Separate Lines Research Articles

Information system of support of economic decisions on the development of the Internet provider network

The paper suggests and confirms the hypothesis about the dependence of the price of internet service provider tariffs on the main economic and demographic determinants, and also defines the list of these determinants. An economic-mathematical model for optimizing the distribution of the budget for the expansion of the Internet provider's network between the execution of connection requests for separate service lines and tariffs has been developed. One of the key elements of the activity of Internet providers is the solution of the "last mile" problem, which consists in providing a communication service between the end user and the provider's Internet access node. Taking into account the orientation of such enterprises to the maximization of their own profit, this problem should be considered in the technical and economic dimension. Solving this problem requires a multidimensional approach that takes into account technology, economics and geography, as well as the significant investment required to expand network coverage and meet the demands of a distributed customer base. Internet providers should take into account the negative impact of possible network congestion, non-linear pricing, as well as consumer demand when optimizing pricing strategies and network development strategies. The developed model was applied to historical data on the activity of the Internet provider. The proposed approaches are combined into a single information system to support economic decision-making for the development of network of Internet providers, which contributes to the implementation of the developed model in practice and allows to increase the efficiency of the production activities of such enterprises. The paper put forward and confirmed the hypothesis about the dependence of prices for fixed Internet connection services on the dollar exchange rate, the cost of connecting to the trunk node, and the population. Approaches to economic decision-making in the management of the Internet provider's activities were further developed, namely, an economic-mathematical model was developed and tested to optimize the allocation of the budget for the expansion of the Internet provider's network between the satisfaction of applications of potential subscribers for connection in the section of individual tariffs of the provider's current tariff grid. As a result of the test of the developed economic-mathematical optimization model on the historical data of the enterprise, the possibility of improving the expected profit relative to the basic plan by 18% was established.

An integrated method for extracting channel network with check dams from high‐resolution DEM on the Loess Plateau

AbstractChannel networks have been widely used to model sediment transport and accumulation. Extracting channel networks in the check dam region from digital elevation models on the Loess Plateau can facilitate effective decision‐making and planning for soil and water conservation. Three methods are generally used to ensure the continuity of channel networks by removing check dams as hydrological barriers: filtering, filling and breaching. However, these methods may still cause disruption and displacement of the channel network owing to the existence of check dams. This study presents the development of an integrated method (improved regional growth and linear feature detection [iRG‐LFD]) for extracting natural continuous channel networks and locating check dams. First, a proposed improved region growth method based on channel and check dam terrain features was used to extract the complete channel network. Subsequently, the line segment detector for extracting straight lines was then improved to separate lines with different slopes. Finally, by combining the channel network and line segment detector results, a cross model was proposed for extracting check dams of different sizes. The experimental results for the Wangmaogou and Zhoutungou catchments showed minimal errors when the proposed method was used to extract the channel network, and F1‐scores of 86.67% and 86.95% were obtained for the predicted check dam samples in the two catchments, respectively. The results indicate that this method can be effectively used to extract continuous natural channel networks and accurately identify check dams and can thus be used to design soil and water conservation measures.

On the number of limit cycles in piecewise smooth generalized Abel equations with many separation lines

This paper investigates generalized Abel equations of the form dx/dθ=A(θ)xp+B(θ)xq, where p, q∈Z≥2, p≠q, and A(θ) and B(θ) are piecewise trigonometrical polynomials of degree m with n−1∈N+ separation lines 0<θ1<θ2<⋯<θn−1<2π. The main objective is to obtain the maximum number of non-zero limit cycles (i.e., non-zero isolated periodic solutions) that the equation can have, denoted by Hθ1,θ2,…,θn−1(m), and to analyze how the number and location of separation lines {θi}i=1n−1 affect Hθ1,θ2,…,θn−1(m). By using the theories of Melnikov functions and ECT-systems, we obtain lower bounds for Hθ1,θ2,…,θn−1(m). Our result extend those of Huang et al. who studied the special case of n=2, and reveal that the lower bounds decrease in the presence of pairs of symmetrical separation lines.

Investigation on formation mechanism of cavitation channel vortex in the runner of Francis turbine

Abstract Cavitation channel vortices generally cause flow state more complex in the runner, leading to the work efficiency is reduced and the cavitation erosion on flow components is enhanced. In this paper, simulation of cavitation flow is carried out for a Francis turbine model, and the evolution of vortices in the runner during cavitation development is analyzed under partial load conditions. The results show that cavitation has a great influence on the morphology and distribution of attached vortices between blades, trailing vortices at the outlet edge of the blades, and vortex near the cone in the runner. With the gradual development of cavitation, the invasion effect of vortex rope in draft tube on the runner is enhanced, and the vortex near runner cone is gradually connected as a whole. Under the effect of the downstream reverse pressure gradient in local low-pressure area, the flow separation area gradually expands to the blade and upstream, and more singular points evolve on flow separation lines, which leads to more trailing vortices at the outlet of the blade and cavitation channel vortices are formed in serious cavitation stage.

Editorial — Across Borders: Questions, Practices and Performances

The relationship between architecture and border studies is, rightly, at the forefront of many architectural scholars' minds, and has seen the inception of other publications, most notably&amp;nbsp; Angeliki Sioli, Nishat Awan and Kristopher Palagi’s edited collection Architecture of Resistance: Negotiating Borders through Spatial Practices (KU Leuven, forthcoming) and a special issue of Architecture and Culture, ‘Border Fictions’ edited by Mohamad Hafeda and Samuel Vardy (again forthcoming). We started putting together this issue of field on borders, &amp;nbsp;‘Across Borders: Questions, Practices and Performances’, the first full collection on architecture and borders to be published, number by defining what we specifically meant by the notion of border. The conventional meaning, as the delineation of territory, has shaped our individual lives: the three of us have moved across borders, territories, communities and languages several times; we have crisscrossed our identities from the colonised Global South, the so called commonwealth colonised antipodes, the settler colonial North America, the (post)communist East of Europe.&amp;nbsp; We have experienced bBorders, as Prem Kumar Rajaram and Carl Grundy-Warr tell us, are not as neutral separation lines: but thethey creatione ofa distinction between centre and periphery, normal and exceptional, belonging and not belonging. Borders enact biopolitics, demarcating (and othering) not only identity but creating zones of exception, a jurisdictions in which bodies (racialised, gendered) can be disciplined and made to conform and cohere. We realised, as we continued our attempt tos of definedefining borders, that any understanding of the bordersthey&amp;nbsp; are is always entangled with other political concepts. The border is the logical consequence of the notion of the utopia that underlies the nation state. An ideal place can only be created if it is set against the other, or its dystopia; the creation of, if there are&amp;nbsp; boundaries, physical or artificial, which make sure that the conditions for the ideal (and the non) place are maintained. Borders, are at once whether material and metaphorical, ; are always at once utopian, colonial, patriarchal, capitalist and hegemonic,&amp;nbsp;

Investigation of genetic diversity using molecular and biochemical markers associated with powdery mildew resistance in different flax (Linum usitatissimum L.) genotypes

Under greenhouse conditions, the resistance of 18 different genotypes of flax to powdery mildew was evaluated. To investigate genetic diversity and identify the molecular and biochemical markers linked to powdery mildew resistance in the tested genotypes, two molecular marker systems—start codon targeted (SCoT) and inter-simple sequence repeat (ISSR)—as well as a biochemical marker (protein profiles, antioxidant enzyme activity, and secondary metabolites) were used. Based on the results, the genotypes were classified into four categories: highly susceptible, susceptible, moderately susceptible, and moderately resistant. The genotypes differed significantly in powdery mildew severity: Polk had a severity of 92.03% and Leona had a severity of 18.10%. Compared to the other genotypes, the moderately resistant genotypes had higher levels of flavonoids, antioxidant enzymes, phenolics, and straw yield; nevertheless, their hydrogen peroxide and malondialdehyde levels were lower. Protein profiles revealed 93.75% polymorphism, although the ISSR marker displayed more polymorphism (78.4%) than the SCoT marker (59.7%). Specific molecular and biochemical markers associated with powdery mildew resistance were identified. The 18 genotypes of flax were divided into two major clusters by the dendrogram based on the combined data of molecular markers. The first main cluster included Leona (genotype number 7), considered moderate resistance to powdery mildew and a separate phenetic line. The second main cluster included the other 17 genotypes, which are grouped together in a sub-cluster. This means that, besides SCoT, ISSR markers can be a useful supplementary technique for molecular flax characterization and for identifying genetic associations between flax genotypes under powdery mildew infection.

Characterization of the Endwall Flow in a Low-Pressure Turbine Cascade Perturbed by Periodically Incoming Wakes, Part 2: Unsteady Blade Surface Measurements Using Pressure-Sensitive Paint

Unsteady pressure-sensitive paint (i-PSP) measurements were performed at a sampling rate of 30 kHz to investigate the near-endwall blade suction surface flow inside a low-pressure turbine cascade operating at engine-relevant high-speed and low-Re conditions. The investigation focuses on the interaction of periodically incoming bar wakes at 500 Hz with the secondary flow and the blade suction surface. The results build on extensive PIV measurements presented in the first part of this two-part publication, which captured the ’negative-jet-effect’ of the wakes throughout the blade passage. The surface pressure distributions are combined with CFD to analyze the flow topology, such as the passage vortex separation line. By analyzing data from phase-locked PIV and PSP measurements, a wake-induced moving pressure gradient negative in space and positive in time is found, which is intensified in the secondary flow region by 33% with respect to midspan. Furthermore, two methods of frequency-filtering based on FFT and SPOD are compared and utilized to associate a pressure fluctuation peak around 678 Hz with separation bubble oscillation.

An Open–Closed Flow Separation in a Compressor Radial Diffuser

Abstract Large eddy simulations (LES) results are used to track flow separation zones in a splittered vaned radial diffuser near the compressor best efficiency at high rotation speed. The topology analysis reveals some closed separations at the corner of the blade and hub or shroud surface. In addition, an open–closed flow separation at the main blade pressure side is observed for the first time. The surface separation has the shape of a sheet at the blade mid-span, and the associated separation line is delimited only at its downstream extremity by a trailing edge node. This flow separation process is robust to a small shift in operating condition, and the separation surface remains essentially unchanged. A large flowrate variation converts the open–closed separation into a more classic closed separation. The evolution in time of the separation surface is also observed, and the authors conclude to the unsteady existence of the open–closed separation.

308 Awardee Talk: Prevention and mitigation of pathogens in feed and feed manufacturing systems

Abstract Prior to 2013, pathogen transmission through feed was focused primarily on bacteria and biosecurity was used to prevent adulterant entry into the ingredients and the feed mills. Following the porcine epidemic diarrhea virus (PEDV) outbreak in 2013, research focused on pathogen mitigation and control quickly became a subject of interest. Since PEDV, multiple endemic viruses and foreign animal diseases have been found to be transmissible in feed or feed ingredients. As African swine fever virus (ASFV) spread closer to the United States and endemic pathogens are a continued pressure on production systems, it is imperative that prevention measures are included in the feed supply chain and options for mitigation are fully elucidated for times of need. Previous research has demonstrated that preventative measures such as boot baths, lines of separation, showers, and changing clothes are effective measures when appropriately maintained. However, these protocols can seem costly and burdensome to employees, especially when the risk of disease transmission appears low. Employee training is difficult as disease transmission is difficult to visualize and exhibit the importance of each measure. Glo Germ, a florescent substance, is a cost-effective training tool which can demonstrate the efficacy of prevention protocols and can identify areas where biosecurity measures have not been properly utilized. Preventative measures are the first line of defense for feed manufacturing systems, but understanding and using mitigation techniques in the event of contamination can limit pathogen spread and protect the rest of the feed supply chain. Pelleting, as a method of thermal inactivation process, has recently been demonstrated to lessen the quantity of detectable viral RNA and decrease the risk of infection. The pelleting process, however, is a point-in-time mitigant and does not decrease the risk of product re-contamination as feed continues down the supply chain. The use of chemical mitigants, like formaldehyde, medium-chain fatty acids, and organic acids, can decrease the presence of bacterial and viral pathogens with longer-lasting mitigation properties. These mitigants can either be used in the feed itself, or as an addition to flushing batches which help disperse the chemical mitigants throughout the feed manufacturing equipment, thus reducing the risk of product re-contamination. In the event more drastic measures must be taken to eliminate pathogen presence from feed mills, gaseous fumigation and the use of portable heaters show promise as methods to decontaminate feed manufacturing equipment without the use of water or complete equipment breakdown. Overall, effective training and implementation of preventative measures are needed to provide pathogen-free feed to production systems, but continued research in mitigation and mill decontamination will further protect the feed supply chain in the event of pathogen contamination.

Abstract 2147: Impact Of Donor Age On Microvasculature Self-assembly Of Induced Pluripotent Stem Cell Derived Endothelial Progenitors

Introduction: Current vascular tissue-engineering using induced pluripotent stem cells (iPSCs) predominantly relies on somatic cells obtained from newborn or fetal donors. However, iPSCs sourced from aged individuals exhibit epigenetic differences in angiogenic genes that may hinder their utility in iPSC derived vasculature. We hypothesized that, due to these differences, iPSCs from aged donors will exhibit decreased vasculogenic potential. Methods: We differentiated iPSCs into endothelial progenitors (iEPs) and encapsulated them in an interpenetrating polymer network hydrogel containing norbornene-functionalized hyaluronic acid and Collagen I at cell densities and hydrogel stiffness optimal for vasculogenesis. Seven days after encapsulation, the hydrogels were fixed, and the resulting microvasculature imaged. We then utilized a previously developed computational pipeline to quantify several vasculogenic properties. Results: We derived iEPs from four separate iPSC lines: 2 sourced from neonatal donors (ND) and 2 from mature donors (MD). Irrespective of donor age, differentiation yielded ~15% (n=4) iEPs of the total cell population. The two ND lines developed a similar plexus, whereas this structure was diminished in one adult line and absent in the second. Between iEPs matched for sex and somatic cell origin, there is a 50% decrease in vessel volume fraction and number of links between vessels, a 66% reduction in the percentage of vessels connected to the largest vessel, and a 43% reduction in branch points between vessels ( Fig. 1 ). Conclusion: Overall, these data suggest MD iEPs are less likely to form dense interconnected microvasculature as compared to ND iEPs. Interestingly, the average diameter did not change across all cell lines. This suggests that while MD iEPs exhibited cell clustering, they were less likely to branch out and interconnect with other clusters of iPSC-EPs to form interconnected networks

Green Marketing In India: Emerging Opportunities And Challenges

Green marketing is a phenomenon which has developed particular important in the modern market. This concept has enabled for the re-marketing and packaging of existing products which already adhere to such guidelines. Additionally, the development of green marketing has opened the door of opportunity for companies to co-brand their products into separate line, lauding the green-friendliness of some while ignoring that of others. Such marketing techniques will be explained as a direct result of movement in the minds of the consumer market. As a result of this businesses have increased their rate of targeting consumers who are concerned about the environment. These same consumers through their concern are interested in integrating environmental issues into their purchasing decisions through their incorporation into the process and content of the marketing strategy for whatever product may be required. This paper discusses how businesses have increased their rate of targeting green consumers, those who are concerned about the environment and allow it to affect their purchasing decisions. The paper identifies the three particular segments of green consumers and explores the challenges and opportunities businesses have with green marketing. The paper also examines the present trends of green marketing in India and describes the reason why companies are adopting it and future of green marketing and concludes that green marketing is something that will continuously grow in both practice and demand.

PEMAKNAAN REZIM PEMILU PASCA PUTUSAN MK NOMOR 55/PUUXVII/2019

The legal basis for transferring regional head election dispute resolution is regulated in article 236C of Law no. 12 of 2008 concerning amendments to Law no. 32 of 2004 concerning Regional Government. This is based on the transfer of election status from the Regional Government regime to the Election Regime. The change in status from Pilkada to Election regime has implications for the transfer of authority in resolving disputes from the Supreme Court to the MK. As regulated in article 1 point 4 of Law no. 22 of 2007 concerning General Election Organizers which states that the Election of Regional Heads and Deputy Regional Heads is an election to elect regional heads and deputy regional heads directly in the Unitary State of the Republic of Indonesia based on Pancasila and the 1945 Constitution of the Republic of Indonesia. From this statement there is an important question regarding the alleged norm dispute between Law no. 22 of 2007 concerning Election Organizers with the 1945 Constitution, because article 22E paragraph (2) of the 1945 Constitution states that General Elections are held to elect members of the People's Representative Council, Regional Representative Council, President and Vice President, and Regional People's Representative Council. So from these two articles it can be seen that there is an indication of inconsistency in the law makers regarding election terminology as regulated in the 1945 Constitution. In the Constitutional Court decision no. 55/PUU-XVII/2019, the Constitutional Court presented a number of other examples of new simultaneous elections which include regional elections in the simultaneous flow. In the Constitutional Court decision no. 55/PUUXVII/2019 was not included in the election regime because it can be seen from the Constitutional Court Decision No. 48/PUU-XVII/2019 and Constitutional Court Decision No. 55/PUU-XVII/2019 where the Constitutional Court did not respond to the theory of regime segregation initiated by the Constitutional Court in Constitutional Court Decision No. 97/PUU-XI/2013. In Constitutional Court Decision No. 55/PUU-XVII/2019 does not want to be trapped in using the regime separation line of thinking again and instead provides a new idea, namely the simultaneity of elections, namely National Elections and Local Elections (which include Regional Elections).

Surgical outcomes of right atrial mass: 5years of experience.

Cardiac masses are relatively rare, with a right atrial mass being even more rare. Right atrial masses pose a diagnostic dilemma owing to the diverse range of potential diagnoses, even when the clinical context and initial imaging modalities are thoroughly evaluated. A right atrial mass can have a varied etiology as it can be a physiological variant, or a neoplastic or a non-neoplastic mass with each having a separate line of management. This paper aims to highlight the etiology and the surgical outcomes of patients having a right atrial mass.

The “Angel-Wing” Combined Labia Minoraplasty/Majoraplasty

Background: Reduction of prominent/hypertrophic/ptotic vulvar labia minora and/or labia majora is an increasingly common surgical procedure in the hands of plastic and cosmetic surgeons and female genital cosmetic and reconstructive surgeons. While several techniques for these reductions are described in the literature and are individually modified by experienced practitioners, 2 procedures for the minora (linear and wedge-type reductions), and the vertically-aligned reduction of redundant majora are the most utilized techniques. It is not unusual for a woman to present to her potential surgeon requesting “work” on both minora and majora. Historically, this has necessitated two separate incision lines (minora and majora) bilaterally, often resulting in a long case, difficult recovery, and a significant potential for visible incision lines and gaping of the vaginal introitus. Objective: To introduce a novel single-incision-line technique for combining labia minoraplasty and labia majoraplasty. Methods: A modification of a classic central V-Wedge technique is affected by “shifting” the wedge incision line across the interlabial fold to encompass a portion of the medial labum majorum, both reducing redundancy and “lifting” the lowermost portion of the majora to correct ptosis. This is accomplished in one incision line with “en-bloc” closure of both minora and majora, placing the incision line mostly within the interlabial fold. Results: The author has completed eight wedge-type combined labia minora-majoraplasties without complication and with 2.5-36 months of follow-up. Discussion: This modification in Wedge design converts two separate procedures into one, making the surgery both less time-consuming, easier to recover from, and more visually esthetic for those patients who are capable of the more rigorous recovery protocol that wedge procedures mandate. Conclusion: The “Angel-Wing combined labia minoraplasty + labia majoraplasty appears to be a relevant option for combined labia minor hypertrophy and labia majora deflation and redundancy.

The Full Non-linear Vortex Tube-Vorton Method: the pre-stall condition

The present hybrid vortex tube-vorton method is based entirely on the Full Multi-wake Vortex Lattice Method (FMVLM) concepts, which means detaching vorticity with precise vortex strength and orientation along all separation lines between each discretized element of a shell-body, including all external edges. Since the classic Vortex Particle Method (VPM) is unstable by itself because it does not conserve the total amount of circulation as time evolves (Kelvin’s circulation theorem), an isolated Vortex (regularized) Filament Method (VFM) approach is implemented to obtain advection of vorticity, while the induced velocity field is obtained through its corresponding full vorton cloud. Further, a novel vortex squeezing/stretching scheme for such a vortex cylinder-sphere approach is proposed based on variation in time for vortex volumes in order to precisely (zero residual) conserve both circulation and vorticity at each time step (for each detached vortex element), while the viscous effect can be accounted for via the Core Spreading Method (CSM).

Investigating mortality salience as a potential causal influence and moderator of responses to laboratory pain.

Because pain can have profound ramifications for quality of life and daily functioning, understanding nuances in the interplay of psychosocial experiences with pain perception is vital for effective pain management. In separate lines of research, pain resilience and mortality salience have emerged as potentially important psychological correlates of reduced pain severity and increased tolerance of pain. However, to date, there has been a paucity of research examining potentially interactive effects of these factors on pain perception. To address this gap, the present experiment investigated mortality salience as a causal influence on tolerance of laboratory pain and a moderator of associations between pain resilience and pain tolerance within a Chinese sample. Participants were healthy young Chinese adults (86 women, 84 men) who first completed a brief initial cold pressor test (CPT) followed by measures of demographics and pain resilience. Subsequently, participants randomly assigned to a mortality salience (MS) condition completed two open-ended essay questions in which they wrote about their death as well as a death anxiety scale while those randomly assigned to a control condition completed analogous tasks about watching television. Finally, all participants engaged in a delay task and a second CPT designed to measure post-manipulation pain tolerance and subjective pain intensity levels. MS condition cohorts showed greater pain tolerance than controls on the post-manipulation CPT, though pain intensity levels did not differ between groups. Moderator analyses indicated that the relationship between the behavior perseverance facet of pain resilience and pain tolerance was significantly stronger among MS condition participants than controls. This experiment is the first to document potential causal effects of MS on pain tolerance and Ms as a moderator of the association between self-reported behavior perseverance and behavioral pain tolerance. Findings provide foundations for extensions within clinical pain samples.

Realization of a quadrupole topological insulator phase in a gyromagnetic photonic crystal

ABSTRACT The field of topological photonics was initiated with the realization of a Chern insulator phase in a gyromagnetic photonic crystal (PhC) with broken time-reversal symmetry (T), hosting chiral edge states that are topologically protected propagating modes. Along a separate line of research, a quadrupole topological insulator was the first higher-order topological phase supporting localized corner states, but has been so far limited to T-invariant systems, as T is a key ingredient in early models. Here we report the realization of a quadrupole topological insulator phase in a gyromagnetic PhC, as a consequence of topological phase transition from the previously demonstrated Chern insulator phase. The phase transition has been demonstrated with microwave measurements, which characterize the evolution from propagating chiral edge states to localized corner states. We also demonstrate the migration of topological boundary states into the continuum, when the gyromagnetic PhC is magnetically tuned. These results extend the quadrupole topological insulator phase into T-broken systems, and integrate topologically protected propagating and localized modes in a magnetically tunable photonic crystal platform.

The associative pattern classifier: Progress in theoretical understanding

The Associative Pattern Classifier (APC) was designed as an associative memory, focusing particularly on pattern classification. This implies that the training memory is constructed in a single operation and pattern classification also occurs in a single process. It is important to note that the APC translates the input patterns through a translation vector, which represents the average of all input patterns. Until now, there is no theoretical framework to explain the inner workings of the APC. Its relevance is inferred from the fact that several studies have been conducted using it as a foundation. This paper seeks to provide a theoretical comprehension of the APC’s operation to facilitate future enhancements. We found the APC creates a system in static equilibrium through concurrent vectors at the origin (translation vector), resulting in a balanced separation of patterns. However, the APC cannot achieve complete pattern separation because of the presence of a neutral region. The neutral region is defined by all the points that define the separation hyperplanes. The points over the hyperplanes cannot be classified by the APC. Additionally, we discovered that the APC is unable to accurately classify the translation vector, which could be included as part of the input patterns. Our previous research showed that the APC is unsuccessful in achieving the linear separation of the AND function. In this research, we broaden the examination of the AND function to illustrate that achieving linear separation is not feasible because the separation line represents a neutral region. The APC demonstrated exceptional performance when tested with artificial datasets where patterns were distributed over balanced regions, thus operating as an efficient multiclass and non-linear classifier. Nevertheless, the performance of the APC is lower when tested with real-world databases, making the APC inaccurate due to its restricted inner workings.

Large-scale excess H i absorption around z ≈ 4 galaxies detected in a background galaxy spectrum in the MUSE eXtremely deep field

ABSTRACT Observationally mapping the relation between galaxies and the intergalactic medium (IGM) is of key interest for studies of cosmic reionization. Diffuse hydrogen gas has typically been observed in H i Lyman-α (Lyα) absorption in the spectra of bright background quasars. However, it is important to extend these measurements to background galaxies as quasars become increasingly rare at high redshift and rarely probe closely separated sight lines. Here, we use deep integral field spectroscopy in the MUSE eXtremely Deep Field to demonstrate the measurement of the Lyα transmission at z ≈ 4 in absorption to a background galaxy at z = 4.77. The H i transmission is consistent with independent quasar sight lines at similar redshifts. Exploiting the high number of spectroscopic redshifts of faint galaxies (500 between z = 4.0–4.7 within a radius of 8 arcmin) that are tracers of the density field, we show that Lyα transmission is inversely correlated with galaxy density, i.e. transparent regions in the Lyα forest mark underdense regions at z ≈ 4. Due to large-scale clustering, galaxies are surrounded by excess H i absorption over the cosmic mean out to 4 cMpc/h70. We also find that redshifts from the peak of the Lyα line are typically offset from the systemic redshift by +170 km s−1. This work extends results from z ≈ 2–3 to higher redshifts and demonstrates the power of deep integral field spectroscopy to simultaneously measure the ionization structure of the IGM and the large-scale density field in the early Universe.

Mach 3.5 Compression Corner Control Using Microvortex Generators

An experimental investigation has been performed to examine the effect of vortex generators (VGs) on a compression corner flow separation. Experiments are conducted at Mach 3.5 along a 23° compression corner with turbulent inflow boundary-layer and Reynolds number 27×104 based on the 6.2-mm boundary-layer thickness. Micro-ramp, standard ramped-vane, and inverted ramped-vane VGs all cause the separation line to ripple and become more three-dimensional, but none eliminate it altogether. Vane-type VGs produce a stronger control effect than micro-ramps. Inverted vanes tend to generate large areas of near-wall low-momentum flow that locally increase separation length, making standard vane configurations more effective at reducing separation size. Velocimetry measurements show that the VG-induced vortices remain coherent and capable of exchanging momentum within the boundary-layer, even downstream of the interaction. Enhanced flow three-dimensionality causes an intensification of areas of increased and decreased momentum downstream of reattachment, resulting in significant flow distortion. Increased near-wall turbulent fluctuations are observed upstream of the interaction in areas where separation length is reduced. These findings are used to propose a mechanism of VG control, highlighting the role of VGs in enhancing mixing in the separated shear layer, leading to earlier reattachment and an overall reduction in separation length.