525 research outputs found

    Comparison of energy-wood and pulpwood thinning systems in young birch stands

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    In early thinnings, a profitable alternative to pulpwood could be to harvest whole trees as energy-wood. In theoretical analyses, we compared the extractible volumes of energy-wood and pulpwood, and their respective gross values in differently aged stands of early birch thinnings at varying intensities of removal. In a parallel field experiment, we compared the productivity at harvest of either pulpwood or energy-wood, and the profitability when the costs of harvesting and forwarding were included. The theoretical analyses showed that the proportion of the total tree biomass removed as pulpwood increased with increasing thinning intensity and stem size. The biomass volume was 1.5–1.7 times larger than the pulpwood volume for a 13.9 diameter at breast height stand and 2.0–3.5 times larger for a 10.4 diameter at breast height stand. In the field experiment, the harvested volume per hectare of energy-wood was almost twice as high as the harvest of pulpwood. The harvesting productivity (trees Productive harvesting Work Time-hour−1) was 205 in the energy-wood and 120 in the pulpwood treatment. The pulpwood treatment generated a net loss, whereas the energy-wood treatment generated a net income, the average difference being €595 ha−1. We conclude that in birch-dominated early thinning stands, at current market prices, harvesting energy-wood is more profitable than harvesting pulpwood

    Gamma-rays from dark matter annihilations strongly constrain the substructure in halos

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    Recently, it has been shown that electrons and positrons from dark matter (DM) annihilations provide an excellent fit to the Fermi, PAMELA, and HESS data. Using this DM model, which requires an enhancement of the annihilation cross section over its standard value to match the observations, we show that it immediately implies an observable level of gamma-ray emission for the Fermi telescope from nearby galaxy clusters such as Virgo and Fornax. We show that this DM model implies a peculiar feature from final state radiation that is a distinctive signature of DM. Using the EGRET upper limit on the gamma-ray emission from Virgo, we constrain the minimum mass of substructures within DM halos to be > 5x10^-3 M_sun -- about four orders of magnitudes larger than the expectation for cold dark matter. This limits the cutoff scale in the linear matter power spectrum to k < 35/kpc which can be explained by e.g., warm dark matter. Very near future Fermi observations will strongly constrain the minimum mass to be > 10^3 M_sun: if the true substructure cutoff is much smaller than this, the DM interpretation of the Fermi/PAMELA/HESS data must be wrong. To address the problem of astrophysical foregrounds, we performed high-resolution, cosmological simulations of galaxy clusters that include realistic cosmic ray (CR) physics. We compute the dominating gamma-ray emission signal resulting from hadronic CR interactions and find that it follows a universal spectrum and spatial distribution. If we neglect the anomalous enhancement factor and assume standard values for the cross section and minimum subhalo mass, the same model of DM predicts comparable levels of the gamma-ray emission from DM annihilations and CR interactions. This suggests that spectral subtraction techniques could be applied to detect the annihilation signal.Comment: 5 pages, 2 figures (published version; minor corrections to figures and result, equation added

    Protein and energy intake, nitrogen balance and nitrogen losses in patients treated with continuous ambulatory peritoneal dialysis

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    Protein and energy intake, nitrogen balance and nitrogen losses in patients treated with continuous ambulatory peritoneal dialysis. The aim of this investigation was to analyze factors which influence the dietary protein intake (DPI), the energy intake and the utilization of ingested protein, and to determine the relationship between various types of nitrogen losses in stable continuous ambulatory peritoneal dialysis (CAPD) patients. We performed 23 nitrogen balance (NB) studies of 6 to 11 days duration in 12 CAPD patients. One study was performed in all patients 3.4 ± 1.2 months after starting CAPD (early studies). The study was then repeated in nine patients after 12.1 ± 2.6 months, and two of these patients were studied again after 16 and 24 months, respectively (late studies). Before each NB study, the dietary intakes prior to the study were assessed in diaries and interviews. During a few days preceding the NB periods and during the NB periods each patient received an individualized diet composed so as to resemble the patients' spontaneously chosen diet regarding DPI and dietary energy intake (DEI). Total nitrogen, protein, urea and creatinine were analyzed in the dialysate and urine collected daily. Total nitrogen was also analyzed in the feces, collected over the whole NB period. Total nitrogen appearance (TNA), non-protein nitrogen appearance (NPNA) and urea nitrogen appearance (UNA) were calculated by correcting total nitrogen output, non-protein nitrogen output, that is, TNA minus the total protein losses (PL) and urea nitrogen output for changes in total body urea nitrogen. Glucose was determined in the collected dialysate and the daily glucose absorption was calculated. DPI varied between 0.62 and 2.09 g/kg/day, DEI between 21 and 42 kcal/kg/day and the peritoneal energy (glucose) intake (PEI) between 4 and 13 kcal/kg/day. DPI (but not DEI) correlated with Kt/Vurea and Kt/VCr and with total and renal clearances for urea and creatinine. NB (not corrected for “unmeasured” nitrogen losses) was positive in most studies, and it correlated with DPI and the total energy intake (TEI) in the early studies, but only with TEI in the late studies. DPI correlated with TNA, NPNA, UNA, non-protein-non-urea nitrogen loss and fecal nitrogen loss. UNA was highly correlated with TNA and NPNA (r = 0.95). We used data from 33 NB studies in CAPD patients (our present data combined with data from the literature) to calculate regression equations describing the relationship between TNA and NPNA, respectively, and UNA. Equations were derived by which the protein equivalent of TNA (PNA), that is, 6.25 TNA, and the protein equivalent of NPNA (PNPNA), that is, 6.25 NPNA, may be calculated from UNA which is directly measured. In stable CAPD patients, who are not strongly catabolic or anabolic, PNA may be used to estimate DPI and PNPNA may be used to estimate the net protein intake (DPI – PL)

    The Photovoltaic Crisis and the Demand-side Generation in Spain

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    The RES-E promotion policy in Spain gave priority to the photovoltaic (henceforth, PV) ground-mounted installations. For years, the coupling of customer-side generation coupled with excess energy exports was never specifically considered. However, some months ago this option was suggested as a way to recover the Spain��s PV sector from the current moratorium on the RES-E policy. A decree draft on on-site generation was issued, its central point being the consideration of electricity exports as delayed consumption rights. But several barriers hinder its entry into force. Unfortunately, Spain could be losing an important opportunity for encouraging PV investments while retail grid parity is being reached. This working paper analyzes the different types of PV demand-side generation from the point of view of consumer-generators and evaluates the economic and technical features of the regulation proposed in Spain and to date still pending

    Function and Structure in Retinal Transplants

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    Embryonic mammalian donor retina transplanted into the subretinal space of a mature host develops into a graft with wellorganized, but atypical retinal structure. We tested the effect of this organization on rabbitto-rabbit graft functional properties, isolating the graft to avoid contamination of graft responses by host retinal activity. Transient ON or ON-OFF spike-like responses and local electroretinograms (L-ERGs) were recorded simultaneously via a single electrode on the graft surface. These response components depended on stimulus diameter, sometimes in a way indicating antagonistic center-surround receptive field organization and spatial tuning (43%). Other times, the responses were an increasing function of stimulus diameter which saturated for large spots (57%). Response amplitudes were transplantation surgery is to be done with therapeutic aims

    Determination of the enterprise financial state by the liss model at the example of SE STC “Precision Mechanics Factory”

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    In order to grow, tumors need to induce supportive alterations in the tumor-bearing organ, by us named tumor instructed normal tissue (TINT) changes. We now examined if the nature and magnitude of these responses were related to tumor size and aggressiveness. Three different Dunning rat prostate tumor cells were implanted into the prostate of immune-competent rats; 1) fast growing and metastatic MatLyLu tumor cells 2) fast growing and poorly metastatic AT-1 tumor cells, and 3) slow growing and non-metastatic G tumor cells. All tumor types induced increases in macrophage, mast cell and vascular densities and in vascular cell-proliferation in the tumor-bearing prostate lobe compared to controls. These increases occurred in parallel with tumor growth. The most pronounced and rapid responses were seen in the prostate tissue surrounding MatLyLu tumors. They were, also when small, particularly effective in attracting macrophages and stimulating growth of not only micro-vessels but also small arteries and veins compared to the less aggressive AT-1 and G tumors. The nature and magnitude of tumor-induced changes in the tumor-bearing organ are related to tumor size but also to tumor aggressiveness. These findings, supported by previous observation in patient samples, suggest that one additional way to evaluate prostate tumor aggressiveness could be to monitor its effect on adjacent tissues
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