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Search Results: 1 - 10 of 401320 matches for " M. Rohling "
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Sensitivity of Red Sea circulation to sea level and insolation forcing during the last interglacial
G. Trommer,M. Siccha,E. J. Rohling,K. Grant
Climate of the Past Discussions , 2011, DOI: 10.5194/cpd-7-1195-2011
Abstract: This study investigates the response of Red Sea circulation to sea level and insolation changes during termination II and across the last interglacial, in comparison with termination I and the Holocene. Sediment cores from the central and northern part of the Red Sea were investigated by micropaleontological and geochemical proxies. The recovery of the planktonic foraminiferal fauna following high salinities during MIS 6 took place at similar sea-level stand (~50 m below present day), and with a similar species succession, as during termination I. This indicates a consistent sensitivity of the basin oceanography and the plankton ecology to sea-level forcing. Based on planktonic foraminifera, we find that increased water exchange with the Gulf of Aden especially occurred during the sea-level highstand of interglacial MIS 5e. From MIS 6 to the peak of MIS 5e, northern Red Sea SST increased from 21 °C to 25 °C, with about 3 °C of this increase taking place during termination II. Changes in planktonic foraminiferal assemblages indicate that the development of the Red Sea oceanography during MIS 5 was strongly determined by insolation and monsoon strength. The SW Monsoon summer circulation mode was enhanced during the termination, causing low productivity in northern central Red Sea core KL9, marked by high abundance of G. sacculifer, which – as in the Holocene – followed summer insolation. Core KL11 records the northern tip of the intruding intermediate water layer from the Gulf of Aden and its planktonic foraminifera fauna shows evidence for elevated productivity during the sea-level highstand in the southern central Red Sea. By the time of MIS 5 sea-level regression, elevated organic biomarker BIT values suggest denudation of soil organic matter into the Red Sea and high abundances of G. glutinata, and high reconstructed chlorophyll-a values, indicate an intensified NE Monsoon winter circulation mode. Our results imply that the amplitude of insolation fluctuations, and the resulting monsoon strength, strongly influence the Red Sea oceanography during sea-level highstands by regulating the intensity of water exchange with the Gulf of Aden. These processes are responsible for the observation that MIS 5e/d is characterized by higher primary productivity than the Holocene.
Patterns of millennial variability over the last 500 ka
M. Siddall,E. J. Rohling,T. Blunier,R. Spahni
Climate of the Past Discussions , 2010,
Abstract: Millennial variability is a robust feature of many paleoclimate records, at least throughout the last several glacial cycles. Here we use the signal from an Antarctic climate event to probe the EPICA Dome C temperature proxy reconstruction through the last 500 ka for similar millennial-scale events. We find that clusters of millennial events occurred in a regular fashion over half of the time during this with a mean recurrence interval of 21 kyr. We find that there is no consistent link between ice-rafted debris deposition and millennial variability. Instead we speculate that changes in the zonality of atmospheric circulation over the North Atlantic form a viable alternative to freshwater release from icebergs as a trigger for millennial variability. We suggest that millennial changes in the zonality of atmospheric circulation over the North Atlantic are linked to precession and that this relationship is modified by the presence of the large, Northern Hemisphere ice sheets during glacial periods.
Locke e a doutrina do direito de resistência
Marcos Rohling
PERI , 2012,
Abstract: Locke é um dos mais influentes pensadores do ocidente. à luz da produ o teórica que seus predecessores medievais e modernos deixaram, formulou uma instigante teoria acerca da origem da autoridade e da sociedade políticas bem como do direito de resistência que assiste aos cidad os. é precisamente acerca deste conceito que se trata esse artigo. Locke estabelece que, sendo a sociedade política formada a partir do pacto voluntário e que, uma vez que o soberano n o cumpra com a sua parte, os cidad os têm, coletivamente, o direito de resistência. Eis que o direito de resistência n o se assenta, desse modo, no direito subjetivo de resistir, mas no direito natural, o qual pode ser conhecido pela raz o, tendo em vista coincidir com as normas morais intersubjetivas.
Lex Humana , 2012,
Abstract: Resumo: A obra de Rawls é, certamente, um manancial de possibilidades e interpreta es, no contexto da filosofia contemporanea. Dworkin, do mesmo modo, é um dos mais notáveis pensadores do direito. A propósito das críticas que sofreu Rawls de que teria dado pouco tratamento ao direito, Dworkin procura interpretar as principais contribui es do filósofo de Harvard à filosofia do direito. Nesse ínterim, confrontando o positivismo jurídico e o interpretativismo, sustenta que a teoria de Rawls estaria inclinada a recepcionar mais uma teoria do direito interpretativista do que uma positivista. Assim, o artigo apresenta a interpreta o de Rawls como um filósofo jurídico levada a efeito por Dworkin avaliando se, realmente, a teoria de Rawls é mais compatível com o positivismo jurídico ou com o interpretativismo.Abstract: Rawls's work is certainly a walth of possibilities and interpretations in context of contemporary philosophy. Dworkin, likewise, is the most remarkable thinkers law. The purpose of the criticisms that Rawls suffered that would have given slightly treatment to law, Dworkin seeks to interpret the main contributioins of the Harvard philosopher to legal philosophy.Meanwhile, confronting legal positivism and interpretativism, argues that Rawls’s theory would be more inclined to greet an interpretive theory of Law than a positivist. Thus, this paper presents the interpretation of Rawls as a legal philosopher carried out by Dworkin assessing whether, indeed, Rawls’s theory is more compatible with legal positivism or with interpretativism.
Universal Quantum Computing with Spin and Valley
Niklas Rohling,Guido Burkard
Physics , 2012, DOI: 10.1088/1367-2630/14/8/083008
Abstract: We investigate a two-electron double quantum dot with both spin and valley degrees of freedom as they occur in graphene, carbon nanotubes, or silicon, and regard the 16-dimensional space with one electron per dot as a four-qubit logic space. In the spin-only case, it is well known that the exchange coupling between the dots combined with arbitrary single-qubit operations is sufficient for universal quantum computation. The presence of the valley degeneracy in the electronic band structure alters the form of the exchange coupling and in general leads to spin-valley entanglement. Here, we show that universal quantum computation can still be performed by exchange interaction and single-qubit gates in the presence of the additional (valley) degree of freedom. We present an explicit pulse sequence for a spin-only controlled-NOT consisting of the generalized exchange coupling and single-electron spin and valley rotations. We also propose state preparations and projective measurements with the use of adiabatic transitions between states with (1,1) and (0,2) charge distributions similar to the spin-only case, but with the additional requirement of controlling the spin and the valley Zeeman energies by an external magnetic field. Finally, we demonstrate a universal two-qubit gate between a spin and a valley qubit, allowing universal gate operations on the combined spin and valley quantum register.
Optimization of electron pumping by harmonic mixing
Niklas Rohling,Frank Grossmann
Physics , 2010, DOI: 10.1103/PhysRevB.83.205310
Abstract: For a symmetric bridge coupled to infinite leads, in the presence of a dipole-coupled external ac-field with harmonic mixing, we solve the Schr\"odinger equation in the time-domain using open boundary conditions as well as in the energy-domain using Floquet scattering theory. As this potential breaks parity and generalized parity, we find a non-vanishing average current. We then optimize the relative amplitude ratio between the fundamental and the second harmonic leading to a maximum in the pump current.
Optimizing electrically controlled echo sequences for the exchange-only qubit
Niklas Rohling,Guido Burkard
Physics , 2015,
Abstract: Recently, West and Fong [New J. Phys. 14, 083002 (2012)] introduced an echo scheme for an exchange-only qubit, which relies entirely on the exchange-interaction. Here, we compare two different exchange-based sequences and two optimization strategies, Uhrig dynamical decoupling (UDD) and optimized filter function dynamical decoupling (OFDD), which were introduced for a single-spin qubit and are applied in this paper to the three-spin exchange-only qubit. The calculation shows that the adaption of the optimization concepts can be achieved by straight-forward calculation. We consider two types of noise spectra, Lorentzian and Ohmic noise. For both spectra, the results reveal a slight dependence of the performance on the choice of the echo sequence.
Tomography scheme for two spin-1/2 qubits in a double quantum dot
Niklas Rohling,Guido Burkard
Physics , 2013, DOI: 10.1103/PhysRevB.88.085402
Abstract: We present a scheme for full quantum state tomography tailored for two spin qubits in a double quantum dot. A set of 15 quantum states allows to determine the density matrix in this two-qubit space by projective measurement. In this paper we choose a set gained from mutually unbiased bases. We determine how those 15 projections can be represented by charge measurements after a spin-to-charge conversion and the application of quantum gates. The quantum gates include exchange-based gates as well as rotations by electron spin resonance (ESR). We assume the experimental realization of ESR operations to be more difficult than the exchange gate operation. Therefore, it is an important result that the ESR gates are limited by a pi/2 rotation for one of the electron spins per measurement.

He You,Hermann Rohling,
,Hermann Rohling

电子与信息学报 , 1994,
Abstract: This paper presents two generalized modified OS-CFAR detectors and an automatic censoring technique. For these two new OS-CFAR detectors, analytic expressions of the false alarm rate, the detection probabilities and the measure of ADT under the Swerling 2 assumption are obtained. Their detection performances are analyzed in homogeneous background and in the presence of strong interfering targets, and they are compared with several previously proposed CFARs.
O horizonte valorativo do gênero entrevista pingue-pongue: o papel social do entrevistado
Silva, Nívea Rohling da;
Trabalhos em Linguística Aplicada , 2010, DOI: 10.1590/S0103-18132010000100007
Abstract: in the present article we aim at presenting and analysis of the conceptual horizon of the genre ping-pong interview, from magazine journalism. the theoretical methodological basis concerns the theory of speech genres and the theory of dialogical analysis of bakhtin circle. the research data is composed by the ping-pong interviews published on the weekly magazines cartacapital, istoé and veja, from october 4th. to november 8th., 2006, which corresponds to the period of the coverage of the second round of the presidential elections in brazil. it is possible to highlight, as research results, the social indexes of value materialized through the social role of the interviewee. the ethos of interviewee is given to the readers that are in an asymmetric relation with the other readers; they are selected according to their social role, which validates and qualifies them to assume the interviewee's position. then, the guide line in the interview is the interviewee and his speech, which is "soaked" with valuation, disbelieved, contested or exalted. the valuation given to the interviewee materializes itself through his social role that is validated by the social "opinions" and by what had already been said about this object (the interviewee).
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