Sum frequency generation as a proxy for ellipsometry: Not just a phase.

Infrared refractive indices of organic materials are typically resolved through IR ellipsometry. This technique takes advantage of optical interference effects to solve the optical constants. These are the same effects that complicate the analysis of coherent spectroscopy experiments on thin films. Vibrational sum frequency generation is an interface-specific coherent spectroscopy that requires spectral modeling to account for optical interference effects to uncover interfacial molecular responses. Here, we explore the possibility of leveraging incident beam geometries and sample thicknesses to simultaneously obtain the molecular responses and refractive indices. Globally fitting a higher number of spectra with a single set of refractive indices increases the fidelity of the fitted parameters. Finally, we test our method on samples with a range of thicknesses and compare the results to those obtained by IR ellipsometry.

A compact, versatile low-energy electron beam ion source.

A new compact Electron Beam Ion Source, the Dresden EBIT-LE, is introduced as an ion source working at low electron beam energies. The EBIT-LE operates at an electron energy ranging from 100 eV to some keV and can easily be modified to an EBIT also working at higher electron beam energies of up to 15 keV. We show that, depending on the electron beam energy, electron beam currents from a few mA in the low-energy regime up to about 40 mA in the high-energy regime are possible. Technical solutions as well as first experimental results of the EBIT-LE are presented. In ion extraction experiments, a stable production of low and intermediate charged ions at electron beam energies below 2 keV is demonstrated. Furthermore, X-ray spectroscopy measurements confirm the possibility of using the machine as a source of X-rays from ions excited at low electron energies.

Demonstration of charge breeding in a compact room temperature electron beam ion trap.

For the first time, a small room-temperature electron beam ion trap (EBIT), operated with permanent magnets, was successfully used for charge breeding experiments. The relatively low magnetic field of this EBIT does not contribute to the capture of the ions; single-charged ions are only caught by the space charge potential of the electron beam. An over-barrier injection method was used to fill the EBIT's electrostatic trap with externally produced, single-charged potassium ions. Charge states as high as K(19+) were reached after about a 3 s breeding time. The capture and breeding efficiencies up to 0.016(4)% for K(17+) have been measured.

Liquid metal alloy ion source based metal ion injection into a room-temperature electron beam ion source.

We have carried out a series of measurements demonstrating the feasibility of using the Dresden electron beam ion source (EBIS)-A, a table-top sized, permanent magnet technology based electron beam ion source, as a charge breeder. Low charged gold ions from an AuGe liquid metal alloy ion source were injected into the EBIS and re-extracted as highly charged ions, thereby producing charge states as high as Au(60 +). The setup, the charge breeding technique, breeding efficiencies as well as acceptance and emittance studies are presented.

Status report of the Dresden EBIS/EBIT developments.

We give an overview about latest developments and measurements with the Dresden electron beam ion source family as compact and economically working table-top sources of highly charged ions. The ion sources are potential tools for various applications such as for use in combination with accelerators in medical particle therapy, as charge breeder or ion trap injector, as ion sources for a new generation of focused ion beam devices and for applications together with time-of-flight secondary mass spectrometers.

Coherent time evolution of a single-electron wave function.

Observation of coherent single-electron dynamics is severely limited by experimental bandwidth. We present a method to overcome this using moving quantum dots defined by surface acoustic waves. Each dot holds a single electron, and travels through a static potential landscape. When the dot passes abruptly between regions of different confinement, the electron is excited into a superposition of states, and oscillates unitarily from side to side. We detect these oscillations by using a weak, repeated measurement of the current across a tunnel barrier, and find close agreement with simulations.

Seroprevalence of Toxoplasma gondii and Bartonella spp. antibodies in cats from Pennsylvania.

Toxoplasma gondii and Bartonella spp. are zoonotic pathogens of cats. In the present study, the prevalence of antibodies to T. gondii and Bartonella spp. were determined in sera from 210 domestic cats from Bensalem, Pennsylvania. Using a modified agglutination test, antibodies to T. gondii were found in 41 (19.5%) of the 210 cats with titers of 1:25 in 4, 1:50 in 9, 1:100 in 7, 1:200 in 3, 1:400 in 3, 1:800 in 5, 1:1,600 in 4, and 1:3,200 or higher in 6. For T. gondii, seroprevalence increased with age of the cat: 15 of 113 (13.2 %) were seropositive compared with 26 of 97 (26.7%) older than 11 mo. Of these 210 cats, 54 (25.7%) were positive for Bartonella spp. antibodies, with titers of 1:64 in 20, 1:128 in 21, 1:256 in 9, and 1:512 in 4. Seventeen cats had antibodies to both organisms. There was no correlation between T. gondii and Bartonella spp. seropositivity. Overall the seroprevalence of T. gondii antibodies in cats in this population is much lower compared with those reported in other localities in the United States and other countries.

Single-electron population and depopulation of an isolated quantum dot using a surface-acoustic-wave pulse.

We use a pulse of surface acoustic waves (SAWs) to control the electron population and depopulation of a quantum dot. The barriers between the dot and reservoirs are set high to isolate the dot. Within a time scale of approximately 100 s the dot can be set to a nonequilibrium charge state, where an empty (occupied) level stays below (above) the Fermi energy. A pulse containing a fixed number of SAW periods is sent through the dot, controllably changing the potential, and hence the tunneling probability, to add (remove) an electron to (from) the dot.

Spontaneous haemopneumothorax: are guidelines overdue?

Spontaneous life threatening haemopneumothorax is an unusual but treatable cause of unexpected circulatory collapse in young patients. Two case histories are presented to illustrate the management of this condition. Diagnosis and initial management depends on early recognition of the clinical pattern by accident and emergency (A&E) staff and/or hospital physicians. Problems may arise for two reasons. Firstly, as the incidence of life threatening spontaneous haemopneumothorax is low, admitting medical staff may not have experienced this condition in the absence of trauma. Secondly, unlike surgeons, staff in these specialties are unlikely to have received training of either traumatic or spontaneous haemopneumothorax. The cases illustrate potential problems. Not only early recognition of the clinical pattern but also proactive intervention in the A&E department are necessary before referral to a cardiothoracic surgeon. Furthermore, we suggest treatment would be improved by the introduction of management guidelines.

Language differences in verbal short-term memory do not exclusively originate in the process of subvocal rehearsal.

Language differences in verbal short-term memory were investigated in two experiments. In Experiment 1, bilinguals with high competence in English and French and monolingual English adults with extremely limited knowledge of French were assessed on their serial recall of words and nonwords in both languages. In all cases recall accuracy was superior in the language with which individuals were most familiar, a first-language advantage that remained when variation due to differential rates of articulation in the two languages was taken into account. In Experiment 2, bilinguals recalled lists of English and French words with and without concurrent articulatory suppression. First-language superiority persisted under suppression, suggesting that the language differences in recall accuracy were not attributable to slower rates of subvocal rehearsal in the less familiar language. The findings indicate that language-specific differences in verbal short-term memory do not exclusively originate in the subvocal rehearsal process. It is suggested that one source of language-specific variation might relate to the use of long-term knowledge to support short-term memory performance.

Experiences from long-term research cooperation between Costa Rican, Nicaraguan, and Swedish institutions.

This paper summarizes experiences from long-term ongoing cooperation between Swedish research institutions and institutions at the National Universities in Nicaragua and Costa Rica. 24 researchers and teachers from the Central American institutions and ten Swedish research students have been trained. In addition to three full doctoral and three licentiate (two-year PhD program) theses, the two programs have so far published 15 articles in English-language, international, refereed journals and about three times as many abstracts for conferences in more than ten countries. A "sandwich" model for training is recommended, where the southern researchers come to the wealthier partner for collaborative analyses and write-ups of the publications, while spending 50-75% of their time in their home countries for data collection. Such collaboration should be planned for a time span of at least eight years and include substantial numbers of researchers and students. Means to minimize the risk of brain drain are suggested. The collaboration has been important for the globalization of the research cultures at the participating institutions and has trained international experts.

[Qualitative research methods in clinical practice]. / Kvalitativa forskningsmetoder i klinisk medicinsk praxis.

Evidence-based medicine (EBM) corresponds to the physician's ambition to integrate his/her experience with the best current scientific knowledge, applying this integrated proficiency to clinical problems. The concept of EBM has become widely accepted and given rise to a global network usually emphasizing the randomized clinical trial (RCT) as the most important scientific method. However, clinical situations are very complex. To a greater or less extent they are all composed of diverse factors, ranging from bio-medical ones to inter-subjective relations, values and beliefs. In addition to RCT and other quantitative procedures, qualitative scientific methods could be used to explore complex clinical problems. Clinical problems always deserve to be addressed from various perspectives. Unfortunately, RCT has acquired such a dominant position as to give the impression that it is the sole preferred method within the EBM framework. Based on three examples, the present article claims that it is the questions asked by an investigation that should determine one's choice of methods, not the reverse. Consequently, we argue that it is important to remember that RCT is just one out of several potential scientific methods. The respective utility of any one method depends on the clinical issue at hand.

[Sick building syndrome should be treated more from a reasonable than an evidence-based point of view]. / Sjuka hus-syndromet får behandlas mer utifrån rimlighet än evidens.

During the past decades, several non-specific syndromes have gradually appeared and eventually been given generic denominations such as "diseases of modern life". One of these is the so called Sick Building Syndrome (SBS), which consists of various combinations of common, non-specific symptoms as well as an absence of signs demonstrable by laboratory tests and other medical examinations or means. The lack of demonstrable biological correlates together with vague etiologic attributions make it unusually problematic to study, resulting in the production of a general, non-specific and sometimes contradictory fund of knowledge. This often transforms instances of SBS to theaters of conflict people by parties with divergent interests. Technical/scientific expertise can provide general advice but not unambiguously contribute to the resolution of the conflicts.

Pests, peasants, and pesticides on the Northern Nicaraguan Pacific Plain.

With the aim of exploring possible reasons for dangerous work practices among small-scale farmers in the Pacific plain of Nicaragua, a qualitative study was performed. Four focus groups were involved. The information gathered was analyzed with an emphasis on the farmers' relationships to and perspectives on their crops, the economy, pests, and pesticide hazards. Factors that had been anticipated, such as poverty, inadequacy of protective devices, and environmental factors, were found to lead to dangerous work practices. Cultural factors also affected the farmers' attitudes in ways that favored hazardous work procedures. This finding, which had not been anticipated, has important practical implications. It suggests that, to be effective, education and training courses on occupational health should assure that their design, language, materials, and execution are culturally relevant and appropriate.

Mortality and cancer incidence among Swedish lumberjacks exposed to phenoxy herbicides.

OBJECTIVES: To determine mortality and cancer incidence relative to exposure to phenoxy herbicides. METHODS: A cohort of Swedish lumberjacks of which 261 were exposed to phenoxy herbicides, and 250 were unexposed, was followed up for mortality from 1954 to 1994, and for cancer incidence from 1958 to 1992. The number of days of exposure to phenoxy herbicides was determined from pay slips. With the county population as a reference, standardised mortality ratios and cancer incidence ratios (SMR and SIR) were calculated. RESULTS: Mortality and cancer incidence were low with two exceptions; a small but highly exposed group of foremen showed an increased cancer incidence (SIR 274, 95% confidence interval (95% CI) 100 to 596), and over all mortality (SMR 141, 95% CI 68 to 260). Of three cases of non-Hodgkin's lymphoma, two were found among the most exposed workers. CONCLUSIONS: The results provide some support to claims of previous studies that exposure to phenoxy herbicides might be related to non-Hodgkin's lymphoma and to an increased overall cancer risk.

Emergence and preservation of a chronically sick building.

STUDY OBJECTIVE: To investigate the merits of case studies as complementary methodological approaches in the study of the sick building syndrome. SETTING AND PARTICIPANTS: A Swedish office building with longstanding health problems, and its inhabitants. DESIGN: This paper is a case study based both on historical and present, quantitative as well as qualitative, documentary material, produced over the years by distinct parties, and on semi-structured interviews. RESULTS: Long drawn conflictive processes within the building were identified. It was revealed that the organisation for dealing with environmental problems was split, and ineffective with poor patterns of communication. It was suggested that this generated a situation of chronic stress leading to the persistence of symptoms. CONCLUSIONS: By their capacity to identify internal processes within building contexts, case study methodology can contribute to a better understanding and management of sick building syndrome. The results of this study suggest that psychosocial factors, among them organisational structures and communication patterns, should be given close attention.