We propose a new model of Earth's bulk composition based on enstatite chondrites (E-chondrites), the only chondrite group isotopically identical to the Earth. This model allows a quantitative study ...of accretion and differentiation processes in the early Earth. Conditions for core formation are evaluated using data on silica–iron equilibrium at high pressure and temperature and the exchange budget equation SiO2+2Fe=Si+2FeO, which is the result of IW and Si–SiO2 oxygen buffers' interaction and controls the evolution of mantle fO2. Based on that equation, ranges for the compositions of the Bulk Silicate Earth, the lower mantle and the core are deduced from the compositions of E-chondrites and their constituents. For these ranges of compositions, we show that during core differentiation, the mantle fO2 evolves naturally from ≈IW-3.2 to IW-1.4±0.1. The model compositions are tightened using geophysical constraints on (1) the amount of light elements in the core, (2) the petrology of the upper and lower mantle and (3) the thermal and convective structure of the lower mantle. Our results indicate that the lower mantle is enriched in Si and Fe, which is consistent with recent geophysical studies, and depleted in highly refractory elements, notably in Uranium and Thorium.
How will research respond to a changing regulatory space?
Large sets of health data can enable innovation and quality measurement but can also create technical challenges and privacy risks. When ...entities such as health plans and health care providers handle personal health information, they are often subject to data privacy regulation. But amid a flood of new forms of health data, some third parties have figured out ways to avoid some data privacy laws, developing what we call “shadow health records”—collections of health data outside the health system that provide detailed pictures of individual health—that allow both innovative research and commercial targeting despite data privacy rules. Now that space for regulatory arbitrage is changing. The long arms of Europe's new General Data Protection Regulation (GDPR) and California's new Consumer Privacy Act (CCPA) will reach shadow health records in many companies. In this article, we lay out the contours of the GDPR's and CCPA's impact on shadow health records and health data more broadly, highlight critical remaining uncertainty, and call for increased clarity from lawmakers and industry on the use of such data for research.
THE RIGHT TO CONTEST AI Kaminski, Margot E.; Urban, Jennifer M.
Columbia law review,
11/2021, Letnik:
121, Številka:
7
Journal Article
Recenzirano
Artificial intelligence (AI) is increasingly used to make important decisions, from university admissions selections to loan determinations to the distribution of COVID-19 vaccines. These uses of AI ...raise a host of concerns about discrimination, accuracy, fairness, and accountability.
In the United States, recent proposals for regulating AI focus largely on ex ante and systemic governance. This Article argues instead—or really, in addition—for an individual right to contest AI decisions, modeled on due process but adapted for the digital age. The European Union, in fact, recognizes such a right, and a growing number of institutions around the world now call for its establishment. This Article argues that despite considerable differences between the United States and other countries, establishing the right to contest AI decisions here would be in keeping with a long tradition of due process theory.
This Article then fills a gap in the literature, establishing a theoretical scaffolding for discussing what a right to contest should look like in practice. This Article establishes four contestation archetypes that should serve as the bases of discussions of contestation both for the right to contest AI and in other policy contexts. The contestation archetypes vary along two axes: from contestation rules to standards and from emphasizing procedure to establishing substantive rights. This Article then discusses four processes that illustrate these archetypes in practice, including the first indepth consideration of the GDPR’s right to contestation for a U.S. audience. Finally, this Article integrates findings from these investigations to develop normative and practical guidance for establishing a right to contest AI.
Turbulent jets and plumes are commonly encountered in industrial and natural environments; they are, for example, key processes during explosive eruptions. They have been the objects of seminal works ...on turbulent free shear flows. Their dynamics is often described with the concept of the so-called entrainment coefficient,
$\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\alpha $
, which quantifies entrainment of ambient fluid into the turbulent flow. This key parameter is well characterized for axisymmetric jets and plumes, but data are scarcer for turbulent planar plumes and jets. The data tend to show that the Gaussian entrainment coefficient in plane pure plumes is about twice the value for plane pure jets. In order to confirm and to explain this difference, we develop a model of entrainment in turbulent plane jets and plumes taking into account the effect of buoyancy on entrainment, as a function of the shape of the velocity, buoyancy and turbulent shear stress profiles. We perform new experiments to better characterize the rate of entrainment in plane pure plumes and to constrain the values of the model parameters. Comparison between theory and experiments shows that the enhancement of entrainment in plane turbulent pure plumes relative to plane turbulent pure jets is well explained by the contribution of buoyancy.
In approximately one fourth of worldwide subduction zones, seismic observations indicate a rotation from trench‐normal to trench‐parallel fast axis orientations in the mantle wedge. To interpret this ...observation we predict the evolution of crystal lattice preferred orientation in mantle wedge material as a function of the amount of water by using a model of polycrystal deformation (D‐Rex) coupled with an analytical corner flow. The resulting seismic signature is obtained from synthetic seismic wave propagation through this mantle wedge. We identify that progressive hydration produces the rotation of fast axis orientations and can generate between the two zones of trench‐parallel and trench‐normal fast axis orientations a morph zone with very small anisotropy and a related decrease in P and S wave velocities. Such a morph zone is not produced by trench‐parallel flow, hence this signature can be used to detect water in the mantle wedge.
Plain Language Summary
A subduction zone's mantle wedge can have a complex pattern of seismic anisotropy where the fast direction often rotates from trench‐parallel close to the trench to trench‐normal in the backarc. This pattern can be interpreted as induced by either 3‐D trench‐parallel flow or by the presence of water close to the trench. Almost all models so far favored the trench‐parallel flow hypothesis, usually based on indirect or complementary indicators such as the evolution of geochemical signatures of volcanoes along the arc. Here we examine a seismic anisotropy observational signature that can be used to discriminate between the two explanations. The concept is defined using an interdisciplinary approach linking a direct modeling of the flow in the subduction wedge and a computation of seismic wave propagation in anisotropic media. We define a unique water‐induced signature that is the presence of a “morph zone” characterized by a weak anisotropy and a decrease of seismic velocities. We apply the model to the Lau Basin where we find this predicted signature, demonstrating for the first time that water rather than trench‐parallel flow is responsible for the observed anisotropy pattern there.
Key Points
Development of trench‐parallel anisotropy in a mantle wedge is modeled using a model of crystals deformation and dynamic recrystallization
Progressive hydration toward the trench produces a “morph zone” with a weak anisotropy and a decrease of VP and VS
Applied to the Lau Basin the model shows that water rather than trench‐parallel flow explain the evolution of seismic anisotropy there
University scientists conducting research on topics of potential health concern often want to partner with a range of actors, including government entities, non-governmental organizations, and ...private enterprises. Such partnerships can provide access to needed resources, including funding. However, those who observe the results of such partnerships may judge those results based on who is involved. This set of studies seeks to assess how people perceive two hypothetical health science research collaborations. In doing so, it also tests the utility of using procedural justice concepts to assess perceptions of research legitimacy as a theoretical way to investigate conflict of interest perceptions. Findings show that including an industry collaborator has clear negative repercussions for how people see a research partnership and that these perceptions shape people's willingness to see the research as a legitimate source of knowledge. Additional research aimed at further communicating procedures that might mitigate the impact of industry collaboration is suggested.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Skill increase in motor performance can be defined as explicitly measuring task success but also via more implicit measures of movement kinematics. Even though these measures are often related, there ...is evidence that they represent distinct concepts of learning. In the present study, the effect of multiple tDCS-sessions on both explicit and implicit measures of learning are investigated in a pointing task in 30 young adults (YA) between 27.07 ± 3.8 years and 30 old adults (OA) between 67.97 years ± 5.3 years. We hypothesized, that OA would show slower explicit skill learning indicated by higher movement times/lower accuracy and slower implicit learning indicated by higher spatial variability but profit more from anodal tDCS compared with YA. We found age-related differences in movement time but not in accuracy or spatial variability. TDCS did not skill learning facilitate learning neither in explicit nor implicit parameters. However, contrary to our hypotheses, we found tDCS-associated higher accuracy only in YA but not in spatial variability. Taken together, our data shows limited overlapping of tDCS effects in explicit and implicit skill parameters. Furthermore, it supports the assumption that tDCS is capable of producing a performance-enhancing brain state at least for explicit skill acquisition.
The toxicity of dietary E 171, a food grade titanium dioxide was evaluated. A recent study reported rats receiving E 171 in water developed inflammation and aberrant crypt foci (ACF) in the ...gastrointestinal tract. Here, rats received food containing E 171 (7 or 100 days). The 100-day study included feeding E 171 after dimethylhydrazine (DMH) or vehicle only pretreatment. Food consumption was similar between treatment groups with maximum total cumulative E 171 exposure being 2617 mg/kg in 7 days and 29,400 mg/kg in 100 days. No differences were observed due to E 171 in the percentage of dendritic, CD4+ T or Treg cells within Peyer's patches or the periphery, or in cytokine production in plasma, sections of jejunum, and colon in 7- or 100-day E 171 alone fed rats. Differences were observed for IL-17A in colon (400 ppm E 171 + DMH) and IL-12p70 in plasma (40 ppm E 171 + DMH). E 171 had no effect on histopathologic evaluations of small and large intestines, liver, spleen, lungs, or testes, and no effects on ACF, goblet cell numbers, or colonic gland length. Dietary E 171 administration (7- or 100-day), even at high doses, produced no effect on the immune parameters or tissue morphology.
•Dietary E 171 did not change immune cell profile in Peyer's patches or peripherally.•Dietary E 171 did not alter inflammatory cytokine profile in GI tract or circulation.•Dietary E 171 did not increase colonic proliferative lesions.•Dietary E 171 did not induce histopathologic changes in small and large intestine, liver, spleen, lungs, or testes.
The germinal center response or reaction (GCR) is a hallmark event of adaptive humoral immunity. Unfolding in the B cell follicles of the secondary lymphoid organs, a GC culminates in the production ...of high-affinity antibody-secreting plasma cells along with memory B cells. By interacting with follicular dendritic cells (FDC) and T follicular helper (Tfh) cells, GC B cells exhibit complex spatiotemporal dynamics. Driving the B cell dynamics are the intracellular signal transduction and gene regulatory network that responds to cell surface signaling molecules, cytokines, and chemokines. As our knowledge of the GC continues to expand in depth and in scope, mathematical modeling has become an important tool to help disentangle the intricacy of the GCR and inform novel mechanistic and clinical insights. While the GC has been modeled at different granularities, a multiscale spatial simulation framework – integrating molecular, cellular, and tissue-level responses – is still rare. Here, we report our recent progress toward this end with a hybrid stochastic GC framework developed on the Cellular Potts Model-based CompuCell3D platform. Tellurium is used to simulate the B cell intracellular molecular network comprising NF-κB, FOXO1, MYC, AP4, CXCR4, and BLIMP1 that responds to B cell receptor (BCR) and CD40-mediated signaling. The molecular outputs of the network drive the spatiotemporal behaviors of B cells, including cyclic migration between the dark zone (DZ) and light zone (LZ) via chemotaxis; clonal proliferative bursts, somatic hypermutation, and DNA damage-induced apoptosis in the DZ; and positive selection, apoptosis via a death timer, and emergence of plasma cells in the LZ. Our simulations are able to recapitulate key molecular, cellular, and morphological GC events, including B cell population growth, affinity maturation, and clonal dominance. This novel modeling framework provides an open-source, customizable, and multiscale virtual GC simulation platform that enables qualitative and quantitative in silico investigations of a range of mechanistic and applied research questions on the adaptive humoral immune response in the future.
The maximum height reached by a turbulent plume rising in a stratified environment is a key tool to estimate the flux released at its source, particularly for large‐scale flows because flux can often ...be very hard to measure directly. This height is known to be mainly controlled by the stratification of the ambient fluid, source buoyancy flux, and the efficiency of turbulent mixing between the plume and the external fluid. The latter effect has been only superficially explored in spite of its fundamental control on the dynamics. Here we show that commonly used one‐dimensional models incorporating a constant entrainment coefficient do not provide satisfying predictions. We propose a new model allowing for variable entrainment which gives excellent predictions of maximum heights reached by laboratory plumes in stratified environments. We then apply our formalism to natural plumes produced by explosive volcanic eruptions under terrestrial, paleo‐Martian, and Venusian conditions and by submarine hydrothermal activity at mid‐ocean ridges. Source mass discharge rates deduced from maximum volcanic column heights for terrestrial eruptions are found to be greater than those estimated with the commonly used constant entrainment parameterization by a factor of 2. In the paleo‐Martian atmosphere, existing models overestimate plume heights by 14–27%. In the current atmosphere of Venus, the maximum height reached by a volcanic plume is also found to be smaller than previously estimated for large eruption rates. The source heat flux released by the TAG field (Atlantic Ocean) deduced from several submarine hydrothermal plumes is found greater by a factor 3 with our model.
PDF
