Complex-valued fractional derivatives on time scales

We introduce a notion of fractional (noninteger order) derivative on an arbitrary nonempty closed subset of the real numbers (on a time scale). Main properties of the new operator are proved and several illustrative examples given.Comment: This is a preprint of a paper whose final and definite form will appear in Springer Proceedings in Mathematics & Statistics, ISSN: 2194-1009. Accepted for publication 06/Nov/201

PULXs as Accreting Magnetars: Observational Manifestations

Pulsating Ultra Luminous X-ray sources (PULXs) are thought to be X-ray bright, accreting, magnetized neutron stars, and could be the first and only evidence for the existence of magnetars in binary systems. Their apparent soft (< 20 keV) X-ray luminosity can exceed the Eddington luminosity for a neutron star (NS) by a few orders of magnitude. Although several scenarios have been proposed to explain the different components observed in the X-ray spectra and the characteristics of the X-ray lightcurve of these system, detailed quantitative calculations are still missing. In particular, the observed soft X-ray lightcurves are almost sinuosidal and show an increase in the pulsed fraction (from 8% up to even 30%) with increasing energy. Here, we present how emission originating from an optically thick envelope, expected to be formed during super-Eddington accretion, can result in pulsed fractions similar to observations

Compact groups from semi-analytical models of galaxy formation -- V: their assembly channels as a function of the environment

We delved into the assembly pathways and environments of compact groups (CGs) of galaxies using mock catalogues generated from semi-analytical models (SAMs) on the Millennium simulation. We investigate the ability of SAMs to replicate the observed CG environments and whether CGs with different assembly histories tend to inhabit specific cosmic environments. We also analyse whether the environment or the assembly history is more important in tailoring CG properties. We find that about half of the CGs in SAMs are non-embedded systems, 40% are inhabiting loose groups or nodes of filaments, while the rest distribute evenly in filaments and voids, in agreement with observations. We observe that early-assembled CGs preferentially inhabit large galaxy systems (~ 60%), while around 30% remain non-embedded. Conversely, lately-formed CGs exhibit the opposite trend. We also obtain that lately-formed CGs have lower velocity dispersions and larger crossing times than early-formed CGs, but mainly because they are preferentially non-embedded. Those lately-formed CGs that inhabit large systems do not show the same features. Therefore, the environment plays a strong role in these properties for lately-formed CGs. Early-formed CGs are more evolved, displaying larger velocity dispersions, shorter crossing times, and more dominant first-ranked galaxies, regardless of the environment. Finally, the difference in brightness between the two brightest members of CGs is dependent only on the assembly history and not on the environment. CGs residing in diverse environments have undergone varied assembly processes, making them suitable for studying their evolution and the interplay of nature and nurture on their traits.Comment: 13 pages, 8 figures. Accepted for publication in MNRA

Hickson-like compact groups inhabiting different environments

Although Compact Groups of galaxies (CGs) have been envisioned as isolated extremely dense structures in the Universe, it is accepted today that many of them could be not as isolated as thought. In this work, we study Hickson-like CGs identified in the Sloan Digital Sky Survey Data Release 16 to analyse these systems and their galaxies when embedded in different cosmological structures. To achieve this goal, we identify several cosmological structures where CGs can reside: Nodes of filaments, Loose Groups, Filaments and cosmic Voids. Our results indicate that 45 per cent of CGs do not reside in any of these structures, i.e., they can be considered non-embedded or isolated systems. Most of the embedded CGs are found inhabiting Loose Groups and Nodes, while there are almost no CGs residing well inside cosmic Voids. Some physical properties of CGs vary depending on the environment they inhabit. CGs in Nodes show the largest velocity dispersions, the brightest absolute magnitude of the first-ranked galaxy, and the smallest crossing times, while the opposite occurs in Non-Embedded CGs. When comparing galaxies in all the environments and galaxies in CGs, CGs show the highest fractions of red/early-type galaxy members in most of the absolute magnitudes ranges. The variation between galaxies in CGs inhabiting one or another environment is not as significant as the differences caused by belonging or not to a CG. Our results suggest a plausible scenario for galaxy evolution in CGs in which both, large-scale and local environments play essential roles.Comment: 16 pages, 9 figures, 1 table, accepted for publication in MNRA

Prostatic stromal tumor with fatal outcome in a young man: histopathological and immunohistochemical case presentation

Stromal tumors of the prostate are rare and only a few cases have been described in the literature, including exceptional cases of stromal tumors with unknown malignant potential (STUMP) and a fatal outcome in young patients. Morphologically distinguishing a STUMP from a stromal sarcoma of the prostate (PSS) is still a challenge. We describe the histopathological and immunohistochemical findings in a 34-year-old man with a malignant specialized cell stromal tumor of the prostate that was diagnosed initially as STUMP, and he developed lung metastases within a few months. The patient attended our hospital because of lower urinary tract symptoms, after having excreted tissue through the urethra a few months before. Ultrasonography and urethrocystoscopy examinations showed a mass arising from the verumontanum, and a transurethral resection (TUR) revealed a highgrade spindle cell sarcoma reminiscent of a phyllode tumor of the breast. The tumor cells were immunoreactive for vimentin, progesterone receptor and, focally, CD34. The preliminary histological findings were subsequently confirmed after radical prostatectomy. The patient developed bilateral lung metastases and died 25 months after the initial diagnosis. Although rare in young patients, the challenging differential diagnosis of STUMP and PSS means that a prostate STUMP diagnosis made on the basis of biopsy or TUR specimens also requires urethrocystoscopic monitoring for the early detection of any progression to PSS. Radical prostatectomy should also be carefully considered

Current status and updated recommendations for diagnosis and treatment of plasma cell myeloma in Switzerland

The availability of drugs such as thalidomide, bortezomib and lenalidomide changed the landscape in myeloma treatment and has extended the median survival up to 10 years with a substantial improvement in quality of life. This development prompted a Swiss expert panel to re-evaluate the current status and formulate updated clinical recommendations for the diagnosis and treatment of plasma cell myeloma. These recommendations should help clinicians in their decision making to achieve the best outcome based on currently available data

Targeting of multiple myeloma-related angiogenesis by miR-199a-5p mimics: in vitro and in vivo anti-tumor activity

Multiple myeloma (MM) cells induce relevant angiogenic effects within the human bone marrow milieu (huBMM) by the aberrant expression of angiogenic factors. Hypoxia triggers angiogenic events within the huBMM and the transcription factor hypoxia-inducible factor-1α (HIF-1α) is over-expressed by MM cells. Since synthetic miR-199a-5p mimics negatively regulates HIF-1α, we here investigated a miRNA-based therapeutic strategy against hypoxic MM cells. We indeed found that enforced expression of miR-199a-5p led to down-modulated expression of HIF-1α as well as of other pro-angiogenic factors such as VEGF-A, IL-8, and FGFb in hypoxic MM cells in vitro. Moreover, miR-199a-5p negatively affected MM cells migration, while it increased the adhesion of MM cells to bone marrow stromal cells (BMSCs) in hypoxic conditions. Furthermore, transfection of MM cells with miR-199a-5p significantly impaired also endothelial cells migration and down-regulated the expression of endothelial adhesion molecules such as VCAM-1 and ICAM-1. Finally, we identified a hypoxia\AKT/miR-199a-5p loop as a potential molecular mechanism responsible of miR-199a-5p down-regulation in hypoxic MM cells. Taken together our results indicate that miR-199a-5p has an important role for the pathogenesis of MM and support the hypothesis that targeting angiogenesis via a miRNA/HIF-1α pathway may represent a novel potential therapeutical approach for this still lethal diseas

Evolution favors protein mutational robustness in sufficiently large populations

BACKGROUND: An important question is whether evolution favors properties such as mutational robustness or evolvability that do not directly benefit any individual, but can influence the course of future evolution. Functionally similar proteins can differ substantially in their robustness to mutations and capacity to evolve new functions, but it has remained unclear whether any of these differences might be due to evolutionary selection for these properties. RESULTS: Here we use laboratory experiments to demonstrate that evolution favors protein mutational robustness if the evolving population is sufficiently large. We neutrally evolve cytochrome P450 proteins under identical selection pressures and mutation rates in populations of different sizes, and show that proteins from the larger and thus more polymorphic population tend towards higher mutational robustness. Proteins from the larger population also evolve greater stability, a biophysical property that is known to enhance both mutational robustness and evolvability. The excess mutational robustness and stability is well described by existing mathematical theories, and can be quantitatively related to the way that the proteins occupy their neutral network. CONCLUSIONS: Our work is the first experimental demonstration of the general tendency of evolution to favor mutational robustness and protein stability in highly polymorphic populations. We suggest that this phenomenon may contribute to the mutational robustness and evolvability of viruses and bacteria that exist in large populations

Reconstructing the three-dimensional GABAergic microcircuit of the striatum

A system's wiring constrains its dynamics, yet modelling of neural structures often overlooks the specific networks formed by their neurons. We developed an approach for constructing anatomically realistic networks and reconstructed the GABAergic microcircuit formed by the medium spiny neurons (MSNs) and fast-spiking interneurons (FSIs) of the adult rat striatum. We grew dendrite and axon models for these neurons and extracted probabilities for the presence of these neurites as a function of distance from the soma. From these, we found the probabilities of intersection between the neurites of two neurons given their inter-somatic distance, and used these to construct three-dimensional striatal networks. The MSN dendrite models predicted that half of all dendritic spines are within 100 mu m of the soma. The constructed networks predict distributions of gap junctions between FSI dendrites, synaptic contacts between MSNs, and synaptic inputs from FSIs to MSNs that are consistent with current estimates. The models predict that to achieve this, FSIs should be at most 1% of the striatal population. They also show that the striatum is sparsely connected: FSI-MSN and MSN-MSN contacts respectively form 7% and 1.7% of all possible connections. The models predict two striking network properties: the dominant GABAergic input to a MSN arises from neurons with somas at the edge of its dendritic field; and FSIs are interconnected on two different spatial scales: locally by gap junctions and distally by synapses. We show that both properties influence striatal dynamics: the most potent inhibition of a MSN arises from a region of striatum at the edge of its dendritic field; and the combination of local gap junction and distal synaptic networks between FSIs sets a robust input-output regime for the MSN population. Our models thus intimately link striatal micro-anatomy to its dynamics, providing a biologically grounded platform for further study