The axial coupling of the nucleon, g
, is the strength of its coupling to the weak axial current of the standard model of particle physics, in much the same way as the electric charge is the strength ...of the coupling to the electromagnetic current. This axial coupling dictates the rate at which neutrons decay to protons, the strength of the attractive long-range force between nucleons and other features of nuclear physics. Precision tests of the standard model in nuclear environments require a quantitative understanding of nuclear physics that is rooted in quantum chromodynamics, a pillar of the standard model. The importance of g
makes it a benchmark quantity to determine theoretically-a difficult task because quantum chromodynamics is non-perturbative, precluding known analytical methods. Lattice quantum chromodynamics provides a rigorous, non-perturbative definition of quantum chromodynamics that can be implemented numerically. It has been estimated that a precision of two per cent would be possible by 2020 if two challenges are overcome
: contamination of g
from excited states must be controlled in the calculations and statistical precision must be improved markedly
. Here we use an unconventional method
inspired by the Feynman-Hellmann theorem that overcomes these challenges. We calculate a g
value of 1.271 ± 0.013, which has a precision of about one per cent.
Abstract
Many classrooms in higher education still rely on a transformative approach to teaching where students attend lectures and earn course grades through examination. In the modern age, ...traditional lectures are argued by some as obsolete and do not address the learning needs of today's students. An emerging pedagogical approach is the concept of the flipped classroom. The flipped classroom can simply be described as students viewing asynchronous video lectures on their own and then engaging in active learning during scheduled class times. In this study, we examined the flipped classroom teaching environment on student learning gains in an Introduction to Equine Science course. Students (n = 130) were asked to view 7.5 h of recorded lectures divided into 8 learning modules, take online quizzes to enforce lecture viewing, take 3 in-class exams, and prepare to participate in active learning during scheduled class times. Active learning approaches included individual activities, paired activities, informal small groups, and large group activities. When compared to students in the traditional lecture format in earlier years, students in the flipped format scored higher on all 3 exams (P < 0.05), with both formats taught by the same instructor. Analysis of ACT scores demonstrated no intellectual capacity differences between the student populations. To evaluate any gains in critical thinking, flipped format students were asked to take the Cornell Critical Thinking Exam (version X). Scores improved from the pretest (50.8 ± 0.57) to the posttest (54.4 ± 0.58; P < 0.01). In the flipped course, no correlations were found with student performance and interactions with online content. Students were asked in class to evaluate their experiences based on a 5-point Likert scale: 1 (strongly disagree) to 5 (strongly agree). The flipped classroom was ranked as an enjoyable learning experience with a mean of 4.4 ± 0.10, while students responded positively to other pointed questions. In formal course evaluations, flipped format students ranked the following higher (P < 0.05): instructor availability to assist students; encouragement of independent, creative, and critical thinking; and amount learned. Overall, the flipped classroom proved to be a positive learning experience for students. As the classroom continues to modernize, pedagogical approaches such as the flipped classroom should be considered for many lecture-style courses taught in the animal sciences.
FLAG Review 2021 Aoki, Y.; Blum, T.; Colangelo, G. ...
The European physical journal. C, Particles and fields,
10/2022, Letnik:
82, Številka:
10
Journal Article
Recenzirano
Odprti dostop
We review lattice results related to pion, kaon,
D
-meson,
B
-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More ...specifically, we report on the determination of the light-quark masses, the form factor
f
+
(
0
)
arising in the semileptonic
K
→
π
transition at zero momentum transfer, as well as the decay constant ratio
f
K
/
f
π
and its consequences for the CKM matrix elements
V
us
and
V
ud
. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of
S
U
(
2
)
L
×
S
U
(
2
)
R
and
S
U
(
3
)
L
×
S
U
(
3
)
R
Chiral Perturbation Theory. We review the determination of the
B
K
parameter of neutral kaon mixing as well as the additional four
B
parameters that arise in theories of physics beyond the Standard Model. For the heavy-quark sector, we provide results for
m
c
and
m
b
as well as those for the decay constants, form factors, and mixing parameters of charmed and bottom mesons and baryons. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. We review the status of lattice determinations of the strong coupling constant
α
s
. We consider nucleon matrix elements, and review the determinations of the axial, scalar and tensor bilinears, both isovector and flavor diagonal. Finally, in this review we have added a new section reviewing determinations of scale-setting quantities.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Antarctic Marginal Ice Zone (MIZ) accounts for 15% of the Southern Ocean's primary production (PP), but limited data has hindered understanding of its variability and connection to carbon export. ...Using a combination of gliders, biogeochemical Argo floats and satellite observations in the northeast Weddell Sea, we show that years with more sea‐ice formation over winter are followed by more intense phytoplankton blooms (∼15% greater daily PP) and export to 100 m (∼50% higher daily carbon export) the following summer. However, the carbon export beyond the deepest winter mixed layer did not vary in proportion to PP, suggesting different drivers of carbon export at depth compared to surface waters. Furthermore, across the entire MIZ, the response of blooms to sea‐ice volume was spatially variable, indicating the need to consider spatial heterogeneity in the response of the biological carbon pump to future sea‐ice changes.
Plain Language Summary
Algae in the ocean surface take up carbon dioxide from the atmosphere through photosynthesis and transfer it to the deep ocean when they die and sink. This process is key to maintaining a habitable planet and is known as the biological carbon pump (BCP). The seasonally ice‐covered ocean around Antarctica is one of the most active areas for algal growth, but also a region of rapid climate change. Because of the difficulty in taking measurements in this remote region, the physical and biological processes that control the growth and sinking of algae and its response to changing sea‐ice remain uncertain. In this study, we use a combination of satellites and autonomous robots to elucidate the role of sea‐ice variability on the BCP. We find that sea‐ice impacts algal growth by its influence on both the light and nutrient conditions needed for photosynthesis. Predicting the amount of algae that subsequently sinks to depth as carbon flux, although influenced by sea‐ice conditions, is more complex and linked to the greater marine ecosystem. Evidence suggests that the species of algae, zooplankton grazing, and the rate at which dead algae breaks down and sinks are important and should be a focus point for further research.
Key Points
High‐resolution in‐situ observations are used to characterize multi‐year phytoplankton bloom phenology and amplitude in the Antarctic Marginal Ice Zone
Years with greater sea‐ice volume drive deeper mixing that tend to support higher magnitude blooms in the northeast Weddell Sea
Carbon export efficiency is affected by bloom magnitude, community composition and water column stratification
FLAG Review 2019 Aoki, S; Aoki, Y; Bečirević, D ...
The European physical journal. C, Particles and fields,
02/2020, Letnik:
80, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We review lattice results related to pion, kaon, D-meson, B-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More ...specifically, we report on the determination of the light-quark masses, the form factor f+(0) arising in the semileptonic K→π transition at zero momentum transfer, as well as the decay constant ratio fK/fπ and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)L×SU(2)R and SU(3)L×SU(3)R Chiral Perturbation Theory. We review the determination of the BK parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. For the heavy-quark sector, we provide results for mc and mb as well as those for D- and B-meson decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. We review the status of lattice determinations of the strong coupling constant αs. Finally, in this review we have added a new section reviewing results for nucleon matrix elements of the axial, scalar and tensor bilinears, both isovector and flavor diagonal.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
During medical pandemics, protective behaviors need to be motivated by effective communication, where finding predictors of fear and perceived health is of critical importance. The varying ...trajectories of the COVID-19 pandemic in different countries afford the opportunity to assess the unique influence of 'macro-level' environmental factors and 'micro-level' psychological variables on both fear and perceived health. Here, we investigate predictors of fear and perceived health using machine learning as lockdown restrictions in response to the COVID-19 pandemic were introduced in Austria, Spain, Poland and Czech Republic. Over a seven-week period, 533 participants completed weekly self-report surveys which measured the target variables subjective fear of the virus and perceived health, in addition to potential predictive variables related to psychological factors, social factors, perceived vulnerability to disease (PVD), and economic circumstances. Viral spread, mortality and governmental responses were further included in the analysis as potential environmental predictors. Results revealed that our models could accurately predict fear of the virus (accounting for approximately 23% of the variance) using predictive factors such as worrying about shortages in food supplies and perceived vulnerability to disease (PVD), where interestingly, environmental factors such as spread of the virus and governmental restrictions did not contribute to this prediction. Furthermore, our results revealed that perceived health could be predicted using PVD, physical exercise, attachment anxiety and age as input features, albeit with smaller effect sizes. Taken together, our results emphasize the importance of 'micro-level' psychological factors, as opposed to 'macro-level' environmental factors, when predicting fear and perceived health, and offer a starting point for more extensive research on the influences of pathogen threat and governmental restrictions on the psychology of fear and health.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In the sea‐ice‐impacted Southern Ocean, the spring sea‐ice melt and its impact on physical processes set the rate of surface water mass modification. These modified waters will eventually subduct ...near the polar front and enter the global overturning circulation. Submesoscale processes modulate the stratification of the mixed layer (ML) and ML properties. Sparse observations in polar regions mean that the role of submesoscale motions in the exchange of properties across the base of the ML is not well understood. The goal of this study is to determine the interplay between sea‐ice melt, surface boundary layer forcing, and submesoscale flows in setting properties of the surface ML in the Antarctic marginal ice zone. High‐resolution observations suggest that fine‐scale lateral fronts arise from either/both mesoscale and submesoscale stirring of sea‐ice meltwater anomalies. The strong salinity‐driven stratification at the base of the ML confines these fronts to the upper ocean, limiting submesoscale vertical fluxes across the ML base. This strong stratification prevents the local subduction of modified waters by submesoscale flows, suggesting that the subduction site that links to the global overturning circulation does not correspond with the location of sea‐ice melt. However, surface‐enhanced fronts increase the potential for Ekman‐driven cross‐frontal flow to modulate the stability of the ML and ML properties. The parameterization of submesoscale processes in coupled‐climate models, particularly those contributing to the Ekman buoyancy flux, may improve the representation of ML heat and freshwater transport in the ice‐impacted Southern Ocean during summer.
Plain Language Summary
Sea‐ice melt around Antarctica is an annual event in which the state of the surface ocean is transformed, during which over 15 trillion liters of freshwater enter the upper ocean. This fresh layer separates the upper ocean from the deep ocean and suppresses the exchange of heat and gases—like carbon dioxide—between the deep ocean and the atmosphere, with important implications for the climate system. Using state‐of‐the‐art autonomous underwater gliders, we observed key physical properties of the surface ocean following the melt of sea‐ice. The presence of fine‐scale fronts (sharp changes in density), of less than 10 km at horizontal scales, revealed that sea‐ice melt not only stabilizes the upper ocean, but also provides additional energy for small eddies and filaments to form. While the eddies are unable to extend deeper than the fresher surface layer, they enhance the ocean response to winds. These findings may contribute to the improvement of global climate models and our understanding of how the ocean will react to changes in sea‐ice under a warmer climate.
Key Points
Sea‐ice meltwater controls the buoyancy of the mixed layer during early summer
Mixed layer eddies grow from mesoscale meltwater lateral gradients but are confined to the surface boundary layer
Observations suggest that mixed layer variability at submesoscales is dominated by wind‐front interactions
•This ESMO Clinical Practice Guideline provides key recommendations for managing malignant pleural mesothelioma.•The optimal diagnostic methods, pathological evaluation and staging are described.•The ...authors make recommendations on the role of surgery and macroscopic complete resection as part of multimodality therapy.•The authors discuss optimal first-line, maintenance and salvage systemic therapies and immune checkpoint inhibitors.•The authors discuss the role of prophylactic, radical and palliative radiotherapy and optimal supportive care.
Flow-enhanced crystal nucleation in a lightly entangled melt of n-pentacontahectane (C150H302, or C150) is examined by nonequilibrium molecular dynamics simulation under steady shear and uniaxial ...extension. Under sufficiently strong flow fields above the melting temperature, strong fluctuations give rise to domains with high local alignment on the Kuhn length-scale. Upon quenching, the nucleation of small crystallites was found to occur preferentially within these domains. This behavior is at odds with classical nucleation theory, wherein it is typically assumed that nucleation occurs uniformly throughout the melt with equal rate. Comparisons are drawn between the simulation results and theories involving the formation of precursors that precede the formation of crystals.
Display omitted
•Strong flow fields create coexisting domains with different levels of local alignment.•Crystal nucleation preferentially occurs in highly-aligned domains.•The observed mechanism conflicts with classical nucleation theory.
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