Resonant third-harmonic generation in a low-loss medium

The linear and nonlinear susceptibilities for resonant third-harmonic generation in an Mg-Kr system using the 3s2-3s 3d two-photon resonance at 431 nm are presented. The Mg-Kr system is shown to be a suitable low-loss medium because of its small one-photon and two-photon absorption cross section. A detailed quantitative analysis up to a power conversion efficiency of 1.2 . 10^-4was carried out. The phase-matching curves and the intensity dependence are in excellent agreement with a nonstationary modification of the theory of resonant third-harmonic generation in high density, phase-matched systems recently presented by Puell et al. [4].     

Using multiple cognitive task analysis methods for supervisory control interface design in high-throughput biological screening processes

Cognitive task analysis (CTA) approaches are currently needed in many domains to provide explicit guidance on redesigning existing systems. This study used goal-directed task analysis (GDTA) along with abstraction hierarchy (AH) modeling to characterize the knowledge structure of biopharmacologists in planning, executing and analyzing the results of high-throughput organic compound screening operations, as well as the lab automation and equipment used in these operations. It was hypothesized that combining the results of the GDTA and AH models would provide a better understanding of complex system operator needs and how they may be addressed by existing technologies, as well as facilitate identification of automation and system interface design limitations. We used comparisons of the GDTA and AH models along with taxonomies of usability heuristics and types of automation in order to formulate interface design and automation functionality recommendations for existing software applications used in biological screening experiments. The proposed methodology yielded useful recommendations for improving custom supervisory control applications that led to prototypes of interface redesigns. The approach was validated through an expert usability evaluation of the redesigns and was shown to be applicable to the life sciences domain.     

Production and trading of biomass for energy – An overview of the global status

The markets for industrially used biomass for energy purposes are developing rapidly toward being international commodity markets. Determining international traded biomass volumes for energy purposes is difficult, for several reasons, such as challenges regarding the compilation of statistics on the topic. While for some markets (pellets and ethanol) separate overviews exist, no comprehensive statistics and summaries aggregating separate biomass streams are available. The aim of this paper is to summarise trade volumes for various biomasses used for energy and to review the challenges related to measurement of internationally traded volumes of biofuels. International trade of solid and liquid biofuels was estimated to be about 0.9 EJ for 2006. Indirect trade of biofuels thorough trading of industrial roundwood and material byproducts comprises the largest proportion of trading, having a share of about 0.6 EJ. The remaining amount consisted of products that are traded directly for energy purposes, with ethanol, wood pellets, and palm oil being the most important commodities. In 2004–2006, the direct trade of biofuels increased 60%, whereas indirect trade has been almost constant. When compared to current global energy use of biomass (about 50 EJ yr⁻¹) and to the long-term theoretical trading potential between the major regions of the world (80–150 EJ yr⁻¹), the development of international trade of biomass for energy purposes is in its initial stage, but it is expected to continue to grow rapidly.     

Opportunities and barriers for international bioenergy trade

Recently, the international trade of various bioenergy commodities has grown rapidly, yet this growth is also hampered by some barriers. The aim of this paper is to obtain an overview of what market actors currently perceive as major opportunities and barriers for the development of international bioenergy trade. The work focuses on three bioenergy commodities: bioethanol, biodiesel and wood pellets. Data were collected through an internet-based questionnaire. The majority of the 141 respondents had an industrial background. Geographically, two-thirds were from (mainly Western) Europe, with other minor contributions from all other continents. Results show that import tariffs and the implementation of sustainability certification systems are perceived as (potentially) major barriers for the trade of bioethanol and biodiesel, while logistics are seen mainly as an obstacle for wood pellets. Development of technical standards was deemed more as an opportunity than a barrier for all commodities. Most important drivers were high fossil fuel prices and climate change mitigation policies. Concluding, to overcome some of the barriers, specific actions will be required by market parties and policy makers. Import tariffs for biofuels could be reduced or abolished, linked to multinational trade agreements and harmonization (including provisions on technical standards and sustainability requirements).     

Liver metabolism during cold ischemic incubation in UW solution in the rat model]

Mother-to-child transmission near the time of birth is the primary route of HIV-1 infection among infants and young children. Throughout the world, 1000 babies a day become infected with HIV, and cumulative global estimates are that 3 million children have been infected since the HIV pandemic began. Although major advances have been made in reducing mother-to-child transmission of HIV-1 in the USA and Europe through the use of an intensive regimen of zidovudine, many research questions remain unresolved. These include (1) viral and host characteristics which hinder or facilitate perinatal HIV transmission (i.e. the role played by viral load, the placenta and obstetric risk factors); (2) the proportion of transmission occurring in utero, intrapartum or during the breast feeding period; and (3) the mode of action of the successful zidovudine regimen. Studies published within the past year have shed light on several of these research topics. In 1996-1997 a number of important studies were published which support a general correlation between maternal viral load and infant HIV infection. The most recent studies do not, however, support the theory that there is a threshold below which transmission cannot occur, and also indicate that zidovudine, given according to the US Public Health Service guidelines, can significantly reduce the risk of transmission across all levels of maternal viral load. Analyses of viral load data from the successful clinical trial with zidovudine (AIDS Clinical Trial Group 076) suggest that its primary action is not by reducing the viral load, and raise the possibility that administering antiretroviral prophylaxis to the infant at the time of highest exposure may be another reason for the reduction in transmission. Obstetric risk factors for mother-to-child HIV transmission have been evaluated in several large cohort studies. A duration of membrane rupture of more than 4 h, and procedures such as amniocentesis, preterm labor, and the presence of sexually transmitted diseases during pregnancy were found to be significant risk factors. Still unresolved is the potential protective effect of cesarean section in reducing the risk of transmission. Likewise, the role played by the placenta in preventing or facilitating perinatal transmission is not well understood, and requires further research. This year did see the publication of consistent findings from diverse geographical regions regarding the probable timing of perinatal HIV transmission. On the basis of the timing of the first infant positive polymerase chain reaction or culture, most transmission would appear to occur around the intrapartum or very late prenatal period, and only approximately 12-14% is related to breast feeding. These advances should help focus and refine future research efforts to reduce mother-to-child HIV transmission worldwide.     

Surface Modification of Nickel/Titanium Alloy and Titanium Surfaces via a Polyelectrolyte Multilayer/Calcium Phosphate Hybrid Coating

The report shows that simple LbL deposition of positively charged chitosan and negatively charged heparin can be used to efficiently modify the native surface of both NiTi and Ti without any previous treatments. Moreover, mineralization of the polymer multilayers with calcium phosphate leads to surfaces with low contact angles around 70 and 20° for NiTi and Ti, respectively. This suggests that a polymer multilayer/calcium phosphate hybrid coating could be useful for making NiTi or Ti implants that are at the same time antibacterial (via the chitosan), suppress blood clot formation (via the heparin), and favor fast endothelialization (via the improved surface hydrophilicity compared to the respective neat material).

     

Buchbesprechungen

Ohne Zusammenfassung     

Selective approach to the treatment of oesophageal cancer

Between September 1985 and December 1994, 322 patients with oesophageal cancer were treated. Of the 190 patients who underwent operation, 173 had an oesophageal resection; in 124 this was performed as an abdominothoracic resection and in 49 by the transhiatal approach. The assessment of radicality after histological examination revealed a curative (R0) resection in 121 patients (70 per cent) and a palliative (R1-R2) resection in 52 (30 per cent). Prognosis was correlated with the extent of mediastinal lymph node dissection. In 77 patients with stage pT1-3 pN0-1 pM0 the 5-year survival rate was 40 per cent after abdominothoracic resection with two-field lymph node dissection and zero after transhiatal resection (P = 0.01). The authors propose a differentiated surgical approach involving abdominothoracic resection with two-field lymph node dissection for patients with limited tumours (pT1-3 pN0-1 M0) if the operative risk is tolerable. Transhiatal resection appears to be effective only in patients with early tumours (Union Internacional Contra la Cancrum stage 0).