Linear optical random projections without holography.

We introduce what we believe to be a novel method to perform linear optical random projections without the need for holography. Our method consists of a computationally trivial combination of multiple intensity measurements to mitigate the information loss usually associated with the absolute-square non-linearity imposed by optical intensity measurements. Both experimental and numerical findings demonstrate that the resulting matrix consists of real-valued, independent, and identically distributed (i.i.d.) Gaussian random entries. Our optical setup is simple and robust, as it does not require interference between two beams. We demonstrate the practical applicability of our method by performing dimensionality reduction on high-dimensional data, a common task in randomized numerical linear algebra with relevant applications in machine learning.

Synthesis of 1,3-Dioxan-2-ones by Photo-Aerobic Selenium-π-Acid Multicatalysis.

An expedient method for the synthesis of cyclic carbonates from homoallylic carbonic acid esters by means of photo-aerobic selenium-π-acid multicatalysis is reported. Until now, conceptually related methods commonly relied either on the stoichiometric addition of electrophiles onto the substrate's alkene moiety or the presence of pre-installed leaving groups in allylic position of said alkene to - in part, catalytically - initiate an intramolecular attack by an adjacent carbonic acid ester group. In sharp contrast, the current study shows that the C-C double bond of homoallylic carbonic acid esters can be directly activated by the catalytic interplay of a pyrylium dye and a diselane using ambient air as the sole oxidant and visible light as an energy source.

Conventional and three-dimensional photography as a tool to map distribution patterns of in-transit melanoma metastases on the lower extremity.

Background: In melanoma, in-transit metastases characteristically occur at the lower extremity along lymphatic vessels. Objectives: The objective of this study was to evaluate conventional or three-dimensional photography as a tool to analyze in-transit metastasis pattern of melanoma of the lower extremity. In addition, we assessed risk factors for the development of in-transit metastases in cutaneous melanoma. Methods: In this retrospective, monocentric study first we compared the clinical data of all evaluable patients with in-transit metastases of melanoma on the lower extremity (n = 94) with melanoma patients without recurrence of disease (n = 288). In addition, based on conventional (n = 24) and three-dimensional photography (n = 22), we defined the specific distribution patterns of the in-transit metastases on the lower extremity. Results: Using a multivariate analysis we identified nodular melanoma, tumor thickness, and ulceration as independent risk factors to develop in-transit metastases ITM (n = 94). In patients with melanoma on the lower leg (n = 31), in-transit metastases preferentially developed along anatomically predefined lymphatic pathways. In contrast when analyzing in-transit metastases of melanoma on the foot (n = 15) no clear pattern could be visualized. In addition, no difference in distance between in-transit metastases and primary melanoma on the foot compared to the lower leg was observed using three-dimensional photography (n = 22). Conclusion: A risk-adapted follow-up of melanoma patients to detect in-transit metastases can be applied by knowledge of the specific lymphatic drainage of the lower extremity. Our current analysis suggests a more complex lymphatic drainage of the foot.

Manipulating cold atoms through a high-resolution compact system based on a multimode fiber.

We show that a standard multimode optical fiber can act as a high-resolution ultra-compact tool to manipulate cold atoms in setups with limited optical access. Spatial light modulators allow us to generate control beams at the in-vacuum fiber end by digital optical phase conjugation. With no additional in-vacuum optics, this system reaches a $ \sim 1\;{\unicode{x00B5}{\rm m}} $∼1µm resolution for a transverse size of only 225 µm. As a demonstration, we use it to optically transport cold atoms towards the in-vacuum fiber end, to load them in optical microtraps, and to re-cool them in optical molasses. This work shows that the rapid progress of optics in complex media opens new, to the best of our knowledge, perspectives for spatially constrained quantum technology platforms combining cold atoms with other optical, electronic, or opto-mechanical systems.

Auditory Categorization of Man-Made Sounds Versus Natural Sounds by Means of MEG Functional Brain Connectivity.

Previous neuroimaging studies have shown that sounds can be discriminated due to living-related or man-made-related characteristics and involve different brain regions. However, these studies have mainly provided source space analyses, which offer simple maps of activated brain regions but do not explain how regions of a distributed system are functionally organized under a specific task. In the present study, we aimed to further examine the functional connectivity of the auditory processing pathway across different categories of non-speech sounds in healthy adults, by means of MEG. Our analyses demonstrated significant activation and interconnection differences between living and man-made object sounds, in the prefrontal areas, anterior-superior temporal gyrus (aSTG), posterior cingulate cortex (PCC), and supramarginal gyrus (SMG), occurring within 80-120 ms post-stimulus interval. Current findings replicated previous ones, in that other regions beyond the auditory cortex are involved during auditory processing. According to the functional connectivity analysis, differential brain networks across the categories exist, which proposes that sound category discrimination processing relies on distinct cortical networks, a notion that has been strongly argued in the literature also in relation to the visual system.

Physicochemical features of ultra-high viscosity alginates.

The physicochemical characteristics of the ultra-high viscosity and highly biocompatible alginates extracted from Lessonia nigrescens (UHV(N)) and Lessonia trabeculata (UHV(T)) were analyzed. Fluorescence and (1)H NMR spectroscopies, viscometry, and multi-angle light scattering (MALS) were used for elucidation of the chemical structure, molar mass, and coil size. The sequential structures from NMR spectroscopy showed high guluronate content for UHV(T), but low for UHV(N). Intrinsic viscosity [eta] measurements exhibited unusual high values (up to 2750 mL/g), whereas [eta] of a commercial alginate was only about 970 mL/g. MALS batch measurements of the UHV-alginates yielded ultra-high values of the weight average molar mass (M(w) up to 1.1x10(6) g/mol) and of the z-average gyration radius (R(G)(z) up to 191 nm). The M(w) and R(G)(z) distributions of UHV-alginates and of ultrasonically degraded fractions were determined using size exclusion chromatography combined with MALS and asymmetrical flow-field-flow fractionation. The M(w) dependency of [eta] and R(G)(z) could be described by [eta]=0.059xM(w)(0.78) and R(G)(z)=0.103xM(w)(x). (UHV(N): x=0.52; UHV(T): x=0.53) indicating that the monomer composition has no effect on coil expansion. Therefore, the equations can be used to calculate M(w) and R(G)(z) values of UHV(T)- and UHV(N)-alginate mixtures as used in immunoisolation. Furthermore, the simple and inexpensive capillary viscometry can be used for real-time validation of the extraction and purification process of the UHV-alginates.

A biophysical approach to the optimisation of dendritic-tumour cell electrofusion.

Electrofusion of tumour and dendritic cells (DCs) is a promising approach for production of DC-based anti-tumour vaccines. Although human DCs are well characterised immunologically, little is known about their biophysical properties, including dielectric and osmotic parameters, both of which are essential for the development of efficient electrofusion protocols. In the present study, human DCs from the peripheral blood along with a tumour cell line used as a model fusion partner were examined by means of time-resolved cell volumetry and electrorotation. Based on the biophysical cell data, the electrofusion protocol could be rapidly optimised with respect to the sugar composition of the fusion medium, duration of hypotonic treatment, frequency range for stable cell alignment, and field strengths of breakdown pulses triggering membrane fusion. The hypotonic electrofusion consistently gave a tumour-DC hybrid rate of up to 19%, as determined by counting dually labelled fluorescent hybrids in a microscope. This fusion rate is nearly twice as high as that usually reported in the literature for isotonic media. The experimental findings and biophysical approach presented here are generally useful for the development of efficient electrofusion protocols, especially for rare and valuable human cells.

Electrotransfection of anchorage-dependent mammalian cells.

Reversible electropermeabilization (or electroporation) of cell membranes is a very efficient method for intracellular delivery of xenomolecules, particularly of DNA. In the case of anchorage-dependent cells, however, enzymatic or mechanical detachment from the substratum is required prior to electropulsing. This can damage the plasma membrane and lead to low transfection yields. Here we present an efficient method for in situ electroporation of mammalian cells while they are attached to a solid substratum. For this purpose an electroporation chamber was constructed that housed a cell culture insert with a cell monolayer grown on a porous filter. By real-time monitoring the transmonolayer resistance, the field pulse parameters resulting in transient and reversible permeabilization of cell membranes were determined for two adherent cell lines, which were found to differ markedly in their sensitivity to electropulsing. Based on the transmonolayer resistance data, the pulsing conditions for optimum electrotransfection of two murine cell lines with plasmid DNA could be established in a very short time. The transfection yield and gene expression were significantly higher in cell monolayers facing the cathode compared to those exposed to field pulses of the reverse direction. This might be due to contribution of the electrophoresis to the translocation of the polyanionic plasmid DNA across the electropermeabilized cell membrane. The experimental setup presented here appears to be a promising tool not only for rapid optimization of in situ electrotransfection of anchorage-dependent cells but also for studying the molecular/biophysical mechanisms of the membrane breakdown and resealing.