Primordial rotating black holes Pacheco, J. A. de Freitas; Silk, Joseph
Physical review. D,
04/2020, Letnik:
101, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Primordial black holes formed in an early postinflation matter-dominated epoch during preheating provide a novel pathway for a source of the dark matter that utilizes known physics in combination ...with plausible speculations about the role of quantum gravity. Two cases are considered here: survival of Planck-scale relics and an early universe accretion scenario for the formation of primordial black holes of asteroid-scale masses.
This book provides an updated state-of-the-art review on new developments in alkali-activation. The main binder of concrete, Portland cement, represents almost 80% of the total CO2 emissions of ...concrete which are about 6 to 7% of the Planet's total CO2 emissions. This is particularly serious in the current context of climate change and it could get even worse because the demand for Portland cement is expected to increase by almost 200% by 2050 from 2010 levels, reaching 6000 million tons/year. Alkali-activated binders represent an alternative to Portland cement having higher durability and a lower CO2 footprint. * Reviews the chemistry, mix design, manufacture and properties of alkali-activated cement-based concrete binders * Considers performance in adverse environmental conditions. * Offers equal emphasis on the science behind the technology and its use in civil engineering.
Background
Epidemiologic studies suggest a relationship between maternal nutrition during pregnancy and the occurrence of asthma and atopic conditions during childhood. However, individual study ...results are conflicting. The objective of this meta‐analysis was to critically examine the current evidence for an association between nutrition (dietary patterns, food groups, vitamins, or oligo‐elements) ingestion during pregnancy and asthma, wheeze, or atopic conditions in childhood.
Methods
The inclusion criteria were as follows: (i) systematic recording of diet during the gestational period and (ii) documentation of asthma, wheezing, eczema, or other atopic disease in the offspring. The primary outcomes were prevalence of asthma or wheeze among the offspring during childhood; and secondary outcomes were prevalence of eczema, allergic rhinitis, or other atopic conditions.
Results
We found 120 titles, s, and citations, and 32 studies (29 cohorts) were included in this analysis. Data on vitamins, oligo‐elements, food groups, and dietary patterns during pregnancy were collected. A meta‐analysis revealed that higher maternal intake of vitamin D odds ratio (OR) = 0.58, 95% confidence interval (CI) = 0.38–0.88, vitamin E (OR = 0.6, 95% CI = 0.46–0.78), and zinc (OR = 0.62, 95% CI = 0.40–0.97) was associated with lower odds of wheeze during childhood. However, none of these or other nutrients was consistently associated with asthma per se or other atopic conditions.
Conclusions
Current evidence suggests a protective effect of maternal intake of each of three vitamins or nutrients (vitamin D, vitamin E, and zinc) against childhood wheeze but is inconclusive for an effect on asthma or other atopic conditions.
Identification of unambiguous signals of volcanic unrest is crucial in hazard assessment. Processes leading to phreatic and phreatomagmatic eruptions remain poorly understood, inhibiting effective ...eruption forecasting. Our 5‐year gas record from Poás volcano, combined with geophysical data, reveals systematic behavior associated with hydrothermal‐magmatic eruptions. Three eruptive episodes are covered, each with distinct geochemical and geophysical characteristics. Periods with larger eruptions tend to be associated with stronger excursions in monitoring data, particularly in SO2/CO2 and SO2 flux. The explosive 2017 phreatomagmatic eruption was the largest eruption at Poás since 1953 and was preceded by dramatic changes in gas and geophysical parameters. The use of drones played a crucial role in gas monitoring during this eruptive period. Hydrothermal sealing and volatile accumulation, followed by top‐down reactivation of a shallow previously emplaced magma body upon seal failure, are proposed as important processes leading to and contributing to the explosivity of the 2017 eruption.
Plain Language Summary
High‐frequency monitoring of phreatic eruptions shows that clear precursory signals often exist to these dangerous explosive events. We interrogate the processes that lead to phreatic eruptions and investigate the intricate connections between magma intrusions and the hydrothermal systems that they feed.
Key Points
Three eruptive phases are characterized in detail through five years of high‐frequency monitoring
We identify and discuss precursors to phreatic and phreatomagmatic eruptions
Enhanced hydrothermal sealing can lead to larger eruptions and top‐down remobilization of magma
Genetic studies require precise phenotype definitions, but electronic medical record (EMR) phenotype data are recorded inconsistently and in a variety of formats.
To present lessons learned about ...validation of EMR-based phenotypes from the Electronic Medical Records and Genomics (eMERGE) studies.
The eMERGE network created and validated 13 EMR-derived phenotype algorithms. Network sites are Group Health, Marshfield Clinic, Mayo Clinic, Northwestern University, and Vanderbilt University.
By validating EMR-derived phenotypes we learned that: (1) multisite validation improves phenotype algorithm accuracy; (2) targets for validation should be carefully considered and defined; (3) specifying time frames for review of variables eases validation time and improves accuracy; (4) using repeated measures requires defining the relevant time period and specifying the most meaningful value to be studied; (5) patient movement in and out of the health plan (transience) can result in incomplete or fragmented data; (6) the review scope should be defined carefully; (7) particular care is required in combining EMR and research data; (8) medication data can be assessed using claims, medications dispensed, or medications prescribed; (9) algorithm development and validation work best as an iterative process; and (10) validation by content experts or structured chart review can provide accurate results.
Despite the diverse structure of the five EMRs of the eMERGE sites, we developed, validated, and successfully deployed 13 electronic phenotype algorithms. Validation is a worthwhile process that not only measures phenotype performance but also strengthens phenotype algorithm definitions and enhances their inter-institutional sharing.
The civil engineering sector accounts for a significant percentage of global material and energy consumption and is a major contributor of waste material. The ability to recycle and reuse concrete ...and demolition waste is critical to reducing environmental impacts in meeting national, regional and global environmental targets. Handbook of recycled concrete and demolition waste summarises key recent research in achieving these goals.Part one considers techniques for managing construction and demolition waste, including waste management plans, ways of estimating levels of waste, the types and optimal location of waste recycling plants and the economics of managing construction and demolition waste. Part two reviews key steps in handling construction and demolition waste. It begins with a comparison between conventional demolition and construction techniques before going on to discuss the preparation, refinement and quality control of concrete aggregates produced from waste. It concludes by assessing the mechanical properties, strength and durability of concrete made using recycled aggregates. Part three includes examples of the use of recycled aggregates in applications such as roads, pavements, high- performance concrete and alkali-activated or geopolymer cements. Finally, the book discusses environmental and safety issues such as the removal of gypsum, asbestos and alkali-silica reaction (ASR) concrete, as well as life-cycle analysis of concrete with recycled aggregates.Handbook of recycled concrete and demolition waste is a standard reference for all those involved in the civil engineering sector, as well as academic researchers in the field. * Summarises key recent research in recycling and reusing concrete and demolition waste to reduce environmental impacts and meet national, regional and global environmental targets * Considers techniques for managing construction and demolition waste, including waste management plans, ways of estimating levels of waste, the types and optimal location of waste recycling plants * Reviews key steps in handling construction and demolition waste
Solar drying is a sustainable process that may impact the quality of dried food. This is because, pigments contained in food are sensitive to sunlight, and exposure to ultraviolet radiation can ...affect them. We applied biopolymer-based coatings on strawberry, from hydro-colloidal solutions of Opuntia ficus indica-mucilage, fenugreek, xanthan gum, gum Arabic, and guar gum to evaluate their potential use as UV filters for solar drying of food. Thermal properties and the optical transmittance, absorbance and reflectance of the coatings were measured to assess their influence on food-sunlight interaction. During the drying experiments, the moisture content, total anthocyanins (TA), and total phenolic compounds (TPC) were measured. Optical and thermal properties are influenced by the biopolymer-based coatings. Also, the optical properties are influenced by the coating thickness. The differences in optical and thermal properties influence the drying process. Differences exist in the drying rate for strawberry slices with coating, compared with those without the coatings. In general, the TA and TPC content in the product are better preserved under solar drying than in control experiments done in a drying oven. A partial transmittance of solar UV radiation is recommended to obtain increased TA and TPC contents in the dried product.
Gravitational waves from binary axionic black holes de Freitas Pacheco, J. A.; Carneiro, S.; Fabris, J. C.
The European physical journal. C, Particles and fields,
05/2019, Letnik:
79, Številka:
5
Journal Article
Recenzirano
Odprti dostop
In a recent paper we have shown that a minimally coupled, self-interacting scalar field of mass
m
can form black holes of mass
M
=
3
/
(
4
m
)
(in Planck units). If dark matter is composed by axions, ...they can form miniclusters that for QCD axions have masses below this value. In this work it is shown that for a scenario in which the axion mass depends on the temperature as
m
∝
T
-
6
, minicluster masses above
0.32
M
⊙
, corresponding to an axion mass of
3
×
10
-
10
eV, exceed
M
and can collapse into black holes. If a fraction of these black holes is in binary systems, gravitational waves emitted during the inspiral phase could be detected by advanced interferometers like LIGO or VIRGO and by the planned Einstein Telescope. For a detection rate of one event per year, the lower limits on the binary fraction are
10
-
4
and
10
-
6
for LIGO and Einstein Telescope respectively.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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