26,939 research outputs found
Geopolitics and economic geography: A commentary on Andy Pikeâs geographical political economy
The geographical political economy (GPE) proposed by Andy Pike (2020. Coping with deindustrialization in the global North and South. International Journal of Urban Sciences, 1â22. https://doi.org/10.1080/12265934.2020.1730225) and his colleagues offers room for a better understanding of the interaction between politics and industrialization of a region. In this commentary, we argue that the political dimension of GPE should be further emphasized and geopolitics should be taken more seriously. Incorporation of geopolitics can improve GPE in two ways: First, it will help GPE capture variegated pathways and institutions of regional economies, which in turn can help reduce the Anglo-American bias in GPE and economic geography. Secondly, attention to geopolitics is a way to achieve a multi-scalar understanding of the regional economy because geopolitical actions at international scale influences what happnes at national and local scales. With examples from East Asia, where the effects of geopolitics are highly visible, we claim there are at least three ways that geopolitics influence regional industrialization. First, geopolitics change the global economy, which can subsequently predispose regional industrialization; second, a superpowerâs geopolitical strategy influences its international economic policy, which can afterwards predispose other nationsâ regional industrialization; lastly, a national state sets a geopolitical strategy which then determines regional policy within the nationâs territory
Temporal expectancies driven by self- and externally generated rhythms
The dynamic attending theory proposes that rhythms entrain periodic fluctuations of attention which modulate the gain of sensory input. However, temporal expectancies can also be driven by the mere passage of time (foreperiod effect). It is currently unknown how these two types of temporal expectancy relate to each other, i.e. whether they work in parallel and have distinguishable neural signatures. The current research addresses this issue. Participants either tapped a 1Hz rhythm (active task) or were passively presented with the same rhythm using tactile stimulators (passive task). Based on this rhythm an auditory target was then presented early, in synchrony, or late. Behavioural results were in line with the dynamic attending theory as RTs were faster for in- compared to out-of-synchrony targets. Electrophysiological results suggested self-generated and externally induced rhythms to entrain neural oscillations in the delta frequency band. Auditory ERPs showed evidence of two distinct temporal expectancy processes. Both tasks demonstrated a pattern which followed a linear foreperiod effect. In the active task, however, we also observed an ERP effect consistent with the dynamic attending theory. This study shows that temporal expectancies generated by a rhythm and expectancy generated by the mere passage of time can work in parallel and sheds light on how these mechanisms are implemented in the brain
Novel Pressure Induced Structural Phase Transition in AgSbTe
We report a novel high pressure structural sequence for the functionally
graded thermoelectric, narrow band gap semiconductor AgSbTe, using angle
dispersive x-ray diffraction in a diamond anvil cell with synchrotron radiation
at room temperature. The compound undergoes a B1 to B2 transition; the
transition proceeds through an intermediate amorphous phase found between 17-26
GPa that is quenchable down to ambient conditions. The pressure induced
structural transition observed in this compound is the first of its type
reported in this ternary cubic family, and it is new for the B1-B2 transition
pathway reported to date. Density Functional Theory (DFT) calculations
performed for the B1 and B2 phases are in good agreement with the experimental
results.Comment: 4 pages, 3 figure
Integrability of a disordered Heisenberg spin-1/2 chain
We investigate how the transition from integrability to nonintegrability
occurs by changing the parameters of the Hamiltonian of a Heisenberg spin-1/2
chain with defects. Randomly distributed defects may lead to quantum chaos. A
similar behavior is obtained in the presence of a single defect out of the
edges of the chain, suggesting that randomness is not the cause of chaos in
these systems, but the mere presence of a defect.Comment: 4 pages, 4 figure
Counting fermionic zero modes on M5 with fluxes
We study the Dirac equation on an M5 brane wrapped on a divisor in a
Calabi--Yau fourfold in the presence of background flux. We reduce the
computation of the normal bundle U(1) anomaly to counting the solutions of a
finite--dimensional linear system on cohomology. This system depends on the
choice of flux. In an example, we find that the presence of flux changes the
anomaly and allows instanton corrections to the superpotential which would
otherwise be absent.Comment: 14 pages. v2: reference added, typos corrected, few change
Continuous-Variable Spatial Entanglement for Bright Optical Beams
A light beam is said to be position squeezed if its position can be
determined to an accuracy beyond the standard quantum limit. We identify the
position and momentum observables for bright optical beams and show that
position and momentum entanglement can be generated by interfering two
position, or momentum, squeezed beams on a beam splitter. The position and
momentum measurements of these beams can be performed using a homodyne detector
with local oscillator of an appropriate transverse beam profile. We compare
this form of spatial entanglement with split detection-based spatial
entanglement.Comment: 7 pages, 3 figures, submitted to PR
Genetic variants in ARID5B and CEBPE are childhood ALL susceptibility loci in Hispanics.
Recent genome-wide studies conducted in European Whites have identified novel susceptibility genes for childhood acute lymphoblastic leukemia (ALL). We sought to examine whether these loci are susceptibility genes among Hispanics, whose reported incidence of childhood ALL is the highest of all ethnic groups in California, and whether their effects differ between Hispanics and non-Hispanic Whites (NHWs). We genotyped 13 variants in these genes among 706 Hispanic (300 cases, 406 controls) and 594 NHW (225 cases, 369 controls) participants in a matched population-based case-control study in California. We found significant associations for the five studied ARID5B variants in both Hispanics (p values of 1.0 Ă 10(-9) to 0.004) and NHWs (p values of 2.2 Ă 10(-6) to 0.018). Risk estimates were in the same direction in both groups (ORs of 1.53-1.99 and 1.37-1.84, respectively) and strengthened when restricted to B-cell precursor high-hyperdiploid ALL (>50 chromosomes; ORs of 2.21-3.22 and 1.67-2.71, respectively). Similar results were observed for the single CEBPE variant. Hispanics and NHWs exhibited different susceptibility loci at CDKN2A. Although IKZF1 loci showed significant susceptibility effects among NHWs (p < 1 Ă 10(-5)), their effects among Hispanics were in the same direction but nonsignificant, despite similar minor allele frequencies. Future studies should examine whether the observed effects vary by environmental, immunological, or lifestyle factors
Nonmagnetic impurity perturbation to the quasi-two-dimensional quantum helimagnet LiCu2O2
A complete phase diagram of Zn substituted quantum quasi-two-dimensional
helimagnet LiCu2O2 has been presented. Helical ordering transition temperature
(T_h) of the original LiCu2O2 follows finite size scaling for less than ~ 5.5%
Zn substitution, which implies the existence of finite helimagnetic domains
with domain boundaries formed with nearly isolated spins. Higher Zn
substitution > 5.5% quenches the long-range helical ordering and introduces an
intriguing Zn level dependent magnetic phase transition with slight thermal
hysteresis and a universal quadratic field dependence for T_c (Zn > 0.055,H).
The magnetic coupling constants of nearest-neighbor (nn) J1 and
next-nearest-neighbor (nnn) J2 (alpha=J2/J1) are extracted from high
temperature series expansion (HTSE) fitting and N=16 finite chain exact
diagonalization simulation. We have also provided evidence of direct
correlation between long-range helical spin ordering and the magnitude of
electric polarization in this spin driven multiferroic material
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