Differing results obtained in the doping of semiconductors by energetic ions

Conflicting results have been reported on the doping of semiconductors by energetic ions. The purpose of this communication is to call attention to certain experimental parameters which are important in resolving these discrepancies

Infektionen und Sepsis durch intravenöse Katheter

Zusammenfassung: Infektionen und mechanische Komplikationen sind beim Einsatz von intravenösen Kathetern häufig und können zu lebensbedrohlichen Situationen führen. Sie sind die häufigste Ursache der gefährlichsten nosokomialen Infektion auf Intensivstationen, der Sepsis. Die Prävention basiert auf einem mehrstufigen Konzept, das dem Risikoprofil der Patienten und der Häufigkeit dieser Infektion in einem Krankenhaus Rechnung trägt. Die Richtlinien des Robert-Koch-Instituts sind eine ausgezeichnete Grundlage, ein Präventionsprogramm risikogerecht für eine Klinik zu definieren. Bei Verdacht auf Kathetersepsis kann der Katheter entweder sofort ersetzt oder gezogen und die Katheterspitze ins Labor geschickt werden, bei weniger kritisch Erkrankten können gleichzeitig Blutkulturen aus dem Katheter und aus einer peripheren Vene abgenommen werden. Mittels Ausbildung zur aseptischen Einlage, der korrekten Pflege und Einsatz des richtigen Katheters nach Infusionsbedarf können die Infektionsraten auf weniger als 1 Kathetersepsis pro 1000 Kathetertage gesenkt werden. Nur in Spezialfällen sind mit Antiobiotika oder Antiseptika beschichtete Katheter sinnvoll, dies vor allem bei Transplantierten und Verbrennungspatiente

Atomic structure of Mn wires on Si(001) resolved by scanning tunneling microscopy

At submonolayer coverage, Mn forms atomic wires on the Si(001) surface oriented perpendicular to the underlying Si dimer rows. While many other elements form symmetric dimer wires at room temperature, we show that Mn wires have an asymmetric appearance and pin the Si dimers nearby. We find that an atomic configuration with a Mn trimer unit cell can explain these observations due to the interplay between the Si dimer buckling phase near the wire and the orientation of the Mn trimer. We study the resulting four wire configurations in detail using high-resolution scanning tunneling microscopy (STM) imaging and compare our findings with STM images simulated by density functional theory.Comment: 4 pages, 4 figure

Of field encounters and metropolitan debates. Research and the making and meaning of the Melanesian "race" during demographic decline.

In this article, I trace the significance of Melanesians’ psychological and intellectual capacities for the making and meaning of racial and demographic knowledge from 1900 to 1935. I begin with descriptions of field encounters in the New Hebrides to discuss how knowledge about race and depopulation was collected, and then move to the meanings of the Melanesian race in researchers’ reports of depopulation in the New Hebrides. I conclude with a discussion of how knowledge of Melanesians figured in metropolitan debates on race and demographic decline. For the historiography of ‘race’ or ‘human variation’, depopulation offers an interesting context in which to explore notions of ‘race’ because population decline was recognised to be such a complex issue. Depopulation provided a context in which to debate ‘hybridity’, ‘racial mixing’ and concomitant concepts like heredity, the environment and cultural adaptation. Through an understanding of what Melanesians meant to these researchers in both field encounters and demographic debates, I argue, we can see both the malleability of racial thinking and the intransigence of racial categorisation at that time

Informed Network Coding for Minimum Decoding Delay

Network coding is a highly efficient data dissemination mechanism for wireless networks. Since network coded information can only be recovered after delivering a sufficient number of coded packets, the resulting decoding delay can become problematic for delay-sensitive applications such as real-time media streaming. Motivated by this observation, we consider several algorithms that minimize the decoding delay and analyze their performance by means of simulation. The algorithms differ both in the required information about the state of the neighbors' buffers and in the way this knowledge is used to decide which packets to combine through coding operations. Our results show that a greedy algorithm, whose encodings maximize the number of nodes at which a coded packet is immediately decodable significantly outperforms existing network coding protocols.Comment: Proc. of the IEEE International Conference on Mobile Ad-hoc and Sensor Systems (IEEE MASS 2008), Atlanta, USA, September 200

Effective Delay Control in Online Network Coding

Motivated by streaming applications with stringent delay constraints, we consider the design of online network coding algorithms with timely delivery guarantees. Assuming that the sender is providing the same data to multiple receivers over independent packet erasure channels, we focus on the case of perfect feedback and heterogeneous erasure probabilities. Based on a general analytical framework for evaluating the decoding delay, we show that existing ARQ schemes fail to ensure that receivers with weak channels are able to recover from packet losses within reasonable time. To overcome this problem, we re-define the encoding rules in order to break the chains of linear combinations that cannot be decoded after one of the packets is lost. Our results show that sending uncoded packets at key times ensures that all the receivers are able to meet specific delay requirements with very high probability.Comment: 9 pages, IEEE Infocom 200

Towards Grower-friendly Apple Crop Thinning by Tree Shading

Light management with shading nets, which reduce sunlight by 74%, might be an alternative to chemicals commonly used for thinning on apple trees. To study the effect of shading on crop load and fruit quality, trials were conducted in field experiments with the cultivars Golden Delicious and Elstar in 2006. Trees were either covered 25 days after full bloom (DAFB) with a net during three days, or until the peak of fruit fall, observed after seven days shading. Ideal time length for optimal crop yield was seven days shading for Elstar and three days shading for Golden Delicious. Alternate bearing could be decreased as flower initiation counts the following year showed. In both experiments, inner quality of fruit such as sugar and firmness showed good values at optimal shading duration compared with chemical + hand thinning. In 2007, a second field trial was conducted with cultivars Golden Delicious and Topaz to study the time period for shading in further detail. Shading was done for three days at 19, 26 and 33 DAFB using two net types (three- and two-meter-net width, covering the trees entirely or only down to 50 cm above ground). For Golden Delicious, shading after 19 and 26 days reduced fruits per 100 flower cluster to the same extent as with chemical + hand thinning. There was no difference between the two net types. For Topaz, shading after 19 days showed the best results. Regarding inner quality of both cultivars, only sugar content for Golden Delicious could be significantly improved after 19 and 26 days shading. Further analyses are still under way (e.g. for acidity). This study is part of an effort for increasing European consumption with fruit from sustainable production systems, the ISAFRUIT-EU-project

The potential negative impact of antibiotic pack on antibiotic stewardship in primary care in Switzerland: a modelling study.

BACKGROUND: In Switzerland, oral antibiotics are dispensed in packs rather than by exact pill-count. We investigated whether available packs support compliance with recommended primary care treatment regimens for common infections in children and adults. METHODS: Hospital-based guidelines for oral community -based treatment of acute otitis media, sinusitis, tonsillopharyngitis, community-acquired pneumonia and afebrile urinary tract infection were identified in 2017 in an iterative process by contacting hospital pharmacists and infectious diseases specialists. Furthermore, newly available national guidelines published in 2019 were reviewed. Available pack sizes for recommended solid, dispersible and liquid antibiotic formulations were retrieved from the Swiss pharmaceutical register and compared with recommended regimens to determine optimal (no leftovers) and adequate (optimal +/- one dose) matches. RESULTS: A large variety of recommended regimens were identified. For adults, optimal and adequate packs were available for 25/70 (36%) and 8/70 (11%) regimens, respectively. Pack-regimen matching was better for WHO Watch (optimal: 15/24, 63%) than Access antibiotics (optimal: 7/39, 18%). For the four paediatric weight-examples and 42 regimens involving child-appropriate formulations, optimal and adequate packs were available for only 14/168 (8%) and 27/168 (16%), respectively. Matching was better for older children with higher body and for longer treatment courses > 7 days. CONCLUSIONS: Fixed antibiotic packs often do not match recommended treatment regimens, especially for children, potentially resulting in longer than necessary treatments and leftover doses in the community. As part of national stewardship, a move to an exact pill-count system, including for child-appropriate solid formulations, should be considered

Irreversible reorganization in a supercooled liquid originates from localised soft modes

The transition of a fluid to a rigid glass upon cooling is a common route of transformation from liquid to solid that embodies the most poorly understood features of both phases1,2,3. From the liquid perspective, the puzzle is to understand stress relaxation in the disordered state. From the perspective of solids, the challenge is to extend our description of structure and its mechanical consequences to materials without long range order. Using computer simulations, we show that the localized low frequency normal modes of a configuration in a supercooled liquid are causally correlated to the irreversible structural reorganization of the particles within that configuration. We also demonstrate that the spatial distribution of these soft local modes can persist in spite of significant particle reorganization. The consequence of these two results is that it is now feasible to construct a theory of relaxation length scales in glass-forming liquids without recourse to dynamics and to explicitly relate molecular properties to their collective relaxation.Comment: Published online: 20 July 2008 | doi:10.1038/nphys1025 Available from http://www.nature.com/nphys/journal/v4/n9/abs/nphys1025.htm