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Peruvian Man Pleads Guilty to Overseeing Call Centers that Threatened and Defrauded Spanish-Speaking U.S. Consumers




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Jerusalem Post: Meet the 107-year-old woman who survived the coronavirus and Spanish flu

Jerusalem Post: Meet the 107-year-old woman who survived the coronavirus and Spanish flu. “After Marilee Shapiro Asher was admitted to the hospital in mid-April sick with COVID-19, her daughter got a call from the doctor telling her she ought to get down there right away. Her mother likely had only 12 hours to live. ‘Well, … Continue reading Jerusalem Post: Meet the 107-year-old woman who survived the coronavirus and Spanish flu




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Translocated Humpback Chub Spawn in Havasu Creek

National Park Service (NPS) biologists found spawning translocated endangered humpback chub (Gila cypha) in Havasu Creek during a recent fisheries monitoring trip that occurred between May 6 and May 15. https://www.nps.gov/grca/learn/news/translocated-humpback-chub-spawn-in-havasu-creek.htm




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Wood and Coal Cofiring In Interior Alaska: Utilizing Woody Biomass From Wildland Defensible-Space Fire Treatments and Other Sources

Cofiring wood and coal at Fairbanks, Alaska, area electrical generation facilities represents an opportunity to use woody biomass from clearings within the borough's wildland-urban interface and from other sources, such as sawmill residues and woody material intended for landfills. Potential benefits of cofiring include air quality improvements, reduced greenhouse gas emissions, market and employment development opportunities, and reduction of municipal wood residues at area landfills. Important issues that must be addressed to enable cofiring include wood chip uniformity and quality, fuel mixing procedures, transportation and wood chip processing costs, infrastructure requirements, and long-term biomass supply. Additional steps in implementing successful cofiring programs could include test burns, an assessment of area biomass supply and treatment needs, and a detailed economic and technical feasibility study. Although Fairbanks North Star Borough is well positioned to use biomass for cofiring at coal burning facilities, long-term cofiring operations would require expansion of biomass sources beyond defensible-space-related clearings alone. Long-term sources could potentially include a range of woody materials including forest harvesting residues, sawmill residues, and municipal wastes.




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CSS play - Space Invader

A CSS3 animated space invader using two divs and linear-gradients, no images.




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Monitoring Forests From Space: Quantifying Forest Change By Using Satellite Data

Change is the only constant in forest ecosystems. Quantifying regional-scale forest change is increasingly done with remote sensing, which relies on data sent from digital camera-like sensors mounted to Earth-orbiting satellites. Through remote sensing, changes in forests can be studied comprehensively and uniformly across time and space.




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True fir spacing trials: 10-year results

Eighteen precommercial thinning trials were established in true fir-hemlock stands in the Olympic Mountains and the west side of the Cascade Range during the period 1987 through 1994. This paper updates a previous report, with results for the first 10 years after establishment. Results are given for (1) all trees, (2) the largest 80 per acre of any species, and (3) those noble fir (Abies procera Rehd.) and Pacific silver fir (Abies amabilis Dougl. ex Forbes) included in the largest 80 per acre. Diameter growth of all species increased with increase in spacing. Height growth of Pacific silver fir decreased with increase in spacing. The largest 80 trees per acre of all species showed some increase in diameter and basal area growth with increased spacing, while height growth declined slightly and volume growth was nearly constant. Over time, these installations will provide a unique source of information on early development of managed stands of these species, for which little information is now available.




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True fir spacing and yield trials-a 20-year update

This report updates data and comparisons from previous reports (Curtis and others 2000, Curtis 2008) on a series of precommercial thinning and yield trials in high-elevation true fir–hemlock stands, using data from the 12 replicates for which 20-year data are now available. The stands were varying mixtures of Pacific silver fir (Abies amabilis (Douglas ex Loudon) Douglas ex Forbes), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and noble fir (Abies procera Rehder). Trends noted in the 2008 report continue. Increment in top height was somewhat reduced at wide spacings. Volume increment and basal area increment increased as the residual number of trees increased. There was a small increase in diameter increment of the 80 largest trees per acre at wide spacing. Relative stand densities on the unthinned plots, as measured by stand density index (SDI) and relative density (RD), are still increasing; it appears that the maximum (not yet attained) is probably at least 20 to 25 percent greater than values observed in Douglas-fir.




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Urban green space and vibrant communities: exploring the linkage in the Portland Vancouver area.

This report investigates the interactions between household location decisions and community characteristics, including green space.




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A spatial database for restoration management capability on national forests in the Pacific Northwest USA

Understanding the capacity to reduce wildfire risk and restore dry forests on Western national forests is a key part of prioritizing new accelerated restoration programs initiated by the Forest Service.




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Historical Forest Structure, Composition, and Spatial Pattern in Dry Conifer Forests of the Western Blue Mountains, Oregon.

In frequent-fire forests of the interior Western United States, historical (prefire suppression) conditions are often used as a reference to set management objectives, guide prescriptions, and monitor treatment effectiveness. We quantified the historical size, density, composition, and spatial patterns of dry mixed-conifer forests in the Blue Mountains of Oregon to establish reference conditions that could be used for ongoing forest-restoration efforts.




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Spanish Broadcasting System Helps Deliver Meals For Healthcare Workers At Miami's Jackson Hospital

SPANISH BROADCASTING SYSTEM joined with the SOUTH FLORIDA HISPANIC CHAMBER OF COMMERCE, HOLIDAY BAKERY, and ART DECO SUPERMARKET AND CAFETERIA to deliver 100 hot meals and treats for … more




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Journalists at two Belfast newspapers threatened by loyalists

Both newspapers are owned by Independent News and Media (INM)




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COVID-19 has unmasked significant health disparities in the U.S.; essay on behalf of the Association of Black Cardiologists suggests solutions




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Telemonitoring plus phone counseling lowers blood pressure among black and Hispanic stroke survivors

Research Highlights: Minority stroke survivors experience better blood pressure control when lifestyle counseling by phone from a nurse is added to home blood pressure telemonitoring. Improved blood pressure control could lower strokes and stroke ...




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The Space Shuttle Era

The final flight of space shuttle Atlantis represents the end of NASA's shuttle program. In this special report, we compile shuttle program news, photos, facts and history. From the launch of Columbia in 1981, to the tragedy of Challenger in 1986, to the final flight of Atlantis in 2011, with videos, photo galleries, a shuttle trivia quiz and more.




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Spanish Beisbol Network

A little taste of Phillies baseball on the Spanish Beisbol Network




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Universitarios reciben becas para ayudar a abordar las disparidades de salud

DALLAS, 5 de mayo de 2020 — Diez estudiantes universitarios recibirán becas de US$10,000 dólares de la American Heart Association que servirán para favorecer el trabajo que desempeñan estos alumnos para cerrar las brechas de disparidad en el ámbito de la...




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Students receive scholarships to help address health disparities

DALLAS, May 5, 2020 — Ten college students are receiving $10,000 scholarships from the American Heart Association for their work to help close health disparity gaps – which appear to contribute to disproportionately high rates of sickness and death among...




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Historical newspaper archives are online

I was happy to read Joe Coffey’s article in Sunday’s paper (“The birth of news in Linn County”) about the history of newspapers in Linn County. But I was disappointed that Mr. Coffey did not include mention of the Metro Libraries’ historical newspaper databases. All of the papers mentioned and pictured in his article (and many more!) are available in scanned, full-text, searchable versions, through the websites of the Cedar Rapids and Marion Public Libraries. There is no charge to browse or search these delightful old editions, and in fact, you don’t even need a library card.

I encourage anyone with an interest in local history, or just with a little time on your hands, to look at some of these old newspapers. It’s a delightful adventure to read about lives in other times.

Jo Pearson

Marion



  • Letters to the Editor

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TTT in SPAAACE

By now, you’ve probably heard of TTT, our quarterly team events. If you haven’t, you should read all about their history. TTT, or Third Third Thursday, is a time for us to look back and look ahead. Twice a year, all four offices come together for an all-hands, conference-style experience. The other two TTTs are celebrated locally and casually. Each office meets for a round-table discussion followed by a fun activity out of the office.

In these meetings, we discuss team and industry changes and review business health metrics. Additionally, at each TTT, both our President, Andy Rankin, and CEO Brian Williams, directly field questions from any member of our team. At our TTTs we’ve talked about team diversity and tech ethics, celebrated our victories, and worked through our failures. The conversations have sparked new understanding, new initiatives, new processes, and have truly shaped the company over time. We come together in the spirit of “progress, not perfection.”

While each office is unique, and the conversation is tailored to and shaped by each audience, the People Team finds ways to make everyone’s TTT similar, particularly our afternoon activity, so we can bond over shared experiences, even miles apart. This summer, we all tried our hands at ax throwing, and just a few weeks ago each of our offices got to venture into Space.

Well, sort of.

After a morning meeting, Boulder visited the Fiske Planetarium at CU Boulder.

Durham visited UNC’s Morehead Planetarium.

And since the Smithsonian is refurbishing the Einstein Planetarium, our Falls Church office made our way to the Udvar Hazy center to catch an Imax show and fly a few jets, via simulator.

Each office also got a taste of space food trying Astronaut ice cream, to mixed reviews.

TTTs are more than fun snacks and field trips. They are about finding common ground with colleagues, challenging each other to grow, and re-connecting with folks you don’t work with day-to-day. They are about setting aside time for frank discussion across disciplines and experience levels, and getting outside the office for new perspectives. They are just a little part of what makes Viget so unique.

Are you ready to join us for our next big TTT adventure? It’s Viget20, and it’s going to be a good one. We're hiring.



  • News & Culture

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TTT in SPAAACE

By now, you’ve probably heard of TTT, our quarterly team events. If you haven’t, you should read all about their history. TTT, or Third Third Thursday, is a time for us to look back and look ahead. Twice a year, all four offices come together for an all-hands, conference-style experience. The other two TTTs are celebrated locally and casually. Each office meets for a round-table discussion followed by a fun activity out of the office.

In these meetings, we discuss team and industry changes and review business health metrics. Additionally, at each TTT, both our President, Andy Rankin, and CEO Brian Williams, directly field questions from any member of our team. At our TTTs we’ve talked about team diversity and tech ethics, celebrated our victories, and worked through our failures. The conversations have sparked new understanding, new initiatives, new processes, and have truly shaped the company over time. We come together in the spirit of “progress, not perfection.”

While each office is unique, and the conversation is tailored to and shaped by each audience, the People Team finds ways to make everyone’s TTT similar, particularly our afternoon activity, so we can bond over shared experiences, even miles apart. This summer, we all tried our hands at ax throwing, and just a few weeks ago each of our offices got to venture into Space.

Well, sort of.

After a morning meeting, Boulder visited the Fiske Planetarium at CU Boulder.

Durham visited UNC’s Morehead Planetarium.

And since the Smithsonian is refurbishing the Einstein Planetarium, our Falls Church office made our way to the Udvar Hazy center to catch an Imax show and fly a few jets, via simulator.

Each office also got a taste of space food trying Astronaut ice cream, to mixed reviews.

TTTs are more than fun snacks and field trips. They are about finding common ground with colleagues, challenging each other to grow, and re-connecting with folks you don’t work with day-to-day. They are about setting aside time for frank discussion across disciplines and experience levels, and getting outside the office for new perspectives. They are just a little part of what makes Viget so unique.

Are you ready to join us for our next big TTT adventure? It’s Viget20, and it’s going to be a good one. We're hiring.



  • News & Culture

spa

TTT in SPAAACE

By now, you’ve probably heard of TTT, our quarterly team events. If you haven’t, you should read all about their history. TTT, or Third Third Thursday, is a time for us to look back and look ahead. Twice a year, all four offices come together for an all-hands, conference-style experience. The other two TTTs are celebrated locally and casually. Each office meets for a round-table discussion followed by a fun activity out of the office.

In these meetings, we discuss team and industry changes and review business health metrics. Additionally, at each TTT, both our President, Andy Rankin, and CEO Brian Williams, directly field questions from any member of our team. At our TTTs we’ve talked about team diversity and tech ethics, celebrated our victories, and worked through our failures. The conversations have sparked new understanding, new initiatives, new processes, and have truly shaped the company over time. We come together in the spirit of “progress, not perfection.”

While each office is unique, and the conversation is tailored to and shaped by each audience, the People Team finds ways to make everyone’s TTT similar, particularly our afternoon activity, so we can bond over shared experiences, even miles apart. This summer, we all tried our hands at ax throwing, and just a few weeks ago each of our offices got to venture into Space.

Well, sort of.

After a morning meeting, Boulder visited the Fiske Planetarium at CU Boulder.

Durham visited UNC’s Morehead Planetarium.

And since the Smithsonian is refurbishing the Einstein Planetarium, our Falls Church office made our way to the Udvar Hazy center to catch an Imax show and fly a few jets, via simulator.

Each office also got a taste of space food trying Astronaut ice cream, to mixed reviews.

TTTs are more than fun snacks and field trips. They are about finding common ground with colleagues, challenging each other to grow, and re-connecting with folks you don’t work with day-to-day. They are about setting aside time for frank discussion across disciplines and experience levels, and getting outside the office for new perspectives. They are just a little part of what makes Viget so unique.

Are you ready to join us for our next big TTT adventure? It’s Viget20, and it’s going to be a good one. We're hiring.



  • News & Culture

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Santa Fe National Forest Spared From Fracking

WildEarth Guardians Press Release Federal Court Overturns Leasing of Lands to Oil and Gas Industry SANTA FE, NM — In a victory for New Mexico’s air, climate, and water, the U.S. District Court for the District of New Mexico today … Continue reading




spa

TTT in SPAAACE

By now, you’ve probably heard of TTT, our quarterly team events. If you haven’t, you should read all about their history. TTT, or Third Third Thursday, is a time for us to look back and look ahead. Twice a year, all four offices come together for an all-hands, conference-style experience. The other two TTTs are celebrated locally and casually. Each office meets for a round-table discussion followed by a fun activity out of the office.

In these meetings, we discuss team and industry changes and review business health metrics. Additionally, at each TTT, both our President, Andy Rankin, and CEO Brian Williams, directly field questions from any member of our team. At our TTTs we’ve talked about team diversity and tech ethics, celebrated our victories, and worked through our failures. The conversations have sparked new understanding, new initiatives, new processes, and have truly shaped the company over time. We come together in the spirit of “progress, not perfection.”

While each office is unique, and the conversation is tailored to and shaped by each audience, the People Team finds ways to make everyone’s TTT similar, particularly our afternoon activity, so we can bond over shared experiences, even miles apart. This summer, we all tried our hands at ax throwing, and just a few weeks ago each of our offices got to venture into Space.

Well, sort of.

After a morning meeting, Boulder visited the Fiske Planetarium at CU Boulder.

Durham visited UNC’s Morehead Planetarium.

And since the Smithsonian is refurbishing the Einstein Planetarium, our Falls Church office made our way to the Udvar Hazy center to catch an Imax show and fly a few jets, via simulator.

Each office also got a taste of space food trying Astronaut ice cream, to mixed reviews.

TTTs are more than fun snacks and field trips. They are about finding common ground with colleagues, challenging each other to grow, and re-connecting with folks you don’t work with day-to-day. They are about setting aside time for frank discussion across disciplines and experience levels, and getting outside the office for new perspectives. They are just a little part of what makes Viget so unique.

Are you ready to join us for our next big TTT adventure? It’s Viget20, and it’s going to be a good one. We're hiring.



  • News & Culture


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Almost invariant subspaces of the shift operator on vector-valued Hardy spaces. (arXiv:2005.02243v2 [math.FA] UPDATED)

In this article, we characterize nearly invariant subspaces of finite defect for the backward shift operator acting on the vector-valued Hardy space which is a vectorial generalization of a result of Chalendar-Gallardo-Partington (C-G-P). Using this characterization of nearly invariant subspace under the backward shift we completely describe the almost invariant subspaces for the shift and its adjoint acting on the vector valued Hardy space.




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Some Quot schemes in tilted hearts and moduli spaces of stable pairs. (arXiv:2005.02202v2 [math.AG] UPDATED)

For a smooth projective variety $X$, we study analogs of Quot functors in hearts of non-standard $t$-structures of $D^b(mathrm{Coh}(X))$. The technical framework is that of families of $t$-structures, as studied in arXiv:1902.08184. We provide several examples and suggest possible directions of further investigation, as we reinterpret moduli spaces of stable pairs, in the sense of Thaddeus (arXiv:alg-geom/9210007) and Huybrechts-Lehn (arXiv:alg-geom/9211001), as instances of Quot schemes.




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Automorphisms of shift spaces and the Higman--Thomspon groups: the one-sided case. (arXiv:2004.08478v2 [math.GR] UPDATED)

Let $1 le r < n$ be integers. We give a proof that the group $mathop{mathrm{Aut}}({X_{n}^{mathbb{N}}, sigma_{n}})$ of automorphisms of the one-sided shift on $n$ letters embeds naturally as a subgroup $mathcal{h}_{n}$ of the outer automorphism group $mathop{mathrm{Out}}(G_{n,r})$ of the Higman-Thompson group $G_{n,r}$. From this, we can represent the elements of $mathop{mathrm{Aut}}({X_{n}^{mathbb{N}}, sigma_{n}})$ by finite state non-initial transducers admitting a very strong synchronizing condition.

Let $H in mathcal{H}_{n}$ and write $|H|$ for the number of states of the minimal transducer representing $H$. We show that $H$ can be written as a product of at most $|H|$ torsion elements. This result strengthens a similar result of Boyle, Franks and Kitchens, where the decomposition involves more complex torsion elements and also does not support practical extit{a priori} estimates of the length of the resulting product.

We also give new proofs of some known results about $mathop{mathrm{Aut}}({X_{n}^{mathbb{N}}, sigma_{n}})$.




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The Shearlet Transform and Lizorkin Spaces. (arXiv:2003.06642v2 [math.FA] UPDATED)

We prove a continuity result for the shearlet transform when restricted to the space of smooth and rapidly decreasing functions with all vanishing moments. We define the dual shearlet transform, called here the shearlet synthesis operator, and we prove its continuity on the space of smooth and rapidly decreasing functions over $mathbb{R}^2 imesmathbb{R} imesmathbb{R}^ imes$. Then, we use these continuity results to extend the shearlet transform to the space of Lizorkin distributions, and we prove its consistency with the classical definition for test functions.




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The $kappa$-Newtonian and $kappa$-Carrollian algebras and their noncommutative spacetimes. (arXiv:2003.03921v2 [hep-th] UPDATED)

We derive the non-relativistic $c oinfty$ and ultra-relativistic $c o 0$ limits of the $kappa$-deformed symmetries and corresponding spacetime in (3+1) dimensions, with and without a cosmological constant. We apply the theory of Lie bialgebra contractions to the Poisson version of the $kappa$-(A)dS quantum algebra, and quantize the resulting contracted Poisson-Hopf algebras, thus giving rise to the $kappa$-deformation of the Newtonian (Newton-Hooke and Galilei) and Carrollian (Para-Poincar'e, Para-Euclidean and Carroll) quantum symmetries, including their deformed quadratic Casimir operators. The corresponding $kappa$-Newtonian and $kappa$-Carrollian noncommutative spacetimes are also obtained as the non-relativistic and ultra-relativistic limits of the $kappa$-(A)dS noncommutative spacetime. These constructions allow us to analyze the non-trivial interplay between the quantum deformation parameter $kappa$, the curvature parameter $eta$ and the speed of light parameter $c$.




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Willems' Fundamental Lemma for State-space Systems and its Extension to Multiple Datasets. (arXiv:2002.01023v2 [math.OC] UPDATED)

Willems et al.'s fundamental lemma asserts that all trajectories of a linear system can be obtained from a single given one, assuming that a persistency of excitation condition holds. This result has profound implications for system identification and data-driven control, and has seen a revival over the last few years. The purpose of this paper is to extend Willems' lemma to the situation where multiple (possibly short) system trajectories are given instead of a single long one. To this end, we introduce a notion of collective persistency of excitation. We will then show that all trajectories of a linear system can be obtained from a given finite number of trajectories, as long as these are collectively persistently exciting. We will demonstrate that this result enables the identification of linear systems from data sets with missing data samples. Additionally, we show that the result is of practical significance in data-driven control of unstable systems.




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New ${cal N}{=},2$ superspace Calogero models. (arXiv:1912.05989v2 [hep-th] UPDATED)

Starting from the Hamiltonian formulation of ${cal N}{=},2$ supersymmetric Calogero models associated with the classical $A_n, B_n, C_n$ and $D_n$ series and their hyperbolic/trigonometric cousins, we provide their superspace description. The key ingredients include $n$ bosonic and $2n(n{-}1)$ fermionic ${cal N}{=},2$ superfields, the latter being subject to a nonlinear chirality constraint. This constraint has a universal form valid for all Calogero models. With its help we find more general supercharges (and a superspace Lagrangian), which provide the ${cal N}{=},2$ supersymmetrization for bosonic potentials with arbitrary repulsive two-body interactions.




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The 2d-directed spanning forest converges to the Brownian web. (arXiv:1805.09399v3 [math.PR] UPDATED)

The two-dimensional directed spanning forest (DSF) introduced by Baccelli and Bordenave is a planar directed forest whose vertex set is given by a homogeneous Poisson point process $mathcal{N}$ on $mathbb{R}^2$. If the DSF has direction $-e_y$, the ancestor $h(u)$ of a vertex $u in mathcal{N}$ is the nearest Poisson point (in the $L_2$ distance) having strictly larger $y$-coordinate. This construction induces complex geometrical dependencies. In this paper we show that the collection of DSF paths, properly scaled, converges in distribution to the Brownian web (BW). This verifies a conjecture made by Baccelli and Bordenave in 2007.




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Effective divisors on Hurwitz spaces. (arXiv:1804.01898v3 [math.AG] UPDATED)

We prove the effectiveness of the canonical bundle of several Hurwitz spaces of degree k covers of the projective line from curves of genus 13<g<20.




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Local mollification of Riemannian metrics using Ricci flow, and Ricci limit spaces. (arXiv:1706.09490v2 [math.DG] UPDATED)

We use Ricci flow to obtain a local bi-Holder correspondence between Ricci limit spaces in three dimensions and smooth manifolds. This is more than a complete resolution of the three-dimensional case of the conjecture of Anderson-Cheeger-Colding-Tian, describing how Ricci limit spaces in three dimensions must be homeomorphic to manifolds, and we obtain this in the most general, locally non-collapsed case. The proofs build on results and ideas from recent papers of Hochard and the current authors.




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Continuity properties of the shearlet transform and the shearlet synthesis operator on the Lizorkin type spaces. (arXiv:2005.03505v1 [math.FA])

We develop a distributional framework for the shearlet transform $mathcal{S}_{psi}colonmathcal{S}_0(mathbb{R}^2) omathcal{S}(mathbb{S})$ and the shearlet synthesis operator $mathcal{S}^t_{psi}colonmathcal{S}(mathbb{S}) omathcal{S}_0(mathbb{R}^2)$, where $mathcal{S}_0(mathbb{R}^2)$ is the Lizorkin test function space and $mathcal{S}(mathbb{S})$ is the space of highly localized test functions on the standard shearlet group $mathbb{S}$. These spaces and their duals $mathcal{S}_0^prime (mathbb R^2),, mathcal{S}^prime (mathbb{S})$ are called Lizorkin type spaces of test functions and distributions. We analyze the continuity properties of these transforms when the admissible vector $psi$ belongs to $mathcal{S}_0(mathbb{R}^2)$. Then, we define the shearlet transform and the shearlet synthesis operator of Lizorkin type distributions as transpose mappings of the shearlet synthesis operator and the shearlet transform, respectively. They yield continuous mappings from $mathcal{S}_0^prime (mathbb R^2)$ to $mathcal{S}^prime (mathbb{S})$ and from $mathcal{S}^prime (mathbb S)$ to $mathcal{S}_0^prime (mathbb{R}^2)$. Furthermore, we show the consistency of our definition with the shearlet transform defined by direct evaluation of a distribution on the shearlets. The same can be done for the shearlet synthesis operator. Finally, we give a reconstruction formula for Lizorkin type distributions, from which follows that the action of such generalized functions can be written as an absolutely convergent integral over the standard shearlet group.




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A reaction-diffusion system to better comprehend the unlockdown: Application of SEIR-type model with diffusion to the spatial spread of COVID-19 in France. (arXiv:2005.03499v1 [q-bio.PE])

A reaction-diffusion model was developed describing the spread of the COVID-19 virus considering the mean daily movement of susceptible, exposed and asymptomatic individuals. The model was calibrated using data on the confirmed infection and death from France as well as their initial spatial distribution. First, the system of partial differential equations is studied, then the basic reproduction number, R0 is derived. Second, numerical simulations, based on a combination of level-set and finite differences, shown the spatial spread of COVID-19 from March 16 to June 16. Finally, scenarios of unlockdown are compared according to variation of distancing, or partially spatial lockdown.




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Continuity in a parameter of solutions to boundary-value problems in Sobolev spaces. (arXiv:2005.03494v1 [math.CA])

We consider the most general class of linear inhomogeneous boundary-value problems for systems of ordinary differential equations of an arbitrary order whose solutions and right-hand sides belong to appropriate Sobolev spaces. For parameter-dependent problems from this class, we prove a constructive criterion for their solutions to be continuous in the Sobolev space with respect to the parameter. We also prove a two-sided estimate for the degree of convergence of these solutions to the solution of the nonperturbed problem.




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Semiglobal non-oscillatory big bang singular spacetimes for the Einstein-scalar field system. (arXiv:2005.03395v1 [math-ph])

We construct semiglobal singular spacetimes for the Einstein equations coupled to a massless scalar field. Consistent with the heuristic analysis of Belinskii, Khalatnikov, Lifshitz or BKL for this system, there are no oscillations due to the scalar field. (This is much simpler than the oscillatory BKL heuristics for the Einstein vacuum equations.) Prior results are due to Andersson and Rendall in the real analytic case, and Rodnianski and Speck in the smooth near-spatially-flat-FLRW case. Similar to Andersson and Rendall we give asymptotic data at the singularity, which we refer to as final data, but our construction is not limited to real analytic solutions. This paper is a test application of tools (a graded Lie algebra formulation of the Einstein equations and a filtration) intended for the more subtle vacuum case. We use homological algebra tools to construct a formal series solution, then symmetric hyperbolic energy estimates to construct a true solution well-approximated by truncations of the formal one. We conjecture that the image of the map from final data to initial data is an open set of anisotropic initial data.




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Type space functors and interpretations in positive logic. (arXiv:2005.03376v1 [math.LO])

We construct a 2-equivalence $mathfrak{CohTheory}^ ext{op} simeq mathfrak{TypeSpaceFunc}$. Here $mathfrak{CohTheory}$ is the 2-category of positive theories and $mathfrak{TypeSpaceFunc}$ is the 2-category of type space functors. We give a precise definition of interpretations for positive logic, which will be the 1-cells in $mathfrak{CohTheory}$. The 2-cells are definable homomorphisms. The 2-equivalence restricts to a duality of categories, making precise the philosophy that a theory is `the same' as the collection of its type spaces (i.e. its type space functor).

In characterising those functors that arise as type space functors, we find that they are specific instances of (coherent) hyperdoctrines. This connects two different schools of thought on the logical structure of a theory.

The key ingredient, the Deligne completeness theorem, arises from topos theory, where positive theories have been studied under the name of coherent theories.




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Smooth non-projective equivariant completions of affine spaces. (arXiv:2005.03277v1 [math.AG])

In this paper we construct an equivariant embedding of the affine space $mathbb{A}^n$ with the translation group action into a complete non-projective algebraic variety $X$ for all $n geq 3$. The theory of toric varieties is used as the main tool for this construction. In the case of $n = 3$ we describe the orbit structure on the variety $X$.




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A Chance Constraint Predictive Control and Estimation Framework for Spacecraft Descent with Field Of View Constraints. (arXiv:2005.03245v1 [math.OC])

Recent studies of optimization methods and GNC of spacecraft near small bodies focusing on descent, landing, rendezvous, etc., with key safety constraints such as line-of-sight conic zones and soft landings have shown promising results; this paper considers descent missions to an asteroid surface with a constraint that consists of an onboard camera and asteroid surface markers while using a stochastic convex MPC law. An undermodeled asteroid gravity and spacecraft technology inspired measurement model is established to develop the constraint. Then a computationally light stochastic Linear Quadratic MPC strategy is presented to keep the spacecraft in satisfactory field of view of the surface markers while trajectory tracking, employing chance based constraints and up-to-date estimation uncertainty from navigation. The estimation uncertainty giving rise to the tightened constraints is particularly addressed. Results suggest robust tracking performance across a variety of trajectories.




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Packing of spanning mixed arborescences. (arXiv:2005.03218v1 [math.CO])

In this paper, we characterize a mixed graph $F$ which contains $k$ edge and arc disjoint spanning mixed arborescences $F_{1}, ldots, F_{k}$, such that for each $v in V(F)$, the cardinality of ${i in [k]: v ext{ is the root of } F_{i}}$ lies in some prescribed interval. This generalizes both Nash-Williams and Tutte's theorem on spanning tree packing for undirected graphs and the previous characterization on digraphs which was given by Cai [in: Arc-disjoint arborescences of digraphs, J. Graph Theory 7(2) (1983), 235-240] and Frank [in: On disjoint trees and arborescences, Algebraic Methods in Graph Theory, Colloquia Mathematica Soc. J. Bolyai, Vol. 25 (North-Holland, Amsterdam) (1978), 159-169].




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Non-relativity of K"ahler manifold and complex space forms. (arXiv:2005.03208v1 [math.CV])

We study the non-relativity for two real analytic K"ahler manifolds and complex space forms of three types. The first one is a K"ahler manifold whose polarization of local K"ahler potential is a Nash function in a local coordinate. The second one is the Hartogs domain equpped with two canonical metrics whose polarizations of the K"ahler potentials are the diastatic functions.




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Generalized Cauchy-Kovalevskaya extension and plane wave decompositions in superspace. (arXiv:2005.03160v1 [math-ph])

The aim of this paper is to obtain a generalized CK-extension theorem in superspace for the bi-axial Dirac operator. In the classical commuting case, this result can be written as a power series of Bessel type of certain differential operators acting on a single initial function. In the superspace setting, novel structures appear in the cases of negative even superdimensions. In these cases, the CK-extension depends on two initial functions on which two power series of differential operators act. These series are not only of Bessel type but they give rise to an additional structure in terms of Appell polynomials. This pattern also is present in the structure of the Pizzetti formula, which describes integration over the supersphere in terms of differential operators. We make this relation explicit by studying the decomposition of the generalized CK-extension into plane waves integrated over the supersphere. Moreover, these results are applied to obtain a decomposition of the Cauchy kernel in superspace into monogenic plane waves, which shall be useful for inverting the super Radon transform.




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Continuation of relative equilibria in the $n$--body problem to spaces of constant curvature. (arXiv:2005.03114v1 [math.DS])

We prove that all non-degenerate relative equilibria of the planar Newtonian $n$--body problem can be continued to spaces of constant curvature $kappa$, positive or negative, for small enough values of this parameter. We also compute the extension of some classical relative equilibria to curved spaces using numerical continuation. In particular, we extend Lagrange's triangle configuration with different masses to both positive and negative curvature spaces.




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On the notion of weak isometry for finite metric spaces. (arXiv:2005.03109v1 [math.MG])

Finite metric spaces are the object of study in many data analysis problems. We examine the concept of weak isometry between finite metric spaces, in order to analyse properties of the spaces that are invariant under strictly increasing rescaling of the distance functions. In this paper, we analyse some of the possible complete and incomplete invariants for weak isometry and we introduce a dissimilarity measure that asses how far two spaces are from being weakly isometric. Furthermore, we compare these ideas with the theory of persistent homology, to study how the two are related.




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Homotopy invariance of the space of metrics with positive scalar curvature on manifolds with singularities. (arXiv:2005.03073v1 [math.AT])

In this paper we study manifolds $M_{Sigma}$ with fibered singularities, more specifically, a relevant space $Riem^{psc}(X_{Sigma})$ of Riemannian metrics with positive scalar curvature. Our main goal is to prove that the space $Riem^{psc}(X_{Sigma})$ is homotopy invariant under certain surgeries on $M_{Sigma}$.




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Maximal Closed Set and Half-Space Separations in Finite Closure Systems. (arXiv:2001.04417v2 [cs.AI] UPDATED)

Several problems of artificial intelligence, such as predictive learning, formal concept analysis or inductive logic programming, can be viewed as a special case of half-space separation in abstract closure systems over finite ground sets. For the typical scenario that the closure system is given via a closure operator, we show that the half-space separation problem is NP-complete. As a first approach to overcome this negative result, we relax the problem to maximal closed set separation, give a greedy algorithm solving this problem with a linear number of closure operator calls, and show that this bound is sharp. For a second direction, we consider Kakutani closure systems and prove that they are algorithmically characterized by the greedy algorithm. As a first special case of the general problem setting, we consider Kakutani closure systems over graphs, generalize a fundamental characterization result based on the Pasch axiom to graph structured partitioning of finite sets, and give a sufficient condition for this kind of closures systems in terms of graph minors. For a second case, we then focus on closure systems over finite lattices, give an improved adaptation of the greedy algorithm for this special case, and present two applications concerning formal concept and subsumption lattices. We also report some experimental results to demonstrate the practical usefulness of our algorithm.