263 research outputs found
Developing Quantum Algorithms for NISQ Hardware
When designing quantum algorithms, we typically abstract away the full capabilities
of the underlying hardware. For near-term applications of quantum hardware, it is
not clear that this is justified. In this thesis, I develop techniques to exploit the greater
underlying control over qubit interactions available in principle in most quantum
hardware. I derive analytic circuit identities for efficiently synthesising multi-qubit
evolutions from two-qubit interactions. I apply these techniques to Hamiltonian
simulation and quantum phase estimation, two of the most important algorithms
within the field of quantum computing. I analyse these techniques under a standard
error model where errors occur per gate, and an error model with a constant error
rate per unit time. For both Hamiltonian simulation and quantum phase estimation I
explore a concrete numerical example: the 2D spin Fermi-Hubbard model
Hamiltonian simulation algorithms for near-term quantum hardware.
The quantum circuit model is the de-facto way of designing quantum algorithms. Yet any level of abstraction away from the underlying hardware incurs overhead. In this work, we develop quantum algorithms for Hamiltonian simulation "one level below" the circuit model, exploiting the underlying control over qubit interactions available in most quantum hardware and deriving analytic circuit identities for synthesising multi-qubit evolutions from two-qubit interactions. We then analyse the impact of these techniques under the standard error model where errors occur per gate, and an error model with a constant error rate per unit time. To quantify the benefits of this approach, we apply it to time-dynamics simulation of the 2D spin Fermi-Hubbard model. Combined with new error bounds for Trotter product formulas tailored to the non-asymptotic regime and an analysis of error propagation, we find that e.g. for a 5 × 5 Fermi-Hubbard lattice we reduce the circuit depth from 1, 243, 586 using the best previous fermion encoding and error bounds in the literature, to 3, 209 in the per-gate error model, or the circuit-depth-equivalent to 259 in the per-time error model. This brings Hamiltonian simulation, previously beyond reach of current hardware for non-trivial examples, significantly closer to being feasible in the NISQ era
Putting the Earth into Science: Resource, Workshop and Field Trip for High School Science Teachers at GeoCanada 2010
Putting the Earth into Science is a classroom resource that takes an interdisciplinary approach to expanding Earth science content in Canadian high schools. In recent history, Earth science has struggled to be identified as a core subject in school curricula. Differing approaches of whether it is placed in social studies (geography) or science has resulted in identity confusion. Alternatively, it is often seen as a specialist area of study, and hence optional. As a solution to this problem, the National EdGEO Workshop Program has developed a series of curricula-based lesson plans to integrate Earth science topics into the core subjects of physics, chemistry, biology and mathematics. The program will attract teachers of diverse science disciplines, and deliver a meaningful educational experience and important career information to high school students who are largely unaware of how Earth science impacts their daily lives. Putting the Earth into Science was launched during a workshop and field trip offered to teachers across Canada in conjunction with GeoCanada 2010.
Sommaire
La Terre en science est une source référence d’activités pédagogiques interdisciplinaires visant à accroître le contenu en sciences de la Terre du programme secondaire des écoles canadiennes. Ces dernières années, les sciences de la Terre ont peiné s’imposer comme matière essentielle du programme scolaire. Selon l’approche, elles étaient tantôt incorporées aux sciences sociales (géographie), tantôt aux sciences physiques, d’où la confusion. Elles sont aussi perçues comme matière spécialisée, et optionnelles à ce titre. Comme solution, le National EdGEO Workshop Program a mis au point une série de plans de cours permettant d’intgérer des thèmes de sciences de la Terre aux matières obligatoires comme la physique, la chimie, la biologie et les mathématiques. Le programme intéressera les enseignants de diverses disciplines scientifiques, et leur proposera une démarche éducationnelle riche, et offrira aux éléves du secondaire les informations essentielles sur la profession, eux qui ignorent en grande partie l’impact des sciences de la Terre dans leur vie quotidienne. La Terre en sciences a été lancée officiellement à l’occasion de la tenue d’un atelier et d’une excursion offerts aux enseignants canadiens lors du congrès GeoCanada 2010
EdGEO: Helping Teachers Teach Earth Science
EdGEO is a national program that supports Earth science workshops for Canadian teachers. Geoscientists and teachers work collaboratively to develop and deliver these curriculum-linked workshops, which provide teachers with the classroom resources, enhanced knowledge, and increased confidence to teach Earth science more effectively. Grants of up to . Cela dit, la capacité d’EdGEO à mener à bien sa mission dépend de la générosité de dons provenant d’associations professionnelles, de sociétés, de fondations et de particuliers. Pourvu de meilleures capacités financières, EdGEO entend compiler les plans de leçon EdGEO mis au point au Canada et élaborer des activités d’apprentissage pour intégrer les sciences de la Terre à l’enseignement de la physique, de la chimie, de la biologie et des mathématiques; toutes ces ressources pourront être télécharger à partir du site Internet d’EdGEO
The Athenian Calendar of Sacrifices: A New Fragment from the Athenian Agora
Presented here is the editio princeps of a new fragment of the late-5th-century b.c. Athenian calendar of sacrifices. The fragment, Agora 17577, was discovered during excavations conducted in the Athenian Agora by the American School of Classical Studies. Inscribed on both faces (Face A: 403-399 b.c., Face B: 410-404 b.c.), it is associated with, but does not join, the group of fragments of Athenian legal inscriptions often referred to as the Law Code of Nikomachos. The text provides important additional evidence for the form of the calendar and the manner of its publication, and casts new light on broader issues of Athenian cult and topography
Archaeological Investigations within San Pedro Springs Park (41BX19), San Antonio, Bexar County, Texas
The University of Texas at San Antonio Center for Archaeological Research (UTSA-CAR) contracted with Adams Environmental, Inc. to provide archaeological services to Capital Improvement Management (CIMS) of the City of San Antonio (COSA) related to the archaeological investigation of selected areas of San Pedro Springs Park in San Antonio, Bexar County, Texas. The CAR conducted archaeological testing at this National Register Site, 41BX19, from early December 2013 to mid-January of 2014. The goals of archaeological investigations were to identify and investigate any proto-historic and historic archaeological deposits associated with Colonial Period occupants of the area, including evidence of the first acequia and associated dam, and the location of the first presidio and villa. In addition, CAR was tasked with the investigation of any prehistoric cultural deposits encountered. This project was performed by staff archaeologists from the CAR. It was conducted under Texas Antiquities Permit No. 6727, with Dr. Steve Tomka serving as Principal Investigator (PI), and Kristi Nichols and Stephen Smith serving as Project Archaeologists. Dr. Tomka departed from UTSA shortly after the completion of fieldwork. At that time, Dr. Raymond Mauldin of CAR assumed PI responsibilities for the project.
One hundred and eleven shovel tests, eleven 1-x-1 m test units, two 50-x-50 cm units, two backhoe trenches, and several auger holes were excavated during this effort. Minimal artifactual evidence of colonial occupants was noted during the archaeological investigations. Several Native American bone tempered sherds that could reflect either Late Prehistoric Leon Plain or Goliad ware were recovered. However, no Spanish Majolicas or lead glazed wares were uncovered, and no gunflints were identified in the lithic assemblage. Due to various utility lines and other obstructions, backhoe trenches to search for the acequia and associated dam could not be excavated. It is likely that areas proposed for investigation of the acequia and associated dam have been disturbed by aforementioned utility lines as well as earlier construction within the park. No evidence of the specific location of the first presidio or villa was located. Shovel testing and test units revealed the presence of historic and prehistoric use of the park, though mixing of historic and prehistoric material, as well as other disturbances (e.g., rodents), was common in the deposits. However, there was an increase in prehistoric material with depth as revealed in shovel testing results. Shovel testing located Feature 1, a burned rock feature that possibly was associated with a sheet midden, as well as several areas with high densities of prehistoric materials. Test excavations, based on these shovel tests, suggest that Feature 1 is a discrete feature that lies below a widespread, low-density distribution of burned rock. Shovel testing also identified a high-density cluster of lithic, bone, and burned rock. The excavation of a 1-x-1 m test unit (TU 4) in this area produced over 4,000 pieces of debitage, with over 50% of this total coming from three levels. Burned rock, a variety of tools, faunal material, and charcoal were present throughout these levels.
Temporal placement of deposits relied on artifact typologies (e.g., ceramic types, lithic projectile points, lithic tool types) as well as two charcoal and four bone collagen radiocarbon dates. Artifact typologies suggest occupation as early as the Early Archaic as reflected by a possible Guadalupe tool. A series of Late Archaic Points (Castroville, Frio, Marcos, and Montell) and Late Prehistoric point forms (Edwards, Perdiz, and Scallorn) are present from several areas. In addition, a possible Middle Archaic La Jita point was recovered. The bone tempered Native American wares could date as early as AD 1250, though they could also reflect proto-historic or colonial age materials. Other ceramics primarily suggest a mid-nineteenth- to midtwentieth-century occupation. Using the midpoints of the 1-sigma distribution, calibrated radiocarbon dates show use of San Pedro Park from as early as 100 AD (CAR 345; 1905 +/- 22 Radiocarbon Years Before Present [RCYBP]) to as recently as the early twentieth century. The more recent end of that range is a function of two late dates from two different areas of the park. The first of these is on a bison bone (CAR 344) that returned a date of 158 +/- 23 RCYBP. The second is on a bone consistent with a bison-sized animal (CAR 346) that produced a date of 155 +/- 23 RCYBP. The corrected, calibrated dates for these two samples range from AD 1670 to the early 1940s using the 1-sigma spread. The wide range of these dates is related to the flat calibration curve late in time. However, the most probable date range (ca. 36% probability) for these two dates is between AD 1729 and 1779, with a roughly 48% probability that they date prior to AD 1779.
Limited testing suggests that, with a few specific exceptions, the upper 30-40 cm of San Pedro Park is extensively disturbed. However, though some disturbances are present, at least three areas have materials in what appears to be good context. These include material dating to the Late Archaic, Late Prehistoric, and possibly the Proto-historic or Colonial Period. Based on historic maps, previous work, and the current investigation, CAR proposes a series of management areas for San Pedro Park. If work in these management areas follows these suggestions for various limits on subsurface impacts, CAR recommends that. renovation activities within the park be allowed to proceed. The Texas Historical Commission (THC), in a letter dated February 4, 2015, agreed with these recommendations. Finally, CAR provides several recommendations for public education facilities within the park.
In accordance with the THC Permit specifications and the Scope of Work for this project, all field notes, analytical notes, photographs, and other project related documents, along with a copy of the final report, will be curated at the CAR. After quantification and completion of analysis, and in consultation with THC and the COSA Office of Historic Preservation, artifacts possessing little scientific value were discarded pursuant to Chapter 26.27(g)(2) of the Antiquities Code of Texas. Artifact classes discarded specific to this project included samples of burned rock and snail shell, all unidentifiable metal, soil samples, and recent (post-1950) material
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Atmospheric Inverse Estimates of Methane Emissions from Central California
Methane mixing ratios measured at a tall-tower are compared to model predictions to estimate surface emissions of CH{sub 4} in Central California for October-December 2007 using an inverse technique. Predicted CH{sub 4} mixing ratios are calculated based on spatially resolved a priori CH{sub 4} emissions and simulated atmospheric trajectories. The atmospheric trajectories, along with surface footprints, are computed using the Weather Research and Forecast (WRF) coupled to the Stochastic Time-Inverted Lagrangian Transport (STILT) model. An uncertainty analysis is performed to provide quantitative uncertainties in estimated CH{sub 4} emissions. Three inverse model estimates of CH{sub 4} emissions are reported. First, linear regressions of modeled and measured CH{sub 4} mixing ratios obtain slopes of 0.73 {+-} 0.11 and 1.09 {+-} 0.14 using California specific and Edgar 3.2 emission maps respectively, suggesting that actual CH{sub 4} emissions were about 37 {+-} 21% higher than California specific inventory estimates. Second, a Bayesian 'source' analysis suggests that livestock emissions are 63 {+-} 22% higher than the a priori estimates. Third, a Bayesian 'region' analysis is carried out for CH{sub 4} emissions from 13 sub-regions, which shows that inventory CH{sub 4} emissions from the Central Valley are underestimated and uncertainties in CH{sub 4} emissions are reduced for sub-regions near the tower site, yielding best estimates of flux from those regions consistent with 'source' analysis results. The uncertainty reductions for regions near the tower indicate that a regional network of measurements will be necessary to provide accurate estimates of surface CH{sub 4} emissions for multiple regions
Diet Complexity and Estrogen Receptor β Status Affect the Composition of the Murine Intestinal Microbiota
ABSTRACT Intestinal microbial dysbiosis contributes to the dysmetabolism of luminal factors, including steroid hormones (sterones) that affect the development of chronic gastrointestinal inflammation and the incidence of sterone-responsive cancers of the breast, prostate, and colon. Little is known, however, about the role of specific host sterone nucleoreceptors, including estrogen receptor β (ERβ), in microbiota maintenance. Herein, we test the hypothesis that ERβ status affects microbiota composition and determine if such compositionally distinct microbiota respond differently to changes in diet complexity that favor Proteobacteria enrichment. To this end, conventionally raised female ERβ +/+ and ERβ −/− C57BL/6J mice (mean age of 27 weeks) were initially reared on 8604, a complex diet containing estrogenic isoflavones, and then fed AIN-76, an isoflavone-free semisynthetic diet, for 2 weeks. 16S rRNA gene surveys revealed that the fecal microbiota of 8604-fed mice and AIN-76-fed mice differed, as expected. The relative diversity of Proteobacteria , especially the Alphaproteobacteria and Gammaproteobacteria , increased significantly following the transition to AIN-76. Distinct patterns for beneficial Lactobacillales were exclusive to and highly abundant among 8604-fed mice, whereas several Proteobacteria were exclusive to AIN-76-fed mice. Interestingly, representative orders of the phyla Proteobacteria , Bacteroidetes , and Firmicutes , including the Lactobacillales , also differed as a function of murine ERβ status. Overall, these interactions suggest that sterone nucleoreceptor status and diet complexity may play important roles in microbiota maintenance. Furthermore, we envision that this model for gastrointestinal dysbiosis may be used to identify novel probiotics, prebiotics, nutritional strategies, and pharmaceuticals for the prevention and resolution of Proteobacteria -rich dysbiosis
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The Rise of the Mesopredator
Apex predators have experienced catastrophic declines throughout the world as a result of human persecution and habitat loss. These collapses in
top predator populations are commonly associated with dramatic increases in the abundance of smaller predators. Known as “mesopredator release,”
this trophic interaction has been recorded across a range of communities and ecosystems. Mesopredator outbreaks often lead to declining prey
populations, sometimes destabilizing communities and driving local extinctions.We present an overview of mesopredator release and illustrate how
its underlying concepts can be used to improve predator management in an increasingly fragmented world. We also examine shifts in North
American carnivore ranges during the past 200 years and show that 60% of mesopredator ranges have expanded, whereas all apex predator ranges
have contracted. The need to understand how best to predict and manage mesopredator release is urgent—mesopredator outbreaks are causing high
ecological, economic, and social costs around the world
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