Possible quantum phase-manipulation of a two-leg ladder in mixed-dimensional fermionic cold atoms

The recent realization of mixed-dimensional systems of cold atoms has attracted much attention from both experimentalists and theorists. Different effective interactions and novel correlated quantum many-body phases may be engineered in these systems, with the different phases being tunable via external parameters. In this article we investigate a two-species Fermi atom mixture: one species of atom exists in two hyperfine states and is confined to move in a two-leg ladder, interacting with an on-site interaction, and the other moves freely in a two dimensional square lattice that contains the two-leg ladder. The two species of atoms interact via an on-site interaction on the ladder. In the limit of weak inter-species interactions, the two-dimensional gas can be integrated out, leading to an effective long-range mediated interaction in the ladder, generated by to the on-site inter-species interaction. We show that the form of the mediated interaction can be controlled by the density of the two-dimensional gas and that it enhances the charge density wave instability in the two-leg ladder after the renormalization group transformation. Parameterizing the phase diagram with various experimentally controllable quantities, we discuss the possible tuning of the macroscopic quantum many-body phases of the two-leg ladder in this mixed-dimensional fermionic cold atom system.Comment: 4 pages and 3 figure

Disagreement and the rationality of religious belief

Concerning religious matters there are a wide variety of views held that are often contradictory. This observation creates a problem when it comes to thinking about the rationality of religious belief. Can religious belief be rational for those who are aware of this widespread disagreement? This is a problem for a view in religious epistemology known as reformed epistemology. Alvin Plantinga, one of the leading defenders of this view, has argued that there is no successful argument to show that religious belief is irrational or in any other way epistemically unacceptable – he calls these arguments de jure arguments. I respond to this claim by seeking to develop two new versions of de jure argument that Plantinga has not dealt with. The first of these I call the return of the Great Pumpkin; and the second, the problem of religious disagreement. The return of the Great Pumpkin is an objection that develops an earlier objection that Plantinga has considered called, simply, the Great Pumpkin objection. This objection is that Plantinga’s methodology for defending the rationality of religious belief could be adopted by anyone, no matter how strange their beliefs – even someone who believed in the Great Pumpkin could use it. I develop this objection further by showing that it would be possible for a person with clearly absurd beliefs to find themselves in the same situation as the hypothetical Christian whom Plantinga is seeking to defend. There is, however, a response available to Plantinga, which involves showing how the historical and sociological context in which the person finds themselves makes a difference to the rationality of some of the beliefs that they hold. This discussion naturally leads into the second version of the de jure argument which asks whether knowledge of several religious communities who hold incompatible beliefs undermines the rationality of religious belief. This discussion engages with work in religious epistemology, but also more widely with the literature on the epistemology of disagreement. I consider whether, and in what circumstances, finding out that others disagree with you could ever rationally require you to give up one or more of your beliefs. This issue involves discussion of epistemic peers and defeaters. One of the arguments I consider is that if a religious believer continues to hold on to her religious beliefs in the face of disagreement then that will give her a reason to think that she is epistemically superior, which will lead to dogmatism, and a sort of epistemic arrogance. I respond to such an argument by showing that there is a problem with the inference involved in this argument

The Case for Personal Interaction: Drop-Off/Pick-Up Methodology for Survey Research

Researchers have struggled with decreases in response rates in surveys using traditional methods. Dropoff/pick-up (DOPU) surveys are an alternative that performs well in some research situations. For studies in small or compact geographic areas, DOPU has achieved higher response rates than mail surveys, although typically at higher costs due to labor and transportation. Other benefits include increased local awareness of research projects and improved outcomes for complex survey projects. Social exchange theory would explain the success of DOPU as due to the method’s personal interaction. Many researchers are unfamiliar with DOPU and prior instructive works are now dated. In an attempt to provide survey researchers another methodological tool, we review prior instructive works, comparative research on the method, and studies using DOPU for data collection. Applying social exchange theory to a synthesis of these prior works, we propose recommended practices for using DOPU and illustrate these with our own experiences

The role of index trading in price formation in the grains and oilseeds markets

We use both Granger-causality and instrumental variables (IV) methods to examine the impact of index fund positions on price returns for the main US grains and oilseed futures markets. Our analysis supports earlier conclusions that Granger-causal impacts are generally not discernible. However, market microstructure theory suggests trading impacts should be instantaneous. IV-based tests for contemporaneous causality provide stronger evidence of price impact. We find even stronger evidence that changes in index positions can help predict future changes in aggregate commodity price indices. This result suggests that changes in index investment are in part driven by information which predicts commodity price changes over the coming months

Orbits of Globular Clusters in the Outer Galaxy: NGC 7006

We present a proper motion study of the distant globular cluster NGC 7006 based on the measurement of 25 photographic plates spanning a 40-year interval. The absolute proper motion determined with respect to extragalactic objects is (-0.96, -1.14) +- (0.35, 0.40) mas/yr. The total space velocity of NGC 7006 in a Galactocentric rest frame is 279 km/s, placing the cluster on one of the most energetic orbits (Ra =102 kpc) known to date for clusters within 40-kpc from the Galactic center. We compare the orbits of four clusters that have apocentric radii larger than 80 kpc (NGC 5466, NGC 6934, NGC 7006 and Pal 13) with those of Galactic satellites with well-measured proper motions. These clusters have orbits that are highly eccentric and of various inclinations with respect to the Galactic plane. In contrast, the orbits of the Galactic satellites are of low to moderate eccentricity and highly inclined. Based on orbit types, chemical abundances and cluster parameters, we discuss the properties of the hypothetical host systems of the remote globular clusters in the Searle-Zinn paradigm. It is apparent that clusters such as NGC 5466, NGC 6934 and NGC 7006 formed in systems that more likely resemble the Fornax dSph, rather than the Sagittarius dSph. We also discuss plausible causes for the difference found so far between the orbit type of outer halo clusters and that of Galactic satellites and for the tentative, yet suggestive phase-space scatter found among outer halo clusters.Comment: 27 pages, 5 figures, to be published in the Astronomical Journa

Optimal experience and personal growth. Flow and the consolidation of place identity

This study examined the relationship between flow experience and place identity, based on eudaimonistic identity theory (EIT) which prioritizes self-defining activities as important for an individual's identification of his/her goals, values, beliefs, and interests corresponding to one's own identity development or enhancement. This study focuses on place identity, the identity's features relating to a person's relation with her/his place. The study is also based on flow theory, according to which some salient features of an activity experience are important for happiness and well-being. Questionnaire surveys on Italian and Greek residents focused on their perceived flow and place identity in relation to their own specific local place experiences. The overall findings revealed that flow experience occurring in one's own preferred place is widely reported as resulting from a range of self-defining activities, irrespective of gender or age, and it is positively and significantly associated with one's own place identity. Such findings provide the first quantitative evidence about the link between flow experienced during meaningfully located self-defining activities and identity experienced at the place level, similarly to the corresponding personal and social levels that had been previously already empirically tested. Results are also discussed in terms of their implications for EIT's understanding and enrichment, especially by its generalization from the traditional, personal identity level up to that of place identity. More generally, this study has implications for maintaining or enhancing one's own place identity, and therefore people place relations, by means of facilitating a person's flow experience within psychologically meaningful place

Embedded, micro-interdigitated flow fields in high areal-loading intercalation electrodes towards seawater desalination and beyond

Faradaic deionization (FDI) is a promising technology for energy-efficient water desalination using porous electrodes containing redox-active materials. Herein, we demonstrate for the first time the capability of a symmetric FDI flow cell to produce freshwater (<17.1 mM NaCl) from concentrated brackish water (118mM), to produce effluent near freshwater salinity (19.1 mM) from influent with seawater-level salinity (496 mM), and to reduce the salinity of hypersaline brine from 781 mM to 227 mM. These remarkable salt-removal levels were enabled by using flow-through electrodes with high areal-loading of nickel hexacyanoferrate (NiHCF) Prussian Blue analogue intercalation material. The pumping energy consumption due to flow-through electrodes was mitigated by embedding an interdigitated array of <100 $\mu$m wide channels in the electrodes using laser micromachining. The micron-scale dimensions of the resulting embedded, micro-interdigitated flow fields (e$\mu$-IDFFs) facilitate flow-through electrodes with high apparent permeability while minimizing active-material loss. Our modeling shows that these e$\mu$-IDFFs are more suitable for our intercalation electrodes because they have >100X lower permeability compared to common redox-flow battery electrodes, for which millimetric flow-channel widths were used exclusively in the past. Total desalination thermodynamic energy efficiency (TEE) was improved by more than ten-fold relative to unpatterned electrodes: 40.0% TEE for brackish water, 11.7% TEE for hypersaline brine, and 7.4% TEE for seawater-salinity feeds. Water transport between diluate and brine streams and charge efficiency losses resulting from (electro)chemical effects are implicated as limiting energy efficiency and water recovery, motivating their investigation for enhancing future FDI performance.Comment: 70 pages, 23 figures. Energy Environ. Sci. (2023