The emptiness formation probability correlation in homogeneous and dimerized XX chains

We review some known properties of the "emptiness formation probability" correlation which we have calculated numerically for spin-1/2 XX chains with constant (homogeneous) or alternating (dimerized) nearest-neighbor coupling and an external field (in $z$ direction) for arbitrary temperature. The long-distance asymptotic behavior of this correlation is known to be Gaussian at zero temperature and exponential at finite temperature for the homogeneous chain. By simple analytical arguments the exponential behavior at finite temperature extends to the dimerized system. Numerical results for the dimerized chain confirm the exponential decay at finite temperature and show Gaussian decay at zero temperature.Comment: Fixed some typos, added two references and remarks on finite-size effects. To be published in Cond. Mat. Phy

Crack in the System: The Racially Motivated Intentions and Consequences of the Anti-Drug Abuse Act of 1986

This thesis regards the history and politics surrounding the 1986 Anti-Drug Abuse Act and the transformation of racism in the United States from the late 19th century to the end of the 20th century. Examining the history of moral drug panics in the U.S., allows for exploration of how criminal law has historically been used to punish unwanted minorities, especially in times of economic uncertainty. Further discussed are the shifts that took place in the 1960s that changed how Americans viewed urban poverty and crime. After the war on poverty became the war on crime, Reagan\u27s war on drugs intensified the punitive ideology of the war on crime through the issue of illegal drugs. The media\u27s onslaught of coverage on the demon drug crack cocaine in 1986 furthered public panic. The media\u27s coverage, steeped in racial animus and depicting crack users and dealers as urban black males, tapped into the public\u27s latent race-based fears. From here, the draconian crack statute was passed by a hasty Congress- affected by the election year sensitivity. Thus, the unjust and unfounded 100-to-1 sentencing disparity between crack and powder cocaine was made law, overwhelmingly punishing young, black males and perpetuating an unequal system that works to stifle black progress and racial equality

The Nature of Some Bituminous Sands from Moffat County, Colorado

Humic acid is a possible cause of the staining found in many sands has been seemingly overlooked in the past. It is a definite cause, and very probably to a much greater extent than realized. Two samples from the Browns Park Formation appear naturally brown in color, but are in reality near white. The brown color is a result of staining due mostly to humic acid and to a lesser extent by a small amount of petroleum present

Mutation-selection models of sequence evolution in population genetics

The equilibrium properties of a number of deterministic mutation- selection models of sequence evolution are investigated. Both two- and four-state sequences are considered, the mutation model is a single-step mutation model. Two types of fitness functions are studied, namely permutation-invariant fitness functions, where the fitness of a sequence depends only on the number of mutations, not on their location within the sequence, and Hopfield-type fitness functions, where the fitness of a sequence is determined by its similarity to a number of predefined patterns. Maximum principles to determine the population mean fitness in equilibrium are derived, where the maximiser gives also the ancestral mean genotype. These maximum principles are used to investigate the error threshold phenomenon, i.e., the phenomenon that for certain fitness functions the population changes at a critical mutation rate from a well localised to a delocalised distribution in sequence space. The error threshold phenomenon is investigated for a four-state model with permutation-invariant fitness functions and for a two-state model with Hopfield-type fitness functions. Both models yield ordered and disordered as well as partially ordered phases

Geschichtsbilder sehen. Narrative Formen als Gegenstand des Lernens mit Geschichten

Im Zuge einer ikonischen Wende in den Geisteswissenschaften hat das Visuelle an Bedeutung für den kritischen Umgang mit Bildungsmedien wie Schulbücher und deren Inhalte gewonnen. Während frühe Arbeiten vor allem eine Kritik an der Vorstellung des Bildes als Anhängsel des Texts übten, erlaubte die Ausweitung des Bildbegriffs eine Annäherung verschiedener semiotischer Ansätze. Am Beispiel von Geschichtsschulbüchern stellt sich der Aufsatz die Frage inwieweit (Schulbuch)Narrative als Bilder verstanden werden können und wie ein solches Verständnis neue methodische Perspektiven auf das Lernen mit dem Bildungsmedium eröffnet. (DIPF/Orig.

Potenziale und Herausforderungen der Struktur historischer Narrationen für das historische Lernen

Narrationen sind das grundlegende Element des Geschichtsunterrichts – darüber besteht in der Disziplin der Geschichtsdidaktik ebenso weitgehende Einigkeit wie darüber, dass es die vornehmliche Aufgabe des Geschichtsunterricht sei, ein reflexives Geschichtsbewusstsein herauszubilden. Abhängig von Auswahl und Umgang mit Narrationen können sich jedoch grundverschiedene Unterrichtsmodelle ergeben. Die kumulative Dissertation von Lucas-Frederik Garske widmet sich in sechs Artikeln der Bedeutung der Struktur von Narrationen für die Vermittlung historischen Denkens. Dabei geht sie der Frage nach, inwiefern eine auf einer chronologischen Narration basierende Unterrichtsprogression und die damit verbundene Praxis im Umgang mit dem Material in Konflikt mit dem Lernziel stehen können. Auf der Basis der Befunde attestiert die Arbeit eine latente Unentschlossenheit in der Zielsetzung des Unterrichts.In history education theory there is a broad consensus that narrations are fundamental to history education and that the primary task of history education is to develop historical consciousness. Depending on the selection and handling of narratives, however, fundamentally different teaching models can result. The cumulative dissertation by Lucas-Frederik Garske is dedicated in six articles to the significance of the structure of narrations for the teaching of historical thinking. In doing so, it explores the question of the extent to which a teaching progression based on a chronological narrative and the correspondent practice in dealing with the material can conflict with the learning objective. On the basis of the findings, the study attests to a latent indecisiveness in the objective of teaching

Remote Controlled Orbiter Capability

The Remote Control Orbiter (RCO) capability allows a Space Shuttle Orbiter to perform an unmanned re-entry and landing. This low-cost capability employs existing and newly added functions to perform key activities typically performed by flight crews and controllers during manned re-entries. During an RCO landing attempt, these functions are triggered by automation resident in the on-board computers or uplinked commands from flight controllers on the ground. In order to properly route certain commands to the appropriate hardware, an In-Flight Maintenance (IFM) cable was developed. Currently, the RCO capability is reserved for the scenario where a safe return of the crew from orbit may not be possible. The flight crew would remain in orbit and await a rescue mission. After the crew is rescued, the RCO capability would be used on the unmanned Orbiter in an attempt to salvage this national asset

Niche hypergraphs

If D = (V,A) is a digraph, its niche hypergraph Nℋ(D) = (V, ℰ) has the edge set ℰ = {ℯ ⊆ V | |e| ≥ 2 ∧ ∃ v ∈ V : e = ND-(v) ∨ ℯ = ND+(v)}. Niche hypergraphs generalize the well-known niche graphs (see [11]) and are closely related to competition hypergraphs (see [40]) as well as double competition hypergraphs (see [33]). We present several properties of niche hypergraphs of acyclic digraphs

What’s the „matter“? Der Materialitätsbegriff des „New Materialism“ und dessen Konsequenzen für feministisch-politische Handlungsfähigkeit

The article tries to highlight some similarities and differences between the meaning of the „material“ of a Marx-informed materialism on the one hand, and the „material“ predominant in theories belonging to the emerging field of feminist „new materialism“ on the other hand. It hopes to contribute to the further development of perspectives of critical social analysis within this field, while at the same time exploring the possibilities and limits of such an endeavour

Untersuchung zur Rolle der Profilaggrin-Peptide FLG176-207, FLG162-184 und FLG162-207 in der kutanen Abwehr

Es wurde die Hypothese aufgestellt, dass Peptidfragmente des Profilaggrins antimikrobielle Eigenschaften aufweisen. Im Rahmen dieser Dissertation war deshalb geplant, drei in antimikrobiell aktiven HPLC-Fraktionen enthaltene FLG-Peptide (FLG176-207, FLG162-207 und FLG162-184) hinsichtlich möglicher antimikrobieller Eigenschaften zu untersuchen