort of Households in Michigan

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156082/1/jiaa161.pdfSEL

Disclosure of Maternal HIV Status to Children: To Tell or Not To Tell . . . That Is the Question

HIV-infected mothers face the challenging decision of whether to disclose their serostatus to their children. From the perspective of both mother and child, we explored the process of disclosure, providing descriptive information and examining the relationships among disclosure, demographic variables, and child adjustment. Participants were 23 mothers and one of their noninfected children (9 to 16 years of age). Sixty-one percent of mothers disclosed. Consistent with previous research, disclosure was not related to child functioning. However, children sworn to secrecy demonstrated lower social competence and more externalizing problems. Differential disclosure, which occurred in one-third of the families, was associated with higher levels of depressive and anxiety symptoms. Finally, knowing more than mothers had themselves disclosed was related to child maladjustment across multiple domains. Clinical implications and the need for future research are considered

'Working out’ identity: distance runners and the management of disrupted identity

This article contributes fresh perspectives to the empirical literature on the sociology of the body, and of leisure and identity, by analysing the impact of long-term injury on the identities of two amateur but serious middle/long-distance runners. Employing a symbolic interactionist framework,and utilising data derived from a collaborative autoethnographic project, it explores the role of ‘identity work’ in providing continuity of identity during the liminality of long-term injury and rehabilitation, which poses a fundamental challenge to athletic identity. Specifically, the analysis applies Snow and Anderson’s (1995) and Perinbanayagam’s (2000) theoretical conceptualisations in order to examine the various forms of identity work undertaken by the injured participants, along the dimensions of materialistic, associative and vocabularic identifications. Such identity work was found to be crucial in sustaining a credible sporting identity in the face of disruption to the running self, and in generating momentum towards the goal of restitution to full running fitness and reengagement with a cherished form of leisure. KEYWORDS: identity work, symbolic interactionism, distance running, disrupted identit

Reanalysis of two eclipsing binaries: EE Aqr and Z Vul

We study the radial-velocity and light curves of the two eclipsing binaries EE Aqr and Z Vul. Using the latest version of the Wilson & Van Hamme (2003) model, absolute parameters for the systems are determined. We find that EE Aqr and Z Vul are near-contact and semi-detached systems, respectively. The primary component of EE Aqr fills about 96% of its 'Roche lobe', while its secondary one appears close to completely filling this limiting volume. In a similar way, we find fill-out proportions of about 72 and 100% of these volumes for the primary and secondary components of Z Vul respectively. We compare our results with those of previous authors.Comment: 13 pages, 8 figures, 10 table

Resting and exercise haemodynamic characteristics of patients with advanced heart failure and preserved ejection fraction

Aims: This study aimed to describe haemodynamic features of patients with advanced heart failure with preserved ejection fraction (HFpEF) as defined by the Heart Failure Association (HFA) of the European Society of Cardiology (ESC). Methods and results: We used pooled data from two dedicated HFpEF studies with invasive exercise haemodynamic protocols, the REDUCE LAP-HF (Reduce Elevated Left Atrial Pressure in Patients with Heart Failure) trial and the REDUCE LAP-HF I trial, and categorized patients according to advanced heart failure (AdHF) criteria. The well-characterized HFpEF patients were considered advanced if they had persistent New York Heart Association classification of III–IV and heart failure (HF) hospitalization < 12 months and a 6 min walk test distance < 300 m. Twenty-four (22%) out of 108 patients met the AdHF criteria. On evaluation, clinical characteristics and resting haemodynamics were not different in the two groups. Patients with AdHF had lower work capacity compared with non-advanced patients (35 ± 16 vs. 45 ± 18 W, P = 0.021). Workload-corrected pulmonary capillary wedge pressure normalized to body weight (PCWL) was higher in AdHF patients compared with non-advanced (112 ± 55 vs. 86 ± 49 mmHg/W/kg, P = 0.04). Further, AdHF patients had a smaller increase in cardiac index during exercise (1.1 ± 0.7 vs. 1.6 ± 0.9 L/min/m2, P = 0.028). Conclusions: A significantly higher PCWL and lower cardiac index reserve during exercise were observed in AdHF patients compared with non-advanced. These differences were not apparent at rest. Therapies targeting the haemodynamic compromise associated with advanced HFpEF are needed

Euclidean Supergravity in Terms of Dirac Eigenvalues

It has been recently shown that the eigenvalues of the Dirac operator can be considered as dynamical variables of Euclidean gravity. The purpose of this paper is to explore the possiblity that the eigenvalues of the Dirac operator might play the same role in the case of supergravity. It is shown that for this purpose some primary constraints on covariant phase space as well as secondary constraints on the eigenspinors must be imposed. The validity of primary constraints under covariant transport is further analyzed. It is show that in the this case restrictions on the tanget bundle and on the spinor bundle of spacetime arise. The form of these restrictions is determined under some simplifying assumptions. It is also shown that manifolds with flat curvature of tangent bundle and spinor bundle and spinor bundle satisfy these restrictons and thus they support the Dirac eigenvalues as global observables.Comment: Misprints and formulae corrected; to appear in Phys. Rev.