Optimum geometric layout of a single cable road     

Leo Bont  Hans Rudolf Heinimann 《European Journal of Forest Research》2012,131(5):1439-1448

Cable-based technologies have been a backbone for harvesting on steep slopes. The layout of a single cable road is challenging because one must identify intermediate support locations and heights that guarantee structural safety and operational efficiency while minimizing set-up and dismantling costs. Our study objectives were to (1) develop an optimization approach for designing the best possible intermediate support layout for a given ground profile, (2) compare optimization procedures between linearized and nonlinear analyses of a cable structure and (3) investigate the effect of simplifying a multi-span representation. Our results demonstrate that the computational effort is 30–60 times greater for an optimization approach based on nonlinear cable mechanical assumptions than when considering linear assumptions. Those nonlinear assumptions also stipulate lower heights for intermediate supports and a larger span length. Finally, compared with the unloaded case, tensile force in the skyline is increased by as much as 80% under load for a single-span skyline configuration. Our approach provides additional value for cable operations because it ensures greater structural safety at a lower cost for installation. Improvements are still needed in developing a stand-alone application that can be easily distributed. Moreover, our rather simple assumptions regarding set-up and dismantling costs must be refined.  相似文献   

An all-silicon passive optical diode     

Fan L  Wang J  Varghese LT  Shen H  Niu B  Xuan Y  Weiner AM  Qi M 《Science (New York, N.Y.)》2012,335(6067):447-450

A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which uses two silicon rings 5 micrometers in radius, is passive yet maintains optical nonreciprocity for a broad range of input power levels, and it performs equally well even if the backward input power is higher than the forward input. The silicon optical diode is ultracompact and is compatible with current complementary metal-oxide semiconductor processing.  相似文献   

Association between Waste Management and Cancer in Companion Animals     

L. Marconato  C. Leo  R. Girelli  S. Salvi  F. Abramo  G. Bettini  S. Comazzi  P. Nardi  F. Albanese  E. Zini 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2009,23(3):564-569

Background: Increased cancer rates have been documented in people residing in areas around Naples characterized by illegal dumping and incineration of waste.
Hypothesis: Risk of cancer in dogs and cats is associated with waste management.
Animals: Four hundred and fifty-three dogs and cats with cancer and 1,554 cancer-free animals.
Methods: Hospital-based case-control study in Naples (low danger) and nearby cities having a history of illegal waste dumping (high danger). Odds ratio (OR) between high- and low-danger areas was calculated for all tumors and various malignancies in dogs and cats.
Results: An increased risk for cancer development was identified in dogs but not in cats residing in high-danger areas (OR: 1.55; 95% confidence interval: 1.18–2.03; P < .01). A 2.39-fold increased risk of lymphoma ( P < .01) accounted for the greater tumor frequency in dogs residing in high-danger areas. The risk of mast cell tumor and mammary cancer did not differ in dogs residing in high- or low-danger areas.
Conclusions and Clinical Importance: Waste emission from illegal dumping sites increases cancer risk in dogs residing in high-danger areas. An increased prevalence of lymphoma has been previously recognized in humans living close to illegal waste dumps. Thus, epidemiological studies of spontaneous tumors in dogs might suggest a role for environmental factors in canine and human carcinogenesis and can predict health hazards for humans.  相似文献   

Measurement of digital laminar and venous temperatures as a means of comparing three methods of topically applied cold treatment for digits of horses     

Reesink HL  Divers TJ  Bookbinder LC  van Eps AW  Soderholm LV  Mohammed HO  Cheetham J 《American journal of veterinary research》2012,73(6):860-866

  相似文献   

Early survival of marble trout Salmo marmoratus: evidence for density dependence?     

S. Vincenzi  A. J. Crivellì  D. Jesensek  J.-F. Rubin  G. A. De Leo 《Ecology of Freshwater Fish》2007,16(2):116-123

Abstract –  The role of endogenous and exogenous factors in regulating population dynamics of freshwater salmonids is still a matter of debate. The aim of the present work was to assess the relative importance of density-dependent and -independent factors in determining the survival of marble trout ( Salmo marmoratus ) yearlings in two populations living in Slovenian streams (Zakojska and Gorska). The investigation was performed by combining a classical life table analysis with Monte Carlo simulation. Size-dependent fecundity was estimated by stripping wild adults in the fish farm. A significant positive relationship was found between length of marble trout females and the number of eggs produced. Egg density was the major determinant of survival from eggs to age 1+ ( σ ₀) in both streams. Residuals of the relationship between σ ₀ and egg density were positively correlated with rainfall only in Zakojska, probably because, within a certain range, more intense rainfalls increases stream flow and, consequently, suitable habitat for trout. Our study shows how density-dependent and environmental factors can interact to determine the survival of marble trout during the first year of life.  相似文献   

Development of a hamster model of Chlamydophila pneumoniae infection     

Irmak K  Turgut K 《Veterinary research communications》2005,29(1):61-68

The purpose of the study was to evaluate haemostatic function in cattle with abomasal displacement (AD) and to reflect the occurrence of disseminated intravascular coagulation (DIC). Ten adult cattle with left displacement of abomasum (LDA) (group I), 10 adult cattle with right displacement of abomasum with volvulus (RDA) (group II) and 10 clinically healthy adult cattle (control group) were used as material. Numbers of platelets (PLT) and coagulation tests (activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), serum fibrin/fibrinogen degradation products (FDPs), fibrinogen) were measured before the surgical treatment of cattle with LDA and RDA. APTT was prolonged only in group II compared with the control and group I (p<0.05). However, when the individual values of coagulation profiles of each cow were evaluated, two cattle in group I and three cattle in group II had at least three abnormal coagulation profiles, which reflect the occurrence of DIC. These cattle died after surgical treatment. The two cattle with LDA had abnormal APTT, FDPs and PLT values; three cattle with RDA had abnormal APTT, PT, TT, FDPs and PLT values. APTT (5 cases), FDPs (5 cases) and thrombocytopenia (5 cases) were the three most common abnormal tests on coagulation profile in the cattle with LDA and RDA. The results of the study indicate that cattle with AD had a spectrum of haemostatic dysfunction and that DIC was a significant risk factor for mortality.  相似文献   

Cultivation and expansion of canine Schwann cells using reexplantation     

Pauls J  Nolte C  Forterre F  Brunnberg L 《Berliner und Münchener tier?rztliche Wochenschrift》2004,117(7-8):341-352

Despite the numerous available possibilities for the surgical treatment of peripheral nerve lesions found in the dog, the success of these treatments is often unsatisfactory. It has been proven that Schwann cells (SC) have a positive influence on the regeneration of nerve stumps. Implanting a guidance channel seeded with autologous SC at the lesion site could be a new therapeutic approach. The aim of this research was to investigate the in vitro cultivation and expansion of canine SC as the main requirement for the treatment referred to above. Biopsies were carried out on 17 nerve samples originating from dogs of different breed, age, gender and condition. The reexplantation method was employed, followed by dissociation using hyaluronidase, collagenase and trypsin and further expansion. The samples were divided into six groups which were treated with a varying combination of mitogens (forskolin, bovine PEX, choleratoxin, heregulin). To obtain the quantities of SC, the specimens were immunostained by a p75-antibody. By employing a growing number of agents it was possible to obtain an increase in both the quantity of cells and purity of cultures. A maximum of 16x10(5) cells per millilitre of suspension was achieved. The largest SC purity measured 27.1%. The maximum SC quantity achieved was 43.3x10(4) SC per millilitre.  相似文献   

Caspase-mediated apoptosis in chicken postovulatory follicle regression     

Sundaresan NR  Saxena VK  Sastry KV  Anish D  Marcus Leo MD  Kantaraja C  Saxena M  Ahmed KA 《Veterinary research communications》2008,32(1):13-19

Chicken postovulatory follicle (POF) regression occurs via the process of apoptosis. However, the signals and initiator pathways responsible for regression of the POF are unknown. In the current study, we examined gene expression patterns of various caspases (caspase-1, -2 and -3) involved in apoptosis by semi-quantitative RT-PCR. The percentage of apoptotic cells during POF regression was also quantified by flow cytometry. Expression of caspase-3 mRNA was noted in the largest preovulatory follicle (F1). However, the initiator caspases (caspase-1 and -2) were not expressed in F1. During the regression of the POF, caspase-3 was activated during initial stages, whereas the initiator caspases were upregulated at the later stages (POF4 and POF5).The percentage of apoptotic cells was significantly higher during the regression of the POF. It might be possible that levels of caspase-3 mRNA do not necessarily reflect the cell’s potential for facilitating apoptosis, as activation of the caspase-3 by initiator caspases is required for its function. We presume that both caspase-1 and caspase-2 were key initiators in the regression of chicken POF and that the apoptosis-mediated regression of POFs might be similar to mammalian corpus luteum involution.  相似文献   

The biological and physical role of mulch in the rehabilitation of crusted soil in the Sahel   总被引：3，自引：0，他引：3  

A. Mando  L. Stroosnijder 《Soil Use and Management》1999,15(2):123-127

Abstract. During three consecutive years (1993–1995) a split-plot design with three replications was used to study the biological and physical role of mulch in the improvement of crusted soil water balance and its productivity in the north of Burkina Faso. The main treatment was the use of an insecticide, to obtain plots with and without soil fauna (SF and NSF). The subsidiary treatment consisted of four mulch types randomly applied on subplots. These were straw of Pennisetum pedicellatum applied at 3 t ha⁻¹, woody material of Pterocarpus lucens applied at 6 t ha⁻¹ and composite (woody material and straw) treatments applied at 4 t ha⁻¹. In addition there was a control, with no mulch (bare plot). Data on soil faunal activity, runoff, sediment accumulation from wind blown soil, vegetation cover and vegetation dry matter yield were collected on all plots.
The biological activity (mainly termites) in mulched plots was the key element in the efficacy of mulching to rehabilitate crusted soil. Water infiltration and dry matter yield were statistically lower on NSF plots than on SF plots and runoff and dry matter yield were not different from the values obtained on bare plots. A significant correlation was found between runoff, all vegetation data and termite-voids. Sediment accumulation due to the physical barrier of the mulch was not found to be a significant factor in the improvement of vegetation performance and the reduction of runoff.  相似文献   

Effects of common carp Cyprinus carpio (L.) and feed addition in rohu Labeo rohita (Hamilton) ponds on nutrient partitioning among fish, plankton and benthos     

Mohammad Mustafizur Rahman  Marc Verdegem  Leo Nagelkerke  Md Abdul Wahab  Ana Milstein  & Johan Verreth 《Aquaculture Research》2008,39(1):85-95

The effects of introducing common carp (CC) and of adding artificial feed to fertilized rohu ponds on water quality and nutrient accumulation efficiency were studied. All ponds were stocked with 15 000 rohu ha^?1. Treatments included ponds with rohu alone, rohu plus 5000 common carp ha^?1 and rohu plus 10 000 CC ha^?1. A comparison was also made between supplementally fed and non‐fed ponds. The overall highest nitrogen (N) and phosphorus (P) concentrations were observed in ponds with 5000 CC ha^?1, followed by ponds with 10 000 and 0 CC ha^?1. The largest fractions of N and P inputs accumulating in fish, phytoplankton and zooplankton were observed in ponds with 5000 CC ha^?1, followed by ponds with 10 000 CC ha^?1 and subsequently ponds without CC. Relatively more nutrients accumulated in benthic organisms in ponds without than in ponds with CC. A smaller fraction of the nutrient input was retained in fish, plankton and benthic organisms in ponds without CC compared with ponds with CC. Compared with 5000 CC ha^?1, stocking 10 000 CC ha^?1 can be considered as overstocking, because this leads to lower fish production and relatively less nutrients retained in plankton and benthic organisms.  相似文献