606 research outputs found
Fast high--voltage amplifiers for driving electro-optic modulators
We describe five high-voltage (60 to 550V peak to peak), high-speed (1-300ns
rise time; 1.3-300MHz bandwidth) linear amplifiers for driving capacitive or
resistive loads such as electro-optic modulators. The amplifiers use bipolar
transistors in various topologies. Two use electron tubes to overcome the speed
limitations of high-voltage semiconductors. All amplifiers have been built.
Measured performance data is given for each.Comment: 9pages, 6figures, 6tables, to appear in Review of Scientific
Instrument
Echnatons âMonotheismusâ â Rezeptionen Amarnas in den Wissenschaften
Positions on Akhenaton in the history of humanities are the topic of this contribution that analyses patterns of constructing Akhenaton mainly as prehistory of Christian monotheism. Egyptologists like H. Brugsch, A. Erman, S. Morenz, J. Assmann, phenomenologists of religion as G. van der Leeuw, F. Heiler and finally Sigmund Freud are part of this adaptation history. It can be seen also as part of the concept of a âEuropean history of religionâ (Burkhard Gladigow) that includes also science as productive force of normativity, world views and ideology
Experimental and numerical investigation of dropletâfiber interaction on mechanically excited fiber
Justice at Sea: Fishersâ politics and marine conservation in coastal Odisha, India
This is a paper about the politics of fishing rights in and around the Gahirmatha marine sanctuary in coastal Odisha, in eastern India. Claims to the resources of this sanctuary are politicised through the creation of a particularly damaging narrative by influential Odiya environmental actors about Bengalis, as illegal immigrants who have hurt the ecosystem through their fishing practices. Anchored within a theoretical framework of justice as recognition, the paper considers the making of a regional Odiya environmentalism that is, potentially, deeply exclusionary. It details how an argument about âillegal Bengalisâ depriving âindigenous Odiyasâ of their legitimate âtraditional fishing rightsâ derives from particular notions of indigeneity and territory. But the paper also shows that such environmentalism is tenuous, and fits uneasily with the everyday social landscape of fishing in coastal Odisha. It concludes that a wider class conflict between small fishers and the state over a sanctuary sets the context in which questions about legitimate resource rights are raised, sometimes with important effects, like when out at sea
Integrated multidimensional sustainability assessment of energy system transformation pathways
Sustainable development embraces a broad spectrum of social, economic and ecological aspects. Thus, a sustainable transformation process of energy systems is inevitably multidimensional and needs to go beyond climate impact and cost considerations. An approach for an integrated and interdisciplinary sustainability assessment of energy system transformation pathways is presented here. It first integrates energy system modeling with a multidimensional impact assessment that focuses on life cycle-based environmental and macroeconomic impacts. Then, stakeholdersâ preferences with respect to defined sustainability indicators are inquired, which are finally integrated into a comparative scenario evaluation through a multi-criteria decision analysis (MCDA), all in one consistent assessment framework. As an illustrative example, this holistic approach is applied to the sustainability assessment of ten different transformation strategies for Germany. Applying multi-criteria decision analysis reveals that both ambitious (80%) and highly ambitious (95%) carbon reduction scenarios can achieve top sustainability ranks, depending on the underlying energy transformation pathways and respective scores in other sustainability dimensions. Furthermore, this research highlights an increasingly dominant contribution of energy systemsâ upstream chains on total environmental impacts, reveals rather small differences in macroeconomic effects between different scenarios and identifies the transition among societal segments and climate impact minimization as the most important stakeholder preferences
The Computational Complexity of Knot and Link Problems
We consider the problem of deciding whether a polygonal knot in 3-dimensional
Euclidean space is unknotted, capable of being continuously deformed without
self-intersection so that it lies in a plane. We show that this problem, {\sc
unknotting problem} is in {\bf NP}. We also consider the problem, {\sc
unknotting problem} of determining whether two or more such polygons can be
split, or continuously deformed without self-intersection so that they occupy
both sides of a plane without intersecting it. We show that it also is in NP.
Finally, we show that the problem of determining the genus of a polygonal knot
(a generalization of the problem of determining whether it is unknotted) is in
{\bf PSPACE}. We also give exponential worst-case running time bounds for
deterministic algorithms to solve each of these problems. These algorithms are
based on the use of normal surfaces and decision procedures due to W. Haken,
with recent extensions by W. Jaco and J. L. Tollefson.Comment: 32 pages, 1 figur
Molecularly defined diffuse leptomeningeal glioneuronal tumor (DLGNT) comprises two subgroups with distinct clinical and genetic features
Diffuse leptomeningeal glioneuronal tumors (DLGNT) represent rare CNS neoplasms which have been included in the 2016 update of the WHO classification. The wide spectrum of histopathological and radiological features can make this enigmatic tumor entity difficult to diagnose. In recent years, large-scale genomic and epigenomic analyses have afforded insight into key genetic alterations occurring in multiple types of brain tumors and provide unbiased, complementary tools to improve diagnostic accuracy. Through genome-wide DNA methylation screening of > 25,000 tumors, we discovered a molecularly distinct class comprising 30 tumors, mostly diagnosed histologically as DLGNTs. Copy-number profiles derived from the methylation arrays revealed unifying characteristics, including loss of chromosomal arm 1p in all cases. Furthermore, this molecular DLGNT class can be subdivided into two subgroups [DLGNT methylation class (MC)-1 and DLGNT methylation class (MC)-2], with all DLGNT-MC-2 additionally displaying a gain of chromosomal arm 1q. Co-deletion of 1p/19q, commonly seen in IDH-mutant oligodendroglioma, was frequently observed in DLGNT, especially in DLGNT-MC-1 cases. Both subgroups also had recurrent genetic alterations leading to an aberrant MAPK/ERK pathway, with KIAA1549:BRAF fusion being the most frequent event. Other alterations included fusions of NTRK1/2/3 and TRIM33:RAF1, adding up to an MAPK/ERK pathway activation identified in 80% of cases. In the DLGNT-MC-1 group, age at diagnosis was significantly lower (median 5 vs 14 years, p < 0.01) and clinical course less aggressive (5-year OS 100, vs 43% in DLGNT-MC-2). Our study proposes an additional molecular layer to the current histopathological classification of DLGNT, of particular use for cases without typical morphological or radiological characteristics, such as diffuse growth and radiologic leptomeningeal dissemination. Recurrent 1p deletion and MAPK/ERK pathway activation represent diagnostic biomarkers and therapeutic targets, respectivelyâlaying the foundation for future clinical trials with, e.g., MEK inhibitors that may improve the clinical outcome of patients with DLGNT
The use effectiveness of the copper T-200 in Matlab, Bangladesh
Using a unique record keeping system, the use effectiveness of the Copper T-200 is examined in rural Bangladesh. In Matlab the Copper T-200 is a highly effective contraceptive modality. The adopters are typically low to medium parity women under 30 years of age. The most important cause of termination among women in the study was voluntary removal of the device. The complaint most often reported was bleeding followed by pain and weakness. The Matlab experience suggests that sustained motivation and regular resupply are the two key components of this highly successful family planning program.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26626/1/0000167.pd
Improved high-fidelity transport of trapped-ion qubits through a multi-dimensional array
We have demonstrated transport of Be+ ions through a 2D Paul-trap array that
incorporates an X-junction, while maintaining the ions near the motional
ground-state of the confining potential well. We expand on the first report of
the experiment [1], including a detailed discussion of how the transport
potentials were calculated. Two main mechanisms that caused motional excitation
during transport are explained, along with the methods used to mitigate such
excitation. We reduced the motional excitation below the results in Ref. [1] by
a factor of approximately 50. The effect of a mu-metal shield on qubit
coherence is also reported. Finally, we examined a method for exchanging energy
between multiple motional modes on the few-quanta level, which could be useful
for cooling motional modes without directly accessing the modes with lasers.
These results establish how trapped ions can be transported in a large-scale
quantum processor with high fidelity.Comment: 16 page
Apparent Alkyl Transfer and Phenazine Formation via an Aryne Intermediate
Treatment of chlorotriaryl derivatives 3a and 3d or fluorotriaryl derivatives 3b and 3e with potassium diisopropylamide afforded alkyl-shifted phenazine derivatives 5a/5b, rather than the expected 9-membered triazaorthocyclophane 2a. The phenazine derivatives were isolated in 78â98% yield depending on the halogen and alkyl group present. In the absence of the halogen (chloro or fluoro), the apparent alkyl shift proceeds more slowly and cannot proceed via the intermediacy of the aryne intermediate. Mechanistic possibilities include intramolecular nucleophilic attack on an aryne intermediate leading to a zwitterionic intermediate and alkyl transfer via a 5-endo-tet process, or via a Smiles rearrangement
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