bluuebunny/crossref_metadata_2025 huggingface dataset:
Aquifer storage and recovery in the Edwards Aquifers, Texas
Authors: Deeds Neil E. , Blumberg Fred
Published: October 2019

Aquifer storage and recovery (ASR) is a proven water-supply strategy that uses an aquifer to store surplus water that will be available for later use when that stored water is needed. Although only three ASR systems are currently operating in Texas, recent incentives from the state, along with changes in regulatory framework, have helped to encourage consideration of ASR as a viable water-supply strategy. The changes in Texas law primarily reduced the power of groundwater conservation districts to regulate ASR, and they put the majority of the role of project authorization in the hands of the Texas Commission on Environmental Quality.

Two Edwards-named aquifers in Texas were considered in this work: the Edwards-Trinity (Plateau) and the Edwards (Balcones Fault Zone) Aquifers. Both of the aquifers have areas that appear to be suitable, from a hydrogeologic standpoint, for ASR. The Edwards hydrostratigraphic unit of the Edwards-Trinity (Plateau) Aquifer has generally good productivity and water quality. However, in some locations, the high natural gradient combined with low porosity may increase the design challenge due to bubble drift. These same characteristics exist in many areas of the freshwater portion of the Edwards (Balcones Fault Zones) Aquifer, although its high productivity makes for very attractive per-well recharge and recover rates. The lower natural gradient (and thus smaller potential for bubble drift) in the brackish portion of the Edwards Aquifer may make it a good candidate in areas where productivity is sufficient.
Tracer testing in the Edwards Aquifer
Authors: Johnson Steven , Schindel Geary M. , Van Brahana John
Published: October 2019

Tracer testing is established as one of the best techniques for determining groundwater velocities and identifying groundwater flow directions in karstic systems. It has been employed in the Edwards (Balcones Fault Zone) Aquifer since the mid-1980s. Nontoxic, fluorescent organic dyes are most commonly used because they are comparatively inexpensive, relatively easily accessible, detectable at low concentrations, and not harmful to organisms that use or dwell in the aquifer or its springs. Tracer tests provide empirical evidence that is difficult to obtain any other way. Tracer tests have shown rapid groundwater velocities in the contributing, recharge, and artesian zones. Groundwater velocities were found to range from 915 to 9150 m/d in the Barton Springs segment of the aquifer; 1–3600 m/d in the San Marcos Springs area; 300–640 m/d near Comal Springs; 13 to >5300 m/d in San Antonio/northern Bexar County; and 1–1367 m/d in Kinney County, Texas. Tracer testing has shown: (1) preferential flow paths are conduit-dominated; (2) in places, there is a hydraulic connection with the underlying Glen Rose Formation; (3) large offsets on faults are not barriers to flow; and (4) portions of the aquifer act as separate pools.
Multilevel monitoring of the Edwards and Trinity Aquifers
Authors: Smith Brian A. , Hunt Brian B.
Published: October 2019

Multiport monitor wells have been used by the Barton Springs/Edwards Aquifer Conservation District (BSEACD) to study complex, multilayer, and stacked aquifers in central Texas. Much of the data from water wells that are used for hydrogeological studies are of limited use owing to the thickness of the aquifers, vertical variation in hydraulic properties, and the often-uncertain completion of the wells. To address these concerns, hydrogeologists and engineers have employed various methods, such as installation of nested wells, multilevel completions in a single borehole, and multiport wells. The BSEACD has used multiport wells to determine vertical variations in an aquifer and the hydraulic relationships between stacked aquifers. With multiport wells, properties such as hydraulic head, temperature, hydraulic conductivity, and water quality of discrete units within an aquifer can be determined. The use of multiport wells has shown how portions of the Upper Trinity lithologic units are hydraulically connected to the overlying Edwards lithologic units, and how the Edwards Aquifer is hydraulically isolated from the Middle and Lower Trinity Aquifers.
87Sr/86Sr record from the Lower Cretaceous pelagic Maiolica limestone (Central Apennines, Italy) and its offset from the global seawater reference curve
Authors: Belza* J. , Alvarez W. , Vanhaecke F. , Claeys P.
Published: October 2019

This study provides a composite record of 87Sr/86Sr, δ18O, and δ13C for three sections in the Tethyan Lower Cretaceous Maiolica formation, a pelagic limestone from the Umbria-Marche Apennines of Italy, carefully tied to a magnetostratigraphically and biostratigraphically calibrated time scale. Although the 87Sr/86Sr record accurately follows the trend of the global marine 87Sr/86Sr reference curve, individual Sr isotope ratio values are relatively high for their inferred stratigraphic position, with all 87Sr/86Sr ratios yielding a fairly uniform +0.00007 to +0.0001 discrepancy. This offset likely results from incorporation of excess 87Sr through isotopic reequilibration with interstitial pore waters during progressive lithification of the calcareous ooze. Although the process occurs principally through dissolution-reprecipitation, buffering the contemporaneous seawater Sr isotopic signature, diffusive communication with the overlying water column and porous sediments will compete with the dissolution-precipitation process, homogenizing pore-fluid concentrations and isotope ratios throughout the sediment column. Because the secular trend in 87Sr/86Sr throughout the Maiolica time frame is one of constant increase before rebounding to lower 87Sr/86Sr ratios in the Barremian, the ratios of the Maiolica carbonates are systematically displaced from that of the seawater in which they were deposited toward more radiogenic (higher 87Sr/86Sr) values. In addition, the carbon and oxygen isotope record of the Maiolica limestone allows identification of the mid-Valanginian Weissert event, characterized by a positive excursion in the δ13C and the δ18O records. Furthermore, the Weissert event correlates with a positive spike (+0.0001) in 87Sr/86Sr. Both the Sr and O isotopic peak signals predate the maximum peak in the δ13C excursion. This is likely a diagenetic artifact and may support the hypothesis of diffusive communication during lithification of the calcareous ooze.
The role of structural inheritance in the evolution of fold-and-thrust belts: Insights from the Umbria-Marche Apennines, Italy
Authors: Tavarnelli* Enrico , Scisciani Vittorio , Patruno Stefano , Calamita Fernando , Pace Paolo , Iacopini David
Published: October 2019

The Umbria-Marche Apennine range, part of the Northern Apennines of Italy, is a classic example of a fold-and-thrust belt developed at the expense of a formerly rifted, passive continental margin that experienced various degrees of postorogenic extension and/or collapse. This setting comprises the outer zones of the Northern Apennines, a collisional orogen, and their adjacent Adriatic foreland domain, where the effects of superposed deformations are mild to very mild, making it possible to recognize and separate structures produced at different times and to correctly establish their relative chronology and time-space relationships. In this paper, we integrated subsurface data (seismic reflection profiles and well logs) and surface structural field evidence with the aim to reconstruct and refine the structural evolution of these two provinces, the Umbria-Marche Apennine range and adjacent Adriatic foreland, which were subject to repeated pulses of alternating extension and compression. The main outcome of this investigation is that the tectonic evolution of the study area may be effectively described in terms of a deformation history characterized by structural inheritance, where structures emanating from the basement and developed during the pre-orogenic rifting stage were effective in controlling stress localization along faults affecting younger sedimentary cover rocks during the subsequent orogenic and postorogenic events.
Positive Ir anomaly at 6.19 m, Massignano, Italy: Most likely not from the Chesapeake Bay impact
Authors: Glass* B.P.
Published: October 2019

Two late Eocene impact spherule layers are known: the North America microtektite layer (from the Chesapeake Bay crater) and the slightly older clinopyroxene (cpx) spherule layer (from Popigai crater). Positive Ir anomalies occur at 5.61 m and 6.19 m above the base of a late Eocene section at Massignano, Italy. The age difference between the two anomalies is ~65 ± 20 k.y. The older Ir anomaly at 5.61 m appears to be associated with the cpx spherule layer. Although no impact spherules or shocked-mineral grains have been found associated with the upper Ir anomaly at 6.19 m, it has been proposed that it may be from the Chesapeake Bay impact. Comparison with other distal ejecta layers suggests that microtektites, but not shocked-mineral grains, from the Chesapeake Bay crater could have been thrown as far as Massignano. However, their absence neither supports nor disproves the hypothesis that the Ir anomaly at 6.19 m is from the Chesapeake Bay impact. On the other hand, the North American microtektite layer is not associated with an Ir anomaly. Furthermore, the average age difference between the cpx spherule layer and the North American microtektite layer appears to be ~18 ± 11 k.y., which is nearly one quarter the age difference between the two Ir anomalies at Massignano. This indicates that the Ir anomaly at 6.19 m is too young to be from the Chesapeake Bay impact, and thus is most likely not from the Chesapeake Bay impact.
Implications for central Italy paleoclimate from 95,000 yr B.P. until the early Holocene as evident from Frasassi Cave speleothems
Authors: Kudielka Gerhard , Bar-Matthews Miryam , Gilmour Mabs , Ayalon Avner , Koeberl Christian , Montanari* Alessandro
Published: October 2019

In this study, we present a composite δ18O and δ13C record obtained from four speleothems from the Grotta Grande del Vento Cave, located within the Frasassi karst system, northeastern Apennines of central Italy. The ages were determined by U-series analysis, employing thermal ionization mass spectrometry (TIMS), and the composite isotopic profile covers most of the time period from ca. 95,000 yr B.P. until ca. 10,000 yr B.P., including the last part of marine isotope stage (MIS) 5, most of the last glacial (MIS 4–2), and the earliest Holocene (MIS 1), with a hiatus lasting from ca. 65,000 to ca. 55,000 yr B.P. We compared this record with other speleothem records from the Eastern Mediterranean, with caves from western Portugal, with two marine records from the Eastern Mediterranean and the Aegean Sea, and with the North Greenland Ice Core Project (NGRIP) ice-core record. The Frasassi speleothem record provides further insight for a wider regional understanding of the paleoclimate record through the discrepancies and similarities between the northeastern Apennines of central Italy and the Western, Eastern, and northeastern Mediterranean regions.

The time interval between ca. 86,000 and 83,000 yr B.P. shows low δ18O values in the Western and Eastern Mediterranean speleothems and the marine records. This period coincides with sapropel (S3) and is associated with increased hydrological activity and warming. On the other hand, Frasassi speleothem δ18O data do not show a similar low trend, suggesting that increased hydrological activity either did not reach the Frasassi region and/or the region received rainfall from other sources and/or the proportion of winter-summer rainfall was different.

Another interval in which different conditions prevailed in the Frasassi region is during the transition from MIS 5 to glacial MIS 4, from ca. 83,000 to 65,000 yr B.P., when Frasassi speleothem δ18O values decreased, whereas all other records show a clear increase in δ18O. Comparison with the NGRIP record suggests that Northern Hemisphere temperature changes are reflected in Frasassi speleothem δ18O fluctuations during this interval.

A major pronounced isotopic event associated with warming and pluvial conditions during the last glacial evident in the entire Mediterranean region between ca. 54,500 and 52,500 yr B.P. is recorded also in the Frasassi speleothem isotopic profile. This event is followed by a transition from wet and warm climatic conditions to cold conditions. The end of the last glacial is associated with climate instability, evident mainly from the very large oscillations in the Frasassi δ13C record. The transition from the last glacial to early Holocene is characterized by a decreasing trend in δ18O and a sharp increase in δ13C values.
Last Glacial Maximum giant sand dunes on the island of Vis, Croatia
Authors: Wacha* Lara , Montanari* Alessandro , Lomax* Johanna , Fiebig* Markus , Lüthgens* Christopher , Korbar* Tvrtko , Koeberl* Christian
Published: October 2019

An ~10-m-thick sequence of Quaternary eolian sands from the island of Vis (Croatia) was investigated with the aim to unravel and understand their origin, characteristics, and age. The sand deposit is situated in a karstic depression in the eastern part of the island at an altitude of ~100 m above sea level (a.s.l.), and it is composed of a subhorizontally laminated unit at the bottom underlying a cross-bedded unit. The sand is very well sorted and fine grained and composed predominantly of carbonate lithic fragments, which most likely originated from the Dinaric karst region. The siliciclastic component of these sands reflects a more complex lithological source, including older sedimentary (e.g., flysch successions in the area, as well as older Quaternary deposits), magmatic, and metamorphic rocks probably originating from the Inner Dinarides, which were eroded and comminuted by glacial and periglacial activity during the last glacial period, and transported toward the Adriatic foreland by major rivers such as the Cetina and Neretva. Grain size and shape characteristics of the sands as well as their sedimentary structure indicate their eolian origin. Optically stimulated luminescence (OSL) dating was applied to determine the depositional age of the sediment. The obtained ages can be correlated to the Last Glacial Maximum (oxygen isotope stage [OIS] 2), implying that during the peak of that glaciation, the central Adriatic basin was dry land, a vast plain exposed to eolian deflation.
Longitudinally extensive transverse myelitis with seropositive chikungunya
Authors: Hameed Sajid , Memon Mubashar , Imtiaz Hina , Kanwar Dureshahwar
Published: October 2019

Chikungunya viral (CHIKV) fever is often a self-limiting febrile illness associated with severe debilitating arthralgia. Neurological complications associated with CHIKV, although rare, have been reported in literature; however, longitudinally extensive transverse myelitis (LTEM) is rarely associated with it. We present a case of a middle-aged man with a 1-week history of low-grade fever and arthralgia followed by urinary retention and quadriplegia. A sensory level was noted at T2. On subsequent investigations, he was diagnosed with LETM. Although LETM is commonly seen in patients with neuromyelitis optica, the other possible etiologies are inflammatory and parainfectious. To date, only two cases of LETM are reported worldwide in association with CHIKV fever and this is the first case from Pakistan. With frequent chikungunya outbreaks, neurological complications are increasingly seen in clinical practice. The knowledge of these associations will result in their early diagnosis and treatment.
Supportive supervision to improve service delivery in low-income countries: is there a conceptual problem or a strategy problem?
Authors: Avortri Gertrude Sika , Nabukalu Joy Belinda , Nabyonga-Orem Juliet
Published: October 2019

Supportive supervision is perceived as an intervention that strengthens the health system, enables health workers to offer quality services and improve performance. Unfortunately, numerous studies show that supervisory mechanisms in many low-income countries (LICs) are suboptimal. Further, the understanding of the concept and its implementation is still shrouded in misinterpretations and inconsistencies. This analysis contributes to a deeper understanding of the concept of supportive supervision and how reorganisation of the approach can contribute to improved performance. The effectiveness of supportive supervision is mixed, with some studies noting that evidence on its role, especially in LICs is inconclusive. Quality of care is a core component of universal health coverage which, accentuates the need for supportive supervision. In the context of LICs, it is imperative for supportive supervision to be implemented as an on-going approach. Factors that affect supportive supervision encompass cultural, social, organizational and context dimensions but the capacity of majority of LIC to address these is limited. To this end, we underscore the need to review the supportive supervision approach to improve its effectiveness, and ensure that facility-based supervision embodies as many of the envisioned qualities as possible. We thus make a case for a stronger focus on internal supportive supervision where internal refers to health facility/unit/ward level. Inherent in the approach is what we refer to as ‘supervisee initiated supportive supervision’. The success of this approach must be anchored on a strong system for monitoring, data and information management at the health facility level.
The Manitoba Personalized Lifestyle Research (TMPLR) study protocol: a multicentre bidirectional observational cohort study with administrative health record linkage investigating the interactions between lifestyle and health in Manitoba, Canada
Authors: Mackay Dylan , Mollard Rebecca C , Granger Matthew , Bruce Sharon , Blewett Heather , Carlberg Jared , Duhamel Todd , Eck Peter , Faucher Patrick , Hamm Naomi C , Khafipour Ehsan , Lix Lisa , McMillan Diana , Myrie Semone , Ravandi Amir , Tangri Navdeep , Azad Meghan , Jones Peter JH
Published: October 2019

Introduction

Lifestyle factors, such as diet, physical activity and sleep, are associated with the development of many chronic diseases. The objective of The Manitoba Personalized Lifestyle Research study is to understand how these lifestyle factors interact with each other and with other factors, such as an individual’s genetics and gut microbiome, to influence health.

Methods

An observational study of adults, with extensive phenotyping by objective health and lifestyle assessments, and retrospective assessment of early life experiences, with retrospective and prospective utilisation of secondary data from administrative health records.

Study population

A planned non-random convenience sample of 840 Manitobans aged 30–46 recruited from the general population, stratified by sex (equal men and women), body mass index (BMI; 60% of participants with a BMI>25 kg/m2) and geography (25% from rural areas). These stratifications were selected based on Manitoba demographics.

Measurements

Lifestyle factors assessed will include dietary pattern, physical activity, cardiovascular fitness, and sleep. Factors such as medical history, socioeconomic status, alcohol and tobacco consumption, cognition, stress, anxiety, and early life experiences will also be documented. A maternal survey will be performed. Body composition and bone density will be measured by dual energy X-ray absorptiometry. Blood pressure, pulse wave velocity, and augmentation index will be measured on two consecutive days. Chronic disease risk biomarkers will be measured in blood and urine samples. DNA will be extracted for genetic analysis. A faecal sample will be collected for microbiome analysis. Participants may provide their Manitoba personal health information number to link their study data with administrative health records.

Ethics and dissemination

Ethics approval has been obtained from the University of Manitoba Health Research Ethics Board (protocol # HS18951; 05/01/2016). Data analysis, release of results and publication of manuscripts are scheduled to start in early 2019. Additional information atwww.TMPLR.ca.

Trial registration number

NCT03674957; Pre-results.
Physical activity and cognitive changes in younger women after breast cancer treatment
Authors: Arneil Melissa , Anderson Debra , Alexander Kimberly , McCarthy Alexandra
Published: October 2019

Objectives

Studies indicate women aged 25–49 years previously treated for cancer report cognitive alterations. Good evidence indicates physical activity can be beneficial after cancer and might additionally benefit cognitive function. This short report presents data from a substudy of the Younger Women’s Wellness after Cancer Program (YWWACP), which explored cognitive alterations and investigated potential associations between physical activity and cognitive function in participants in the YWWACP. The primary aim of this substudy was to determine in younger women previously treated for breast cancer (1) whether subjectively reported cognitive function changed over time and (2) if physical activity is associated with subjectively reported cognitive function, and if time had an impact on this.

Methods

All participants had completed breast cancer treatment. Data were collected at baseline (n=41) and at 12 weeks. Measures assessed demographics, self-reported physical activity, cognitive function, sleep quality, stress, anxiety and depression using validated and reliable, subjectively reported instruments.

Results

Cognitive function and physical activity scores increased across the time points, with cognitive function revealing a statistically significant increase over time (p=0.004). Statistical testing revealed that physical activity was not correlated with cognitive function and that change in physical activity was not correlated with change in cognitive function.

Conclusion

These data provide early evidence that cognitive function and physical activity improved over time in this sample. However, interpretations of a correlation between physical activity and cognitive function should be made with caution, and future research would benefit from larger samples.
Hospital performance and clinical leadership: new evidence from Iran
Authors: Kakemam Edris , Goodall Amanda H
Published: October 2019

Purpose

There is growing interest in the potential need for clinical involvement in leadership and management of hospitals. Most studies of clinical leadership use US and European data. This paper contributes the first evidence for the country of Iran. It examines three different forms of hospital system: public, private and social security organisation, and these include teaching and non-teaching hospitals. This study adds to a small but growing literature that examines the possible value of ‘expert’ clinical leaders.

Method

This study uses data from 72 general hospitals in the city of Tehran. The data were collected for years 2015 and 2016. Data Envelopment Analysis is used to assess hospital performance. Hospitals’ chief operating officers are divided into two groups:clinicians, the majority of whom are physicians (doctors), andnon-medically trained managers.

Findings

The average performance scores for hospitals with clinical managers and non-clinically trained managers are equal to 96.68±5.50 and 89.78±7.20, respectively (p<0.001). Performance is thus higher under clinical managers. Outcome differences are observed in each of the three types of ownership and in teaching and non-teaching hospitals. The advantage in performance-score varies, when comparing the clinically led institutions and managerially led institutions, by between 5 and 10 points on a 0–100 scale. These differences remain after regression-equation adjustment for other influences.

Practical implications

Succession planning and targeted leadership development is made more efficient with greater awareness about the kinds of leaders and managers that enhance organisational performance.
Time to get to sleep
Authors: Farquhar Michael
Published: October 2019

Struggling to fall or to stay asleep? It's a common problem and can be particularly challenging when working irregular and antisocial hours. Michael Farquhar offers some advice on how to increase your chances of getting the rest you need.
Jennifer Poland
Authors: Jones Gary Clayton , Denny Hamish , Davies Jerry
Published: October 2019

A woman of ideas. As a teacher with an interest in learning methods, she set up the profession's first continuing education pack, which were loaned to vets across the world.
BFKL equation in the next-to-leading order: solution at large impact parameters
Authors: Contreras Carlos , Levin Eugene , Meneses Rodrigo
Published: October 2019

In this paper, we show (1) that the NLO corrections do not change the power-like decrease of the scattering amplitude at large impact parameter ($$b^2 \,>\,r^2 \exp ( 2{\bar{\alpha }}_S\eta (1 + 4 {\bar{\alpha }}_S) )$$b2>r2exp(2α¯Sη(1+4α¯S)), whererdenotes the size of scattering dipole and$$\eta = \ln (1/x_{Bj} )$$η=ln(1/xBj)for DIS), and, therefore, they do not resolve the inconsistency with unitarity; and (2) they lead to an oscillating behaviour of the scattering amplitude at largeb, in direct contradiction with the unitarity constraints. However, from the more practical point of view, the NLO estimates give a faster decrease of the scattering amplitude as a function ofb, and could be very useful for description of the experimental data. It turns out, that in a limited range ofb, the NLO corrections generates the fast decrease of the scattering amplitude withb, which can be parameterized as$$N\, \propto \,\exp ( -\,\mu \,b )$$N∝exp(-μb)with$$\mu \, \propto \,1/r$$μ∝1/rin accord with the numerical estimates in Cepila et al. (Phys Rev D 99(5):051502,10.1103/PhysRevD.99.051502,arXiv:1812.02548[hep-ph], 2019).
A localized Penrose inequality and quasi-local mass
Authors: Wang Qizhi
Published: October 2019

In this paper, we use spinorial method to define a new quasi-local mass with reference to a Schwarzchild manifold. In the proof of the main theorem, spinors are defined on manifold with two boundary components. Through the Reilly formula, we get the new quasi-local mass is nonnegative. Combined with Riemannian–Penrose inequality, we derive a localized Penrose inequality.
ANALYSIS OF THE CO-MOVEMENT BETWEEN LOCAL GOVERNMENT DEBT RISK AND BANK RISK IN CHINA
Authors: ZHENG CHANGJUN , HUANG SIWEI , QIAN NINGYU
Published: October 2019

We characterize the debt risk and bank risk of local governments in China with a dynamic factor model that decomposes 31 provincial data of China into country, regional, and idiosyncratic components. The result shows the presence of co-movement between local government debt risk and bank risk. The country, regional, and province factors explain 62%, 16%, and 22% of local government debt risk, respectively, and 28%, 8%, and 64% of commercial bank risk, respectively. Sub-sample analysis reveals that the country factor has become less volatile and its importance typically increases across all provinces after the reform of local government debt financing pattern (e.g., the introduction of Document No. 43).
Hereditary automorphic Lie algebras
Authors: Knibbeler Vincent , Lombardo Sara , Sanders Jan A.
Published: October 2019

We show that automorphic Lie algebras which contain a Cartan subalgebra with a constant-spectrum, called hereditary, are completely described by 2-cocycles on a classical root system taking only two different values. This observation suggests a novel approach to their classification. By determining the values of the cocycles on opposite roots, we obtain the Killing form and the abelianization of the automorphic Lie algebra. The results are obtained by studying equivariant vectors on the projective line. As a byproduct, we describe a method to reduce the computation of the infinite-dimensional space of said equivariant vectors to a finite-dimensional linear computation and the determination of the ring of automorphic functions on the projective line.
On the regularity of the total variation minimizers
Authors: Porretta Alessio
Published: October 2019

We prove regularity results for the unique minimizer of the total variation functional, currently used in image processing analysis since the work by Rudin, Osher and Fatemi. In particular, we show that if the source term [Formula: see text] is locally (respectively, globally) Lipschitz, then the solution has the same regularity with local (respectively, global) Lipschitz norm estimated accordingly. The result is proved in any dimension and for any (regular) domain. So far we extend a similar result proved earlier by Caselles, Chambolle and Novaga for dimension [Formula: see text] and (in case of the global regularity) for convex domains.
Symplectic deformations of Floer homology and non-contractible periodic orbits in twisted disc bundles
Authors: Gong Wenmin
Published: October 2019

In this paper, we establish the existence of periodic orbits belonging to any [Formula: see text]-atoroidal free homotopy class for Hamiltonian systems in the twisted disc bundle, provided that the compactly supported time-dependent Hamiltonian function is sufficiently large over the zero section and the magnitude of the weakly exact [Formula: see text]-form [Formula: see text] admitting a primitive with at most linear growth on the universal cover is sufficiently small. The proof relies on showing the invariance of Floer homology under symplectic deformations and on the computation of Floer homology for the cotangent bundle endowed with its canonical symplectic form.

As a consequence, we also prove that, for any non-trivial atoroidal free homotopy class and any positive finite interval, if the magnitude of a magnetic field admitting a primitive with at most linear growth on the universal cover is sufficiently small, the twisted geodesic flow associated to the magnetic field has a periodic orbit on almost every energy level in the given interval whose projection to the underlying manifold represents the given free homotopy class. This application is carried out by showing the finiteness of the restricted Biran–Polterovich–Salamon capacity.
Lie automorphic loops under half-automorphisms
Authors: Merlini Giuliani Maria De Lourdes , Dos Anjos Giliard Souza
Published: October 2019

Automorphic loops or [Formula: see text]-loops are loops in which all inner mappings are automorphisms. This variety of loops includes groups and commutative Moufang loops. Given a Lie ring [Formula: see text] we can define an operation [Formula: see text] such that [Formula: see text] is an [Formula: see text]-loop. We call it Lie automorphic loop. A half-isomorphism [Formula: see text] between multiplicative systems [Formula: see text] and [Formula: see text] is a bijection from [Formula: see text] onto [Formula: see text] such that [Formula: see text] for any [Formula: see text]. It was shown by [W. R. Scott, Half-homomorphisms of groups, Proc. Amer. Math. Soc. 8 (1957) 1141–1144] that if [Formula: see text] is a group then [Formula: see text] is either an isomorphism or an anti-isomorphism. This was used to prove that a finite group is determined by its group determinant. Here, we show that every half-automorphism of a Lie automorphic loop of odd order is either an automorphism or an anti-automorphism.
Study on Atomic Oxygen Exposure and Hard Particle Impact of Polyimide Nanocomposites
Authors: Novikov Lev S. , Voronina Ekaterina N. , Chernik Vladimir N. , Chirskaya Natalia P. , Zhang Weigui
Published: October 2019

Atomic oxygen (AO) exposure and hard microparticle impact on polyimide nanocomposites were performed by a ground-based magnetoplasmodynamic accelerator and electrostatic accelerator, respectively. The computer simulation of the AO erosion of polyimide nanocomposites was carried out with Monte Carlo method. It is found that the polyimide nanocomposites are significantly more durable to AO exposure than the pure polyimide material. Besides, in the case of combined hard microparticle impact and AO exposure, the regions around craters created by hard microparticle impact are etched more intensively than the undamaged areas of the polyimide nanocomposite sample surface.
Approximation of the power functions of Roy’s largest root test under general spiked alternatives
Authors: Hou Zhiqiang , Liu Yan , Bai Zhidong , Hu Jiang
Published: October 2019

Roy’s largest root is a common test statistic in multivariate analysis, statistical signal processing and related fields. According to Anderson [An Introduction to Multivariate Statistical Analysis, 3rd edn. (Wiley, New York, 2003)], it is numerically known that compared with the other three tests of linear hypotheses, Roy’s largest root test has the highest power under rank-one alternatives. Therefore, it is important to study the asymptotic distribution of the largest root under rank-one alternatives to obtain an estimation of the power. To the best of our knowledge, no one had solved the problem until Johnstone and Nadler [Roy’s largest root test under rank-one alternatives, Biometrika 104(1) (2017) 181–193] presented a tractable approximation of the distribution of Roy’s largest root test where the alternative is of rank one and the variance of the noise tends to zero. It is natural to ask how Roy’s largest root test performs under other alternatives, for example, rank-finite alternatives. Therefore, we are more interested in the power estimates of Roy’s largest root test under wider alternatives, namely, whether its power is still higher than that of the other three tests of linear hypotheses. In fact, the distribution of the largest root under rank-finite alternatives can be characterized as the distribution of the largest sample eigenvalue among several spiked models. In this paper, we employ the asymptotic results of the spiked eigenvalues derived by Bai and Yao [Central limit theorems for eigenvalues in a spiked population model, Ann. Inst. Henri. Poincarè Probab. Statist. 44(3) (2008) 447–474; On sample eigenvalues in a generalized spiked population model, J. Multivar. Anal. 106 (2012) 167–177] and Wang and Yao [Extreme eigenvalues of large-dimensional spiked Fisher matrices with application, Ann. Statist. 45 (2017) 415–460] to obtain the approximate power of Roy’s largest root test under a high-dimensional setting; more importantly, our results are distribution-free and applicable to cases involving rank-finite alternatives.
Physical and biological functioning in Proterozoic rivers: evidence from the archetypal pre-vegetation alluvium of the Torridon Group, NW Scotland
Authors: McMahon William J. , Davies Neil S.
Published: October 2019

In modern rivers, vegetation affects hydrological, geomorphological and sedimentological functioning, so extant fluvial systems can provide only partial analogues for those rivers that operated before the evolution of land plants. However, pre-vegetation rivers were the norm for the first 90% of Earth's history and so a better understanding of their sedimentary product can provide insights into both the fundamental underlying mechanisms of river behaviour and the ways in which fluvial processes operated on ancient Earth. In addition to a short review of the history of research into pre-vegetation alluvium, this paper presents a fieldwork-based case study of the later Proterozoic Torridon Group, which contains some of the most extensive and easily accessible exposures of pre-vegetation alluvium worldwide. Three alluvial architectural deposits have been recognized: (1) channel-bedform deposits (
c.
80%); (2) barform deposits (
c.
20%); and (3) out-of-channel deposits (≪1%). Channel-bedform deposits have erosional bases and most frequently stack vertically to form thick multistorey channel-bedform sequences. The preferential preservation of these deposits, which record the deepest parts of river channels, suggests that channel migration had a dominant control on preservation in the Torridon Group. Less frequently, channel-bedform deposits pass upwards into a genetically related barform deposit. Barform preservation in these instances is interpreted to be due to channel avulsion, which protected the barforms from reworking. Channel-bar thickness, measured from the basal erosional surface of a channel-bedform deposit to the top of its associated barform deposit, indicates minimum water depths of 1.7 to 8.0 m. Downstream-accreting barform deposits are most frequent, but lateral and upstream modes of accretion are also well represented. Dominant southeastward-palaeoflow directions imply that the Torridonian rivers were sourced from the Grenvillian Mountain Belt. The preserved architectural deposits and narrow dispersal of palaeocurrent data are explained by interpreting the Torridon Group as the alluvium of dominantly low-sinuosity rivers, with signatures recording autogenic fluvial adjustments. In the few rare instances where out-of-channel deposits are preserved, they contain fossil evidence for microbial mats, which prove that not all Proterozoic river systems were wholly abiotic. The overall characteristics of the Torridon alluvium, in terms of its ubiquitous highly tabular beds of sand-grade or coarser material, make it an archetypal example of pre-vegetation alluvium as known globally.

Thematic collection:
This article is part of the SJG Collection on Early-Career Research available at:
https://www.lyellcollection.org/cc/SJG-early-career-research
Efficient Decentralized LTL Monitoring Framework Using Tableau Technique
Authors: Bataineh Omar , Rosenblum David S. , Reynolds Mark
Published: October 2019

This paper presents a novel framework for decentralized monitoring of Linear Temporal Logic (LTL) formulas, under the situation where processes are synchronous and the formula is represented as a tableau. The tableau technique allows one to construct a semantic tree for the input LTL formula, which can be used to optimize the decentralized monitoring of LTL in various ways. Given a system
P
and an LTL formula φ, we construct a tableau T
φ
. The tableau T
φ
is used for two purposes: (a) to synthesize an efficient round-robin communication policy for processes, and (b) to find the minimal ways to decompose the formula and communicate observations of processes in an efficient way. In our framework, processes can propagate truth values of both atomic and compound formulas (non-atomic formulas) depending on the syntactic structure of the input LTL formula and the observation power of processes. We demonstrate that this approach of decentralized monitoring based on tableau construction is more straightforward, more flexible, and more likely to yield efficient solutions than alternative approaches.
CLOTHO: directed test generation for weakly consistent database systems
Authors: Rahmani Kia , Nagar Kartik , Delaware Benjamin , Jagannathan Suresh
Published: October 2019

Relational database applications are notoriously difficult to test and debug. Concurrent execution of database transactions may violate complex structural invariants that constraint how changes to the contents of one (shared) table affect the contents of another. Simplifying the underlying concurrency model is one way to ameliorate the difficulty of understanding how concurrent accesses and updates can affect database state with respect to these sophisticated properties. Enforcing serializable execution of all transactions achieves this simplification, but it comes at a significant price in performance, especially at scale, where database state is often replicated to improve latency and availability.

To address these challenges, this paper presents a novel testing framework for detecting serializability violations in (SQL) database-backed Java applications executing on weakly-consistent storage systems. We manifest our approach in a tool, CLOTHO, that combines a static analyzer and model checker to generate abstract executions, discover serializability violations in these executions, and translate them back into concrete test inputs suitable for deployment in a test environment. To the best of our knowledge, CLOTHO, is the first automated test generation facility for identifying serializability anomalies of Java applications intended to operate in geo-replicated distributed environments. An experimental evaluation on a set of industry-standard benchmarks demonstrates the utility of our approach.
Verifying safety and accuracy of approximate parallel programs via canonical sequentialization
Authors: Fernando Vimuth , Joshi Keyur , Misailovic Sasa
Published: October 2019

We present Parallely, a programming language and a system for verification of approximations in parallel message-passing programs. Parallely's language can express various software and hardware level approximations that reduce the computation and communication overheads at the cost of result accuracy.

Parallely's safety analysis can prove the absence of deadlocks in approximate computations and its type system can ensure that approximate values do not interfere with precise values. Parallely's quantitative accuracy analysis can reason about the frequency and magnitude of error. To support such analyses, Parallely presents an approximation-aware version of canonical sequentialization, a recently proposed verification technique that generates sequential programs that capture the semantics of well-structured parallel programs (i.e., ones that satisfy a symmetric nondeterminism property). To the best of our knowledge, Parallely is the first system designed to analyze parallel approximate programs.

We demonstrate the effectiveness of Parallely on eight benchmark applications from the domains of graph analytics, image processing, and numerical analysis. We also encode and study five approximation mechanisms from literature. Our implementation of Parallely automatically and efficiently proves type safety, reliability, and accuracy properties of the approximate benchmarks.
Qubit allocation as a combination of subgraph isomorphism and token swapping
Authors: Siraichi Marcos Yukio , Santos Vinícius Fernandes dos , Collange Caroline , Pereira Fernando Magno Quintão
Published: October 2019

In 2016, the first quantum processors have been made available to the general public. The possibility of programming an actual quantum device has elicited much enthusiasm. Yet, such possibility also brought challenges. One challenge is the so called Qubit Allocation problem: the mapping of a virtual quantum circuit into an actual quantum architecture. There exist solutions to this problem; however, in our opinion, they fail to capitalize on decades of improvements on graph theory. In contrast, this paper shows how to model qubit allocation as the combination of Subgraph Isomorphism and Token Swapping. This idea has been made possible by the publication of an approximative solution to the latter problem in 2016. We have compared our algorithm against five other qubit allocators, all independently designed in the last two years, including the winner of the IBM Challenge. When evaluated in "Tokyo", a quantum architecture with 20 qubits, our technique outperforms these state-of-the-art approaches in terms of the quality of the solutions that it finds and the amount of memory that it uses, while showing practical runtime.
Modular verification of heap reachability properties in separation logic
Authors: Ter-Gabrielyan Arshavir , Summers Alexander J. , Müller Peter
Published: October 2019

The correctness of many algorithms and data structures depends on reachability properties, that is, on the existence of chains of references between objects in the heap. Reasoning about reachability is difficult for two main reasons. First, any heap modification may affect an unbounded number of reference chains, which complicates modular verification, in particular, framing. Second, general graph reachability is not supported by first-order SMT solvers, which impedes automatic verification.

In this paper, we present a modular specification and verification technique for reachability properties in separation logic. For each method, we specify reachability only locally within the fragment of the heap on which the method operates. We identify relative convexity, a novel relation between the heap fragments of a client and a callee, which enables (first-order) reachability framing, that is, extending reachability properties from the heap fragment of a callee to the larger fragment of its client, enabling precise procedure-modular reasoning. Our technique supports practically important heap structures, namely acyclic graphs with a bounded outdegree as well as (potentially cyclic) graphs with at most one path (modulo cycles) between each pair of nodes. The integration into separation logic allows us to reason about reachability and other properties in a uniform way, to verify concurrent programs, and to automate our technique via existing separation logic verifiers. We demonstrate that our verification technique is amenable to SMT-based verification by encoding a number of benchmark examples into the Viper verification infrastructure.
Staged abstract interpreters: fast and modular whole-program analysis via meta-programming
Authors: Wei Guannan , Chen Yuxuan , Rompf Tiark
Published: October 2019

It is well known that a staged interpreter is a compiler: specializing an interpreter to a given program produces an equivalent executable that runs faster. This connection is known as the first Futamura projection. It is even more widely known that an abstract interpreter is a program analyzer: tweaking an interpreter to run on abstract domains produces a sound static analysis. What happens when we combine these two ideas, and apply specialization to an abstract interpreter?

In this paper, we present a unifying framework that naturally extends the first Futamura projection from concrete interpreters to abstract interpreters. Our approach derives a sound staged abstract interpreter based on a generic interpreter with type-level binding-time abstractions and monadic abstractions. By using different instantiations of these abstractions, the generic interpreter can flexibly behave in one of four modes: as an unstaged concrete interpreter, a staged concrete interpreter, an unstaged abstract interpreter, or a staged abstract interpreter. As an example of abstraction without regret, the overhead of these abstraction layers is eliminated in the generated code after staging. We show that staging abstract interpreters is practical and useful to optimize static analysis, all while requiring less engineering effort and without compromising soundness. We conduct three case studies, including a comparison with Boucher and Feeley’s abstract compilation, applications to various control-flow analyses, and a demonstration for modular analysis. We also empirically evaluate the effect of staging on the execution time. The experiment shows an order of magnitude speedup with staging for control-flow analyses.
A fault-tolerant programming model for distributed interactive applications
Authors: Mogk Ragnar , Drechsler Joscha , Salvaneschi Guido , Mezini Mira
Published: October 2019

Ubiquitous connectivity of web, mobile, and IoT computing platforms has fostered a variety of distributed applications with decentralized state. These applications execute across multiple devices with varying reliability and connectivity. Unfortunately, there is no declarative fault-tolerant programming model for distributed interactive applications with an inherently decentralized system model.

We present a novel approach to automating fault tolerance using high-level programming abstractions tailored to the needs of distributed interactive applications. Specifically, we propose a calculus that enables formal reasoning about applications' dataflow within and across individual devices. Our calculus reinterprets the functional reactive programming model to seamlessly integrate its automated state change propagation with automated crash recovery of device-local dataflow and disconnection-tolerant distribution with guaranteed automated eventual consistency semantics based on conflict-free replicated datatypes. As a result, programmers are relieved of handling intricate details of distributing change propagation and coping with distribution failures in the presence of interactivity. We also provides proofs of our claims, an implementation of our calculus, and an empirical evaluation using a common interactive application.