Wavefront and ray-density plots using seventh-order matrices

The optimization of an optical system benefits greatly from a study of its aberrations and an identification of each of its elements' contribution to the overall aberration figures. The matrix formalism developed by one of the authors was the object of a previous paper and allows the expression of image-space coordinates as high-order polynomials of object-space coordinates. In this paper we approach the question of aberrations, both through the evaluation of the wavefront evolution along the system and its departure from the ideal spherical shape and the use of ray density plots. Using seventh-order matrix modeling, we can calculate the optical path between any two points of a ray as it travels along the optical system and we define the wavefront as the locus of the points with any given optical path; the results are presented on the form of traces of the wavefront on the tangential plane, although the formalism would also permit sagital plane plots. Ray density plots are obtained by actual derivation of the seventh-order polynomials.Comment: 15 pages, 5 figure

Reaction Time of a Group of Physics Students

The reaction time of a group of students majoring in Physics is reported here. Strong co-relation between fatigue, reaction time and performance have been seen and may be useful for academicians and administrators responsible of working out time-tables, course structures, students counsellings etc.Comment: 10 pages, 4 figure

Nachweis von PAK-metabolisierenden Mikroorganismen durch kulturelle und molekularbiologische Verfahren

Zielsetzung der Arbeit war der Nachweis von PAK-abbauenden Mikroorganismen in Umweltproben mittels klassischer mikrobiologischer Arbeitstechniken und molekular-biologischer Methoden. Durch selektive Anreicherung wurden Bakterien mit der Fähigkeit Polyzyklische Aromatische Kohlenwasserstoffe (PAK) abzubauen, in aquatischen und terrestrischen Umweltproben nachgewiesen. Unabhängig von der Belastung der Standorte mit PAK wurden aus allen untersuchten Habitaten Bakterien isoliert, die mit Naphthalin oder Phenanthren als alleiniger Kohlenstoff- und Energiequelle wachsen konnten. Die 23 isolierten PAK-abbauenden Bakterien konnten als Mitglieder der Gattungen Sphingomonas, Acidovorax, Comamonas, Pseudomonas, Rhodococcus und Paenibacillus identifiziert werden und waren somit den alpha-, beta- und gamma-Subklassen der Proteobakterien und den Entwicklungslinien der grampositiven Bakterien mit hohem und niedrigem GC-Gehalt der DNA zuzuordnen. Die größte Gruppe bildeten mit 10 der 23 Isolate Vertreter der Gattung Pseudomonas, die alle Naphthalin metabolisierten. Die Quantifizierung des Naphthalin-Abbaus mittels gaschromatographischer Verfahren zeigte, daß in Flüssigmedium vorhandenes kristallines Naphthalin (0,05%, w/v) von den meisten Stämmen nach nur zwei Tagen Kultivierungsdauer vollständig metabolisiert wurde. Die getesteten Rhodococcus Isolate bauten Naphthalin wesentlich langsamer ab, als die verschiedenen Isolate, die den Proteobakterien zugeordnet wurden. Der dreikernige Aromat Phenanthren wurde von den getesteten Bakterienstämmen langsamer abgebaut als Naphthalin. Innerhalb von fünf Tagen wurde die Phenanthrenmenge im Medium auf 40-60% der Ausgangsmenge reduziert. Die Untersuchung des Naphthalinabbaus durch Zellen, die zuvor in Naphthalin-haltigem Medium bzw. in Vollmedium vorkultiviert worden waren, ergab, daß die Enzyme für den Abbau von Naphthalin in Abwesenheit eines Induktors nicht exprimiert wurden. Ebenso zeigte sich, daß Zellen, die in Medium mit Naphthalin oder Phenanthren kultiviert wurden, wesentlich höhere Catechol 2,3-Dioxygenase (C23O)-Aktivitäten aufwiesen als in Voll-medium gewachsene Zellen. Zum Nachweis von PAK-Abbauern auf molekulargenetischer Ebene wurden, basierend auf bekannten Sequenzen, PCR-Primer und Oligonukleotidsonden für codierende Abschnitte der C23O entwickelt, und, in Kombination mit Primern und Oligonukleotidsonden, zur Detektion der initialen PAK-Dioxygenase (entwickelt von R. Moser, TU-Berlin), eingesetzt. Mit den entworfenen Primern und Sonden konnten die C23O-Sequenzabschnitte bei allen PAK-abbauenden Referenzstämmen und Isolaten, die der Gattung Pseudomonas und Sphingomonas zugehörten, spezifisch detektiert werden. Durch die Anwendung spezifischer Primer und Sonden konnten dabei die Gene der C23O für Vertreter der Pseudomonaden und Sphingomonaden getrennt voneinander erfaßt werden. Sequenzanalysen der erhaltenen PCR-Amplifikate zeigten, daß die C23O-Gene innerhalb der Gattungen Pseudomonas bzw. Sphingomonas mit über 75% Sequenzähnlichkeit sehr gut konserviert sind. Dagegen waren Sequenzen der katabolischen Gene der PAK-abbauenden Comamonas-, Acidovorax- oder Rhodococcus-Vertreter offensichtlich zu verschieden, verglichen mit den Pseudomonas- und Sphingomonas-Sequenzen, um sie mittels der entwickelten Primer und Sonden detektieren zu können. Die Diversität der C23O zeigte sich auch bei der spezifischen enzymatischen Aktivität, die im Bereich von 0,1 bis 650 mU mg-1 Protein variierte. Dabei wurde die höchste spezifische Aktivität für verschiedene Pseudomonas-Stämme nachgewiesen. Die entwickelten Primer wurden auf ihre Anwendbarkeit getestet, PAK-abbauende Bakterien in Umweltproben kultivierungsunabhängig zu detektieren. Verschiedene DNA-Isolierungsmethoden und Techniken zur Aufreinigung der isolierten DNA wurden getestet und variiert. Bei der DNA-Isolierung aus Belebtschlammproben wurden Substanzen coextrahiert, die stark hemmenden Einfluß auf die PCR hatten. Die weitere Aufreinigung der DNA führte zu starken Verlusten der ursprünglichen DNA-Mengen und damit zu einer Reduzierung der zu detektierenden Zielsequenzen. Die extrahierte und gereinigte DNA aus unterschiedlichen Belebtschlammproben wurde in der PCR zur Detektion von initiale Dioxygenase- und C23O-codierenden Genabschnitten eingesetzt. Während codierende Bereiche der initialen Dioxygenase in der Belebtschlammprobe der Kläranlage Gießen mit den entwickelten Primern nachgewiesen werden konnten (R. Moser, TU-Berlin), wurden bei der Verwendung der C23O-spezifischen Primer keine PCR-Amplifikate erhalten. Offensichtlich lag die Zahl der C23O-Zielsequenzen in den untersuchten Umweltpoben unterhalb des Detektionslimits. In der extrahierten DNA aus anderen Belebtschlammproben konnten C23O-codierende Abschnitte detektiert werden. Die erhaltenen PCR-Amplifikate waren aber in allen Fällen sehr schwach. Die Ergebnisse zeigen, daß zur Detektion von katabolischen Genen, die in geringen Konzentrationen in Umweltproben vorliegen, spezielle Methoden zur Aufreinigung der DNA-Rohextrakte etabliert werden müssen

The determinants of hotels' marketing managers' green marketing behaviour

Little is known about the factors underlying the pro-environmental behaviour of marketing managers. This paper explores the determinants of green marketing practices in the Red Sea hotel sector in Egypt. The research model assesses green marketing practices against the personal and organisational values of the marketing managers, together with a range of organisational and demographic variables expected to influence hotels' environmental behaviour. From a valid sample of 89 marketing managers responsible for 194 hotels, it was found that organisational contextual variables, and in particular targeting Western tourists, being affiliated to an international hotel chain and the marketers' own demographics, including age, academic subject studied and gender, were the best predictors of more proactive green marketing. Personal environmental values did not explain the pro-environmental behaviour of marketers, and the organisational environmental values that had explained part of their ethical behaviour had resulted from voluntarism rather than utilitarian or conformance-based values. Government policies also appeared to be ineffective determinants. The implications for green marketing practices are also discussed. © 2010 Taylor & Francis

The effect of distance on reaction time in aiming movements

Target distance affects movement duration in aiming tasks but its effect on reaction time (RT) is poorly documented. RT is a function of both preparation and initiation. Experiment 1 pre-cued movement (allowing advanced preparation) and found no influence of distance on RT. Thus, target distance does not affect initiation time. Experiment 2 removed pre-cue information and found that preparing a movement of increased distance lengthens RT. Experiment 3 explored movements to targets of cued size at non-cued distances and found size altered peak speed and movement duration but RT was influenced by distance alone. Thus, amplitude influences preparation time (for reasons other than altered duration) but not initiation time. We hypothesise that the RT distance effect might be due to the increased number of possible trajectories associated with further targets: a hypothesis that can be tested in future experiments

What explains the uneven take-up of ISO 14001 at the global level?: a panel-data analysis

Since its release in the mid-1990s, close to 37 000 facilities have been certified to ISO 14001, the international voluntary standard for environmental management systems. Yet, despite claims that the standard can be readily adapted to very different corporate and geographic settings, its take-up has been highly geographically variable. This paper contributes to a growing body of work concerned with explaining the uneven diffusion of ISO 14001 at the global level. Drawing from the existing theoretical and empirical literature we develop a series of hypotheses about how various economic, market, and regulatory factors influence the national count of ISO 14001 certifications. These hypotheses are then tested using econometric estimation techniques with data for a panel of 142 developed and developing countries. We find that per capita ISO 14001 counts are positively correlated with income per capita, stock of foreign direct investment, exports of goods and services to Europe and Japan, and pressure from civil society. Conversely, productivity and levels of state intervention are negatively correlated. The paper finishes by offering a number of recommendations to policymakers concerned with accelerating the diffusion of voluntary environmental standards

Numerical study of one-dimensional and interacting Bose-Einstein condensates in a random potential

We present a detailed numerical study of the effect of a disordered potential on a confined one-dimensional Bose-Einstein condensate, in the framework of a mean-field description. For repulsive interactions, we consider the Thomas-Fermi and Gaussian limits and for attractive interactions the behavior of soliton solutions. We find that the disorder average spatial extension of the stationary density profile decreases with an increasing strength of the disordered potential both for repulsive and attractive interactions among bosons. In the Thomas Fermi limit, the suppression of transport is accompanied by a strong localization of the bosons around the state k=0 in momentum space. The time dependent density profiles differ considerably in the cases we have considered. For attractive Bose-Einstein condensates, a bright soliton exists with an overall unchanged shape, but a disorder dependent width. For weak disorder, the soliton moves on and for a stronger disorder, it bounces back and forth between high potential barriers.Comment: 13 pages, 13 figures, few typos correcte

Disorder-induced trapping versus Anderson localization in Bose-Einstein condensates expanding in disordered potentials

We theoretically investigate the localization of an expanding Bose-Einstein condensate with repulsive atom-atom interactions in a disordered potential. We focus on the regime where the initial inter-atomic interactions dominate over the kinetic energy and the disorder. At equilibrium in a trapping potential and for small disorder, the condensate shows a Thomas-Fermi shape modified by the disorder. When the condensate is released from the trap, a strong suppression of the expansion is obtained in contrast to the situation in a periodic potential with similar characteristics. This effect crucially depends on both the momentum distribution of the expanding BEC and the strength of the disorder. For strong disorder, the suppression of the expansion results from the fragmentation of the core of the condensate and from classical reflections from large modulations of the disordered potential in the tails of the condensate. We identify the corresponding disorder-induced trapping scenario for which large atom-atom interactions and strong reflections from single modulations of the disordered potential play central roles. For weak disorder, the suppression of the expansion signals the onset of Anderson localization, which is due to multiple scattering from the modulations of the disordered potential. We compute analytically the localized density profile of the condensate and show that the localization crucially depends on the correlation function of the disorder. In particular, for speckle potentials the long-range correlations induce an effective mobility edge in 1D finite systems. Numerical calculations performed in the mean-field approximation support our analysis for both strong and weak disorder.Comment: New Journal of Physics; focus issue "Quantum Correlations in Tailored Matter - Common perspectives of mesoscopic systems and quantum gases"; 30 pages, 10 figure

Environmental performance policy indicators for the public sector: The case of the defence sector

The development of environmental performance policy indicators for public services, and in particular for the defence sector, is an emerging issue. Despite a number of recent initiatives there has been little work done in this area, since the other sectors usually focused on are agriculture, transport, industry, tourism and energy. This type of tool can be an important component for environmental performance evaluation at policy level, when integrated in the general performance assessment system of public missions and activities. The main objective of this research was to develop environmental performance policy indicators for the public sector, specifically applied to the defence sector. Previous research included an assessment of the environmental profile, through the evaluation of how environmental management practices have been adopted in this sector and an assessment of environmental aspects and impacts. This paper builds upon that previous research, developing an indicator framework-SEPI-supported by the selection and construction of environmental performance indicators. Another aim is to discuss how the current environmental indicator framework can be integrated into overall performance management. The Portuguese defence sector is presented and the usefulness of this methodology demonstrated. Feasibility and relevancy criteria are applied to evaluate the set of indicators proposed, allowing indicators to be scored and indicators for the policy level to be obtained. (c) 2006 Elsevier Ltd. All rights reserved