Spatially encoded localized wavepackets for ultrafast optical data transfer

Arrays of highly localized wavepackets enable for an efficient multichannel processing of optical data because of their undistorted propagation in space and time domain. Reconfigurable arrangements of supercollimated and temporally nondiffracting few-cycle pulses were generated by microaxicons programmed into the phase map of a liquid-crystal-on-silicon spatial light modulator. As an example, the transfer of quick response code data with few-femtosecond pulses of a Ti:sapphire laser oscillator is reported. Data encoding in beam arrays via maps of temporal and spectral moments is proposed

Oral diabetes medication monotherapy and short-term mortality in individuals with type 2 diabetes and coronary artery disease

Objective To determine whether sulfonylurea use, compared with non-sulfonylurea oral diabetes medication use, was associated with 2-year mortality in individuals with well-controlled diabetes and coronary artery disease (CAD). Research design and methods We studied 5352 US veterans with type 2 diabetes, obstructive CAD on coronary angiography, hemoglobin A1c ≤7.5% at the time of catheterization, and taking zero or one oral diabetes medication (categorized as no medications, non-sulfonylurea medication, or sulfonylurea). We estimated the association between medication category and 2-year mortality using inverse probability of treatment-weighted (IPW) standardized mortality differences and IPW multivariable Cox proportional hazards regression. Results 49%, 35%, and 16% of the participants were on no diabetes medications, non-sulfonylurea medications, and sulfonylureas, respectively. In individuals on no medications, non-sulfonylurea medications, and sulfonylureas, the unadjusted mortality rates were 6.6%, 5.2%, and 11.9%, respectively, and the IPW-standardized mortality rates were 5.9%, 6.5%, and 9.7%, respectively. The standardized absolute 2-year mortality difference between non-sulfonylurea and sulfonylurea groups was 3.2% (95% CI 0.7 to 5.7) (p=0.01). In Cox proportional hazards models, the point estimate suggested that sulfonylurea use might be associated with greater hazard of mortality than non-sulfonylurea medication use, but this finding was not statistically significant (HR 1.38 (95% CI 1.00 to 1.93), p=0.05). We did not observe significant mortality differences between individuals on no diabetes medications and non-sulfonylurea users. Conclusions Sulfonylurea use was common (nearly one-third of those taking medications) and was associated with increased 2-year mortality in individuals with obstructive CAD. The significance of the association between sulfonylurea use and mortality was attenuated in fully adjusted survival models. Caution with sulfonylurea use may be warranted for patients with well-controlled diabetes and CAD, and metformin or newer diabetes medications with cardiovascular safety data could be considered as alternatives when individualizing therapy

Photo‐biocatalytic Cascades:Combining Chemical and Enzymatic Transformations Fueled by Light

In the field of green chemistry, light – an attractive natural agent – has received particular attention for driving biocatalytic reactions. Moreover, the implementation of light to drive (chemo)enzymatic cascade reactions opens up a golden window of opportunities. However, there are limitations to many current examples, mostly associated with incompatibility between the enzyme and the photocatalyst. Additionally, the formation of reactive radicals upon illumination and the loss of catalytic activities in the presence of required additives are common observations. As outlined in this review, the main question is how to overcome current challenges to the exploitation of light to drive (chemo)enzymatic transformations. First, we highlight general concepts in photo-biocatalysis, then give various examples of photo-chemoenzymatic (PCE) cascades, further summarize current synthetic examples of PCE cascades and discuss strategies to address the limitations

Thermoelectric Response of an Interacting Two-Dimensional Electron Gas in Quantizing Magnetic Field

We present a discussion of the linear thermoelectric response of an interacting electron gas in a quantizing magnetic field. Boundary currents can carry a significant fraction of the net current passing through the system. We derive general expressions for the bulk and boundary components of the number and energy currents. We show that the local current density may be described in terms of ``transport'' and ``internal magnetization'' contributions. The latter carry no net current and are not observable in standard transport experiments. We show that although Onsager relations cannot be applied to the local current, they are valid for the transport currents and hence for the currents observed in standard transport experiments. We relate three of the four thermoelectric response coefficients of a disorder-free interacting two-dimensional electron gas to equilibrium thermodynamic quantities. In particular, we show that the diffusion thermopower is proportional to the entropy per particle, and we compare this result with recent experimental observations.Comment: 18 pages, 2 postscript figures included. Revtex with epsf.tex and multicol.sty. In the revised version, the comparison with experimental observations at $\nu=1/2, 3/2$ is extended to include the possibility of corrections due to weak impurity scattering. The conclusions that we reach regarding the applicability of the composite fermion model at these filling fractions are not affecte

First measurement of the Non-instantaneous response Time of a χ(3) nonlinear optical effect

The third harmonic of a few-cycle pulse, generated at different dielectric surfaces, is investigated using interferometric frequency-resolved optical gating. We present direct experimental evidence for a non-instantaneous nonlinear response in a TiO2 thin film whereas surface third-harmonic generation in a SiO2 sample does not show any indication for non-instanteneity. To the best of our knowledge, this constitutes the first report of a non-instantaneous nonlinear optical response of a dielectric optical material

Einfluss von separater und kombinierter Einarbeitung von Gülle und Biokohle auf die Bildung von Makroaggregaten bei konstanter und variierender Bodenfeuchte

Organische Bodenzusatzstoffe können einen positiven Einfluss auf die Bildung von Makroaggregaten (>250 µm) im Boden haben was sich wiederum positiv auf die Kohlenstoffspeicherung auswirkt. Die diesbezüglichen Effekte von Gülle und Biokohle sowie der Bodenfeuchte sind aber weitestgehend unbekannt. Ziel dieser Studie war daher zu klären, welchen Einfluss die separate und kombinierte Einarbeitung von Gülle und Biokohle auf die Bildung von Makroaggregaten unter konstanter und variierender Bodenfeuchte haben. Hierfür wurden vier schluffig-lehmige Böden beprobt und anschließend die Makroaggregate zerstört. Die Proben wurden dann bei 15 °C für 60 Tage bei konstanter Bodenfeuchte und drei Trocknungs-Wiederbefeuchtungszyklen und nach Einarbeitung der folgenden Gülle- (in kg N ha-1) und Biokohlegaben (in % der Bodentrockenmasse) inkubiert: Kontrolle, Biokohle (12), Gülle (150), Biokohle (6) + Gülle (75), Biokohle (12) + Gülle (75), Biokohle (6) + Gülle (150) und Biokohle (12) + Gülle (150). Im Verlauf der Inkubation wurden die CO2 Emission gemessen und nach Abschluss des Experimentes die mikrobielle Biomasse bestimmt. Anschließend wurden die Makroaggregate abgetrennt und hinsichtlich ihres Kohlenstoffgehaltes analysiert. Die Makroaggregate der Biokohlevarianten mit und ohne zusätzlicher Gülleeinbringung wiesen gleiche oder höhere Kohlenstoffgehalte im Vergleich zur Kontrolle und der Variante mit separater Gülleeinbringung auf was auf einen Einschluss von Biokohle in diese Aggregate hindeutet. Die Trocknung und Wiederbefeuchtung der Proben resultierte in geringeren Mengen an Makroaggregaten was besonders für die Böden zutraf in denen Biokohle und Gülle eingebracht wurde. Die Trocknung der Gülle scheint einen irreversiblen negativen Effekt auf deren Aggregierungswirkung zu haben, was zu einer Abnahme in den Makroaggregaten im Vergleich zu den Proben führt, die bei konstanter Bodenfeuchte inkubiert wurden. Darüber hinaus deuten die geringere mikrobielle Biomasse und CO2 Emissionen für die Proben unter variierender Bodenfeuchte auf eine geringere mikrobielle Aktivität und Eintrag mikrobieller Aggregatbildner hin. Neben Menge und Typ der organischen Bodenzusatzstoffe scheinen auch klimatisch bedingte Unterschiede in der Bodenfeuchte einen Einfluss auf die Bildung und Stabilität von Makroaggregaten im Boden zu haben

Converging Technologies, Shifting Boundaries

No abstrac

Action research and democracy

This contribution explores the relationship between research and learning democracy. Action research is seen as being compatible with the orientation of educational and social work research towards social justice and democracy. Nevertheless, the history of action research is characterized by a tension between democracy and social engineering. In the social-engineering approach, action research is conceptualized as a process of innovation aimed at a specific Bildungsideal. In a democratic approach action research is seen as research based on cooperation between research and practice. However, the notion of democratic action research as opposed to social engineering action research needs to be theorized. So called democratic action research involving the implementation by the researcher of democracy as a model and as a preset goal, reduces cooperation and participation into instruments to reach this goal, and becomes a type of social engineering in itself. We argue that the relationship between action research and democracy is in the acknowledgment of the political dimension of participation: ‘a democratic relationship in which both sides exercise power and shared control over decision-making as well as interpretation’. This implies an open research design and methodology able to understand democracy as a learning process and an ongoing experiment

Probabilistic Anonymity

The concept of anonymity comes into play in a wide range of situations, varying from voting and anonymous donations to postings on bulletin boards and sending mails. A formal definition of this concept has been given in literature in terms of nondeterminism. In this paper, we investigate a notion of anonymity based on probability theory, and we we discuss the relation with the nondeterministic one. We then formulate this definition in terms of observables for processes in the probabilistic $pi$-calculus, and propose a method to verify automatically the anonymity property. We illustrate the method by using the example of the dining cryptographers