Metacommunity Dynamics Of Benthic Macroinvertebrates In A Large River

Metacommunity ecology focuses on the interaction between local communities and is inherently linked to dispersal as a result. Within this framework, communities are structured by a combination of in-site responses to the immediate environment (species sorting), stochasticity (patch dynamics), and connections to other communities via distance between communities and dispersal (neutrality), and source-sink dynamics (mass effects; see Chapter 1 for a detailed description of metacommunity theory, the study site, and macroinvertebrate communities found). In Chapter 2 I describe spatial scale of study and dispersal ability as both have the ability to influence the degree to which communities interact. However, little is known about how these factors influence the importance of all metacommunity dynamics. I compared dispersal mode of immature aquatic insects and dispersal ability of winged adults across multiple spatial scales in a large river. The strongest drivers of river communities were patch dynamics, followed by species sorting, then neutrality. Active dispersers during aquatic lifestages on average exhibited lower patch dynamics, higher species sorting, and significant mass effects compared to passive dispersers. Active and strong dispersers also had a scale-independent influence of neutrality, while neutrality was stronger at broader spatial scale for passive and weak dispersers. These results indicate as dispersal ability increases patch dynamics decreases, species sorting increases, and neutrality should decrease. The perceived influence of neutrality may also be dependent on spatial scale and dispersal ability. In Chapter 3 I describe how river benthic macroinvertebrate communities may influence tributary invertebrate communities via adult flight and tributaries may influence mainstem communities via immature drift. This relationship may also depend on relative mainstem and tributary size, as well as abiotic tributary influence on mainstem habitat. To investigate the interaction between a larger river and tributary I sampled mainstem benthic invertebrate communities and quantified habitat of a 7th order river (West Branch Susquehanna River) above and below a 5th order tributary confluence, as well as 0.95-3.2 km upstream in the tributary. Non-metric multidimensional scaling showed similar patterns of clustering between sampling locations for both habitat characteristics and invertebrate communities. In addition, mainstem river communities and habitat directly downstream of the tributary confluence cluster tightly together, intermediate between tributary and mid-channel river samples. In Bray-Curtis dissimilarity comparisons between tributary and mainstem river communities the furthest upstream tributary communities were least similar to river communities. Middle tributary samples were also closest by Euclidean distance to the upstream mainstem riffle and exhibited higher similarity to mid-channel samples than the furthest downstream tributary communities. My results indicate river and tributary benthic invertebrate communities may interact and likely result in direct and indirect mass effects of a tributary on the downstream mainstem community by invertebrate drift and habitat restructuring via material delivery from the tributary. I also showed likely direct effects of adult dispersal from the river and oviposition in proximal tributary locations where Euclidian, rather than river, distance may be more important in determining river-tributary interactions.

Transmission dynamics of extended-spectrum β-lactamase-producing Enterobacteriaceae in the tertiary care hospital and the household setting

Studies about transmission rates of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in hospitals and households are scarce.

The Dynamics of the Policies of Ethnic Cleansing in Silesia in the Nineteenth and Twentieth Centuries

Through studying German, Polish and Czech publications on Silesia, Mr. Kamusella found that most of them, instead of trying to objectively analyse the past, are devoted to proving some essential "Germanness", "Polishness" or "Czechness" of this region. He believes that the terminology and thought-patterns of nationalist ideology are so deeply entrenched in the minds of researchers that they do not consider themselves nationalist. However, he notes that, due to the spread of the results of the latest studies on ethnicity/nationalism (by Gellner, Hobsbawm, Smith, Erikson Buillig, amongst others), German publications on Silesia have become quite objective since the 1980s, and the same process (impeded by under funding) has been taking place in Poland and the Czech Republic since 1989. His own research totals some 500 pages, in English, presented on disc. So what are the traps into which historians have been inclined to fall? There is a tendency for them to treat Silesia as an entity which has existed forever, though Mr. Kamusella points out that it emerged as a region only at the beginning of the 11th century. These same historians speak of Poles, Czechs and Germans in Silesia, though Mr. Kamusella found that before the mid-19th century, identification was with an inhabitant's local area, religion or dynasty. In fact, a German national identity started to be forged in Prussian Silesia only during the Liberation War against Napoleon (1813-1815). It was concretised in 1861 in the form of the first Prussian census, when the language a citizen spoke was equated with his/her nationality. A similar census was carried out in Austrian Silesia only in 1881. The censuses forced the Silesians to choose their nationality despite their multiethnic multicultural identities. It was the active promotion of a German identity in Prussian Silesia, and Vienna's uneasy acceptance of the national identities in Austrian Silesia which stimulated the development of Polish national, Moravian ethnic and Upper Silesian ethnic regional identities in Upper Silesia, and Polish national, Czech national, Moravian ethnic and Silesian ethnic identities in Austrian Silesia. While traditional historians speak of the "nationalist struggle" as though it were a permanent characteristic of Silesia, Mr. Kamusella points out that such a struggle only developed in earnest after 1918. What is more, he shows how it has been conveniently forgotten that, besides the national players, there were also significant ethnic movements of Moravians, Upper Silesians, Silesians and the tutejsi (i.e. those who still chose to identify with their locality). At this point Mr. Kamusella moves into the area of linguistics. While traditionally historians have spoken of the conflicts between the three national languages (German, Polish and Czech), Mr Kamusella reminds us that the standardised forms of these languages, which we choose to dub "national", were developed only in the mid-18th century, after 1869 (when Polish became the official language in Galicia), and after the 1870s (when Czech became the official language in Bohemia). As for standard German, it was only widely promoted in Silesia from the mid 19th century onwards. In fact, the majority of the population of Prussian Upper Silesia and Austrian Silesia were bi- or even multilingual. What is more, the "Polish" and "Czech" Silesians spoke were not the standard languages we know today, but a continuum of West-Slavic dialects in the countryside and a continuum of West-Slavic/German creoles in the urbanised areas. Such was the linguistic confusion that, from time to time, some ethnic/regional and Church activists strove to create a distinctive Upper Silesian/Silesian language on the basis of these dialects/creoles, but their efforts were thwarted by the staunch promotion of standard German, and after 1918, of standard Polish and Czech. Still on the subject of language, Mr. Kamusella draws attention to a problem around the issue of place names and personal names. Polish historians use current Polish versions of the Silesian place names, Czechs use current Polish/Czech versions of the place names, and Germans use the German versions which were in use in Silesia up to 1945. Mr. Kamusella attempted to avoid this, as he sees it, nationalist tendency, by using an appropriate version of a place name for a given period and providing its modern counterpart in parentheses. In the case of modern place names he gives the German version in parentheses. As for the name of historical figures, he strove to use the name entered on the birth certificate of the person involved, and by doing so avoid such confusion as, for instance, surrounds the Austrian Silesian pastor L.J. Sherschnik, who in German became Scherschnick, in Polish, Szersznik, and in Czech, Sersnik. Indeed, the prospective Silesian scholar should, Mr. Kamusella suggests, as well as the three languages directly involved in the area itself, know English and French, since many documents and books on the subject have been published in these languages, and even Latin, when dealing in depth with the period before the mid-19th century. Mr. Kamusella divides the policies of ethnic cleansing into two categories. The first he classifies as soft, meaning that policy is confined to the educational system, army, civil service and the church, and the aim is that everyone learn the language of the dominant group. The second is the group of hard policies, which amount to what is popularly labelled as ethnic cleansing. This category of policy aims at the total assimilation and/or physical liquidation of the non-dominant groups non-congruent with the ideal of homogeneity of a given nation-state. Mr. Kamusella found that soft policies were consciously and systematically employed by Prussia/Germany in Prussian Silesia from the 1860s to 1918, whereas in Austrian Silesia, Vienna quite inconsistently dabbled in them from the 1880s to 1917. In the inter-war period, the emergence of the nation-states of Poland and Czechoslovakia led to full employment of the soft policies and partial employment of the hard ones (curbed by the League of Nations minorities protection system) in Czechoslovakian Silesia, German Upper Silesia and the Polish parts of Upper and Austrian Silesia. In 1939-1945, Berlin started consistently using all the "hard" methods to homogenise Polish and Czechoslovakian Silesia which fell, in their entirety, within the Reich's borders. After World War II Czechoslovakia regained its prewar part of Silesia while Poland was given its prewar section plus almost the whole of the prewar German province. Subsequently, with the active involvement and support of the Soviet Union, Warsaw and Prague expelled the majority of Germans from Silesia in 1945-1948 (there were also instances of the Poles expelling Upper Silesian Czechs/Moravians, and of the Czechs expelling Czech Silesian Poles/pro-Polish Silesians). During the period of communist rule, the same two countries carried out a thorough Polonisation and Czechisation of Silesia, submerging this region into a new, non-historically based administrative division. Democratisation in the wake of the fall of communism, and a gradual retreat from the nationalist ideal of the homogeneous nation-state with a view to possible membership of the European Union, caused the abolition of the "hard" policies and phasing out of the "soft" ones. Consequently, limited revivals of various ethnic/national minorities have been observed in Czech and Polish Silesia, whereas Silesian regionalism has become popular in the westernmost part of Silesia which remained part of Germany. Mr. Kamusella believes it is possible that, with the overcoming of the nation-state discourse in European politics, when the expression of multiethnicity and multilingualism has become the cause of the day in Silesia, regionalism will hold sway in this region, uniting its ethnically/nationally variegated population in accordance with the principle of subsidiarity championed by the European Union.

Photodissociation dynamics of tert-butylnitrite following excitation to the S(1) and S(2) states. A study by velocity-map ion-imaging and 3D-REMPI spectroscopy

Excitation of tert-butylnitrite into the first and second UV absorption bands leads to efficient dissociation into the fragment radicals NO and tert-butoxy in their electronic ground states (2)Π and (2)E, respectively. Velocity distributions and angular anisotropies for the NO fragment in several hundred rotational and vibrational quantum states were obtained by velocity-map imaging and the recently developed 3D-REMPI method. Excitation into the well resolved vibronic progression bands (k = 0, 1, 2) of the NO stretch mode in the S(1) ← S(0) transition produces NO fragments mostly in the vibrational state with v = k, with smaller fractions in v = k - 1 and v = k - 2. It is concluded that dissociation occurs on the purely repulsive PES of S(1) without barrier. All velocity distributions from photolysis via the S(1)(nπ*) state are monomodal and show high negative anisotropy (β ≈ -1). The rotational distributions peak near j = 30.5 irrespective of the vibronic state S(1)(k) excited and the vibrational state v of the NO fragment. On average 46% of the excess energy is converted to kinetic energy, 23% and 31% remain as internal energy in the NO fragment and the t-BuO radical, respectively. Photolysis via excitation into the S(2) ← S(0) transition at 227 nm yields NO fragments with about equal populations in v = 0 and v = 1. The rotational distributions have a single maximum near j = 59.5. The velocity distributions are monomodal with positive anisotropy β ≈ 0.8. The average fractions of the excess energy distributed into translation, internal energy of NO, and internal energy of t-BuO are 39%, 23%, and 38%, respectively. In all cases ∼8500 cm(-1) of energy remain in the internal degrees of freedom of the t-BuO fragment. This is mostly assigned to rotational energy. An ab initio calculation of the dynamic reaction path shows that not only the NO fragment but also the t-BuO fragment gain large angular momentum during dissociation on the purely repulsive potential energy surface of S(2).

A novel computer simulation method for simulating the multiscale transduction dynamics of signal proteins

Signal proteins are able to adapt their response to a change in the environment, governing in this way a broad variety of important cellular processes in living systems. While conventional molecular-dynamics (MD) techniques can be used to explore the early signaling pathway of these protein systems at atomistic resolution, the high computational costs limit their usefulness for the elucidation of the multiscale transduction dynamics of most signaling processes, occurring on experimental timescales. To cope with the problem, we present in this paper a novel multiscale-modeling method, based on a combination of the kinetic Monte-Carlo- and MD-technique, and demonstrate its suitability for investigating the signaling behavior of the photoswitch light-oxygen-voltage-2-Jα domain from Avena Sativa (AsLOV2-Jα) and an AsLOV2-Jα-regulated photoactivable Rac1-GTPase (PA-Rac1), recently employed to control the motility of cancer cells through light stimulus. More specifically, we show that their signaling pathways begin with a residual re-arrangement and subsequent H-bond formation of amino acids near to the flavin-mononucleotide chromophore, causing a coupling between β-strands and subsequent detachment of a peripheral α-helix from the AsLOV2-domain. In the case of the PA-Rac1 system we find that this latter process induces the release of the AsLOV2-inhibitor from the switchII-activation site of the GTPase, enabling signal activation through effector-protein binding. These applications demonstrate that our approach reliably reproduces the signaling pathways of complex signal proteins, ranging from nanoseconds up to seconds at affordable computational costs.

Dynamics of Shifting Cultivation Landscapes in Northern Lao PDR Between 2000 and 2009 Based on an Analysis of MODIS Time Series and Landsat Images

The rotational nature of shifting cultivation poses several challenges to its detection by remote sensing. Consequently, there is a lack of spatial data on the dynamics of shifting cultivation landscapes on a regional, i.e. sub-national, or national level. We present an approach based on a time series of Landsat and MODIS data and landscape metrics to delineate the dynamics of shifting cultivation landscapes. Our results reveal that shifting cultivation is a land use system still widely and dynamically utilized in northern Laos. While there is an overall reduction in the areas dominated by shifting cultivation, some regions also show an expansion. A review of relevant reports and articles indicates that policies tend to lead to a reduction while market forces can result in both expansion and reduction. For a better understanding of the different factors affecting shifting cultivation landscapes in Laos, further research should focus on spatially explicit analyses.

Measurement of charged-particle event shape variables in inclusive √(s)=7 TeV proton-proton interactions with the ATLAS detector

The measurement of charged-particle event shape variables is presented in inclusive inelastic pp collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the LHC. The observables studied are the transverse thrust, thrust minor, and transverse sphericity, each defined using the final-state charged particles' momentum components perpendicular to the beam direction. Events with at least six charged particles are selected by a minimum-bias trigger. In addition to the differential distributions, the evolution of each event shape variable as a function of the leading charged-particle transverse momentum, charged-particle multiplicity, and summed transverse momentum is presented. Predictions from several Monte Carlo models show significant deviations from data.

High-resolution computer simulation of the dynamics of isoelectric focusing using carrier ampholytes: focusing with concurrent electrophoretic mobilization is an isotachophoretic process

Focusing of four hemoglobins with concurrent electrophoretic mobilization was studied by computer simulation. A dynamic electrophoresis simulator was first used to provide a detailed description of focusing in a 100-carrier component, pH 6-8 gradient using phosphoric acid as anolyte and NaOH as catholyte. These results are compared to an identical simulation except that the catholyte contained both NaOH and NaCl. A stationary, steady-state distribution of carrier components and hemoglobins is produced in the first configuration. In the second, the chloride ion migrates into and through the separation space. It is shown that even under these conditions of chloride ion flux a pH gradient forms. All amphoteric species acquire a slight positive charge upon focusing and the whole pattern is mobilized towards the cathode. The cathodic gradient end is stable whereas the anodic end is gradually degrading due to the continuous accumulation of chloride. The data illustrate that the mobilization is a cationic isotachophoretic process with the sodium ion being the leading cation. The peak height of the hemoglobin zones decreases somewhat upon mobilization, but the zones retain a relatively sharp profile, thus facilitating detection. The electropherograms that would be produced by whole column imaging and by a single detector placed at different locations along the focusing column are presented and show that focusing can be commenced with NaCl present in the catholyte at the beginning of the experiment. However, this may require detector placement on the cathodic side of the catholyte/sample mixture interface.

Simulating the impact of four control strategies on the population dynamics of Neospora caninum infection in Swiss dairy cattle

A dynamic deterministic simulation model was developed to assess the impact of different putative control strategies on the seroprevalence of Neospora caninum in female Swiss dairy cattle. The model structure comprised compartments of "susceptible" and "infected" animals (SI-model) and the cattle population was divided into 12 age classes. A reference model (Model 1) was developed to simulate the current (status quo) situation (present seroprevalence in Switzerland 12%), taking into account available demographic and seroprevalence data of Switzerland. Model 1 was modified to represent four putative control strategies: testing and culling of seropositive animals (Model 2), discontinued breeding with offspring from seropositive cows (Model 3), chemotherapeutic treatment of calves from seropositive cows (Model 4), and vaccination of susceptible and infected animals (Model 5). Models 2-4 considered different sub-scenarios with regard to the frequency of diagnostic testing. Multivariable Monte Carlo sensitivity analysis was used to assess the impact of uncertainty in input parameters. A policy of annual testing and culling of all seropositive cattle in the population reduced the seroprevalence effectively and rapidly from 12% to <1% in the first year of simulation. The control strategies with discontinued breeding with offspring from all seropositive cows, chemotherapy of calves and vaccination of all cattle reduced the prevalence more slowly than culling but were still very effective (reduction of prevalence below 2% within 11, 23 and 3 years of simulation, respectively). However, sensitivity analyses revealed that the effectiveness of these strategies depended strongly on the quality of the input parameters used, such as the horizontal and vertical transmission factors, the sensitivity of the diagnostic test and the efficacy of medication and vaccination. Finally, all models confirmed that it was not possible to completely eradicate N. caninum as long as the horizontal transmission process was not interrupted.