Dynamic State Estimation for Load Bus Protection on Inverter-Interfaced Microgrids

Inverter-interfaced microgrids results in challenges when designing protection systems. Traditional time-overcurrent, admittance, and differential protection methods are unsuitable on account of lack of fault current, excessively short lines, or a prohibitive number of protective devices needing to be installed. Current practice is to force all inverters to shut down during fault conditions, weakening resilience and reducing reliability. Dynamic state estimation (DSE), which has been explored for both line protection and load bus protection before, is a potential solution to these challenges to create widely utilizable, highly reliable protection systems. However, it has only been tested for load protection with ideal voltage sources, which do not capture the short-circuit behavior of inverter-interfaced generation, notably low fault current and unbalanced output voltage. This paper aims to extend the state-of-the-art on DSE load protection: the performance of DSE during short-circuit conditions with a grid-forming inverter with current-limiting behavior during fault conditions is investigated.Comment: 5 pages. 3 figures. 1 table

Shear rate threshold for the boundary slip in dense polymer films

The shear rate dependence of the slip length in thin polymer films confined between atomically flat surfaces is investigated by molecular dynamics simulations. The polymer melt is described by the bead-spring model of linear flexible chains. We found that at low shear rates the velocity profiles acquire a pronounced curvature near the wall and the absolute value of the negative slip length is approximately equal to thickness of the viscous interfacial layer. At higher shear rates, the velocity profiles become linear and the slip length increases rapidly as a function of shear rate. The gradual transition from no-slip to steady-state slip flow is associated with faster relaxation of the polymer chains near the wall evaluated from decay of the time autocorrelation function of the first normal mode. We also show that at high melt densities the friction coefficient at the interface between the polymer melt and the solid wall follows power law decay as a function of the slip velocity. At large slip velocities the friction coefficient is determined by the product of the surface induced peak in the structure factor, temperature and the contact density of the first fluid layer near the solid wall.Comment: 37 pages, 16 figure

The Static and Dynamic Lattice Changes Induced by Hydrogen Adsorption on NiAl(110)

Static and dynamic changes induced by adsorption of atomic hydrogen on the NiAl(110) lattice at 130 K have been examined as a function of adsorbate coverage. Adsorbed hydrogen exists in three distinct phases. At low coverages the hydrogen is itinerant because of quantum tunneling between sites and exhibits no observable vibrational modes. Between 0.4 ML and 0.6 ML, substrate mediated interactions produce an ordered superstructure with c(2x2) symmetry, and at higher coverages, hydrogen exists as a disordered lattice gas. This picture of how hydrogen interacts with NiAl(110) is developed from our data and compared to current theoretical predictions.Comment: 36 pages, including 12 figures, 2 tables and 58 reference

Challenges for Routine Health System Data Management in a Large Public Programme to Prevent Mother-to-Child HIV Transmission in South Africa

Background: Recent changes to South Africa's prevention of mother-to-child transmission of HIV (PMTCT) guidelines have raised hope that the national goal of reducing perinatal HIV transmission rates to less than 5% can be attained. While programmatic efforts to reach this target are underway, obtaining complete and accurate data from clinical sites to track progress presents a major challenge. We assessed the completeness and accuracy of routine PMTCT data submitted to the district health information system (DHIS) in three districts of Kwazulu-Natal province, South Africa. Methodology/Principal Findings: We surveyed the completeness and accuracy of data reported for six key PMTCT data elements between January and December 2007 from all 316 clinics and hospitals in three districts. Through visits to randomly selected sites, we reconstructed reports for the same six PMTCT data elements from clinic registers and assessed accuracy of the monthly reports previously submitted to the DHIS. Data elements were reported only 50.3% of the time and were “accurate” (i.e. within 10% of reconstructed values) 12.8% of the time. The data element “Antenatal Clients Tested for HIV” was the most accurate data element (i.e. consistent with the reconstructed value) 19.8% of the time, while “HIV PCR testing of baby born to HIV positive mother” was the least accurate with only 5.3% of clinics meeting the definition of accuracy. Conclusions/Significance: Data collected and reported in the public health system across three large, high HIV-prevalence Districts was neither complete nor accurate enough to track process performance or outcomes for PMTCT care. Systematic data evaluation can determine the magnitude of the data reporting failure and guide site-specific improvements in data management. Solutions are currently being developed and tested to improve data quality

Reactive Desorption of CO Hydrogenation Products under Cold Pre-stellar Core Conditions

The astronomical gas-phase detection of simple species and small organic molecules in cold pre-stellar cores, with abundances as high as $\sim$$10^{-8}-10^{-9}$ n$_\text{H}$, contradicts the generally accepted idea that at $10$ K, such species should be fully frozen out on grain surfaces. A physical or chemical mechanism that results in a net transfer from solid-state species into the gas phase offers a possible explanation. Reactive desorption, i.e., desorption following the exothermic formation of a species, is one of the options that has been proposed. In astronomical models, the fraction of molecules desorbed through this process is handled as a free parameter, as experimental studies quantifying the impact of exothermicity on desorption efficiencies are largely lacking. In this work, we present a detailed laboratory study with the goal of deriving an upper limit for the reactive desorption efficiency of species involved in the CO-H$_2$CO-CH$_3$OH solid-state hydrogenation reaction chain. The limit for the overall reactive desorption fraction is derived by precisely investigating the solid-state elemental carbon budget, using reflection absorption infrared spectroscopy and the calibrated solid-state band-strength values for CO, H$_2$CO and CH$_3$OH. We find that for temperatures in the range of $10$ to $14$ K, an upper limit of $0.24\pm 0.02$ for the overall elemental carbon loss upon CO conversion into CH$_3$OH. This corresponds with an effective reaction desorption fraction of $\leq$$0.07$ per hydrogenation step, or $\leq$$0.02$ per H-atom induced reaction, assuming that H-atom addition and abstraction reactions equally contribute to the overall reactive desorption fraction along the hydrogenation sequence. The astronomical relevance of this finding is discussed.Comment: 9 pages, 7 figure

Concurrent breast stroma sarcoma and breast carcinoma: a case report

<p>Abstract</p> <p>Introduction</p> <p>Breast cancer is one of the most important health problems in the world and affects a great number of women over the entire globe. This group of tumors rarely presents as bilateral disease and, when it does happen, normally occurs within the same histological type. We report a rare case of concurrent bilateral breast cancer with two different histology types, a breast carcinoma and a breast sarcoma, in a 42-year-old woman referred to our hospital.</p> <p>Case presentation</p> <p>A 42-year-old Caucasian woman admitted to our institute in August 1999, presented with a nodule in the left breast of 3.0 × 2.5 cm, and, in the right breast, one of 1.0 cm, suspected of malignancy and with a clinically negative armpit. Biopsies had revealed invasive mammary carcinoma (right breast) and sarcoma (left breast). She was submitted to bilateral modified radical mastectomy. A histological study showed an invasive mammary carcinoma degree II lobular pleomorphic type with invasion of seven of the 19 excised axillary nodes in the right breast and, in the left breast, a sarcoma of the mammary stroma, for which the immunohistochemistry study was negative for epithelial biomarkers and positive for vimentin. Later, she was submitted for chemotherapy (six cycles of 75 mg/m²5-fluorouracil, epirubicin and cyclophosphamide) followed by radiotherapy of the thoracic wall and axillary nodes on the left. Hormone receptors were positive in the tumor of the right breast, and tamoxifen, 20 mg, was prescribed on a daily basis (five years) followed by letrozole, 2.5 mg, also daily (five years). She presented no sign of negative evolution in the last consultation.</p> <p>Conclusion</p> <p>The risk of development of bilateral breast cancer is about 1% each year within a similar histological type, but it is higher in tumors with lobular histology. In this case, the patient presented, simultaneously, two histologically distinct tumors, thus evidencing a rare situation.</p

A Tale of Two Transients: GW 170104 and GRB 170105A

We present multi-wavelength follow-up campaigns by the AstroSat CZTI and GROWTH collaborations in search of an electromagnetic counterpart to the gravitational wave event GW 170104. At the time of the GW 170104 trigger, the AstroSat CZTI field of view covered 50.3% of the sky localization. We do not detect any hard X-ray (>100 keV) signal at this time, and place an upper limit of $\approx 4.5\times {10}^{-7}\,\mathrm{erg}\,{\mathrm{cm}}^{-2}\,{{\rm{s}}}^{-1}$, for a 1 s timescale. Separately, the ATLAS survey reported a rapidly fading optical source dubbed ATLAS17aeu in the error circle of GW 170104. Our panchromatic investigation of ATLAS17aeu shows that it is the afterglow of an unrelated long, soft GRB 170105A, with only a fortuitous spatial coincidence with GW 170104. We then discuss the properties of this transient in the context of standard long GRB afterglow models

Neuroinflammation, Mast Cells, and Glia: Dangerous Liaisons

The perspective of neuroinflammation as an epiphenomenon following neuron damage is being replaced by the awareness of glia and their importance in neural functions and disorders. Systemic inflammation generates signals that communicate with the brain and leads to changes in metabolism and behavior, with microglia assuming a pro-inflammatory phenotype. Identification of potential peripheral-to-central cellular links is thus a critical step in designing effective therapeutics. Mast cells may fulfill such a role. These resident immune cells are found close to and within peripheral nerves and in brain parenchyma/meninges, where they exercise a key role in orchestrating the inflammatory process from initiation through chronic activation. Mast cells and glia engage in crosstalk that contributes to accelerate disease progression; such interactions become exaggerated with aging and increased cell sensitivity to stress. Emerging evidence for oligodendrocytes, independent of myelin and support of axonal integrity, points to their having strong immune functions, innate immune receptor expression, and production/response to chemokines and cytokines that modulate immune responses in the central nervous system while engaging in crosstalk with microglia and astrocytes. In this review, we summarize the findings related to our understanding of the biology and cellular signaling mechanisms of neuroinflammation, with emphasis on mast cell-glia interactions