Measuring specialization in species interaction networks     

Nico Blüthgen  Florian Menzel  Nils Blüthgen 《BMC ecology》2006,6(1):9-12

Background  

Network analyses of plant-animal interactions hold valuable biological information. They are often used to quantify the degree of specialization between partners, but usually based on qualitative indices such as 'connectance' or number of links. These measures ignore interaction frequencies or sampling intensity, and strongly depend on network size.  相似文献   

An echocardiographic study of healthy Border Collies with normal reference ranges for the breed     

Jake H. Jacobson  June A. Boon  Janice M. Bright 《Journal of Veterinary Cardiology》2013,15(2):123-130

ObjectivesThe objectives of this study were to obtain standard echocardiographic measurements from healthy Border Collies and to compare these measurements to those previously reported for a general population of dogs.AnimalsStandard echocardiographic data were obtained from twenty apparently healthy Border Collie dogs. These data (n = 20) were compared to data obtained from a general population of healthy dogs (n = 69).MethodsBorder Collies were deemed healthy based on normal history, physical examination, complete blood count, serum biochemical profile, electrocardiogram, and blood pressure, with no evidence of congenital or acquired heart disease on echocardiographic examination. Standard two dimensional, M-mode, and Doppler echocardiographic measurements were obtained and normal ranges determined. The data were compared to data previously obtained at our hospital from a general population of normal dogs.ResultsTwo dimensional, M-mode, and Doppler reference ranges for healthy Border Collies are presented in tabular form. Comparison of the weight adjusted M-mode echocardiographic means from Border Collies to those from the general population of dogs showed Border Collies to have larger left ventricular systolic and diastolic dimensions, smaller interventricular septal thickness, and lower fractional shortening.ConclusionsThere are differences in some echocardiographic parameters between healthy Border Collies and the general dog population, and the echocardiographic reference ranges provided in this study should be used as breed specific reference values for Border Collies.  相似文献   

Atrial Septal Defect in a Ferret (Mustela putorius furo)     

Kim M. van Schaik-Gerritsen  Nico J. Schoemaker  Marja J.L. Kik  Niek J. Beijerink 《Journal of Exotic Pet Medicine》2013,22(1):70-75

A 2-year-old, male castrated ferret (Mustela putorius furo) was presented with progressive abdominal distention and loss of muscle mass despite normal appetite. Physical examination findings included pale mucous membranes, a prolonged capillary refill time, a pulse rate greater than 300 beats/min, and severe abdominal distention. Abdominal ultrasound showed free abdominal fluid and an enlarged liver with distended hepatic veins and caudal vena cava. During the echocardiographic examination, abnormalities observed included a 2-mm-diameter left-to-right shunting atrial septal defect (ASD) with concurrent severe dilatation of the right atrium and eccentric hypertrophy of the right ventricle with mild pulmonary hypertension. All other echocardiographic measurements were within normal limits. The owner declined treatment, and the ferret was euthanized. Postmortem examination confirmed the ultrasonographic findings. The free abdominal fluid (200 mL) was a non-septic fibropurulent exudate. Decompensated right-sided heart failure due to ASD and exudative peritonitis of undetermined origin were the final diagnoses. To our knowledge, this is the first report of an ASD in a ferret.  相似文献   

Suitability of granular carbon as an anode material for sediment microbial fuel cells     

Jan B. A. Arends  Evelyne Blondeel  Steve R. Tennison  Nico Boon  Willy Verstraete 《Journal of Soils and Sediments》2012,12(7):1197-1206

Purpose

Sediment microbial fuel cells (S-MFCs) are bio-electrochemical devices that are able to oxidize organic matter directly into harvestable electrical power. The flux of organic matter into the sediment is rather low; therefore, other researchers have introduced plants for a continuous supply of organic matter to the anode electrode. Until now only interconnected materials have been considered as anode materials in S-MFCs. Here, granular carbon materials were investigated for their suitability as an anode material in S-MFCs.

Materials and methods

Laboratory microcosms with eight different electrode materials (granules, felts and cloths) were examined with controlled organic matter addition under brackish conditions. Current density, organic matter removal and microbial community composition were monitored using 16S rRNA gene PCR followed by denaturing gradient gel electrophoresis (DGGE). The main parameters investigated were the influence of the amount of electrode material applied to the sediment, the size of the granular material and the electrode configuration.

Results and discussion

Felt material had an overall superior performance in terms of current density per amount of applied electrode material; felt and granular anode obtained similar current densities (approx. 50?C60?mA?m^?2), but felt materials required 29?% less material to be applied. Yet, when growing plants, granular carbon is more suited because it is considered to restore, upon disturbance, the electrical connectivity within the anode compartment. Small granules (0.25?C0.5?mm) gave the highest current density compared to larger granules (1?C5?mm) of the same material. Granules with a rough surface had a better performance compared to smooth granules of the same size. The different granular materials lead to a selection of distinct microbial communities for each material, as shown by DGGE.

Conclusions

Granular carbon is suitable as an anode material for S-MFCs. This opens the possibility for application of S-MFCs in cultivated areas. In a wider context, the application of granular carbon electrodes can also be an option for in situ bioremediation of contaminated soils.  相似文献   

Factors affecting fish yield and profit in fish pen culture in flooded ricefields     

Nam Cao Quoc  Nico Vromant  Duong Le Thanh  Frans Ollevier 《Aquaculture International》2012,20(5):827-845

In recent years, a rotational system consisting of two rice crops followed by a fish pen culture during the monsoon flood period was adopted in parts of the flood-prone region of the Mekong Delta. In this paper, we use the survey data from 51 fish pen farmers at Co Do and Vinh Thanh district, Can Tho City, to investigate the factors affecting fish yield and profit in such fish pen culture system. The net yield of all stocked fish varies from 377 to 3,782?kg/ha/crop while the return above variable costs varies from ?5.3 to 9.8 million VND/ha/crop. Low fish price at harvest and the difficulty to sell below market sized fish at a period of oversupply are the main problems for fish pen culture. Fish net yield significantly increases with stocking density and is linked with specific polycultures. Common carp and bighead carp perform best in fish pen culture, both in production and profit considerations. Harvest body mass of common carp is mainly limited by increasing common carp stocking density. Therefore, a stocking density of common carp of about 6,000 fish/ha is recommended to obtain the optimum combination of reasonable body masses, and a good price, as well as a high return above fingerling costs.  相似文献   

Species-specific and generic biomass equations for seedlings and saplings of European tree species     

Peter Annighöfer  Aitor Ameztegui  Christian Ammer  Philippe Balandier  Norbert Bartsch  Andreas Bolte  Lluís Coll  Catherine Collet  Jörg Ewald  Nico Frischbier  Tsegay Gebereyesus  Josephine Haase  Tobias Hamm  Bastian Hirschfelder  Franka Huth  Gerald Kändler  Anja Kahl  Heike Kawaletz  Christian Kuehne  André Lacointe  Na Lin  Magnus Löf  Philippe Malagoli  André Marquier  Sandra Müller  Susanne Promberger  Damien Provendier  Heinz Röhle  Jate Sathornkich  Peter Schall  Michael Scherer-Lorenzen  Jens Schröder  Carolin Seele  Johannes Weidig  Christian Wirth  Heino Wolf  Jörg Wollmerstädt  Martina Mund 《European Journal of Forest Research》2016,135(2):313-329

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Initial Carbon Storage in New Tephra Layers of Mt. Talang in Sumatra as Affected by Pioneer Plants     

Dian Fiantis  Malik Nelson  Jusop Shamshuddin  Tee Boon Goh  Eric Van Ranst 《Communications in Soil Science and Plant Analysis》2016,47(15):1792-1812

To date, no global data on carbon sequestration at the initial weathering phase of tephra deposits are available. To study carbon storage in the new volcanic deposit, tephra layers were reconstructed for a period of 46 months. The tephra samples were collected immediately after eruption of Mount (Mt.) Talang on 12 April 2005, over portions of the Solok District in West Sumatra, Indonesia. Pot experiments were filled with and without soil materials and covered with the collected tephra. The pot experiments were conducted in a wired house. The tephra was applied in 0, 2.5 and 5 cm depths to simulate natural tephra deposition. Every day 250 ml of filtered water was added and allowed to percolate. Solid fraction from the tephra layer was collected and analyzed at regular intervals and primary plant succession was observed over a period of 4 years. After 2 months, blue-green algae (cyanobacteria) started to colonize the bare surface tephra layer to form an algae mat. After 16 months, the surface was transformed into a green biofilm of lichen. Vascular plants (grasses and shrubs) started to be established after 2 years. Total carbon (TC) content of the tephra layer was increased significantly from 0.19 to 1.75% or eight times higher after 46 months of incubation. Higher TC storage was found in the 2.5 cm compared to that of the 5.0 cm tephra layer, which was reconstructed above the soil, with values of 1.75 and 0.89%, respectively. On the contrary, lesser amount of TC was accumulated in the single tephra layer (without soil underneath). Between 71 and 90% of TC was considered as total organic carbon (TOC). The labile organic carbon (LOC) content in the 2.5 cm and 5.0 cm of tephra layer was found to be 0.22 and 0.77%, respectively, at the end of incubation. This experiment confirmed the potential of tephra to capture carbon from the atmosphere with the help of nonvascular plants and then by vascular plants and finally sink them in the tephra layer.  相似文献   

Increased risk of BVDV infection of calves from pregnant dams on communal Alpine pastures in Switzerland     

Siegwart N  Hilbe M  Hässig M  Braun U 《Veterinary journal (London, England : 1997)》2006,172(2):386-388

Skin biopsies and blood samples from 117 calves, the offspring of dams that had been pastured on communal Alpine pastures while pregnant, were examined for bovine viral diarrhoea virus (BVDV) antigen. Immunohistochemical evaluation of skin biopsy samples revealed BVDV antigen in nine (7.7%) calves, and ELISA testing of serum samples was positive for BVDV antigen in six (5.1%). Three calves with positive skin biopsy samples and negative serum results were < 11 days old; it was assumed that maternal antibody interfered with the ELISA testing. Serum samples that were collected at a later date from two of the three calves were positive for BVDV antigen. These results were significantly different from those of a previous study in which the prevalence of persistently infected calves in an average Swiss cattle population was 0.64%. It was concluded that the risk of infection with BVDV is high in cattle sharing a communal Alpine pasture.  相似文献   

Accountability of experts in the Danish national park process     

Dorthe H. Lund  Tove Enggrob Boon  Iben Nathan 《Forest Policy and Economics》2009,11(5-6):437-445

In 2002 the Danish Minister of Environment initiated a process to investigate the possibilities of establishing national parks in Denmark. For this purpose experts were mobilised to investigate the status and potentials of the areas in question.The national park process was extensive in scope and complex, and in theory such complexity is assumed to make it difficult for non-experts to understand all the relevant aspects of policy. This exclusion of non-experts may lead to scientification of politics. Furthermore politicisation of science might occur as experts might advocate political interests disguised as objective science, and policy-makers might select results that further their own interests. As a result policy-makers risk losing a source of legitimacy, scientists risk losing credibility and the citizens risk losing the possibility to hold policy-makers accountable for their decisions, which puts democracy at risk.This paper examines the accountability relationships that experts were a part of in the national park process. These include accountability towards the employer, towards the buyer and towards the general public. The purpose is to determine if these relationships were adequate to circumvent the problems associated with scientification of politics and to discuss how accountability relationships and thereby democracy could be strengthened.The empirical analysis shows that in the national park process experts were mainly accountable towards the National Forest and Nature Agency. There were formal accountability relationships between the experts and the local steering committees and the national advisory group, but these relationships were less significant. Moreover, despite the fact that the process was deemed unusually open to the public by the participants, the relationship between experts and the public cannot be characterised as an accountability relationship and could have been improved by including experts in the deliberative fora of the process.  相似文献   

Decoupling from international food safety standards: how small-scale indigenous farmers cope with conflicting institutions to ensure market participation     

Geovana Mercado  Carsten Nico Hjortsø  Benson Honig 《Agriculture and Human Values》2018,35(3):651-669

Although inclusion in formal value chains extends the prospect of improving the livelihoods of rural small-scale producers, such a step is often contingent on compliance with internationally-promoted food safety standards. Limited research has addressed the challenges this represents for small rural producers who, grounded in culturally-embedded food safety conceptions, face difficulties in complying. We address this gap here through a multiple case study involving four public school feeding programs that source meals from local rural providers in the Bolivian Altiplan. Institutional logics theory is used to describe public food safety regulations and to compare them to food safety conceptions in the local indigenous Aymara rural setting. We identify a value-based conflict that leads to non-compliance of formal food safety rules that jeopardizes the participation of small farmers in the market. These include: (1) partial adoption of formal rules; (2) selective adoption of convenient rules; and (3) ceremonial adoption to avoid compliance. Decoupling strategies allow local actors to largely disregard the formal food safety regulations while accommodating traditional cultural practices and continuing to access the market. However, these practices put the long-term sustainability of the farmers’ participation in potentially favorable opportunities at risk.  相似文献