Cosmic evolution of bars in simulations of galaxy formation

We investigate the evolution of two bars formed in fully self-consistent hydrodynamic simulations of the formation of Milky Way-mass galaxies. One galaxy shows higher central mass concentration and has a longer and stronger bar than the other at $z = 0$. The stronger bar evolves by transferring its angular momentum mainly to the dark halo. Consequently the rotation speed of the bar decreases with time, while the amplitude of the bar increases with time. These features qualitatively agree with the results obtained by idealized simulations. The pattern speed of the stronger bar largely goes up and down within a half revolution in its early evolutionary stage. These oscillations occur when the bar is misaligned with the $m = 4$ mode Fourier component. These oscillations correlate with the oscillations in the triaxilality of the dark matter halo, but differently from the way identified by idealized simulations. The amplitude of the weaker bar does not increase despite the fact that its rotation slows down with time.This result contradicts what is expected from idealized simulations and is caused by the decline of the central density associated with the mass loss and feedback from the stellar populations. The amplitude of the weaker bar is further weakens by the angular momentum injection by the interactions with stellar clumps in the disk. In the both galaxies, the bars are terminated around the 4:1 resonance.Comment: 17 pages, 18 figures, accepted for publication in PAS

Advanced high speed data and clock transmission over optical fibre for square kilometre telescope array

There is an ever present need from Internet users for more bandwidth. This is manifested by continuous increase in bandwidth demanding applications such as 5G wireless, new end user consumer links like thunderbolt, video conferencing, high definition video-on-demand transmitted over the Internet and massive data transfers required with and within data centres for backup, storage and data processing in cloud computing. Fibre optic communications technologies are playing a pivotal role in communication, being a major enabling technology in our increasingly Internet-centric society. As network services continue to become more dynamic and diverse, Internet service providers are faced with a challenge of cost reduction in the transmission network, power and spectral efficiency as well as scalability of the optical network infrastructure to support incremental expansions and virtual machines. Intelligent design of terrestrial optical networks to allow for simultaneous signal transmission through shared network infrastructure, and the use of low cost, power efficient, high bandwidth transmitters such as vertical surface emitting lasers (VCSELs) as well as exploitation of spectral efficient in-complex advanced modulation formats is a viable approach to this situation. In this study, techniques for spectral efficiency upgrade and simultaneous transmission of data signal, reference frequency (RF) clock signal and pulse-per-second (PPS) over shared infrastructure have experimentally been optimized in a laboratory environment for adoption in next-generation telescope array networks such as the Square Kilometre Array (SKA), time keeping systems such as banking systems, Coordinated Universal Time(UTC) timing and Global Positioning Systems (GPS), as well as high capacity spectral efficient short reach optical fibre networks such as data centres. This work starts by experimentally optimizing VCSEL technology for simultaneous transmission of 10 Gbps data and 1.712 GHz RF clock signal over a single G. 655 optical fibre of length 24.75 Km at different channel spacing and different propagation direction for implementation in a cost effective next-generation telescope array network. The wavelength tuneability property of VCSEL transmitters allows for wavelength adjustment, a key requirement for simultaneous data and RF clock signal transmission over a single optical fibre. A receiver sensitivity of -19.19 dBm was experimentally achieved at back-to-back analysis. A 24.75 Km of simultaneous data and RF clock signal transmission performed at 0.4 nm channel spacing introduced a transmission penalty of 1.07 dB and 1.63 dB for counter and co-propagation scheme respectively. This work mainly utilized direct modulation and direct detection using a positive intrinsic negative (PIN) due to its simplicity and cost effectiveness. A novel modulation technique for simultaneous data and polarization-based pulse-per-second timing clock signal transmission using a single VCSEL carrier is experimentally demonstrated. Two signal types, a directly modulated 10 Gbps data signal and a polarization-based pulse per second (PPS) clock signal are modulated onto a single mode 10 GHz bandwidth VCSEL carrier at 1310 nm. Spectral efficiency is maximized by exploiting the inherent orthogonal polarization switching of the xiv VCSEL with changing bias in transmission of the PPS signal. A 10 Gbps VCSEL transmission with PPS over 11 Km of G.652 fibre introduced a transmission penalty of 0.52 dB. The contribution of PPS clock signal to this penalty was found to be 0.08 dB. A technique for simultaneous directly modulated data and phase modulated reference clock signal transmission over a signal channel in wavelength division multiplexing (WDM) solutions is experimentally demonstrated. This is to prepare solutions to the ever-increasing demand over gigabit/s, terabit/s and gigahertz capacities in WDM-based terrestrial optical fibre transmission systems such as telescope array networks. a total capacity of 30 Gbps (310 Gbps) data and 12 GHz ( 4 3 GHz) reference clock signal are multiplexed at a channel spacing of 100 GHz and simultaneously transmitted over a single mode G.655 fibre of length 24.73 Km. The recovery of the phase modulated RF clock signal using a differential delay line interferometry technique is experimentally demonstrated. A 625 Gbps (2525 Gbps) DWDM data transmission system is further implemented in simulation by multiplexing 25 channels at 25 Gbps per channel using 50 GHz channel spacing. A four level pulse amplitude modulation (4-PAM) data modulation format employing VCSELs is experimentally demonstrated for adoption in high bitrate networks such as big data science projects and data centre networks. 4-PAM offers a good trade-off between complexity, efficiency, reach, and sensitivity. A software defined digital signal processing (DSP) receiver is designed and implemented in MATLAB to recover the transmitted 4-PAM data signal cost effectively without the necessity of costly receiver hardware. A novel technique for maximizing carrier spectral efficiency through simultaneous 20 Gbps 4-PAM data and phase modulated 2 GHz RF clock signal transmission on a single mode 10 GHz bandwidth VCSEL carrier at 1310 nm is experimentally demonstrated for the first time to the best of our knowledge. Data transmission and clock stability performance of the designed high spectral efficient VCSEL-based link network is evaluated through BER curve plots, phase noise measurements and Allan variance analysis respectively. VCSEL-based Raman amplification is experimentally demonstrated as a viable approach for RF clock signal distribution in extended reach astronomical telescope array networks and other extended reach terrestrial optical fibre network application. This is achieved by adopting two pumping techniques namely forward pumping and backward pumping. A maximum on off gain of 5.7 dB and 1.5 dB was experimentally attained for forward pumping and backward pumping at 24 dBm pump power respectively, while a maximum 100.8 Km fibre transmission achieved experimentally. In summary, this study has successfully demonstrated in-complex, spectral efficient, low cost and power efficient simultaneous data signal, reference frequency (RF) clock signal and pulse-per-second (PPS) transmission techniques over shared network infrastructure. Simultaneous transmission of data, RF clock and PPS timing signal is relevant in nextgeneration telescope array networks such as the Square Kilometre Array (SKA), time keeping systems such as banking systems, Coordinated Universal Time (UTC) timing and Global Positioning Systems (GPS), as well as high capacity spectral efficient short reach optical fibre networks such as data centres

Predictors for Incident Mild Parkinsonian Signs in Older Japanese

Background: Mild parkinsonian signs are important clinical symptoms related to the decline of motor and cognitive functions. We aimed to identify predictors for the incidence of mild parkinsonian signs in older Japanese by conducting an 8-year longitudinal community-based cohort study. Methods: Participants aged 65 years or older, living in Ama-cho, a rural island town in western Japan, underwent a baseline assessment of motor function, cognitive function, depression score, the Pittsburgh Sleep Quality Index (PSQI), the Tanner questionnaire, and cerebral white matter lesions on brain magnetic resonance imaging from 2008 to 2010, and then underwent a follow-up neurological examination from 2016 to 2017. Mild parkinsonian signs were defined according to a modified Unified Parkinson’s Disease Rating Scale score. Results: Of the 316 participants without mild parkinsonian signs at baseline, 94 presented with incident mild parkinsonian signs at follow-up. In addition to an absence of exercise habits, a higher score on the Tanner questionnaire, PSQI, and deep white-matter hyperintensity Fazekas scores were significant independent predictors for incidence of mild parkinsonian signs. Conclusion: We suggest multiple factors related to incidence of mild parkinsonian signs. Vascular lesions and sleep disorders are associated with a pathogenesis of mild parkinsonian signs, the Tanner questionnaire is useful for early detection of subclinical mild parkinsonian signs, and exercise has a possibility of being associated with preventing onset of mild parkinsonian signs

Influence of organization structure on diversification strategy and performance of an organization Critical literature review

The contentious debate by management scholars and researchers on whether strategy influences structure or if it is structure that influences strategy has been going on for some time now. We endeavored to conduct an extensive desk review aimed at establishing if indeed there is any interrelationship between organizational structure and diversification strategy or if organization structure does influence diversification strategy and performance of an organization. Different subsections of this paper present theoretical and in some instances empirical findings by other scholars and researchers on theories relating to organization structure, diversification strategy and organizational performance. From the discussed theories and research findings, the paper concludes that there exists an interdependent relationship between organization structure and diversification strategy which ultimately impacts on the performance of an organization

A Single-institution Study on Predictors of Short-term Progression from Mild Cognitive Impairment in Parkinson’s Disease to Parkinson’s Disease with Dementia

Background: Patients with non-demented Parkinson’s disease (PD) sometime have mild cognitive impairment (MCI), and mild cognitive impairment in Parkinson’s disease (PD-MCI) may convert to Parkinson’s disease with dementia (PDD) within several years. Cognitive impairment also occurs in the early stages of the disease, gradually progressing to lower quality of life and instrumental activities of daily living. It is important to elucidate the predictors of progression from PD-MCI to PDD via longitudinal studies. Methods: This was a single center, case-control study. We analysed data from 49 patients with PD-MCI diagnosed as level I using the Movement Disorder Society PD-MCI criteria at baseline who had completed 1.5 years of follow-up. We defined patients who progressed to PDD as patients with progressive PD-MCI and patients who did not progress to PDD as patients with non-progressive PD-MCI. Depression, apathy, sleep disorders, constipation, light-headedness, hallucinations, impulse control disorders (ICDs) and impulsive-compulsive behaviors (ICBs) at baseline were statistically analysed as predictors of progression. Results: Of the 49 PD-MCI patients, 33 did not convert to PDD (non-progressive PD-MCI), and 16 converted to PDD (progressive PD-MCI). The Mini-Mental State Examination (MMSE) score, light-headedness and ICDs were elucidated as predictors of progressive PD-MCI via a multivariate logistic regression model. The adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for each item were MMSE score, OR 0.324, 95% CI 0.119-0.882, P = 0.027; light-headedness, OR 27.665, 95% CI 2.263-338.185, P= 0.009; and ICDs, OR 53.451, 95% CI 2.298-291.085, P = 0.010. Conclusion: Cognitive function, ICDs and light-headedness may be risk factors for the development of PDD in PD-MCI patients

生後の神経新生を介したメダカ終脳の構築機構の解析

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 武田 洋幸, 東京大学教授 岡 良隆, 東京大学教授 久保 健雄, 東京大学准教授 伊藤 啓, 東京大学准教授 竹内 秀明University of Tokyo(東京大学

Prevalence of Dementia and Mild Cognitive Impairment in the Rural Island Town of Ama-cho, Japan

Aims: In order to determine the prevalence of dementia and mild cognitive impairment (MCI), we conducted a population-based study in Japan. Methods: Participants included 924 subjects aged 65 years or older who resided in the town of Ama-cho. In phase 1 of the study, the Mini-Mental State Examination and Clinical Dementia Rating were administered for screening purposes. In phase 2 of the study, the subjects who screened positive were further examined by neurologists. Dementia and MCI were diagnosed by means of DSM-IV and International Working Group on MCI criteria, respectively. Results: By the prevalence date of June 1, 2010, 24 subjects had deceased or lived outside the town. In total, 723 of the remaining 900 subjects received a phase 1 test. In phase 2, 98 subjects were diagnosed with amnestic MCI, 113 subjects with non-amnestic MCI, and 82 subjects with dementia. Of the subjects who did not receive the phase 1 test, 66 subjects were diagnosed as having dementia according to data from their town medical card or the Long-term Care Insurance System. The crude prevalence of amnestic MCI, non-amnestic MCI, and dementia were 10.9, 12.6, and 16.4%, respectively. Conclusion: Consistent with the striking increase in the number of elderly individuals, we report higher prevalence of MCI and dementia in Japan than previously described

In vitro activation and enzyme kinetic analysis of recombinant midgut serine proteases from the Dengue vector mosquito Aedes aegypti

<p>Abstract</p> <p>Background</p> <p>The major Dengue virus vector <it>Aedes aegypti </it>requires nutrients obtained from blood meal proteins to complete the gonotrophic cycle. Although bioinformatic analyses of <it>Ae. aegypti </it>midgut serine proteases have provided evolutionary insights, very little is known about the biochemical activity of these digestive enzymes.</p> <p>Results</p> <p>We used peptide specific antibodies to show that midgut serine proteases are expressed as zymogen precursors, which are cleaved to the mature form after blood feeding. Since midgut protein levels are insufficient to purify active proteases directly from blood fed mosquitoes, we engineered recombinant proteins encoding a heterologous enterokinase cleavage site to permit generation of the bona fide mature form of four midgut serine proteases (AaET, AaLT, AaSPVI, AaSPVII) for enzyme kinetic analysis. Cleavage of the chromogenic trypsin substrate BApNA showed that AaET has a catalytic efficiency (k_cat/K_M) that is ~30 times higher than bovine trypsin, and ~2-3 times higher than AaSPVI and AaSPVII, however, AaLT does not cleave BApNA. To measure the enzyme activities of the mosquito midgut proteases using natural substrates, we developed a quantitative cleavage assay based on cleavage of albumin and hemoglobin proteins. These studies revealed that the recombinant AaLT enzyme was indeed catalytically active, and cleaved albumin and hemoglobin with equivalent efficiency to that of AaET, AaSPVI, and AaSPVII. Structural modeling of the AaLT and AaSPVI mature forms indicated that AaLT is most similar to serine collagenases, whereas AaSPVI appears to be a classic trypsin.</p> <p>Conclusions</p> <p>These data show that <it>in vitro </it>activation of recombinant serine proteases containing a heterologous enterokinase cleavage site can be used to investigate enzyme kinetics and substrate cleavage properties of biologically important mosquito proteases.</p