Initial Spread Research Articles

Demystifying a Hidden Trend: Do Temperature Variations Affect COVID-19 Virus Spread?

A new type of severe acute respiratory syndrome (SARS) virus, called as COVID-19, has started spreading around the globe like a fire after the very first case was reported, in December 2019. Till the end of March 2020, it infected around one million people and took life of more than thirty six thousand people. Data analytics of environmental factors and meteorological parameters like regional temperatures is necessary in order to understand the spread pattern, emergence, and re-emergence of a global pandemic like COVID-19. Therefore, in this study, by employing exploratory data analytics techniques, we aim to examine the relationship between average regional temperatures and the rate of spread of this virus across different regions around the globe. In this regard, an early stage outbreak analysis of COVID-19 spread has been presented to uncover any prospective impact of regional temperature variations on the initial spread rate of COVID-19. In order to reach an unbiased conclusion, a number of other variables are considered in this study which include population density, the count of days since a location encountered the very first case, the number of tests and the ratio of positive to total tests conducted per location. After in-depth analysis, we found that a bounded relationship between average temperature and spread rate of COVID-19 exists, that is, the spread rate of the virus is found to be slower in regions bearing extreme temperature. For validation, the extracted insights are discussed in the light of existing studies.

Quantum and classical phase-space dynamics of a free-electron laser

In a quantum mechanical description of the free-electron laser (FEL) the electrons jump on discrete momentum ladders, while they follow continuous trajectories according to the classical description. In order to observe the transition from quantum to classical dynamics, it is not sufficient that many momentum levels are involved. Only if additionally the initial momentum spread of the electron beam is larger than the quantum mechanical recoil, caused by the emission and absorption of photons, the quantum dynamics in phase space resembles the classical one. Beyond these criteria, quantum signatures of averaged quantities like the FEL gain might be washed out.

COVID-19 from veterinary medicine and one health perspectives: What animal coronaviruses have taught us

Coronaviruses (CoVs) are enveloped, single-stranded, positive-sense RNA viruses displaying an exceptional genetic plasticity driven by accumulation of point mutations and recombination events. This genetic variation is responsible for continuous emergence of viral strains with increased virulence, different tissue tropism and/or expanded host range (Buonavoglia et al., 2006). CoVs are currently classified within four genera, Alphacoronavirus, Betacoronavirus, Gammacoronavirus and Deltacoronavirus, that recognise bats, birds and likely rodents as natural reservoirs. In December 2019, cases of undiagnosed pneumonia started being reported in Wuhan, Hubei, China. On January 9 2020, the Chinese authorities indicated that a novel CoV was associated with the severe respiratory disease. The first patient with unexplained pneumonia, identified in December 8 2019, came from Wuhan South China Seafood Market. Initially, other patients were linked to the same seafood and live animal market, suggesting an animal origin for the initial spread to humans. Subsequent investigations revealed that the crowded seafood market only boosted circulation of the novel CoV and spread it to the whole city in early December 2019, whereas based on the genome data the virus likely began spreading from person to person in early December or even as early as late November. The first documented human case has been dated back to November 17 2019. The novel human CoV (HCoV) is a betacoronavirus genetically related to Severe acute respiratory syndrome (SARS) CoV and only distantly related to Middle East respiratory syndrome CoV (MERS-CoV) and it was designated as SARS type 2 CoV (SARS-CoV-2). Similar to the other hypervirulent HCoVs, SARS-CoV-2 has a putative animal origin, likely descended from a related bat CoV that spilled over to humans either directly or after adaptation in another animal species, such as the Malayan pangolin (Lam et al., 2020). SARS-CoV-2 is highly related genetically (96% nt) to a SARS-like bat CoV (Zhou et al., 2020) The SARS-CoV-2 induced disease, referred to as CoronaVirus Disease 2019 (COVID-19), affects the respiratory tract, with a number of patients displaying severe pneumonia and requiring hospitalisation and admission to intermediate or intensive care units. Unlike SARS and MERS, COVID-19 is characterised by low lethality rates and high frequency of asymptomatic or paucisymptomatic infections that likely favoured the spread of this new pandemic (Lai et al., 2020). As SARS-CoV-2 started spreading globally, between February and March 2020, potential spill over exposure (viral RNA) was noted in companion animals, likely due to their strict social interactions with humans. SARS-CoV-2 RNA was detected in two dogs and a cat without clinical signs in Hong Kong and in a cat with gastroenteric and respiratory signs in Bruxelles, all which lived in close contact with infected COVID-19 human patients.1 , 2 This noted analogous findings observed during the 2002–2003 spread of SARS-CoV.3

Early stage of liquid drop spreading on tunable nanostructured surfaces

In this study, the early stage of liquid droplet spreading on tunable nanostructures was investigated through high resolved and fast imaging visualization. It is well-known that the early stage of water droplet spreading on a solid surface features an inertia dominance on resistive droplet motion in a short period (~0.01 sec). The spreading dynamic law of this stage differs greatly from those of the classical spreading stage, after the inertia regime, being determined by the balance between a spreading force and viscous friction. The effect of triple line physics associated with the surface properties is generally underestimated in the early inertial regime by a relatively short period and strong inertia momentum, and such physics result in the nature of the spreading (Dt1/2). Here, we designed tunable nanostructures that can modify the nature law of the early droplet spreading. The results suggest that the increase of initial spreading momentum attribute to the capillary wicking effect controlled by the nanostructure morphology.

Chromosome maps of young LMC clusters: an additional case of coeval multiple populations

ABSTRACT Recent studies have revealed that the multiple populations (MPs) phenomenon does not occur only in ancient and massive Galactic globular clusters (GCs), but it is also observed in external galaxies, where GCs sample a wide age range with respect to the Milky Way. However, for a long time, it was unclear whether we were looking at the same phenomenon in different environments or not. The first evidence that the MPs phenomenon is the same regardless of cluster age and host galaxy came out recently, when an intermediate-age cluster from the Small Magellanic Cloud, Lindsay 1, and a Galactic GC have been directly compared. By complementing those data with new images from the Hubble Space Telescope (HST), we extend the comparison to two clusters of different ages: NGC 2121 (∼2.5 Gyr) and NGC 1783 (∼1.5 Gyr), from the Large Magellanic Cloud. We find a clear correlation between the RGB (red giant branch) width in the pseudo-colour CF275W, F343N, F438W and the age of the cluster itself, with the older cluster having larger σ(CF275W, F343N, F438W)RGB and vice versa. Unfortunately, the σ values cannot be directly linked to the N-abundance variations within the clusters before properly taking account the effect of the first dredge-up. Such HST data also allow us to explore whether multiple star formation episodes occurred within NGC 2121. The two populations are indistinguishable, with an age difference of only 6 ± 12 Myr and an initial helium spread of 0.02 or lower. This confirms our previous results, putting serious constraints on any model proposed to explain the origin of the chemical anomalies in GCs.

Compaction Dynamics during Progenitor Cell Self-Assembly Reveal Granular Mechanics

Summary We study the self-assembly dynamics of human progenitor cells in agarose microwells that are used for production of chondrogenic organoids. Using image analysis on time-lapse microscopy, we estimate the aggregate area in function of time for a large number of aggregates. In control conditions, the aggregate radius follows an exponential relaxation that is consistent with the dewetting dynamics of a liquid film. Upon introducing Y-27632 Rho kinase inhibitor, the compatibility with the liquid model is lost, and slowed-down relaxation dynamics are observed. We demonstrate that these aggregates behave as granular piles undergoing compaction, with density relaxation that follows a stretched exponential. Using simulations with an individual cell-based model, we construct a phase diagram of cell aggregates that suggests that the aggregate in presence of Rho kinase inhibitor approaches glass transition.

Coating biopolymer nanofibers with carbon nanotubes accelerates tissue healing and bone regeneration through orchestrated cell- and tissue-regulatory responses

Tailoring the surface of biomaterial scaffolds has been a key strategy to modulate the cellular interactions that are helpful for tissue healing process. In particular, nanotopological surfaces have been demonstrated to regulate diverse behaviors of stem cells, such as initial adhesion, spreading and lineage specification. Here, we tailor the surface of biopolymer nanofibers with carbon nanotubes (CNTs) to create a unique bi-modal nanoscale topography (500nm nanofiber with 25nm nanotubes) and report the performance in modulating diverse in vivo responses including inflammation, angiogenesis, and bone regeneration. When administered to a rat subcutaneous site, the CNT-coated nanofiber exhibited significantly reduced inflammatory signs (down-regulated pro-inflammatory cytokines and macrophages gathering). Moreover, the CNT-coated nanofibers showed substantially promoted angiogenic responses, with enhanced neoblood vessel formation and angiogenic marker expression. Such stimulated tissue healing events by the CNT interfacing were evidenced in a calvarium bone defect model. The in vivo bone regeneration of the CNT- coated nanofibers was significantly accelerated, with higher bone mineral density and up-regulated osteogenic signs (OPN, OCN, BMP2) of in vivo bone forming cells. The in vitro studies using MSCs could demonstrate accelerated adhesion and osteogenic differentiation and mineralization, supporting the osteo-promoting mechanism behind the in vivo bone forming event. These findings highlight that the CNTs interfacing of biopolymer nanofibers is highly effective in reducing inflammation, promoting angiogenesis, and driving adhesion and osteogenesis of MSCs, which eventually orchestrate to accelerate tissue healing and bone regeneration process. STATEMENT OF SIGNIFICANCE: Here we demonstrate that the interfacing of biopolymer nanofibers with carbon nanotubes (CNTs) could modulate multiple interactions of cells and tissues that are ultimately helpful for the tissue healing and bone regeneration process. The CNT-coated scaffolds significantly reduced the pro-inflammatory signals while stimulating the angiogenic marker expressions. Furthermore, the CNT-coated scaffolds increased the bone matrix production of bone forming cells in vivo as well as accelerated the adhesion and osteogenic differentiation of MSCs in vitro. These collective findings highlight that the CNTs coated on the biopolymer nanofibers allow the creation of a promising platform for nanoscale engineering of biomaterial surface that can favor tissue healing and bone regeneration process, through a series of orchestrated events in anti-inflammation, pro-angiogenesis, and stem cell stimulation.

A 3D numerical study of a molten solder droplet's wetting and solidifying on a pillar with application to electronic packaging

The 3D problem of spreading and solidification of a molten solder droplet (with a melting temperature of Tm and a radius of Rd) on a circular pillar (with a radius Rpillar and a height Hpillar, having a contact angle θpillar at wall temperature Tpillar) above a substrate has important applications in electronic packaging. In this paper, effects of pillar's contact angle and wall temperature on droplet dynamics and solidification of the solder droplet are studied numerically based on a newly developed 3D multi-component, triple- phase-change LB model. For pillar's wall temperature equal to the melting temperature of the molten droplet (Tpillar = Tm), no solidification takes place in the droplet after its contact with the pillar, and droplet's spreading characteristics depend on the pillar's contact angle. If pillar's contact angle (θpillar) is smaller than a critical contact angle (θpillar)cr, i.e., θpillar < (θpillar)cr, the solder droplet spreads toward the edge of the pillar's top, turning around the corner of the pillar and spreading downward along the pillar's side wall. Based on LB simulated results, a map in terms of (θpillar) versus (Rd/Rpillar) is presented, showing regimes of droplet spreading and not spreading around the corner of the pillar. An analytical expression for predicting the critical contact angle of the pillar is derived, which is shown to divide these two regimes in the map. LB simulations are also carried out for the case when pillar's wall temperature is lower than the melting temperature of the molten droplet (i.e., Tpillar < Tm). Under this situation, it is shown that although no solidification takes place during the initial spreading motion, but solder bumps begin to be formed subsequently due to solidification and droplet's spreading motion is arrested as a result. Since formation of solder bumps on pillar's side wall may lead to short circuit of electric connection between solder bumps with other electric sources in the gap between the pillars, it is important to prevent the formation of solder bumps on pillar's side wall. For this purpose, a map of (θpillar) versus (Rd/Rpillar) at different Stefan numbers (denoting the effect of pillar's wall temperature Tpillar) is obtained to define the regime in which no solder bumps are formed on the pillar's side wall.

Assessing the Accuracy of Forward-Looking Information in Debt Contract Negotiations: Management Forecast Accuracy and Private Loans

ABSTRACTWe examine a possible mechanism by which the lender can evaluate the borrower's ability to produce accurate forward-looking information. Forward-looking information is important to lenders to project the borrower's future performance and the loan's expected payoff. However, unlike historical financial statements, forward-looking information cannot be verified by lenders or external auditors. We contend that the borrower's past forecast accuracy provides a measure that allows the lender to assess the borrower's ability to produce accurate forward-looking information, allowing the lender to gain greater confidence in the borrower's projections of future value. Consistent with this argument, we find that the borrower's past forecast accuracy is negatively associated with the loan's initial interest spread. We also find that this relation is concentrated among non-relationship loans and borrowers with greater earnings volatility. Finally, we find that debt contracts to borrowers with more accurate managerial forecasts exhibit less interest rate mispricing.JEL Classifications: G30; M40; M41.

Phylogeographic and taxonomic considerations on Goniolimon tataricum (Plumbaginaceae) and its relatives from south-eastern Europe and the Apennine Peninsula

Goniolimon species are mainly components of the Eurasian steppe or steppe-like rocky vegetation, with some taxa occurring also in south-eastern Europe and northern Africa. We analysed the variability of: (i) two maternally inherited plastid loci (rpl32-trnL and 3′rps16-5′trnK) in 110 individuals of six currently accepted species from the Balkans and one species from the Apennines, to provide new insights into their origin and evolutionary history; and (ii) quantitative morphological characters (14 independent characters and one ratio character) in 641 individuals of three species of which two are morphologically and ecologically similar (G. italicum and G. tataricum) and the third, G. dalmaticum, was frequently misidentified as G. tataricum in the past, to provide new taxonomic treatment for proposed G. tataricum subspecies. We delineated several quantitative and five qualitative characters studied in a more limited sample as diagnostic for the identification of four subspecies (three newly described and one in a new rank) of G. tataricum. The history of westward peripheral populations of this species in the Balkans and the Apennines was rather complex and driven by local geo-historic events. These events facilitated multiple waves of east–west expansion of lineages originating from sources outside of the Balkan Peninsula which periodically diversified and occupied localised areas in the Balkans during the Pleistocene. An initial spread of an ancient G. tataricum lineage throughout south-eastern Europe probably occurred during the Messinian Salinity Crisis. Inter- and intraspecific hybridisation/introgression, as well as retention of ancestral polymorphisms, was common in G. tataricum and related taxa over time.

Influential Nodes Identification in Complex Networks via Information Entropy.

Identifying a set of influential nodes is an important topic in complex networks which plays a crucial role in many applications, such as market advertising, rumor controlling, and predicting valuable scientific publications. In regard to this, researchers have developed algorithms from simple degree methods to all kinds of sophisticated approaches. However, a more robust and practical algorithm is required for the task. In this paper, we propose the EnRenew algorithm aimed to identify a set of influential nodes via information entropy. Firstly, the information entropy of each node is calculated as initial spreading ability. Then, select the node with the largest information entropy and renovate its l-length reachable nodes’ spreading ability by an attenuation factor, repeat this process until specific number of influential nodes are selected. Compared with the best state-of-the-art benchmark methods, the performance of proposed algorithm improved by 21.1%, 7.0%, 30.0%, 5.0%, 2.5%, and 9.0% in final affected scale on CEnew, Email, Hamster, Router, Condmat, and Amazon network, respectively, under the Susceptible-Infected-Recovered (SIR) simulation model. The proposed algorithm measures the importance of nodes based on information entropy and selects a group of important nodes through dynamic update strategy. The impressive results on the SIR simulation model shed light on new method of node mining in complex networks for information spreading and epidemic prevention.

The emergence of hunter-gatherer pottery in the Urals and West Siberia: New dating and stable isotope evidence

The emergence of pottery among Stone Age hunter-gatherer societies of Eurasia constitutes one of the major open questions in Old World prehistory. Located halfway between the earliest Late Glacial cores of pottery production in East Asia, and Eastern Europe with forager ceramic starting around 6000 cal BC, the Urals and West Siberia are a key region in various scenarios currently under discussion. A lack of reliable absolute dates has been hindering an in-depth understanding of the temporal and spatial scales of the initial spread of the ceramic innovation. A Russian-German dating programme has now created a more reliable chronology of the early pottery phase, based on 28 AMS dates from across the study region. Taking freshwater reservoir effects into account, we can show that the earliest reliable evidence for pottery stems from the West Siberian forest steppes and Urals foothills, dating to the end of the 7th millennium cal BC. Over the following centuries, the innovation spread rapidly north into the taiga. Here, the early pottery horizon coincides with a unique set of innovations and intensification in the settlement system and the socio-economic sphere, including the appropriation of vast previously barely settled regions, the emergence of complex and even fortified settlements, and of ritual mounds. Pilot isotopic analyses of pottery charred crusts indicate diverse functions of the early vessels that were apparently not restricted to the processing of fish. The emerging wider picture indicates a surprisingly late, largely concurrent appearance of pottery in hunter-gatherer groups over extensive areas along the southern fringes of the taiga to both sides of the Urals at the end of the 7th millennium cal BC which is apparently not connected to the earlier, Late Pleistocene ceramic traditions in Trans-Baikalia and further East. Possible links to the 8.2 ka climatic event, other underlying triggers as well as the detailed chronology of these developments are still poorly understood and require further archaeological, biomolecular and typological studies.

Assessment and improvement of the 2019 ASHRAE handbook model for exhaust-to-intake dilution calculations for rooftop exhaust systems (ASHRAE 1823-RP)

The HVAC Applications volume of the 2019 ASHRAE Handbook: Chapter 46 gives multiple procedures for sizing building exhaust stacks and fans. The most complex of these procedures directly calculates dilution at a receptor of interest using plume theory and several empirical constants. There is suggestion in the literature that this model leads to overly conservative dilution predictions in some cases. The purpose of this work is to determine whether the ASHRAE model can be improved to give more accurate dilution predictions. First, the predictions of the existing equation are evaluated against several existing wind tunnel and full-scale studies and their shortcomings noted. The results show that the 2019 model under-predicts observed dilution mainly in two cases: near the stack and when the plume is within the assumed recirculation region. The assumptions for initial plume spread, height of recirculation zone region, plume spread and plume trajectory were varied parametrically to identify a better model. This optimized model can increase dilution predictions by factors between 2 and 500, while bounding measured data in all cases analyzed. This can reduce the required momentum ratio by 20–70%, leading to much more efficient fan sizing and operation.

Rapid Cell Type-Dependent Uptake of 0N4R TAU Monomer is not Solely Heparin Sulfate Proteoglycan Dependen

The brains of Alzheimer's patients typically show a distribution of extracellular amyloid plaques, composed of Aβ and neurofibrillary tangles, composed of postranslationally-modified and abnormally aggregated tau protein. The mechanism underlying the initial conversion and spread of pathological tau aggregates remains unknown. Recent work suggests that tau species can be released into the extracellular space and be subsequently endocytosed via negatively-charged heparan sulfate proteoglycans (HSPGs) available on the cell surface. Here, we produced monomeric 0N4R tau in both nonphosphorylated and phosphorylated states via recombinant expression in E. coli and purified for testing in cell culture. Using live-cell confocal microscopy and flow cytometry, we show that soluble 0N4R monomer can be rapidly endocytosed by multiple cell types and that this uptake is independent of phosphorylation state. Furthermore, we demonstrate that HSPGs enhance, but are not essential, for cellular endocytosis of both phosphorylated and non-phosphorylated tau. Current studies are focused on the impact of isoform type and degree of aggregation on uptake rate.

Melonic Turbulence

We propose a new application of random tensor theory to studies of non-linear random flows in many variables. Our focus is on non-linear resonant systems which often emerge as weakly non-linear approximations to problems whose linearized perturbations possess highly resonant spectra of frequencies (non-linear Schr\"odinger equations for Bose-Einstein condensates in harmonic traps, dynamics in Anti-de Sitter spacetimes, etc). We perform Gaussian averaging both for the tensor coupling between modes and for the initial conditions. In the limit when the initial configuration has many modes excited, we prove that there is a leading regime of perturbation theory governed by the melonic graphs of random tensor theory. Restricting the flow equation to the corresponding melonic approximation, we show that at least during a finite time interval, the initial excitation spreads over more modes, as expected in a turbulent cascade. We call this phenomenon melonic turbulence.

Analysis and improvement of material flow during extrusion process using spreading pocket die for large-size, flat-wide, and multi-ribs profile

Spreading extrusion is an advanced technology to produce the solid aluminum profiles with large-size, flat-wide, and thin-walled structures. Currently, little research has been reported on the hot extrusion process through spreading pocket die for manufacturing these kinds of aluminum profiles. It is a challenging task for die engineers to control the billet through die cavity with a uniform velocity. Reasonable structure design for spreading pocket die can eliminate extrusion defects and improve the performance of extrudate. In this paper, virtual tryout of spreading extrusion process for a large-size, flat-wide, and multi-ribs aluminum profile was performed through arbitrary Lagrangian-Eulerian simulation. Firstly, spreading pocket die was designed based on the theory of metal plastic flowing. The uniformity of flow velocity distribution on the cross-section of die exit was evaluated quantitatively through standard deviation calculation. Then, a series of structure modifications for the spreading pocket die was proposed to improve material flow during die cavity based on the simulated results. Thirdly, a synthetical comparison of extrusion formability for the modified and initial spreading pocket dies was carried out, including the metal flow behavior, exit temperature, residual stress of extrudate, and peak extrusion force. Finally, the modified extrusion dies were manufactured, and corresponding extrusion experiment was performed to verify the effectiveness and reliability of numerical simulations. The key design points of spreading pocket die for large-size, flat-wide, and multi-ribs aluminum profile were concluded.

A Newly Created Meso-, Micro-, and Nano-Scale Rough Titanium Surface Promotes Bone-Implant Integration.

Titanium implants are the standard therapeutic option when restoring missing teeth and reconstructing fractured and/or diseased bone. However, in the 30 years since the advent of micro-rough surfaces, titanium’s ability to integrate with bone has not improved significantly. We developed a method to create a unique titanium surface with distinct roughness features at meso-, micro-, and nano-scales. We sought to determine the biological ability of the surface and optimize it for better osseointegration. Commercially pure titanium was acid-etched with sulfuric acid at different temperatures (120, 130, 140, and 150 °C). Although only the typical micro-scale compartmental structure was formed during acid-etching at 120 and 130 °C, meso-scale spikes (20–50 μm wide) and nano-scale polymorphic structures as well as micro-scale compartmental structures formed exclusively at 140 and 150 °C. The average surface roughness (Ra) of the three-scale rough surface was 6–12 times greater than that with micro-roughness only, and did not compromise the initial attachment and spreading of osteoblasts despite its considerably increased surface roughness. The new surface promoted osteoblast differentiation and in vivo osseointegration significantly; regression analysis between osteoconductivity and surface variables revealed these effects were highly correlated with the size and density of meso-scale spikes. The overall strength of osseointegration was the greatest when the acid-etching was performed at 140 °C. Thus, we demonstrated that our meso-, micro-, and nano-scale rough titanium surface generates substantially increased osteoconductive and osseointegrative ability over the well-established micro-rough titanium surface. This novel surface is expected to be utilized in dental and various types of orthopedic surgical implants, as well as titanium-based bone engineering scaffolds.

HIV infection does not alter interferon α/β receptor 2 expression on mucosal immune cells.

The innate immune response induced by type I interferons (IFNs) plays a critical role in the establishment of HIV infection. IFNs are induced early in HIV infection and trigger an antiviral defense program by signaling through the IFNα/β receptor (IFNAR), which consists of two subunits, IFNAR1 and IFNAR2. Changes in IFNAR expression in HIV target cells, as well as other immune cells, could therefore have important consequences for initial HIV spread. It was previously reported that IFNAR2 expression is increased in peripheral blood CD4+ CXCR4+ T cells of HIV+ patients compared to HIV uninfected controls, suggesting that HIV infection may alter the IFN responsiveness of target cells. However, the earliest immune cells affected by HIV in vivo reside in the gut-associated lymphoid tissue (GALT). To date, it remains unknown if IFNAR expression is altered in GALT immune cells in the context of HIV infection and exposure to IFNs, including the 12 IFNα subtypes. Here, we analyzed the expression of surface bound and soluble IFNAR2 on Lamina propria mononuclear cells (LPMCs) isolated from the GALT of HIV- individuals and in plasma samples of HIV+ patients. IFNAR2 expression varied between different T cells, B cells and natural killer cells, but was not altered following HIV infection. Furthermore, expression of the soluble IFNAR2a isoform was not changed in HIV+ patients compared to healthy donors, nor in LPMCs after HIV-1 infection ex vivo. Even though the 12 human IFNα subtypes trigger different biological responses and vary in their affinity to both receptor subunits, stimulation of LPMCs with different recombinant IFNα subtypes did not result in any significant changes in IFNAR2 surface expression. Our data suggests that potential changes in the IFN responsiveness of mucosal immune cells during HIV infection are unlikely dictated by changes in IFNAR2 expression.

Pattern of loco-regional relapses and treatment in pediatric esthesioneuroblastoma: The French very rare tumors group (Fracture) contribution.

Esthesioneuroblastoma (ENB) is a rare neuroectodermal tumor that seldom occurs during childhood. Multimodal treatments are currently proposed, but the place of each therapy is still in debate. Our objective is to describe clinical evolution, especially the pattern of relapses and determine contributors to tumor progression. Medical charts of all children (≤18 years) affected by ENB treated in France from January 1990 to December 2015 were retrospectively analyzed. Eighteen patients were selected (10 males). Median age at diagnosis was 12.2 years (0.9-18). Tumor extension was Kadish stage A (n=1), B (n=3), C (n=10), and D (n=4). Hyams histological grades were I (n=1), II (n=3), III (n=6), and IV (n=6) (in two cases not defined). Initial cervical nodal spread was assessed by magnetic resonance imaging (n=15), computed tomography scan (n=16), fluorodeoxyglucose-positron emission tomography-computed tomography (n=7), and cytological/histological analysis (n=2). N1 stage was confirmed by imaging in two of 18 cases and one of two cases had cervical node dissection with neck irradiation (58Gy). After a median follow-up of survivors of 7.6 years (3.8-17.9), 10 patients developed neuromeningeal progression, whereas no cervical nodal relapse occurred and only eight survived. Both 5-year overall and event-free survival rates were 44.4% (±11.7%). The poor prognosis is mainly related to neuromeningeal dissemination that should be considered during treatment strategy. However, cervical lymph node relapse is rare.

Emittance preservation through density ramp matching sections in a plasma wakefield accelerator

In plasma wakefield acceleration, the witness beam's emittance needs to be preserved when it propagates through a plasma stage. The plasma includes density ramps at both the entrance and the exit. Using the Wentzel-Kramers-Brillouin solution of a single particle's motion, analytical expressions for the evolution of the beam emittance and the Twiss parameters in an arbitrary adiabatic plasma profile are provided neglecting the acceleration of the beam inside the plasma. It is shown that the beam emittance can be preserved under the matching condition even when the beam has an initial energy spread. It is also shown that the emittance growth for an unmatched beam is minimized when it is focused to the same vacuum plane for a matched beam. The emittance evolution from 3D QuickPIC simulation results agree well with the theoretical results. In the some of the proposed experiments on nearly completed FACET II facility, the matching condition may not be perfectly satisfied and the wake may not be perfectly symmetric. It is shown that for a given set of beam parameters that are consistent with FACET II capabilities, even when the assumptions of the theory are not satisfied, the emittance growth can still be minimized by choosing the optimal focal plane. Last, another issue that may cause emittance growth in realistic plasmas is also examined. When using a lithium plasma source in FACET II experiments a helium buffer gas is used. The plasma is formed from field ionization which can lead to a nonlinear focusing force when there are nonuniform helium ions due to its high ionization potential. For an initial beam emittance of $20\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$, the helium ionization is found to be small and the witness beam's emittance can be preserved.