The effect of human disturbance on vegetation at the Wehr Nature Center in Whitnall Park

During 1975 and 1976, I studied (Nowak, 1976) two woodlands at the Wehr Nature Center in WhitnaLl Park, Milwaukee County (Figure 1). My purpose was to document the vegetational changes brought about by human disturbance. The Wehr Woods, adjacent to the Wehr Nature Center Building, had been lumbered and grazed; while the woods along College Avenue is subjected to seasonal flooding, a result of road construction which had altered the drainage pattern. In each woodland, a disturbed portion was compared with an adjacent, relatively undisturbed area. The heavily lumbered and grazed portion of the Wehr woods will be referred to as the cutover area and an adjacent uncut and ungrazed maple woods is designated the mature area . The woods affected by ponding in spring and early summer along College Avenue will be referred to as the flooded area and the adjacent unflooded woods as the non-flooded area

Fine structure of exciton excited levels in a quantum dot with a magnetic ion

The fine structure of excited excitonic states in a quantum dot with an embedded magnetic ion is studied theoretically and experimentally. The developed theory takes into account the Coulomb interaction between charged carriers, the anisotropic long-range electron-hole exchange interaction in the zero-dimensional exciton, and the exchange interaction of the electron and the hole with the $d$-electrons of a Mn ion inserted inside the dot. Depending on the relation between the quantum dot anisotropy and the exciton-Mn coupling the photoluminescence excitation spectrum has a qualitatively different behavior. It provides a deep insight into the spin structure of the excited excitonic states.Comment: 6 pages, 6 figure

Cores e corantes dos bordados de Castelo Branco: interação de contextos formais e não formais na educação em química

Els brodats de colors de Castelo Branco (Portugal) van ser objecte del desenvolupament d'un projecte per millorar la relació entre l'educació formal i no formal en química i en la formació de professors i divulgadors de la cultura. La qüestió principal se centra en la possibilitat d'identificar i obtenir els tints antics i actuals que s'utilitzen per tenyir la seda. Es presenten dues activitats experimentals: l'extracció d'un colorant natural i l'ús de mordent amb un tint sintètic.The colourful embroidery of Castelo Branco (Portugal) was the theme for the development of a project that enhances the relationship between formal and non-formal contexts in chemistry education and in the training of teachers and cultural animators. The central question concerns the possibility of identifying and obtaining the old and modern dyes that are used for dyeing silk. We present two experimental activities: extraction of a natural dye and use of mordant with a synthetic dye

Correlated Photon Emission from a Single II-VI Quantum Dot

We report correlation and cross-correlation measurements of photons emitted under continuous wave excitation by a single II-VI quantum dot (QD) grown by molecular-beam epitaxy. A standard technique of microphotoluminescence combined with an ultrafast photon correlation set-up allowed us to see an antibunching effect on photons emitted by excitons recombining in a single CdTe/ZnTe QD, as well as cross-correlation within the biexciton ($X_{2}$)-exciton ($X$) radiative cascade from the same dot. Fast microchannel plate photomultipliers and a time-correlated single photon module gave us an overall temporal resolution of 140 ps better than the typical exciton lifetime in II-VI QDs of about 250ps.Comment: 4 pages, 3 figures, to appear in Appl. Phys. Let

Nitrogen deficiency impacts on leaf cell and tissue structure with consequences for senescence associated processes in Brassica napus

International audienceImprovement of nutrient use efficiency is a major goal for several crop plants, especially Brassica napus. Indeed, the low nitrogen use efficiency (NUE) in this crop results in negative economic and ecological consequences. The low NUE of oilseed rape is mainly due to low remobilization of nitrogen from vegetative parts to growing organs. Remobilization of leaf nitrogen takes place during senescence, a process known to strongly modify cell and tissue structure. This study focused on the impact of moderate N depletion, expected to induce 30% reduction of seed yield, on these structural modifications. Two genotypes (Aviso and Express) were studied, with different tolerance of nitrogen depletion, evaluated through seed yield and dry mass production. Structural modifications of leaf cells and tissues were investigated through NMR relaxometry and light microscopy. Lower tolerance of N depletion was associated with higher impact on senescence associated structural modification pattern. The link between leaf structure modifications and nutrient remobilization is discussed. It is proposed that leaf structure monitoring during senescence through NMR device could be developed to select genotypes with high NUE

Een kwestie van vertrouwen: Een ontwerpgericht onderzoek naar het verbeteren van het contact met ouders in het ‘grootstedelijke’ vmbo als bijdrage aan preventie van schooluitval

__Abstract__ De problematiek van schooluitval in de grootstedelijke context vormt de aanleiding tot dit onderzoek. Als eerste wordt de omvang en aard van de lokale, nationale en internationale schooluitval en de maatregelen ten bestrijding en preventie van dit voortijdig schoolverlaten besproken (hoofdstuk 1). Aangezien onderzoekers en beleidsmakers suggereren dat ouders een rol kunnen spelen in de preventie van schooluitval, is vervolgens een literatuurstudie gedaan naar de kennis die aanwezig is over wat ouders kunnen bijdragen aan schoolsucces van hun kinderen en aan preventie van schooluitval (hoofdstuk 2). De weergave van deze literatuurstudie vormt het theoretisch kader van het onderzoek. Dit kader is gebruikt bij zowel de vormgeving van de instrumenten van de veldstudie als bij ontwikkeling van de handreiking. Tot slot komen het methodologische kader, de onderzoeksvraag en -opzet en de keuze voor ontwerpgericht wetenschappelijk onderzoek aan de orde (hoofdstuk 3)

Remote optical addressing of single nano-objects

We present a scheme for remotely addressing single nano-objects by means of near-field optical microscopy that makes only use of one of the most fundamental properties of electromagnetic radiation: its polarization. A medium containing optically active nano-objects is covered with a thin metallic film presenting sub-wavelength holes. When the optical tip is positioned some distance away from a hole, surface plasmons in the metal coating are generated which, by turning the polarization plane of the excitation light, transfer the excitation towards a chosen hole and induce emission from the underlying nano-objects. The method, easily applicable to other systems, is demonstrated for single quantum dots (QDs) at low temperature. It may become a valuable tool for future optical applications in the nanoworld

Standards of aminoglycoside therapeutic drug monitoring in a South African private hospital: perspectives and implications

Background: Therapeutic drug monitoring (TDM) is essential to ensure that aminoglycoside peak concentrations are high enough for effective antimicrobial treatment and trough levels are low enough to minimise toxicity. Inappropriate utilisation of TDM may lead to suboptimal therapy, toxicity and waste of resources. This study aimed to investigate the standard of aminoglycoside TDM performed in adult hospitalised patients.Design: An observational, descriptive, cross-sectional study.Setting: A 221-bed private hospital.Participants: All patients, older than 18 years, on intravenous aminoglycosides for more than 48 hours were included.Interventions: None, was observational. A computerised database and patient files were used to obtain the information required for this study. Descriptive statistical analysis was used.Main outcomes measures: Aminoglycoside blood levels and estimated glomerular filtration rate (eGFR) in the patients.Results: One hundred and three (103) patients were included: 65 on gentamicin and 38 on amikacin. Blood levels were performed in only 19 gentamicin (29.23%) and 22 amikacin (57.89%) patients. Trough levels were taken more than 2 hours before the next dose in 12 gentamicin (63.16%) and 12 amikacin (54.54%) patients. The majority of patients (96.92% on gentamicin and 84.21% on amikacin) received once daily doses. TDM was performed in all patients with an estimated glomerular filtration rate (eGFR) lower than 60 mL/min/1.73m2 and in 23.31% of gentamicin patients and 56.76% of amikacin patients with an eGFR higher than 60 mg/min/1.73m2.Conclusions: Incorrect sampling times and unnecessary levels taken in patients with normal renal function indicate a need for aminoglycoside treatment guidelines in the private hospital.Funding: NoneKeywords: Aminoglycosides, Dosing considerations, South Africa, Therapeutic DrugMonitoring, Sampling time