2,817 research outputs found
Economic Possibilities of Shipping though Northern Sea Route1
AbstractGlobal warming and climate change haves brought a new issue in the Arctic sea. Therefore, we can now explore new shipping routes through the Arctic Ocean instead of the existing commercial route. In particular, the Northern Sea Route (NSR) is one of the feasible shipping routes and, has provided tremendous shipping benefits. If the NSR becomes commercialized, we will be able to save about 5,000 nautical miles in distance and sailing time. In this study, we will emphasize some of the important results on the possibility of commercializing the shipping route in the Arctic. The NSR may bring positive economic effects in terms of shipping distance and time. For example, when utilizing the NSR, the maximum cargo traffic between Asia and Europe is expected to be around 46 million TEU. However, we also need to consider an expensive passage fee that is currently imposed by Russia. In conclusion, we maintain our efforts to protect the environment in the Arctic, in terms of logistics, and we need to explore every possible avenue to bring possible economic benefits to the North Pacific countries
Putative cell adhesion membrane protein Vstm5 regulates neuronal morphology and migration in the central nervous system
During brain development, dynamic changes in neuronal membranes perform critical roles in neuronal morphogenesis and migration to create functional neural circuits. Among the proteins that induce membrane dynamics, cell adhesion molecules are important in neuronal membrane plasticity. Here, we report that V-set and transmembrane domain-containing protein 5 (Vstm5), a cell-adhesion-like molecule belonging to the Ig superfamily, was found in mouse brain. Knock-down of Vstm5 in cultured hippocampal neurons markedly reduced the complexity of dendritic structures, as well as the number of dendritic filopodia. Vstm5 also regulates neuronal morphology by promoting dendritic protrusions that later develop into dendritic spines. Using electroporationin utero, we found that Vstm5 overexpression delayed neuronal migration and induced multiple branches in leading processes during corticogenesis. These results indicate that Vstm5 is a new cell-adhesion-like molecule and is critically involved in synaptogenesis and corticogenesis by promoting neuronal membrane dynamics.SIGNIFICANCE STATEMENTNeuronal migration and morphogenesis play critical roles in brain development and function. In this study, we demonstrate for the first time that V-set and transmembrane domain-containing protein 5 (Vstm5), a putative cell adhesion membrane protein, modulates both the position and complexity of central neurons by altering their membrane morphology and dynamics. Vstm5 is also one of the target genes responsible for variations in patient responses to treatments for major depressive disorder. Our results provide the first evidence that Vstm5 is a novel factor involved in the modulation of the neuronal membrane and a critical element in normal neural circuit formation during mammalian brain development.</jats:p
Motif Dynamics in Signed Directional Complex Networks
Complex networks evolve and vary their structure as time goes by. In
particular, the links in those networks have both a sign and a directionality.
To understand their structural principles, we measure the network motifs, which
are patterns that appear much more than one would expect in randomized
networks, considering both link properties. We propose motif dynamics, which is
a study to investigate the change in the number of motifs, and applied the
motif dynamics to an open evolving network model and empirical data. We confirm
that a non-cyclic motif has a greater correlation with the system size than a
cyclic structural motif. Furthermore, the motif dynamics can give us insight
into the friendship between freshmen in a university
Exploring the relationship between the spatial distribution of roads and universal pattern of travel-route efficiency in urban road networks
Urban road networks are well known to have universal characteristics and
scale-invariant patterns, despite the different geographical and historical
environments of cities. Previous studies on universal characteristics of the
urban road networks mostly have paid attention to their network properties but
often ignored the spatial networked structures. To fill the research gap, we
explore the underlying spatial patterns of road networks. In doing so, we
inspect the travel-route efficiency in a given road network across 70 global
cities which provides information on the usage pattern and functionality of the
road structure. The efficiency is quantified by the detour patterns of the
travel routes, estimated by the detour index (DI). The DI is a long-standing
popular measure, but its spatiality has been barely considered so far. In this
study, we probe the behavior of DI with respect to spatial variables by
scanning the network radially from a city center. Through empirical analysis,
we first discover universal properties in DI throughout most cities, which are
summarized as a constant behavior of DI regardless of the radial position from
a city center and clear collapse into a single curve for DIs for various radii
with respect to the angular distance. Especially, the latter enables us to know
the scaling factor in the length scale. We also reveal that the core-periphery
spatial structure of the roads induces the universal pattern, which is
supported by an artificial road network model. Furthermore, we visualize the
spatial DI pattern on the city map to figure out the city-specific
characteristics. The most and least efficient connections of several
representative cities show the potential for practical implications in
analyzing individual cities.Comment: 11 pages, 6 figure
Dual quadratic differentials and entire minimal graphs in Heisenberg space
We define holomorphic quadratic differentials for spacelike surfaces with
constant mean curvature in the Lorentzian homogeneous spaces
with isometry group of dimension 4, which are dual to
the Abresch-Rosenberg differentials in the Riemannian counterparts
, and obtain some consequences. On the one hand, we
give a very short proof of the Bernstein problem in Heisenberg space, and
provide a geometric description of the family of entire graphs sharing the same
differential in terms of a 2-parameter conformal deformation. On the other
hand, we prove that entire minimal graphs in Heisenberg space have negative
Gauss curvature.Comment: 19 page
Effectiveness of vaccination and quarantine policies to curb the spread of COVID-19
A pandemic, the worldwide spread of a disease, can threaten human beings from
the social as well as biological perspectives and paralyze existing living
habits. To stave off the more devastating disaster and return to a normal life,
people make tremendous efforts at multiscale levels from individual to
worldwide: paying attention to hand hygiene, developing social policies such as
wearing masks, social distancing, quarantine, and inventing vaccines and
remedy. Regarding the current severe pandemic, namely the coronavirus disease
2019, we explore the spreading-suppression effect when adopting the
aforementioned efforts. Especially the quarantine and vaccination are
considered since they are representative primary treatments for block spreading
and prevention at the government level. We establish a compartment model
consisting of susceptible (S), vaccination (V), exposed (E), infected (I),
quarantined (Q), and recovered (R) compartments, called SVEIQR model. We look
into the infected cases in Seoul and consider three kinds of vaccines, Pfizer,
Moderna, and AstraZeneca. The values of the relevant parameters are obtained
from empirical data from Seoul and clinical data for vaccines and estimated by
Bayesian inference. After confirming that our SVEIQR model is plausible, we
test the various scenarios by adjusting the associated parameters with the
quarantine and vaccination policies around the current values. The quantitative
result obtained from our model could suggest a guideline for policy making on
effective vaccination and social policies.Comment: 8 pages, 5 figure
The Spitzer c2d Survey of Nearby Dense Cores. V. Discovery of a VeLLO in the "Starless" Dense Core L328
This paper reports the discovery of a Very Low Luminosity Object (VeLLO) in
the "starless" dense core L328, using the Spitzer Space Telescope and ground
based observations from near-infrared to millimeter wavelengths. The Spitzer 8
micron image indicates that L328 consists of three subcores of which the
smallest one may harbor a source, L328-IRS while two other subcores remain
starless. L328-IRS is a Class 0 protostar according to its bolometric
temperature (44 K) and the high fraction ~72 % of its luminosity emitted at
sub-millimeter wavelengths. Its inferred "internal luminosity" (0.04 - 0.06
Lsun) using a radiative transfer model under the most plausible assumption of
its distance as 200 pc is much fainter than for a typical protostar, and even
fainter than other VeLLOs studied previously. Note, however, that its inferred
luminosity may be uncertain by a factor of 2-3 if we consider two extreme
values of the distance of L328-IRS (125 or 310 pc). Low angular resolution
observations of CO do not show any clear evidence of a molecular outflow
activity. But broad line widths toward L328, and Spitzer and near-infrared
images showing nebulosity possibly tracing an outflow cavity, strongly suggest
the existence of outflow activity. Provided that an envelope of at most ~0.1
Msunis the only mass accretion reservoir for L328-IRS, and the star formation
efficiency is close to the canonical value ~30%, L328-IRS has not yet accreted
more than 0.05 Msun. At the assumed distance of 200 pc, L328-IRS is destined to
be a brown dwarf.Comment: 29 pages, 8 figures, 1 table, to be published in Astrophysical
Journa
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