Seasonal changes in burrow geometry of the common mole rat (Rodentia: Bathyergidae)

Sociality in mole rats has been suggested to have evolved as a response to the widely dispersed food resources and the limited burrowing opportunities that result from sporadic rainfall events. In the most arid regions, individual foraging efficiency is reduced, and energetic constraints increase. In this study, we investigate seasonal differences in burrow architecture of the social Cryptomys hottentotus hottentotus in a mesic region. We describe burrow geometry in response to seasonal weather conditions for two seasons (wet and dry). Interactions occurred between seasons and colony size for the size of the burrow systems, but not the shape of the burrow systems. The fractal dimension values of the burrow systems did not differ between seasons. Thus, the burrow complexity was dependent upon the number of mole rats present in the social group.     

氨对垃圾焚烧飞灰浸出特性的影响及地球化学模拟

垃圾焚烧飞灰可能因为选择性非催化还原法(SNCR)脱硝过程中氨泄漏、垃圾携带的渗滤液受热挥发等原因而吸附氨.本研究中采用人为添加氨水,在pH为3.66～12.44范围内,研究氨对飞灰中溶解性有机碳(DOC)和重金属浸出的影响,并利用地球化学模拟软件Visual MINTEQ从金属化学形态分布上分析氨对飞灰浸出的影响机制.结果表明,DOC在pH>9和有高浓度氨(≥1 357 mg·L-1)存在时,其浸出量大幅增加,而在浸出液中氨的水平不高于537 mg·L-1时则受氨的影响很小;在pH<6时,飞灰中各金属主要以自由态的金属离子和金属-氯络离子形态大量溶出,且受氨的影响较小;而在pH为8～12的碱性环境中和氨浓度较高时(≥3 253 mg·L-1),氨与金属生成了可溶性的金属-氨配合物,能显著增加Cd、Cu、Ni、Zn的浸出,且在pH=9附近时浸出量达到最大值,但氨对Al和Pb的浸出影响甚微;在pH>12时,Cd、Cu、Ni、Zn主要以羟基金属离子形式存在.在氨浓度为3 253 mg·L-1时,通过利用Visual MINTEQ模拟浸出值与试验数据的对比,发现Al、Pb、Zn的浸出主要由溶解/沉淀模型控制,而Cd、Cu、Ni由溶解/沉淀模型和表面吸附反应模型同时控制,且Visual MINTEQ模型能较好地预测飞灰中Al、Cu、Pb、Zn的浸出特性.     

Resistance mash welding for joining of copper conductors for electric motors

The automotive industry is developing designs and manufacturing processes for a new generation of electric motors intended for use in hybrid and electric vehicles. This paper is focused on using solid-state welding to join rectangular wires in the fabrication of motor stators. Resistance welding has not typically been applied to copper due to its very high electrical conductivity; however through optimization of the current and pressure profiles, excellent quality copper-to-copper joints have been demonstrated with a technique known as resistance mash welding. A better understanding of resistance mash welding characteristics will help advancements in its application for stators. The limitations of this application will be discussed.     

Detection of Viruses in Coastal Seawater Using <Emphasis Type="Italic">Mytilus Galloprovincialis</Emphasis> as an Accumulation Matrix

The purpose of this study was to demonstrate that shellfish can be used to detect enteric viruses in marine waters where they are present at very low concentrations. Aqua-cultured mussels were placed in the sea just off the mouth of a drainage channel affected by human and animal faecal contamination. Samples were taken from the channel, the sea and the mussels at intervals over two 4-week periods. The samples were tested to verify the presence of both rotaviruses and E. coli. Rotaviruses were detected by Real Time-PCR, typed by multiplex PCR and subsequently sequenced. E. coli was enumerated in water matrices by a filtering method and in mussels by the MPN method. The presence of E. coli in the examined matrices demonstrates contamination of faecal origin throughout the studied environments. Rotaviruses were recorded in channel waters, but not in sea water. In both experiments, rotaviruses were detected in mussels 21 and 28 days after being placed in the sea water off the channel mouth. The use of mussels thus enabled the detection of rotaviruses in waters where the high dilution rendered direct investigation impossible. This study indicates that mussels can be used in marine virological surveillance programs.     

Greenhouse gas mitigation and offset options for suckler cow farms: an economic comparison for the Swiss case

We assessed the economic suitability of 4 greenhouse gas (GHG) mitigation options and one GHG offset option for an improvement of the GHG balance of a representative Swiss suckler cow farm housing 35 Livestock units and cultivating 25 ha grassland. GHG emissions per kilogram meat in the economic optimum differ between the production systems and range from 18 to 21.9 kg CO₂-eq./kg meat. Only GHG offset by agroforestry systems showed the potential to significantly reduce these emissions. Depending on the production system agroforestry systems could reduce net GHG emissions by 66% to 7.3 kg CO₂-eq./kg meat in the most intensive system and by 100% in the most extensive system. In this calculation a carbon sequestration rate of 8 t CO₂/ha/year was assumed. The potential of a combination of the addition of lipids to the diet, a cover of the slurry tank and the application of nitrification inhibitors only had the potential to reduce GHG emissions by 12% thereby marginal abatement costs are increasing much faster than for agroforestry systems. A reduction of the GHG emissions to 7.5 kg CO₂-eq./kg meat—possible with agroforestry only—raised costs between 0.03 CHF/kg meat and 0.38 CHF/kg meat depending on the production system and the state of the system before the reduction. If GHG emissions were reduced maximally average costs ranged between 0.37 CHF/kg meat, if agroforestry had the potential to reduce net GHG emissions to 0 kg CO₂-eq., to 1.17 CHF/kg meat if also other options had to be applied.     

Population dynamics and regulation in the cave salamander <Emphasis Type="Italic">Speleomantes strinatii</Emphasis>

Time series analysis has been used to evaluate the mechanisms regulating population dynamics of mammals and insects, but has been rarely applied to amphibian populations. In this study, the influence of endogenous (density-dependent) and exogenous (density-independent) factors regulating population dynamics of the terrestrial plethodontid salamander Speleomantes strinatii was analysed by means of time series and multiple regression analyses. During the period 1993–2005, S. strinatii population abundance, estimated by a standardised temporary removal method, displayed relatively low fluctuations, and the autocorrelation function (ACF) analysis showed that the time series had a noncyclic structure. The partial rate correlation function (PRCF) indicated that a strong first-order negative feedback dominated the endogenous dynamics. Stepwise multiple regression analysis showed that the only climatic factor influencing population growth rate was the minimum winter temperature. Thus, at least during the study period, endogenous, density-dependent negative feedback was the main factor affecting the growth rate of the salamander population, whereas stochastic environmental variables, such as temperature and rainfall, seemed to play a minor role in regulation. These results stress the importance of considering both exogenous and endogenous factors when analysing amphibian long-term population dynamics.     

Body mass estimations for <Emphasis Type="Italic">Plateosaurus engelhardti</Emphasis> using laser scanning and 3D reconstruction methods

Both body mass and surface area are factors determining the essence of any living organism. This should also hold true for an extinct organism such as a dinosaur. The present report discusses the use of a new 3D laser scanner method to establish body masses and surface areas of an Asian elephant (Zoological Museum of Copenhagen, Denmark) and of Plateosaurus engelhardti, a prosauropod from the Upper Triassic, exhibited at the Paleontological Museum in Tübingen (Germany). This method was used to study the effect that slight changes in body shape had on body mass for P. engelhardti. It was established that body volumes varied between 0.79 m³ (slim version) and 1.14 m³ (robust version), resulting in a presumable body mass of 630 and 912 kg, respectively. The total body surface areas ranged between 8.8 and 10.2 m², of which, in both reconstructions of P. engelhardti, ∼33% account for the thorax area alone. The main difference between the two models is in the tail and hind limb reconstruction. The tail of the slim version has a surface area of 1.98 m², whereas that of the robust version has a surface area of 2.73 m². The body volumes calculated for the slim version were as follows: head 0.006 m³, neck 0.016 m³, fore limbs 0.020 m³, hind limbs 0.08 m³, thoracic cavity 0.533 m³, and tail 0.136 m³. For the robust model, the following volumes were established: 0.01 m³ head, neck 0.026 m³, fore limbs 0.025 m³, hind limbs 0.18 m³, thoracic cavity 0.616 m³, and finally, tail 0.28 m³. Based on these body volumes, scaling equations were used to assess the size that the organs of this extinct dinosaur have.     

Prenatal cannibalism in an insect

Host selection and infection strategies of parasitoids often correlate with high parental investment and low numbers of progeny. In this study, we investigate how additional internal mechanisms might shape brood size and fitness of the offspring. Emblemasoma auditrix is a parasitoid fly in which about 38 larvae hatch simultaneously in utero. After host location, a single larva is deposited into the host, where it rapidly develops and pupates after about 5 days. The search for hosts can take several weeks, and during that time, the larvae arrest their development and remain in the first larval instar. Nevertheless, the larvae increase in weight within the uterus, and this growth correlates to a decrease in the number of larvae, although no larvae are deposited. Thus, our data indicate a first case of prenatal cannibalism in an invertebrate with larvae feeding on each other within the uterus of the adult.     

First Castorid (Mammalia,Rodentia) from the Middle Miocene of Southeast Asia

Today and in the Tertiary, the geographical distribution of castorids is limited throughout all of the northern continents. Fossils of the Castoridae genus Steneofiber are abundant in many localities of Eurasia from the late Oligocene to Pliocene period. Recently, Steneofiber fossils were discovered in two localities of northern Thailand, Mae Moh and Chiang Muan coal mines, in layers of late middle Miocene age. These discoveries represent the first records of castorids from Southeast Asia and correspond to their southernmost known range. The focus of this study is to describe this new Thai species of Steneofiber and to define its wear stages from the molar occlusal surfaces by using micro-CT scan analysis. The CT scan technique permits the analysis of the virtual occlusal surface changes from wear, allowing easier comparison to related species of Steneofiber cheek teeth without destroying the teeth. The new species, Steneofiber siamensis n. sp., can be distinguished from the other species of Steneofiber by several distinct characters, longer mesostriid on p4, presence of premesostria and metastria on P4, which are smaller than most of the other known species. The occurrence of this new castorid also supports a subtropical to tropical paleoclimate for these two localities of northern Thailand.     

Direct evidence of hybodont shark predation on Late Jurassic ammonites

Sharks are known to have been ammonoid predators, as indicated by analysis of bite marks or coprolite contents. However, body fossil associations attesting to this predator–prey relationship have never been described so far. Here, I report a unique finding from the Late Jurassic of western France: a complete specimen of the Kimmeridgian ammonite Orthaspidoceras bearing one tooth of the hybodont shark Planohybodus. Some possible tooth puncture marks are also observed. This is the first direct evidence of such a trophic link between these two major Mesozoic groups, allowing an accurate identification of both organisms. Although Planohybodus displays a tearing-type dentition generally assumed to have been especially adapted for large unshelled prey, our discovery clearly shows that this shark was also able to attack robust ammonites such as aspidoceratids. The direct evidence presented here provides new insights into the Mesozoic marine ecosystem food webs.