Any portal in a storm : factors influencing Internet portal choice

Includes bibliographical references.This exploratory study examines issues surrounding the use of Internet portals, which are web sites or services that offer a broad array of resources and services such as e-mail, community forums, news, a search engine, and online shopping. In particular, this paper examines the reasons a person uses a portal, and the features that are commonly perceived to be important to users. The author designed a survey to determine what attracts Internet users to portals and what factors they consider when making portal choices in continuing to use them. Analysis of the research results indicate that most significantly, particular features are in general what initially attract portal use, and satisfaction with performance encourages continued use. These results are important to web site developers for determining what users desire, and to information systems and marketing research for emphasizing theories suggesting what attracts users to web sites. Portal users benefit from the probable improvements to portals made because of research that developers have found to apply to attract and keep users at their sites.B.S. (Bachelor of Science

Waltheriones and trypanosoma cruzi – elucidating potential mechanisms of action

Natural products, and phytochemicals in particular, constitute a huge potential for drug discovery and medical use against parasitic diseases. Novel drugs and safer and more efficacious treatment options are urgently needed to fight neglected tropical diseases such as Chagas disease, caused by Trypanosoma cruzi. So far, antichagasic drug discovery was marked by the lack of financial resources and restricted by low throughput. Research subsequently fell back on drug repurposing and target-based approaches, which did not translate to new drugs against Chagas disease. Understanding drug action and discovering potential mechanisms of action is vital in finding alternative, safe, and efficacious treatment options. Waltheriones are a group of natural compounds isolated from the plant Waltheria indica, a plant occurring in tropical and subtropical area. Their activity against T. cruzi observed in protozoan phenotypic screens and the high selectivity towards the parasitic cells make the waltheriones very attractive for research, potentially leading to a candidate drug or advancing the knowledge about a novel drug target in T. cruzi. In my Ph.D. thesis, I have investigated drug action of the waltheriones against T. cruzi by using cell biological and molecular approaches. Untargeted exposure metabolomics of extracellular epimastigote T. cruzi with waltherione revealed an accumulation of acylcarnitines, indicating an effect on fatty acid metabolism downstream of carnitine palmitoyltransferase 1 (CPT1). This finding was further investigated using isotopically labelled palmitate and NMR or mass spectrometry. This demonstrated that β-oxidation is functional in the vector form of T. cruzi. However, no effect of waltherione on β-oxidation or TCA metabolites was observed. In vitro drug resistance selection was used as a starting point for finding possible mechanisms of resistance and possible mechanisms of action. Selecting for drug resistance in T. cruzi toward waltheriones proved to be difficult. Waltherione-resistant T. cruzi were generated and analysed with comparative transcriptomics revealing a candidate resistance mutation in a mitoribosomal protein. In conclusion, untargeted exposure metabolomics and comparative transcriptomics point to a mitochondrial involvement in waltherione drug action and a possible drug resistance mechanism. Stage-specific waltherione sensitivity profiles in different protozoan parasites further consolidate the hypothesis that the mode of action of waltheriones against T. cruzi involves interference with mitochondrial metabolism

Prompting meaningful analysis from pre-service teachers using elementary mathematics video vignettes

Learning from video vignettes is a theoretically grounded and popular professional development activity. In online professional development communities, however, responses to video are often shallow and lack meaningful commentary about the issues that surround teaching and learning mathematics. Given the lack of apparent involvement with the video content in online commentaries, this investigation examined whether more deeply analytical comments could be elicited from pre-service teachers in response to video clips posted to the Everyday Mathematics Virtual Learning Community (VLC). By altering the framing conditions that accompany video clips on the VLC, this experiment tested whether differences in prompts caused variations in pre-service teachers' depth of commentary. Findings highlight the malleability of pre-service teachers' commentary, as responses were more analytical when asked to focus on the teacher portrayed in the video; when asked to focus on students' understanding, contrary to expectations, pre-service teachers' responses tended to be descriptive. Yet these descriptions were not simple, but rich and detailed. This may be a fundamental precursor to analysis of student thinking—and perhaps an appropriate first step for novice or pre-service teachers

Phylogeny and Trichome Evolution in the Plant Family Brassicaceae

The plant family Brassicaceae is economically important and contains the model genetic system Arabidopsis thaliana. Previous phylogenetic studies indicated that the historic classification system of the family was highly artificial, with several tribes likely to be para- or polyphyletic. However, these studies sampled fewer than 30 of the 338 genera of the family. We expanded the sampling of genera by four-fold and inferred phylogeny from both the chloroplast gene ndhF and the nuclear gene phytochrome A (PHYA) to determine which of the previously delimited 19 tribes of the family were monophyletic. Results from both ndhF and PHYA confirmed that the majority of Brassicaceae tribes were para- or polyphyletic. Thus, monophyletic clades from the ndhF phylogeny were used to produce a new tribal classification of the family to replace the previous, highly artificial system. PHYA phylogenetic analyses confirmed the likely monophyly of most of these new tribes. In addition, both markers retrieve phylogenies with three major clades (lineages I-III), each of which is comprised of several of the newly erected tribes. Lineages I-III are the only statistically supported nodes in phylogenies of Brassicaceae beyond the tribal level, and thus are the best hypotheses of relationships deeper in the history of the family. Phylogenetic results and SEM (scanning electron microscopy) were also used to test scenarios of trichome (epidermal hair) evolution. Brassicaceae trichomes consist of a single cell and achieve intricate, highly branched morphologies that are characterized as dendritic, medifixed, or stellate; some species produce unbranched, simple trichomes. Results from ndhF, PHYA and SEM indicate that dendritic and medifixed trichomes evolved numerous times in the history of the family, while stellate trichomes may have a single origin. Finally, we applied findings from trichome developmental studies in Arabidopsis thaliana to other trichome producing species across the family by assaying a marker of early trichome development to explore the homology of Brassicaceae trichomes with different morphologies. Results from this study indicate that differences in the number of trichome branches in Brassicaceae likely results from the action of genes associated with the cytoskeleton rather than ones active in the cell cycle

Charakterisierung einer bakteriellen Gemeinschaft aus dem Süßwasser mit dem Schwerpunkt auf dem horizontalen Gentransfer durch Konjugation und Transduktion

Beilstein F. Charakterisierung einer bakteriellen Gemeinschaft aus dem Süßwasser mit dem Schwerpunkt auf dem horizontalen Gentransfer durch Konjugation und Transduktion. Bielefeld (Germany): Bielefeld University; 2005.Innerhalb dieser Arbeit wurde aus den drei Bielefelder Teichen im Oetkerpark, am Schlosshof und am Meierteich eine bakterielle Gemeinschaft isoliert und charakterisiert. Von 848 verschiedenen Isolaten konnten 367 Bakterienstämme durch Vergleiche ihrer Gesamtproteinmuster und anschließender Sequenzanalyse ihrer 16S-rDNA 14 verschiedenen Bakteriengattungen zugeordnet werden. Die abundantesten Gattungen sind hierbei Pseudomonas und Aeromonas. Kleinere Gruppen konnten den Gattungen Flexibacter, Flavobacterium, Bacillus, Arthrobacter, Escherichia, Hydrogenophaga, Brevundimonas, Shigella, Chromobacterium, Streptomyces, Pantoea und Rahnella zugeordnet werden. Unter 600 auf ihren Plasmidgehalt untersuchten Bakterienstämmen wurden 75 plasmidhaltige detektiert, was einem Plasmidgehalt von 12.5 Prozent entspricht. Besonders auffällig erwies sich hierbei die mit 12 Isolaten zahlenmäßig sehr kleine E. coli-Gruppe. Alle Isolate dieser Art sind ausnahmslos plasmidhaltig und beinhalten bis zu 11 verschiedene Plasmide. Ein Großteil dieser Plasmide ist kleiner als 4 kb und aufgrund fehlender Funktion als cryptisch zu bezeichnen. Die durchgeführten Antibiotika- und Schwermetallresistenztests ergaben keine Hinweise auf plasmidkodierte Resistenzen. Die isolierten Plasmide entsprechen größtenteils nicht den bisher bekannten Inkompatibilitätsgruppen, welche unter Verwendung klinischer Plasmide erstellt wurden. Lediglich zwei Plasmide aus den E. coli-Isolaten konnten den Inkompatibilitätsgruppen IncY und IncI zugeordnet werden. Mit Mobilisierungsexperimenten wurde einerseits der Transfer des Plasmides pSunny durch endogene Plasmide der Isolate aus dem Süßwasser oder andererseits der Transfer des Plasmides selbst analysiert. Von insgesamt 25 untersuchten Isolaten (der Bakteriengattungen Aeromonas, Pseudomonas, Rahnella, Escherichia sowie nicht näher bestimmten Gattungen) oder Plasmiden waren 15 in der Lage, pSunny zu mobilisieren oder selbst mobilisiert zu werden. Insgesamt betrachtet sind 60 Prozent aller untersuchten Plasmide mobilisierbar oder können pSunny mobilisieren und sind daraus folgend potentiell konjugativ. Sieben Plasmide konnten mit Hilfe eines in vitro Transposonmutagenesesystems mit einem Kanamycinresistenzgen markiert werden. Vier dieser Plasmide kamen allerdings aufgrund ihrer zu geringen Größe für eine selbstständige Konjugation nicht in Frage. Für die übrigen drei transposonmarkierten Plasmide aus den Gruppen Aeromonas (pO50), Rahnella (pO60) und E. coli (pM101.7) konnte ein konjugativer Transfer gezeigt werden. Bei dem Plasmid pM101.7 handelt es sich um ein broad host range Plasmid, für das ein Transfer innerhalb verschiedener Proteobakteriengruppen gezeigt werden konnte. Die Genorganisation der Tral- und Trall-Region von pM101.7 zeigt Homologien zu der des Plasmides pBi1063 aus Stenotrophomonas maltophilia. Die Sequenzierung des kleinsten cryptischen Plasmides des E. coli-Isolates pM101 ergab, dass dieses 1832 kb große Plasmid nur für sein eigenes Rep-Protein kodiert. Aus Wasserproben der beschriebenen Teiche sowie anliegender Gewässer konnten 39 Bakteriophagen für Wirte der Gattungen Aeromonas, Brevundimonas, Escherichia, Pseudomonas, Arthrobacter sowie nicht näher spezifizierten Gattungen isoliert werden. Durch UV-Induktion wurden aus zwei Aeromonas Isolaten sowie aus zwei E. coli Isolaten je ein Prophage induziert. Mittels Elektronenmikroskopie konnten 19 Bakteriophagen der Ordnung der Caudalovirales zugeordnet werden. Hiervon entfallen auf die Familie der Siphoviridae 42 Prozent, auf die Familie der Podoviridae 32 Prozent und 26 Prozent aller Phagen konnten der Familie der Myoviridae zugeordnet werden. Alle Phagen enthalten lineare DNA. Die DNA-Größe von 31 Bakteriophagen wurde durch Pulsfeldgelelektrophorese bestimmt und liegt zwischen 27 kb (Aeromonas [Phi]18P) und 180 kb (Aeromonas [Phi]O238), wobei die meisten DNAs in ihrer Größe ungefähr der von [lambda] entsprechen. Bei fünf der untersuchten Bakteriophagen-DNAs konnten kohäsive Enden detektiert werden. Durch [lambda]-Exonuklease Verdau konnten bei weiteren 16 Phagen-DNAs terminal redundante Endstrukturen nachgewiesen werden. Die DNAs von vier dieser Phagen, der Gattungen Aeromonas ([Phi]S32D), Escherichia ([Phi]M101.11 und [Phi]O221.15) sowie Arthrobacter ([Phi]O262), sind zusätzlich zyklisch permutiert. Die sieben Bakteriophagen der Brevundimonas vesicularis Gruppe wurden nach morphologischen und molekularbiologischen Charakteristika eingehender untersucht und in zwei Gruppen eingeteilt. Die erste Gruppe enthält drei genetisch sehr eng miteinander verwandte Phagen. Die zweite Gruppe beinhaltet drei Phagen, die genetisch sehr unterschiedlich sind, aber gleiche Plaque- und Partikelmorphologie zeigen. 17 Bakteriophagen wurden auf die Fähigkeit zur Transduktion von Plasmiden getestet. Es konnte hierbei für fünf Phagen mit Wirten aus den Gruppen E. coli und Pseudomonas eine Transduktion des Plasmides pSunny gezeigt werden. Die Transduktion des Kanamycin-Markergens aphA2 wurde für zwölf Phagen getestet. Hierbei konnte gezeigt werden, dass alle Bakteriophagen, die Plasmide transduzieren können, auch in der Lage sind, das verwendete Markergen weiterzugeben

Postcraniotomy Headache: Etiologies and Treatments.

PURPOSE OF REVIEW Postcraniotomy headache (PCH) is a highly underappreciated and very common adverse event following craniotomy. RECENT FINDINGS Analgetic medication with opioids often interferes with neurologic evaluation in the acute phase of recovery and should be kept to a minimal, in general, in the treatment of chronic pain as well. We provide an update on the latest evidence for the management of acute and chronic PCH. Especially in the neurosurgical setting, enhanced recovery after surgery protocols need to include a special focus on pain control. Patients at risk of developing chronic pain must be identified and treated as early as possible

What Maximum Ankle Torque is Appropriate for Training Patients with Non-insertional Achilles Tendinopathy?

Background and Purpose: The capacity of the Achilles tendon during a 1-repetition eccentric maximum contraction is largely unknown. This study examined the maximum ankle torque during a concentric/ eccentric heel raise/lowering task and while running in healthy individuals and participants with chronic Achilles tendinopathy. These findings were applied to a 10-week training program for a patient with chronic Achilles tendinopathy. Methods: A total of 13 subjects (9 healthy and 4 with Achilles tendinopathy) participated in this study. Subjects were asked to perform a maximum eccentric contraction wearing a weighted vest while collecting 3-dimensional biomechanical variables. Subjects also ran along an instrumented runway to assess torque at the ankle joint. All participants completed VISA-A Outcomes: On the VISA-A, subjects with Achilles tendinopathy (AT) scored on average 28 points less than the healthy controls and were 27% weaker. The peak ankle torque during a single leg lowering task and running was 3.1 Nm/kg and appeared similar between controls and participants with chronic AT. Findings of the study when applied in a 10-week high load eccentric rehabilitation program demonstrated improved tendon characteristics and VISA-A score. Conclusion: Unhealthy tendons likely can tolerate high loads during rehabilitation and AT programs should consist of progressive resistive exercises instead of movements that emphasize repetitions

Supporting children’s conceptual understanding of fractions with manipulatives and gesture

Fractions—their concepts, procedures, and symbolic notation—are well-known for the difficulty they present children, beginning in elementary school, and often, persisting long after. However, promoting children’s development of flexible and robust conceptual knowledge in this content area is critical for their success both in and out of school. The overarching goal of this project is to investigate the tools that support elementary school-aged children’s fraction learning by focusing on two different, yet related areas in cognitive science: physical action on objects (i.e., working with concrete manipulatives) and gesture. The first study identifies the specific mental models about fractions children develop and express through their speech and gesture. The second paper presents a comparative case study that examines how two children’s coordination of speech, gesture, and manipulatives reveals their fraction knowledge. By honing in on how children use gesture and/or manipulatives at times to their advantage and, at others, to their disadvantage, these two studies explore children’s existing knowledge to understand the nature of their fraction concepts, and ultimately, to inform the design of educational interventions that foster learning. The third, and final, study experimentally tests how variations in tools across an instructional intervention affect children’s learning of fraction notation and magnitude estimation. Preliminary results suggest that three of the four conditions—a gesture-based lesson, a manipulatives and gesture-based lesson, as well as a pencil and paper-based control, but not the manipulative-based lesson—led to learning gains from pre- to posttest on magnitude-estimation problems. None of the conditions, however, were successful at promoting transfer to problems, which included area-model estimation and fraction-magnitude comparison, beyond the intervention’s purview. Taken together, these three studies lend further insight into the affordances and constraints of using manipulatives and gesture to support the development of flexible and generalizable mathematics knowledge, concentrating specifically on a topic that challenges children as well as adults—fractions