Arid processes in the SE-Brazilian relief evolution during the last glacial

The general index-plain "Sulamericana" can be found in vast areas of SE-Brazil. It is mainly conserved with the help of a duricrust and covered by laterite. The next younger element of relief-evolution, a level 40 to 60 m below the Sulamericana, is completely different: the weathered rock is covered by a stoneline and a fine-textured sediment. This structure was examined with the help of granulometry, analyses of heavy minerals, thermoluminescence datings, pollen analyses and 14C-datings. Different conditions for the development of stonelines may occur according to the climatic conditions at the time of their origin; in this case it must be assumed that the stonelines were formed by slope-wash due to episodic precipitation under the condition of nearly complete absence of vegetation (geologic or climatic reasons). They are a clear post-Sulamericana development. A fine-textured sediment was deposited on top of the stonelines. The material of the fine-textured sediment was, according to the then prevailing conditions, transported by as well slope-wash as eolian processes; especially for the "demi-oranges" we must assume eolian transport. The material was probably derived partly from the local material which covers the remnants of the Sulamericana, but may be seen as an eolian sediment transported for long distances as well. The time of the deposition of the fine-textured sediment on the stonelines coincides with the climax of the last Glacial; the 14C-dating indicates 19,700 years B.P., the thermoluminescence-dating about 20,000 years B.P.. The climatic conditions were probably semi-arid. These results are supported by the findings of other researches of the Southamerican climate during the last Glacial

Chemical defenses of the Caribbean sponges Agelas wiedenmayeri and Agelas conifera

Previous studies have determined that Caribbean reef sponges of the genus Agelas are chemically defended from fish predation by brominated pyrrole alkaloids, and that the compounds responsible for this defense have been elucidated for one species, Agelas clathrodes. In this study, we expand our understanding of chemical defense in this common sponge genus to include the characterization of defensive metabolites in the tissues of Agelas wiedenmayeri and Agelas conifera. Bioassay-directed isolation of defensive metabolites was undertaken using fish feeding assays carried out in laboratory aquaria and in the field. Agelas wiedenmayeri contained the same two major metabolites as Agelas clathrodes, 4,5-dibromopyrrole-2-carboxylic acid (1), and oroidin (2), in addition to a small amount of bromoageliferin (7). The two major metabolites were present at higher concentrations in samples of Agelas wiedenmayeri than in Agelas clathrodes, and their relative concentrations were reversed, with Agelas wiedenmayeri on average containing more 4,5-dibromopyrrole-2-carboxylic acid (1) (2.0 mg/mL) than oroidin (2) (0.8 mg/mL). Agelas conifera contained a mixture of dimeric bromopyrrole alkaloids dominated by sceptrin (3), with <10% each of dibromosceptrin (5), bromoageliferin (7), dibromoageliferin (8), ageliferin (6), and bromosceptrin (4). Mean concentration of sceptrin (3) in sponge tissue was 5.3 mg/mL; this compound deterred feeding of reef fish in aquarium assays at 1.0 mg/mL, the lowest concentration assayed. Sceptrin (3) concentrations were higher in sponges collected in the southern Bahama Islands than those collected in the middle Bahamas, but reasons for this variation remain unclear. The structure-activity relationship of the pyrrole group was investigated by assaying derivatives of the active metabolites. Feeding deterrent activity of the molecule was enhanced by the addition of bromine to the pyrrole group, but not affected by exchange of the heteroatom from N to O or S. Combining an understanding of the structure-activity relationship of Agelas metabolites with an understanding of the variation in these metabolites across the genus may provide insight into the evolution of defensive chemistry in this highly successful taxa of pan-tropical sponges

Operative Therapie von akral lokalisierten Melanomen

Zusammenfassung: Akrolentiginöse Melanome (ALM) umfassen 4-10% der kutanen Melanome bei Hellhäutigen. Patienten mit ALM wird oft eine schlechtere Prognose zugeschrieben, meist aufgrund zu später Diagnosestellung. Unter Einsatz der 3D-Histologie können akral lokalisierte Melanome mit kontinuierlichem Ausbreitungsmuster lokal chirurgisch mit kleineren Sicherheitsabständen und einem guten funktionellen und kosmetischen Ergebnis behandelt werden. In einer Studie wurden bei 244Patienten mit ALM die konventionelle Histologie vs. 3D-Histologie neben anderen prognostischen Parametern verglichen. Klinische und chirurgische Risikofaktoren beeinflussen die Prognose des ALM. Tumordicke und Ulzeration sind die wichtigsten Risikofaktoren. Die 3D-Histologie in Paraffintechnik ermöglicht es, Sicherheitsabstände zu reduzieren und Lokalrezidive zu vermeiden. Subunguale Melanome machen nur etwa 2-3% der kutanen Melanome beim kaukasischen und etwa 20% der Melanome beim afrikanischen oder asiatischen Hauttyp aus und werden klinisch häufig fehldiagnostiziert. Sie sind oft an Daumen und Großzehe lokalisiert. Die Entfernung von subungualen Melanomen mit 3D-Histologie und tumorfreien Schnitträndern unter Einschluss der Nagelmatrix kann als sichere Strategie angesehen werden, welche die Prognose nicht beeinträchtigt. Funktion und Kosmetik eines Fingers oder Zehs bleiben erhalten. Amputationen bei subungualen Melanomen sollten fortgeschrittenen Verläufen mit Knochen- oder Gelenkbefall vorbehalten bleibe

Nanoscale structuring of tungsten tip yields most coherent electron point-source

This report demonstrates the most spatially-coherent electron source ever reported. A coherence angle of 14.3 +/- 0.5 degrees was measured, indicating a virtual source size of 1.7 +/-0.6 Angstrom using an extraction voltage of 89.5 V. The nanotips under study were crafted using a spatially-confined, field-assisted nitrogen etch which removes material from the periphery of the tip apex resulting in a sharp, tungsten-nitride stabilized, high-aspect ratio source. The coherence properties are deduced from holographic measurements in a low-energy electron point source microscope with a carbon nanotube bundle as sample. Using the virtual source size and emission current the brightness normalized to 100 kV is found to be 7.9x10^8 A/sr cm^2

Quantitative electron phase imaging with high sensitivity and an unlimited field of view

As it passes through a sample, an electron beam scatters, producing an exit wavefront rich in information. A range of material properties, from electric and magnetic field strengths to specimen thickness, strain maps and mean inner potentials, can be extrapolated from its phase and mapped at the nanoscale. Unfortunately, the phase signal is not straightforward to obtain. It is most commonly measured using off-axis electron holography, but this is experimentally challenging, places constraints on the sample and has a limited field of view. Here we report an alternative method that avoids these limitations and is easily implemented on an unmodified transmission electron microscope (TEM) operating in the familiar selected area diffraction mode. We use ptychography, an imaging technique popular amongst the X-ray microscopy community; recent advances in reconstruction algorithms now reveal its potential as a tool for highly sensitive, quantitative electron phase imaging

Calibration of multi-layered probes with low/high magnetic moments

We present a comprehensive method for visualisation and quantification of the magnetic stray field of magnetic force microscopy (MFM) probes, applied to the particular case of custom-made multi-layered probes with controllable high/low magnetic moment states. The probes consist of two decoupled magnetic layers separated by a non-magnetic interlayer, which results in four stable magnetic states: ±ferromagnetic (FM) and ±antiferromagnetic (A-FM). Direct visualisation of the stray field surrounding the probe apex using electron holography convincingly demonstrates a striking difference in the spatial distribution and strength of the magnetic flux in FM and A-FM states. In situ MFM studies of reference samples are used to determine the probe switching fields and spatial resolution. Furthermore, quantitative values of the probe magnetic moments are obtained by determining their real space tip transfer function (RSTTF). We also map the local Hall voltage in graphene Hall nanosensors induced by the probes in different states. The measured transport properties of nanosensors and RSTTF outcomes are introduced as an input in a numerical model of Hall devices to verify the probe magnetic moments. The modelling results fully match the experimental measurements, outlining an all-inclusive method for the calibration of complex magnetic probes with a controllable low/high magnetic moment

The synaptic vesicle-associated protein amphiphysin is the 128-kD autoantigen of stiff-man syndrome with breast cancer

Stiff-Man syndrome (SMS) is a rare disease of the central nervous system (CNS) characterized by progressive rigidity of the body musculature with superimposed painful spasms. An autoimmune origin of the disease has been proposed. In a caseload of more than 100 SMS patients, 60% were found positive for autoantibodies directed against the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD). Few patients, all women affected by breast cancer, were negative for GAD autoantibodies but positive for autoantibodies directed against a 128-kD synaptic protein. We report here that this antigen is amphiphysin. GAD and amphiphysin are nonintrinsic membrane proteins that are concentrated in nerve terminals, where a pool of both proteins is associated with the cytoplasmic surface of synaptic vesicles. GAD and amphiphysin are the only two known targets of CNS autoimmunity with this distribution. This finding suggests a possible link between autoimmunity directed against cytoplasmic proteins associated with synaptic vesicles and SMS

Theatre and time ecology: deceleration in Stifters Dinge

This article explores the production of ‘time ecology’ in two works of postdramatic theatre: Heiner Goebbels’ Stifters Dinge (2007) and Philippe Quesne’s L’Effet de Serge (2007). By focusing on the practice of deceleration, it argues that theatre’s ecological potential resides not so much in its ability to represent the world, but rather in its capacity for producing new types of temporal experience that purposefully seek to break with modernity’s regime of historicity and the accelerated rhythms that it has given rise to. Importantly, my concern with deceleration is not an argument for slowness per se; on the contrary, I am interested in highlighting the presence of multiple and interpenetrating timescales and rhythms. As well as exposing the full extent of theatre’s temporal potential, such a concern with postdramatic ‘chronographies’ offers an implicit critique of dramatic theatre’s extant practices of eco-dramaturgy that, all too often, attempt to construct a linear narrative which is invested in conventional sequential models of temporality (beginning, middle, end)