Tunneling induced electron transfer between separated protons

We study electron transfer between two separated nuclei using local control theory. By conditioning the algorithm in a symmetric system formed by two protons, one can favored slow transfer processes, where tunneling is the main mechanism, achieving transfer efficiencies close to unity assuming fixed nuclei. The solution can be parametrized using sequences of pump and dump pi pulses, where the pump pulse is used to excite the electron to a highly excited state where the time for tunneling to the target nuclei is on the order of femtoseconds. The time delay must be chosen to allow for full population transfer via tunneling, and the dump pulse is chosen to remove energy from the state to avoid tunneling back to the original proton. Finally, we study the effect of the nuclear kinetic energy on the transfer efficiency. Even in the absence of relative motion between the protons, the spreading of the nuclear wave function is enough to reduce the yield of electronic transfer to less than one half.Comment: 7 pages, 8 figure

Mapping Invasive Giant Goldenrod (Solidago gigantea) with Multispectral Images Acquired by Unmanned Aerial Vehicle

Invasive alien species are one of the main threats to worldwide biodiversity loss. Unmanned aerial vehicles with multispectral sensors offer a cost-effective alternative to monitor invasive plant species at a centimetre scale. Giant Goldenrod (Solidago gigantea) is one of the most problematic invasive alien plant species in Switzerland and controlling this species – especially in nature protection areas – is a priority. In this study, a methodology is developed to detect the Giant Goldenrod coverage via unmanned aerial vehicle (UAV) equipped with multispectral sensors. Very high resolution maps (6.5 cm) are produced and high accuracy is achieved for the classification of the Giant Goldenrod coverage with a kappa coefficient of 0.902 and an overall accuracy of 92.12%. These results indicate that UAV equipped with multispectral sensors is a valuable tool in monitoring and combatting invasive alien species

Discerning the spatio-temporal disease patterns of surgically induced OA mouse models

Osteoarthritis (OA) is the most common cause of disability in ageing societies, with no effective therapies available to date. Two preclinical models are widely used to validate novel OA interventions (MCL-MM and DMM). Our aim is to discern disease dynamics in these models to provide a clear timeline in which various pathological changes occur. OA was surgically induced in mice by destabilisation of the medial meniscus. Analysis of OA progression revealed that the intensity and duration of chondrocyte loss and cartilage lesion formation were significantly different in MCL-MM vs DMM. Firstly, apoptosis was seen prior to week two and was narrowly restricted to the weight bearing area. Four weeks post injury the magnitude of apoptosis led to a 40–60% reduction of chondrocytes in the non-calcified zone. Secondly, the progression of cell loss preceded the structural changes of the cartilage spatio-temporally. Lastly, while proteoglycan loss was similar in both models, collagen type II degradation only occurred more prominently in MCL-MM. Dynamics of chondrocyte loss and lesion formation in preclinical models has important implications for validating new therapeutic strategies. Our work could be helpful in assessing the feasibility and expected response of the DMM- and the MCL-MM models to chondrocyte mediated therapies

Linguistische Korpora im Spanischunterricht. Eine didaktische Exploration.

Die Arbeit mit Sprachkorpora als Datenbanken mit realen Sprachzeugnissen ist kein neuer Forschungsansatz. Korpora werden seit geraumer Zeit in der sprachwissenschaftlichen Forschung verwendet, um neue Erkenntnisse über den Sprachgebrauch spanischer Muttersprachler zu gewinnen – in den Unterricht haben sie allerdings noch kaum Einzug gehalten. Viel zu selten werden reale Texte in den Spanischunterricht eingebunden und die Mehrheit der Übungen und Texte in Lehrwerken wurde von Lehrbuchautoren frei erfunden oder stark redigiert und gekürzt. Um den Lernenden den tatsächlichen Sprachgebrauch näher zu bringen, ist die vermehrte Verwendung von muttersprachlichem Material unabdinglich. Die Sprachkorpora sind – was ihre Handhabung, ihren Aufbau und das darin enthaltene Sprachmaterial anbelangt – keineswegs zu kompliziert, um sie auf die universitäre Forschung zu beschränken. Korpora fördern selbstständiges und individuelles Lernen anhand realer Sprachdaten und bieten daher mindestens zwei Motivationsfaktoren für Schüler - selbstreguliertes Lernen und Ansporn durch den Umgang mit muttersprachlichem Material. Anhand der Texte und Konkordanzen der Korpora können Schüler selbstständig ihre Sprachkenntnisse überprüfen und Ideen für die eigene Sprachproduktion sammeln. Sie verstehen Zusammenhänge zwischen Lexemen wie Kollokationen, Synonyme und Phraseologismen, und ermitteln die relative Häufigkeit, mit welcher bestimmte Ausdrücke von Muttersprachlern verwendet werden. Jedoch nicht nur das Vokabular, sondern auch das Wissen über grammatikalische Strukturen und Aussprachebesonderheiten können mithilfe von Korpora erweitert sowie das Textverständnis und die Landeskunde geschult werden. Im Bereich des Englischunterrichts ist die Korpuslinguistik schon seit längerer Zeit etabliert und ermöglicht den Schülern anhand realer Daten aus englischen Korpora die Fremdsprache so zu erlernen, wie diese von Muttersprachlern gesprochen wird. Ziel dieser Dissertation war es nun, eine Übersicht über die derzeit verfügbaren Korpora der spanischen Sprache zu geben, die Funktionen der bislang existierenden Korpora sowie deren Vor- und Nachteile zu beschreiben, die spanischen Sprachkorpora auf deren Nutzbarkeit für den Unterricht zu überprüfen, Möglichkeiten und Grenzen für deren Anwendung im Unterricht aufzuzeigen und anhand konkreter Beispiele die Verwendung im Unterricht zu exemplifizieren. Zudem wurde exemplarisch ein Spezialkorpus aus Lehrbuchtexten entwickelt, anhand dessen zum einen die Erstellung eines eigenen Korpus und zum anderen dessen Nutzungsmöglichkeiten für den Spanischunterricht veranschaulicht werden konnten

Phylogenetic distribution and membrane topology of the LytR-CpsA-Psr protein family

BACKGROUND: The bacterial cell wall is the target of many antibiotics and cell envelope constituents are critical to host-pathogen interactions. To combat resistance development and virulence, a detailed knowledge of the individual factors involved is essential. Members of the LytR-CpsA-Psr family of cell envelope-associated attenuators are relevant for beta-lactam resistance, biofilm formation, and stress tolerance, and they are suggested to play a role in cell wall maintenance. However, their precise function is still unknown. This study addresses the occurrence as well as sequence-based characteristics of the LytR-CpsA-Psr proteins. RESULTS: A comprehensive list of LytR-CpsA-Psr proteins was established, and their phylogenetic distribution and clustering into subgroups was determined. LytR-CpsA-Psr proteins were present in all Gram-positive organisms, except for the cell wall-deficient Mollicutes and one strain of the Clostridiales. In contrast, the majority of Gram-negatives did not contain LytR-CpsA-Psr family members. Despite high sequence divergence, the LytR-CpsA-Psr domains of different subclusters shared a highly similar, predicted mixed alpha/beta-structure, and conserved charged residues. PhoA fusion experiments, using MsrR of Staphylococcus aureus, confirmed membrane topology predictions and extracellular location of its LytR-CpsA-Psr domain. CONCLUSIONS: The LytR-CpsA-Psr domain is unique to bacteria. The presence of diverse subgroups within the LytR-CpsA-Psr family might indicate functional differences, and could explain variations in phenotypes of respective mutants reported. The identified conserved structural elements and amino acids are likely to be important for the function of the domain and will help to guide future studies of the LytR-CpsA-Psr proteins

Induction kinetics of the Staphylococcus aureus cell wall stress stimulon in response to different cell wall active antibiotics

BACKGROUND: Staphylococcus aureus activates a protective cell wall stress stimulon (CWSS) in response to the inhibition of cell wall synthesis or cell envelope damage caused by several structurally and functionally different antibiotics. CWSS induction is coordinated by the VraSR two-component system, which senses an unknown signal triggered by diverse cell wall active agents. RESULTS: We have constructed a highly sensitive luciferase reporter gene system, using the promoter of sas016 (S. aureus N315), which detects very subtle differences in expression as well as measuring > 4 log-fold changes in CWSS activity, to compare the concentration dependence of CWSS induction kinetics of antibiotics with different cell envelope targets. We compared the effects of subinhibitory up to suprainhibitory concentrations of fosfomycin, D-cycloserine, tunicamycin, bacitracin, flavomycin, vancomycin, teicoplanin, oxacillin, lysostaphin and daptomycin. Induction kinetics were both strongly antibiotic- and concentration-dependent. Most antibiotics triggered an immediate response with induction beginning within 10 min, except for tunicamycin, D-cycloserine and fosfomycin which showed lags of up to one generation before induction commenced. Induction characteristics, such as the rate of CWSS induction once initiated and maximal induction reached, were strongly antibiotic dependent. We observed a clear correlation between the inhibitory effects of specific antibiotic concentrations on growth and corresponding increases in CWSS induction kinetics. Inactivation of VraR increased susceptibility to the antibiotics tested from 2- to 16-fold, with the exceptions of oxacillin and D-cycloserine, where no differences were detected in the methicillin susceptible S. aureus strain background analysed. There was no apparent correlation between the induction capacity of the various antibiotics and the relative importance of the CWSS for the corresponding resistance phenotypes. CONCLUSION: CWSS induction profiles were unique for each antibiotic. Differences observed in optimal induction conditions for specific antibiotics should be determined and taken into account when designing and interpreting CWSS induction studies

Accelerated Partial Breast Irradiation: Using the CyberKnife as the Radiation Delivery Platform in the Treatment of Early Breast Cancer

We evaluate the CyberKnife (Accuray Incorporated, Sunnyvale, CA, USA) for non-invasive delivery of accelerated partial breast irradiation (APBI) in early breast cancer patients. Between 6/2009 and 5/2011, nine patients were treated with CyberKnife APBI. Normal tissue constraints were imposed as outlined in the National Surgical Adjuvant Breast and Bowel Project B-39/Radiation Therapy Oncology Group 0413 (NSABP/RTOG) Protocol (Vicini and White, 2007). Patients received a total dose of 30 Gy in five fractions (group 1, n = 2) or 34 Gy in 10 fractions (group 2, n = 7) delivered to the planning treatment volume (PTV) defined as the clinical target volume (CTV) +2 mm. The CTV was defined as either the lumpectomy cavity plus 10 mm (n = 2) or 15 mm (n = 7). The cavity was defined by a T2-weighted non-contrast breast MRI fused to a planning non-contrast thoracic CT. The CyberKnife Synchrony system tracked gold fiducials sutured into the cavity wall during lumpectomy. Treatments started 4–5 weeks after lumpectomy. The mean PTV was 100 cm3 (range, 92–108 cm3) and 105 cm3 (range, 49–241 cm3) and the mean PTV isodose prescription line was 70% for groups 1 and 2, respectively. The mean percent of whole breast reference volume receiving 100 and 50% of the dose (V100 and V50) for group 1 was 11% (range, 8–13%) and 23% (range, 16–30%) and for group 2 was 11% (range, 7–14%) and 26% (range, 21–35.0%), respectively. At a median 7 months follow-up (range, 4–26 months), no acute toxicities were seen. Acute cosmetic outcomes were excellent or good in all patients; for those patients with more than 12 months follow-up the late cosmesis outcomes were excellent or good. In conclusion, the lack of observable acute side effects and current excellent/good cosmetic outcomes is promising. We believe this suggests the CyberKnife is a suitable non-invasive radiation platform for delivering APBI with achievable normal tissue constraints

Unveiling electrotransformation of Moraxella catarrhalis as a process of natural transformation

The human respiratory tract pathogen Moraxella catarrhalis is a naturally competent microorganism. However, electrotransformation has long been used to introduce foreign DNA into this organism. This study demonstrated that electrotransformants obtained with linear or circular nonreplicating plasmid DNA originated exclusively from natural transformation processes taking place during the recovery phase after the application of current. Only replicating plasmid DNA could be introduced into M. catarrhalis by electrotransformation, in a type IV pilus-independent manner. Electrotransformation with homologous genomic DNA indicated that restriction of double-stranded DNA was independent of type III restriction-methylation systems. Nontransformability of M. catarrhalis by electrotransformation was observed using double- as well as single-stranded DNA. In addition, the study showed that natural competence is a very constant feature of M. catarrhali

Impulsive alignment of 4He-CH3I: a theoretical study

We simulate the non-adiabatic laser alignment of the weakly bound 4He-CH3I complex based on a quantum mechanical wave packet calculation for a model He-CH3I interaction potential. Two different regimes are found depending on the laser intensity. At intensities typical of non-adiabatic alignment experiments, the rotational dynamics resembles that of the isolated molecule. This is attributed to the fact that after the initial prompt alignment peak the complex rapidly dissociates. The subsequent revival pattern is due to the free rotation of the molecule detached from the helium atom. It is superimposed to a flat background corresponding to ∼20% of the wave packet which remains bound, containing lower rotational excitation. At lower intensities, dissociation is avoided but the rotational excitation is not high enough to provide an efficient alignment and a broad non-regular structure is observed. Besides, the interaction of the He atom with the molecule quenches any possible alignment. These interpretations are based on the calculation of different observables related to the rotational motion. We compare our findings with recent experimental and theoretical results of non-adiabatic alignment of linear molecules solvated in helium nanodroplets or weakly interacting with one helium atom