The effects of precipitation manipulation on carbohydrate dynamics and mortality in a piñon-juniper woodland

Drought-induced forest mortality is an increasing global problem with far-reaching consequences, yet mortality mechanisms remain poorly understood. Depletion of non-structural carbohydrate (NSC) stores has been implicated as a major factor in drought-induced mortality, but experimental field tests are rare. We conducted an ecosystem-scale precipitation manipulation experiment and evaluated leaf and twig NSC dynamics of two co-occurring conifers with different water regulation strategies; the relatively drought-averse piñon pine (Pinus edulis) and relatively drought-tolerant oneseed juniper (Juniperus monosperma). Experimental drought caused decreased leaf starch in dying trees of both species and increased allocation to glucose and fructose in juniper, consistent with osmoregulation requirements. For both species, average leaf starch content between drought treatment initiation and mortality was a good predictor (R2 = 0.77) of survival duration. These results, along with observations of drought-induced reductions to photosynthesis and growth, implicate carbon starvation as an important process during mortality of these two conifer species

Science is perception: what can our sense of smell tell us about ourselves and the world around us?

Human sensory processes are well understood: hearing, seeing, perhaps even tasting and touch—but we do not understand smell—the elusive sense. That is, for the others we know what stimuli causes what response, and why and how. These fundamental questions are not answered within the sphere of smell science; we do not know what it is about a molecule that … smells. I report, here, the status quo theories for olfaction, highlighting what we do not know, and explaining why dismissing the perception of the input as ‘too subjective’ acts as a roadblock not conducive to scientific inquiry. I outline the current and new theory that conjectures a mechanism for signal transduction based on quantum mechanical phenomena, dubbed the ‘swipe card’, which is perhaps controversial but feasible. I show that such lines of thinking may answer some questions, or at least pose the right questions. Most importantly, I draw links and comparisons as to how better understanding of how small (10’s of atoms) molecules can interact so specially with large (10 000’s of atoms) proteins in a way that is so integral to healthy living. Repercussions of this work are not just important in understanding a basic scientific tool used by us all, but often taken for granted, it is also a step closer to understanding generic mechanisms between drug and receptor, for example

Immunology of the canine eye in health and disease: A concise review

The canine eye is an immune-privileged organ that is provided with systems to prevent and control the local immune response, which could have a detrimental impact. The entry of blood-derived antigens is hindered by the blood-ocular barriers and potential invading pathogens are tackled by local antimicrobial molecules. Despite the existence of numerous immune-competent cells, the anterior chamber of the eye is characterised by low responsiveness. This review is focused on the innate and adaptive immunity employed to control health and disease in the canine eye

Molecular recognition in olfaction

The mechanism by which the chemical identity of odourants is established by olfactory receptors is a matter of intense debate. Here we present an overview of recent ideas and data with a view to summarising what is known, and what has yet to be determined. We outline the competing theories, and summarise experimental results employing isotopes obtained for mammals, insects, and individual receptors that enable us to judge the relative correctness of the theories

Communication through noisy, random-multipath channels

Thesis (Sc.D.) Massachusetts Institute of Technology. Dept. of Electrical Engineering, 1956.Vita.Bibliography: leaves 97-98.by George Lewis Turin.Sc.D

Current and noise expressions for radio-frequency single-electron transistors

We derive self-consistent expressions of current and noise for single-electron transistors driven by time-dependent perturbations. We take into account effects of the electrical environment, higher-order co-tunneling, and time-dependent perturbations under the two-charged state approximation using the Schwinger-Kedysh approach combined with the generating functional technique. For a given generating functional, we derive exact expressions for tunneling currents and noises and present the forms in terms of transport coefficients. It is also shown that in the adiabatic limit our results encompass previous formulas. In order to reveal effects missing in static cases, we apply the derived results to simulate realized radio-frequency single-electron transistor. It is found that photon-assisted tunneling affects largely the performance of the single-electron transistor by enhancing both responses to gate charges and current noises. On various tunneling resistances and frequencies of microwaves, the dependence of the charge sensitivity is also discussed.Comment: 18 pages, 9 figure

Automated Structural-level Alignment of Multi-view TLS and ALS Point Clouds in Forestry

Access to highly detailed models of heterogeneous forests from the near surface to above the tree canopy at varying scales is of increasing demand as it enables more advanced computational tools for analysis, planning, and ecosystem management. LiDAR sensors available through different scanning platforms including terrestrial, mobile and aerial have become established as one of the primary technologies for forest mapping due to their inherited capability to collect direct, precise and rapid 3D information of a scene. However, their scalability to large forest areas is highly dependent upon use of effective and efficient methods of co-registration of multiple scan sources. Surprisingly, work in forestry in GPS denied areas has mostly resorted to methods of co-registration that use reference based targets (e.g., reflective, marked trees), a process far from scalable in practice. In this work, we propose an effective, targetless and fully automatic method based on an incremental co-registration strategy matching and grouping points according to levels of structural complexity. Empirical evidence shows the method's effectiveness in aligning both TLS-to-TLS and TLS-to-ALS scans under a variety of ecosystem conditions including pre/post fire treatment effects, of interest to forest inventory surveyors

Comparative analysis of viral shedding in pediatric and adult subjects with central nervous system-associated enterovirus infections from 2013 to 2015 in Switzerland.

Several enterovirus (EV) genotypes can result in aseptic meningitis, but their routes of access to the central nervous system remain to be elucidated and may differ between the pediatric and adult populations. To assess the pattern of viral shedding in pediatric and adult subjects with acute EV meningitis and to generate EV surveillance data for Switzerland. All pediatric and adult subjects admitted to the University Hospitals of Geneva with a diagnosis of EV meningitis between 2013 and 2015 were enrolled. A quantitative EV real-time reverse transcriptase (rRT)-PCR was performed on the cerebrospinal fluid (CSF), blood, stool, urine and respiratory specimens to assess viral shedding and provide a comparative analysis of pediatric and adult populations. EV genotyping was systematically performed. EV positivity rates differed significantly between pediatric and adult subjects; 62.5% of pediatric cases (no adult case) were EV-positive in stool and blood for subjects for whom these samples were all collected. Similarly, the EV viral load in blood was significantly higher in pediatric subjects. Blood C-reactive protein levels were lower and the number of leucocytes/mm3 in the CSF were higher in non-viremic than in viremic pediatric subjects, respectively. A greater diversity of EV genotypes was observed in pediatric cases, with a predominance of echovirus 30 in children ≥3 years old and adults. In contrast to adults, EV-disseminated infections are predominant in pediatric subjects and show different patterns of EV viral shedding. This observation may be useful for clinicians and contribute to modify current practices of patient care

Could humans recognize odor by phonon assisted tunneling?

Our sense of smell relies on sensitive, selective atomic-scale processes that are initiated when a scent molecule meets specific receptors in the nose. However, the physical mechanisms of detection are not clear. While odorant shape and size are important, experiment indicates these are insufficient. One novel proposal suggests inelastic electron tunneling from a donor to an acceptor mediated by the odorant actuates a receptor, and provides critical discrimination. We test the physical viability of this mechanism using a simple but general model. Using values of key parameters in line with those for other biomolecular systems, we find the proposed mechanism is consistent both with the underlying physics and with observed features of smell, provided the receptor has certain general properties. This mechanism suggests a distinct paradigm for selective molecular interactions at receptors (the swipe card model): recognition and actuation involve size and shape, but also exploit other processes.Comment: 10 pages, 1 figur