Weltweite Kataloge und Artenzahlen der Spinnentierordnungen (Arachnida)

Volume: 41Start Page: 41End Page: 4

Adiabatic steering and determination of dephasing rates in double dot qubits

We propose a scheme to prepare arbitrary superpositions of quantum states in double quantum--dots irradiated by coherent microwave pulses. Solving the equations of motion for the dot density matrix, we find that dephasing rates for such superpositions can be quantitatively infered from additional electron current pulses that appear due to a controllable breakdown of coherent population trapping in the dots.Comment: 5 pages, 4 figures. To appear in Phys. Rev.

Nanomechanical resonators operating as charge detectors in the nonlinear regime

We present measurements on nanomechanical resonators machined from Silicon-on-Insulator substrates. The resonators are designed as freely suspended Au/Si beams of lengths on the order of 1 - 4 um and a thickness of 200 nm. The beams are driven into nonlinear response by an applied modulation at radio frequencies and a magnetic field in plane. The strong hysteresis of the magnetomotive response allows sensitive charge detection by varying the electrostatic potential of a gate electrode.Comment: 8 pages, 6 figure

Anaplastic, T-cell, Non-Hodgkin's Lymphoma Presenting with Haematuria

Non-Hodgkin's lymphoma (NHL) represents about 3% of new cancer cases[1]. Bladder involvement has been found in approximately 3-13% of NHL patients when studied at postmortem[2]. Although accounting for only 0.2% of all primary bladder tumours, the majority of bladder lymphomas are B-cell lymphomas. T-cell lymphoma of the bladder is incredibly rare. We describe a case of anaplastic, T-cell lymphoma presenting with haematuria and loin pain, with unilateral upper tract obstruction

Adiabatic Transfer of Electrons in Coupled Quantum Dots

We investigate the influence of dissipation on one- and two-qubit rotations in coupled semiconductor quantum dots, using a (pseudo) spin-boson model with adiabatically varying parameters. For weak dissipation, we solve a master equation, compare with direct perturbation theory, and derive an expression for the `fidelity loss' during a simple operation that adiabatically moves an electron between two coupled dots. We discuss the possibility of visualizing coherent quantum oscillations in electron `pump' currents, combining quantum adiabaticity and Coulomb blockade. In two-qubit spin-swap operations where the role of intermediate charge states has been discussed recently, we apply our formalism to calculate the fidelity loss due to charge tunneling between two dots.Comment: 13 pages, 8 figures, to appear in Phys. Rev.

Technical Comments: Sea Level History

Bilal U. Haq and his co-workers have completed an important update of the chronology of coastal onlap and eustatic fluctuations in Mesowic and Cenowic time. Seismic stratigraphic results are augmented in the new charts by outcrop and well-log studies to document an impressive total of 119 sea level cycles since the beginning of the Triassic. In addition, the Cretaceous results have been published officially for the first time. However, apart from distinguishing between relative changes of coastal onlap and eustasy, the methodology and assumptions are much the same as those used to construct the first version of the "sea level curve" in 1977. In a recent evaluation of the seismic stratigraphic record of sea level change, we drew attention to two problems in particular. 1) All of the observed depositional cycles are assumed by Haq et al. to be eustatic. 2) The global onlap chart, which forms the basis for the smoothed eustatic curve, has little physical meaning

Stratigraphic Controls on a Salt-Withdrawal Intraslope Minibasin, North-Central Green Canyon, Gulf of Mexico: Implications for Misinterpreting Sea Level Change

Three-dimensional seismic data from the Fuji basin, a salt-controlled intraslope minibasin in north-central Green Canyon, Gulf of Mexico, reveal complex interactions between gravity- and suspension-driven sedimentation. Seismic volumes for late Pleistocene (sim470 ka) to Holocene fill within the Fuji basin consist of approximately 45% mass transport complexes (MTCs), 5% channelized sandy turbidites, and 50% hemipelagites and muddy turbidites. At least ten MTCs within the Fuji basin flowed radially toward its depocenter, either from basin flanks (i.e., intrabasinal) or as a result of larger-scale salt motion (i.e., extrabasinal). Sediment transport directions are inferred on the basis of elongate basal incisions and smaller-scale scours, head scarps, fold orientation within the complexes, and stratigraphic thinning trends at downdip margins. An amalgamated set of three channelized sandy turbidite complexes less than 350 m (1148 ft) thick and 3 km (1.8 mi) across represents the main sand delivery pathway into the Fuji basin. These deposits are thought to be due to shelf bypass, and possibly, to proximity to the Pleistocene shoreline. Hemipelagites and muddy turbidites are homogeneous, and their thickness is relatively consistent at basin scale. This facies represents background sedimentation. A process-driven model has been developed involving halokinetic autocyclicity as the primary control on sedimentation in the Fuji basin. Passive salt motion accounts better for both the directions of sediment transport and the frequency of late Pleistocene–Holocene MTCs than currently popular eustatic and steady-state bathymetric models. The conclusion is significant in casting doubt on the generally assumed importance of eustasy in controlling off-shelf lowstand sedimentation and in implying marked variations in stratigraphic details at length scales of less than 10 km (6.2 mi)

Is There a Role for Sequence Stratigraphy in Chronostratigraphy?

Sequence stratigraphy revolutionized the field of stratigraphy in the late 1970s and 1980s by providing an interpretive depositional framework for integrating diverse stratigraphic data at the scale of sedimentary basins. However, a lack of consensus on criteria for recognizing, mapping and hence dating sequence boundaries, interpretations of uneven quality, and doubts about the universal eustatic origin and global synchrony of unconformity-related sequences limit the usefulness of sequence stratigraphy in chronostratigraphy

A unique case of a malignant sertoli cell tumour with cutaneous metastasis

Pure Sertoli cell tumours (SCTs) represent less than 1% of testicular neoplasms and malignant forms are rare. We present a unique case of a 69-year-old man who initially underwent inguinal orchidectomy for a malignant SCT. He then subsequently developed a paraumbilical cutaneous lesion which was histologically identical to the primary tumour. SCTs rarely metastasise. This is the first case of SCT with cutaneous metastasis described in the literature