Intellectual Property Paranoia and the Writing Center

The current atmosphere of numerous academic institutions is one of suspicion regarding intellectual ethical transgressions. Universities that have longstanding honor systems, like Southwestern University, dismiss this paranoia as being unrelated to their establishment because the honor code system protects them. The honor code incites additional thought regarding consultation methods in writing centers like Southwestern’s Debbie Ellis Writing Center (DEWC). One must question what Southwestern students are truly affirming when writing “I have neither given nor received aid on this examination, nor have I seen anyone else do so” on an assignment they have taken to the writing center (Southwestern University 58). Are they saying they did not benefit from their visit to the writing center, or are they merely affirming that they did not engage in unethical behavior? According to Stephen North, “Nearly everyone who writes likes–and needs–to talk about his or her writing…. A writing center is an institutional response to this need” (North 71). In addition to fulfilling the needs of the university’s writers by creating a place for discussions about writing, the writing center complicates the supposedly clear ethical and non-ethical dichotomy of the honor code system by being an institutionalized exception to that system. As an exception to the honor code system, the DEWC calls into question the viability of that system and the ideas of intellectual property that serve as its foundations.University Writing Cente

Raman cross section of spin ladders

We demonstrate that a two-triplet resonance strongly renormalizes the Raman spectrum of two-leg spin ladders and moreover suggest this to be the origin of the asymmetry of the magnetic Raman continuum observed in CaV2O5.Comment: 2 pages, 1 figur

Transferrin polymorphism of common carp: link with disease resistance

Iron is fundamental to the biology of eukaryotic cells since it plays a key role in many metabolic functions. Iron concentrations are tightly regulated, for example by ferritin, because excessive iron leads to tissue damage. Iron cannot cross cellular membranes directly and most cells acquire iron from the iron transporting protein transferrin (Tf), via transferrin receptors. During nutritional immunity the body reacts with a metabolic adjustment in order to render important nutrients unavailable to invading microorganisms. However, pathogens also have evolved a range of mechanisms to acquire iron from the host (chapter 1). In the study described in this thesis, we used a natural host-parasite model of common carp (Cyprinus carpio L.) infected with Trypanoplasma borreli, a protozoan kinetoplastid, extracellular blood parasite of carp to get more insight in the competition for iron between host and parasite. Transferrin of common carp is highly polymorphic with several alleles identified according to differences in electrophoretic mobility. We studied the implications of Tf polymorphisms for iron binding and modulation of immune function. We performed a series of challenge experiments infecting five genetically different, commercially exploited carp lines with T. borreli. Our results indicated that Tf genotype may influence the susceptibility to pathogens. We observed a significant association of the DD genotype of Tf with low parasitaemia in two resistant carp lines (Polish ‘R2’ and ‘K’), but a reverse association in the most susceptible carp line ‘D’ (chapter 2). We also showed that variation in resistance to T. borreli could be controlled by sex-related genetic factors. Examination of parasite growth in vitro, in culture media supplemented with 3% serum taken from fish with different Tf genotypes, showed a faster decrease in number of parasites in media supplemented with serum from DD-typed animals (chapter 2). In general, pathogens also have mechanisms to acquire iron from the host. We developed a method for Tf depletion of carp serum using specific antibodies to carp Tf, and compared T. borreli multiplication and survival in the presence or absence of Tf in vitro. Parasites were dying in medium containing Tf-depleted serum, which clearly showed that Tf is essential for parasite growth and multiplication (chapter 3). We isolated two allelic forms of carp Tf (alleles D and G) to purity using rivanol precipitation and ion-exchange chromatography (chapter 5). We showed that parasite growth in vitro could be reconstituted by the addition of purified Tf to Tf-depleted serum (chapter 3). We observed differences in T. borreli multiplication and survival in culture media containing different sera typed differently for Tf genotypes (chapter 3). We identified four complete coding sequences for common carp Tf alleles C, D, F and G, and confirmed the overall similarity of the carp Tf three-dimensional structure to Tfs of other species. We could show that carp Tf differs significantly in critical iron-binding sites in the N-lobe of the molecule, as compared to other non-cyprinid fish species (chapter 4). The substitution of a majority of the iron-coordinating residues in the Nlobe indeed seems to affect the ability to bind iron, which may be compensated for by higher serum concentrations of Tf (chapter 7). Comparison of constitutive gene expression of two Tf alleles D and G showed a comparably high gene expression level in liver and small but consistent differences in gene expression for allele D over allele G in other immunologically important organs (chapter 4). Our data suggest that the allelic polymorphism is not related to differences in iron binding and/or binding to the host Tf receptor but could be linked with other factors, such as competition for iron with pathogens (chapter 4). Transferrin itself may also exert effects that are not directly linked with maintaining iron levels and Tf cleavage products have been shown to stimulate macrophages to produce large amounts of nitric oxide (NO). To study the induction of NO in carp head kidney-derived macrophages, we isolated two allelic forms of carp Tf (alleles D and G) to purity and showed that the level of activation of macrophages by Tf was different for the D and G allele (chapter 5). Differences in NO levels induced could be related to different cleavage forms of the two alleles D and G, as shown by Western blot, confirming that full-length Tf cannot induce NO. The D-type Tf cleavage products induced significantly higher nitric oxide (NO) production than cleavage products of Gtype Tf. (chapter 5). Transferrin uptake by trypanosome parasites involves Tf binding to a receptor. The TfR-Tf complex then is internalised and transported to lysosomes, where Tf is proteolytically degraded. We described the cloning and sequencing of a cathepsin L-like cysteine proteinase from T. borreli and production of a recombinant and biologically active enzyme (chapter 6). We demonstrated that the T. borreli cysteine proteinase is able to digest host transferrin. Likely, Tf cleavage fragments are released from the trypanosomes while iron would remain parasite-associated, possibly contributing to thepathogenicity of the parasite by inducing high amounts of NO in carp macrophages (chapter 7). Our study dealt with different aspects of Tf polymorphism, discussing the role of Tf in immunity of common carp and the influence of allelic polymorphism on competition for iron between host and pathogen (chapter 7). Further investigations should shed more light on the selective advantage of particular alleles to provide a basis for incorporating Tf as a genetic marker in marker-assisted selection programmes for increased resistance to diseases. This could contribute to improved survival of carp kept under semiintensive farming systems in ponds. <br/

The Kondo lattice model from strong-coupling viewpoint

We present some preliminary results on the phase diagram of the 2D S=1/2 Kondo lattice model at finite doping. As a starting point the Hamiltonian is written in terms of local spin and charge excitations, and the interactions between these modes are subsequently treated in various perturbative schemes. We find that a paramagnetic-magnetic quantum phase transition does occur, and, at least on a superficial level, the Kondo effect does not break down at the critical point. The latter result however might well be a consequence of the inherent bias of our starting point and/or the level of approximation.Comment: 4 pages, to appear in the Proceedings of SCES 2001, Ann Arbor, August 200

The Activity of Lysosomal Enzymes in The Healthy Men’S Blood After Single Finnish Sauna Procedure – Preliminary Study

Introduction. The aim of the paper was to investigate the effect of single Finnish sauna procedure on the activity of acid phosphatase (AcP), cathepsin D (CTS D), arylsulfatase (ASA) and inhibitor of proteases α-1-antitrypsin (AAT) in healthy men’s blood. Materialandmethods. Men (n=7) performed sauna procedure (3 entries, each 10 min) in temperature of 90oC and relative air humidity of 10%. Men cooled their whole body (cold shower) after each exit from sauna. The blood was taken from basilic vein before the entry to sauna, 15 and 60 min after the procedure. Obtained results of activity of AcP, AAT and ASA were statistically analyzed by using ANOVA test. Statistically analysis of CTS D activity was performed by Mann-Whitney test. The changes of the level p0.05). The tendency was also observed when comparing the activity of AcP, ASA, CTS D and AAT 15 min after sauna to their activity before sauna (p>0.05). In turn, the activity of AAT and ASA insignificantly increased 60 min after Finnish sauna comparing to the activity measured 15 min after procedure (p>0.05). Conclusion. Single Finnish sauna procedure increases stabilization of lysosomal membranes.Wstęp. Celem pracy było zbadanie wpływu jednorazowego zabiegu sauny fińskiej na aktywność kwaśnej fosfatazy (AcP), arylosulfatazy (ASA), katepsyny D (CTS D) i inhibitora proteaz α-1-antytrypsyny (AAT) we krwi zdrowych mężczyzn. Materiał i metody. Mężczyzn (n=7) poddano działaniu sauny (3 wejścia, każde 10 min) w temperaturze 90oC i 10% względnej wilgotności powietrza. Po każdym wyjściu z sauny mężczyźni schładzali całe ciało pod zimnym prysznicem. Krew pobrano z żyły odłokciowej przed wejściem do sauny oraz 15 i 60 min po zabiegu. Uzyskane wyniki aktywności AcP, AAT i ASA poddano analizie statystycznej za pomocą testu ANOVA. Analizę statystyczną aktywności CTS D wykonano testem Manna-Whitneya. Zmiany na poziome p0,05). Tendencję do obniżenia obserwowano również porównując aktywność AcP, ASA, CTS D oraz AAT 15 min po saunie z ich aktywnością przed sauną (p>0,05). Aktywność AAT i ASA z kolei nieznacznie wzrosła 60 min po saunie fińskiej w porównaniu do aktywności zmierzonej 15 min po zabiegu (p>0,05). Wnioski.  Jednorazowy zabieg sauny fińskiej zwiększa stabilność błon lizosomalnych

Explaining Differential Item Functions with different testing cultures

Der Fokus der Dissertation liegt auf der Betrachtung von Items zur Messung von fremdsprachlichem Leseverständnis in verschiedenen europäischen Ländern. Insbesondere wird der Einfluss unterschiedlicher Testkulturen auf die internationale Vergleichbarkeit und Validität dieser Items analysiert. Haupthypothese der Arbeit ist, dass sich Differentielle Item Funktionen (DIF, z.B. Holland & Wainer, 1993), eine durch Gruppenzugehörigkeit verursachte Varianz der Itemschwierigkeit, durch unterschiedliche Profile von Stärken und Schwächen von Gruppen im Hinblick auf sprachliche Teilaspekte vorhersagen lassen sollten. Dem liegt die Annahme zugrunde, dass in unterschiedlichen Bildungskulturen unterschiedliche Schwerpunkte bezüglich der unterrichteten sprachlichen Teilaspekte existieren. Ferner wird angenommen, dass sich dies auf den in einem Land konstruierten Testitems abbilden sollte, indem bestimmte schwierigkeitsbestimmende Charakteristika eines Items (z.B. Schwierigkeit von Vokabular/ Grammatik) mehr oder weniger häufig bei der Itemkonstruktion verwendet wurden. Signifikante Unterschiede dahingehend bei in unterschiedlichen Ländern konstruierten Items sollte demzufolge auf unterschiedliche testkulturelle Profile von Ländern hinweisen. Die Hauptfragestellung der Arbeit lautet: „Existiert ein Zusammenhang zwischen Differentiellen Item Funktionen und Indikatoren nationaler Testkulturen bei Aufgaben zur Messung des fremdsprachlichen Leseverständnissen in englischer und deutscher Sprache?“ Die Analysen wurden am Datensatz der europäischen EBAFLS-Studie (European Bank of Anchor Items for Foreign Language Skills; Fandel et al., 2007) durchgeführt. Im Rahmen der Studie wurden Daten an ca. 10.500 Schülern der 9.-11. Klasse in acht europäischen Ländern in den Sprachen Englisch, Deutsch und Französisch erhoben; die verwendeten Testitems stammten aus den verschiedenen Teilnehmerländern. Experten ordneten die Items hinsichtlich der verschiedenen Itemcharakteristika mit Hilfe des Kategorisierungsinstruments „Dutch Grid“ (Alderson et al., 2006) ein. Für diese Dissertation wurden die EBAFLS Items und Datensätze zur Messung des fremdsprachlichen Leseverständnissen für Englisch (Länder: Frankreich, Deutschland, Spanien, Ungarn) und Deutsch (Länder: Frankreich, Niederlande, Ungarn, Schweden) verwendet. In einem ersten Auswertungsschritt wurden zunächst für die Analysen notwendige Voraussetzungen überprüft: die Rasch-Skalierbarkeit der Items innerhalb der Länder, die Anzahl signifikanter DIF-Parameter zwischen den einzelnen Länderpaarungen, sowie das Vorhandensein unterschiedlicher testkultureller Profile der Teilnehmerländer im Sinne unterschiedlich häufig vorkommender Itemcharakteristika bei den in den unterschiedlichen Ländern konstruierten Items. Es zeigte sich, dass diese Voraussetzungen als gegeben angesehen werden konnten. Des Weiteren wurden anhand der unterschiedlichen testkulturellen Profile Hypothesen hinsichtlich der zu erwartenden Stärken und Schwächen der einzelnen Länder im Hinblick auf Items mit bestimmten kognitiv-linguistischen Charakteristika formuliert. Im zweiten Analyseschritt zeigten sich innerhalb aller Länder korrelative Zusammenhänge zwischen den ausgewählten Itemcharakteristika und der Itemschwierigkeit. Somit konnten die Itemcharakteristika auch für weitere Analysen, d.h. zur Erklärung von Unterschieden der Itemschwierigkeiten zwischen den Ländern, verwendet werden. Im dritten Auswertungsschritt wurden zunächst paarweise DIF-Parameter (zw. jeweils 2 Ländern) berechnet. Zur Analyse von Zusammenhängen zwischen DIF und den Itemcharakteristika wurden dann die Itemcharakteristika mit den DIF-Parametern korreliert sowie im Rahmen einer multiplen Regression als Prädiktoren für DIF eingesetzt. Die Korrelationen lagen zwischen r = -.47 und r = .47. Dabei bedeutet eine negativer Zusammenhang, dass dieses Item aus Sicht der Fokusgruppe eine im Vergleich zur Referenzgruppe niedrigere Itemschwierigkeit aufweist, und somit ein Zusammenhang zwischen einem Itemmerkmal und für diese Gruppe vorteilhaften DIF besteht, bzw. umgekehrt. In einem letzten Schritt wurde überprüft, inwieweit die Richtung der gefundenen Zusammenhänge mit den testkulturellen Profilen einhergeht. Kommt ein Itemmerkmal bei den Items der Fokusgruppe signifikant häufiger vor als beiden Items der Referenzgruppe, sollte dies mit einem negativen, d.h. vorteilhaften, Zusammenhang zwischen diesem Itemmerkmal und DIF einhergehen und umgekehrt. Es zeigte sich, dass 23 von 29 (Englisch) bzw. 25 von 34 (Deutsch) signifikanten Korrelationen ihrer Richtung nach den aufgrund der Testkultur aufgestellten Hypothesen entsprachen. Ferner konnte zwischen 21% und 49% der DIF-Varianz anhand von Prädiktoren erklärt werden, die ihrer Richtung nach den aufgrund der testkulturellen Profile gemachten Annahmen entsprachen. Die Hauptannahme, dass ein Zusammenhang zwischen Differentiellen Item Funktionen und Testkulturen existiert, konnte somit insgesamt beibehalten werden.Since more and more cross-national Large-Scale Studies are being conducted within the educational context, comparing the results in a culturally fair way and keeping an extra eye on validity and fairness becomes crucial. This is often done by analysing the test items for Differential Item Functioning (DIF). If an item shows DIF, this means that students from different countries have different probabilities of answering an item correct, although they are on the same ability level. In this case, the difference in item difficulty is only due to group membership and not to true ability differences. Within this dissertation, I am trying to explain DIF with different underlying testing cultures in different countries. It is hypothesized that test items partly reflect the testing culture of the country where they were constructed. Especially in cross-national comparison studies, test items are usually constructed in the different partaking countries. That different testing cultures might be one source of differential item functioning was already supported by different studies (e.g. Klieme & Baumert, 2001; Artelt & Baumert 2004). This dissertation therefore deals with the question whether DIF can at least partly be explained by different testing cultures. The data used for the analyses was taken from the European Large Scale Study EBAFLS (European Bank of Anchor items for Foreign Language skills; e.g. Fandel et al., 2007); the items were taken from the same study and were constructed within the participating countries. Additionally, all EFL and GFL items were judged with regard to cognitive-linguistic item characteristics (itemtype, location of information, authenticity, abstractness, vocabulary, grammar) by language experts. For this dissertation, two samples of the EBAFLS study have been analysed: one for German as FL (students from France, Netherlands, Hungary, Sweden; n = 3170), and one for English as FL (students from France, Germany, Hungary, Spain; n = 4204). Depending on the country of origin, students were between 15 and 17 years old. In a first step, to determine characteristics of testing cultures, it was analysed whether the items of the different countries differ with regard to frequencies or levels of difficulty-determining item-characteristics such as difficulty of grammar, difficulty of vocabulary, or item type. It was assumed that the more often a certain characteristic appears within the items of a country, the more this belongs to the testing culture of that group. Therefore, the presence of this characteristic should make an item easier for the respective group and vice versa. Results indicated that items which were constructed in different countries also differed significantly concerning the frequency of certain difficulty-determining item characteristics, which was interpreted as different testing cultures. In a second step, multiple regression analyses with item difficulty as dependent variable and item characteristics as predictors were performed within each country. Item difficulties within each country were estimated within a 1PL-IRT Model.Results showed that item characteristics explained 25 % - 39% of variance of the item difficulty for EFL items, and 43% - 58% of variance for GFL items. Therefore, item characteristics could be used for further analyses. In a third step, DIF parameters were estimated for all pairs of countries per language by using a one-parameter IRT-model. Subsequently, correlations between DIF and item characteristics were computed for each pair of countries. Furthermore, a multiple linear regression was applied to explain DIF with cognitive-linguistic item characteristics as predictors. Significant correlations between item characteristics and DIF ranged from r = -.47 to r = .47. A negative correlation indicates that the item is less difficult (item difficulty is lower) for the focus group than for the reference group, and vice versa. In a last step, it was analysed whether significant correlations and predictors point to the expected direction, i.e. make an item more or less difficult for students depending on whether the item characteristic plays an important role within the respective testing culture or not. It was hypothesized that item characteristics which are important within a certain testing culture should make the item easier for those students compared to a group where this is not the case, and vice versa. Most of the significant correlations (English: 23 of 29; German: 25 of 34) pointed to the hypothesized direction, i.e. made an item more or less easy for students depending on whether the item characteristic was an important part of their testing culture or not. Furthermore, between 21% and 49% of DIF Variance could be explained by predictors that were consistent with the different testing cultures. The results support the assumption that DIF can at least partly be explained by different testing cultures

Single-hole dynamics in the half-filled two-dimensional Kondo-Hubbard model

We consider the Kondo lattice model in two dimensions at half filling. In addition to the fermionic hopping integral $t$ and the superexchange coupling $J$ the role of a Coulomb repulsion $U$ in the conduction band is investigated. We find the model to display a magnetic order-disorder transition in the U-J plane with a critical value of J_c which is decreasing as a function of U. The single particle spectral function A(k,w) is computed across this transition. For all values of J > 0, and apart from shadow features present in the ordered state, A(k,w) remains insensitive to the magnetic phase transition with the first low-energy hole states residing at momenta k = (\pm \pi, \pm \pi). As J -> 0 the model maps onto the Hubbard Hamiltonian. Only in this limit, the low-energy spectral weight at k = (\pm \pi, \pm \pi) vanishes with first electron removal-states emerging at wave vectors on the magnetic Brillouin zone boundary. Thus, we conclude that (i) the local screening of impurity spins determines the low energy behavior of the spectral function and (ii) one cannot deform continuously the spectral function of the Mott-Hubbard insulator at J=0 to that of the Kondo insulator at J > J_c. Our results are based on both, T=0 Quantum Monte-Carlo simulations and a bond-operator mean-field theory.Comment: 8 pages, 7 figures. Submitted to PR