896 research outputs found
Asymptotic analysis of model selection criteria for general hidden Markov models
© 2020 Elsevier B.V. The paper obtains analytical results for the asymptotic properties of Model Selection Criteria – widely used in practice – for a general family of hidden Markov models (HMMs), thereby substantially extending the related theory beyond typical ‘i.i.d.-like’ model structures and filling in an important gap in the relevant literature. In particular, we look at the Bayesian and Akaike Information Criteria (BIC and AIC) and the model evidence. In the setting of nested classes of models, we prove that BIC and the evidence are strongly consistent for HMMs (under regularity conditions), whereas AIC is not weakly consistent. Numerical experiments support our theoretical results
Relaxing a constraint on the number of messengers in a low-scale gauge mediation
We propose a mechanism for relaxing a constraint on the number of messengers
in low-scale gauge mediation models. The Landau pole problem for the
standard-model gauge coupling constants in the low-scale gauge mediation can be
circumvented by using our mechanism. An essential ingredient is a large
positive anomalous dimension of messenger fields given by a large Yukawa
coupling in a conformal field theory at high energies. The positive anomalous
dimension reduces the contribution of the messengers to the beta function of
the standard-model gauge couplings.Comment: 22pages; v2:explanations expanded in sec.3.2, reference adde
Venture Capital in Japan: A Financial Instrument Supporting the Innovativeness of the Japanese Economy
Two factors: First, the relatively small number of new companies as well as the number of companies subject to liquidation over the year ("firm turnover") in Japan, and second, the insignificant prestige associated with the profession of entrepreneur do not foster growth in the dynamics of this form of financing ventures. The cited indicator for Japan in among the lowest in comparison with other highly developed countries1, while the profession of entrepreneur is not the foremost dream of college graduates. They would much rather prefer realizing their professional careers as members of the government bureaucracy or employees of a major corporation2. However, this mindset is slowly changing, if for no other reason then, in spite of popular conviction, because most small companies are not established during periods of prosperity, but near the end of the downward phase of the economic cycle. That is exactly the phase Japan has been dealing with for several years now. Young, creative people, recruited from the unemployed, are seeking self-employment, using all possible opportunities embedded in the "again starting up" machinery of the economy.Dwa czynniki: pierwszy - stosunkowo mała liczba nowych firm, a także firm likwidowanych w skali roku ("firm turnover") w Japonii oraz drugi - niewielki prestiż, jakim cieszy się zawód przedsiębiorcy, nie sprzyjają dynamizacji omawianej formy finansowania przedsięwzięć. Cytowany wskaźnik, dla Japonii należy do najniższych w porównaniu z innymi krajami wysoko rozwiniętymi (Grabowiecki 2000), zaś profesja przedsiębiorcy nie jest szczytem marzeń ludzi po studiach. Znacznie bardziej chcieliby oni swoją karierę zawodową realizować jako członkowie rządowej biurokracji lub pracownicy dużej korporacji (Corver 2008, s. 2). Ta świadomość ulega jednak stopniowej zmianie, chociażby dlatego, że wbrew popularnym przekonaniom, większość niewielkich przedsiębiorstw, powstaje nie w okresie prosperity, lecz pod koniec spadkowej fazy cyklu koniunkturalnego. Z taką fazą mamy do czynienia w Japonii od paru lat. Młodzi, kreatywni ludzie, rekrutujący się z bezrobotnych, poszukują samozatrudnienia, wykorzystują wszelakie szanse, tkwiące w "ruszającej na powrót" maszynerii gospodark (Yonekura, Lynskey 2003, s. 11)
Asymptotic Analysis of Model Selection Criteria for General Hidden Markov Models
The paper obtains analytical results for the asymptotic properties of Model
Selection Criteria -- widely used in practice -- for a general family of hidden
Markov models (HMMs), thereby substantially extending the related theory beyond
typical i.i.d.-like model structures and filling in an important gap in the
relevant literature. In particular, we look at the Bayesian and Akaike
Information Criteria (BIC and AIC) and the model evidence. In the setting of
nested classes of models, we prove that BIC and the evidence are strongly
consistent for HMMs (under regularity conditions), whereas AIC is not weakly
consistent. Numerical experiments support our theoretical results
Variant Supercurrents and Linearized Supergravity
In this paper the variant supercurrents based on consistency and completion
in off-shell N=1 supergravity are studied. We formulate the embedding relations
for supersymmetric current and energy tensor into supercurrent multiplet.
Corresponding linearized supergravity is obtained with appropriate choice of
Wess-Zumino gauge in each gravity supermultiplet.Comment: v1: 9 pp; v2: minor changes; v3: 10 pp, published versio
Mechanism of Cross-Species Prion Transmission An Infectious Conformation Compatible withTwo Highly Divergent Yeast Prion Proteins
SummaryEfficiency of interspecies prion transmission decreases as the primary structures of the infectious proteins diverge. Yet, a single prion protein can misfold into multiple infectious conformations, and such differences in “strain conformation” also alter infection specificity. Here, we explored the relationship between prion strains and species barriers by creating distinct synthetic prion forms of the yeast prion protein Sup35. We identified a strain conformation of Sup35 that allows transmission from the S. cerevisiae (Sc) Sup35 to the highly divergent C. albicans (Ca) Sup35 both in vivo and in vitro. Remarkably, cross-species transmission leads to a novel Ca strain that in turn can infect the Sc protein. Structural studies reveal strain-specific conformational differences in regions of the prion domain that are involved in intermolecular contacts. Our findings support a model whereby strain conformation is the critical determinant of cross-species prion transmission while primary structure affects transmission specificity by altering the spectrum of preferred amyloid conformations
ALS mutations in the TIA-1 prion-like domain trigger highly condensed pathogenic structures
筋萎縮性側索硬化症(ALS)の発症機構の一端を解明 --タンパク質の高密度な凝縮構造が鍵--. 京都大学プレスリリース. 2022-09-13.T cell intracellular antigen-1 (TIA-1) plays a central role in stress granule (SG) formation by self-assembly via the prion-like domain (PLD). In the TIA-1 PLD, amino acid mutations associated with neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) or Welander distal myopathy (WDM), have been identified. However, how these mutations affect PLD self-assembly properties has remained elusive. In this study, we uncovered the implicit pathogenic structures caused by the mutations. NMR analysis indicated that the dynamic structures of the PLD are synergistically determined by the physicochemical properties of amino acids in units of five residues. Molecular dynamics simulations and three-dimensional electron crystallography, together with biochemical assays, revealed that the WDM mutation E384K attenuated the sticky properties, whereas the ALS mutations P362L and A381T enhanced the self-assembly by inducing β-sheet interactions and highly condensed assembly, respectively. These results suggest that the P362L and A381T mutations increase the likelihood of irreversible amyloid fibrillization after phase-separated droplet formation, and this process may lead to pathogenicity
High-Mass Cloud Cores in the eta Carinae Giant Molecular Cloud
We carried out an unbiased survey for massive dense cores in the giant
molecular cloud associated with eta Carinae with the NANTEN telescope in 12CO,
13CO, and C18O 1-0 emission lines. We identified 15 C18O cores. Two of the 15
cores are associated with IRAS point sources whose luminosities are larger than
10^4 Lo, which indicates that massive star formation is occuring within these
cores. Five cores including the two with IRAS sources are associated with MSX
point sources. We detected H13CO+ (1-0) emission toward 4 C18O cores, one of
which is associated with neither IRAS nor MSX point sources. This core shows
the presence of a bipolar molecular outflow in 12CO (2-1), which indicates that
star formation is also occuring in the core. In total, six C18O cores out of 15
are experienced star formation, and at least 2 of 15 are massive-star forming
cores in the eta Car GMC. We found that massive star formation occurs
preferentially in cores with larger column density, mass, number density, and
smaller ratio of virial mass to LTE mass Mvir/M. We also found that the cores
in the eta Car GMC are characterized by large line width and Mvir/M on average
compared to the cores in other GMCs. We investigated the origin of a large
amount of turbulence in the eta Car GMC. We propose the possibility that the
large turbulence was pre-existing when the GMC was formed, and is now
dissipating. Mechanisms such as multiple supernova explosions in the Carina
flare supershell may have contributed to form a GMC with a large amount of
turbulence.Comment: 41 pages, including 11 fugures and 9 tables. Accepted by ApJ. Author
changed. Paper with high resolution figures is available at
http://astrol.cias.osakafu-u.ac.jp/~yonekura/work/paper/etaCar
On the Trace Anomaly and the Anomaly Puzzle in N=1 Pure Yang-Mills
The trace anomaly of the energy-momentum tensor is usually quoted in the form
which is proportional to the beta function of the theory. However, there are in
general many definitions of gauge couplings depending on renormalization
schemes, and hence many beta functions. In particular, N=1 supersymmetric pure
Yang-Mills has the holomorphic gauge coupling whose beta function is one-loop
exact, and the canonical gauge coupling whose beta function is given by the
Novikov-Shifman-Vainshtein-Zakharov beta function. In this paper, we study
which beta function should appear in the trace anomaly in N=1 pure Yang-Mills.
We calculate the trace anomaly by employing the N=4 regularization of N=1 pure
Yang-Mills. It is shown that the trace anomaly is given by one-loop exact form
if the composite operator appearing in the trace anomaly is renormalized in a
preferred way. This result gives the simplest resolution to the anomaly puzzle
in N=1 pure Yang-Mills. The most important point is to examine in which scheme
the quantum action principle is valid, which is crucial in the derivation of
the trace anomaly.Comment: 25 pages, 1 figure; v2:slight correction in sec.5, minor addition in
appendi
Extending the limits of globule detection -- ISOPHOT Serendipity Survey Observations of interstellar clouds
A faint MJysr bipolar globule was discovered with the
ISOPHOT 170 m Serendipity Survey (ISOSS). ISOSS J 20246+6541 is a cold
( K) FIR source without an IRAS pointsource counterpart.
In the Digitized Sky Survey B band it is seen as a 3\arcmin size bipolar
nebulosity with an average excess surface brightness of
mag/\arcsec . The CO column density distribution determined by
multi-isotopic, multi-level CO measurements with the IRAM-30m telescope agrees
well with the optical appearance. An average hydrogen column density of
cm was derived from both the FIR and CO data. Using a
kinematic distance estimate of 400 pc the NLTE modelling of the CO, HCO,
and CS measurements gives a peak density of cm. The
multiwavelength data characterise ISOSS 20246+6541 as a representative of a
class of globules which has not been discovered so far due to their small
angular size and low 100m brightness. A significant overabundance of
CO is found . This is likely due to
isotope selective chemical processes.Comment: 5 pages, 3 figure
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