Leiden University Document Attesting the Studies of Mathematics

A document attesting the studies of Albertus C. Van Raalte in the field of mathematics at Leiden University.https://digitalcommons.hope.edu/vrp_1830s/1001/thumbnail.jp

Recent Decisions

Comments on recent decisions by Daniel W. Hammer, John E. Kennedy, William J. Harte, Patrick F. McCartan, William D. Bailey, Jr., Donald L. Very, William C. Rindone, Jr., and Eugene F. Waye

Overexpression of hMTH1 mRNA: a molecular marker of oxidative stress in lung cancer cells

AbstractHuman MutT homologue (hMTH1) mRNA was overexpressed in SV-40-transformed non-tumorigenic human bronchial epithelial cells (BEAS-2B cells) and in 11 out of 12 human lung cancer cell lines relative to normal human bronchial epithelial cells. Expression levels of hMTH1 mRNA were inversely proportional to cellular levels of 8-oxo-deoxyguanosine. Together, these results suggest that hMTH1 gene expression may represent a molecular marker of oxidative stress that could ultimately be used to elucidate the temporal relationships between oxidative stress, genomic instability and the development of lung cancer

Optical properties of pyrochlore oxide Pb2Ru2O7−δPb_{2}Ru_{2}O_{7-{\delta}}

We present optical conductivity spectra for $Pb_{2}Ru_{2}O_{7-{\delta}}$ single crystal at different temperatures. Among reported pyrochlore ruthenates, this compound exhibits metallic behavior in a wide temperature range and has the least resistivity. At low frequencies, the optical spectra show typical Drude responses, but with a knee feature around 1000 \cm. Above 20000 \cm, a broad absorption feature is observed. Our analysis suggests that the low frequency responses can be understood from two Drude components arising from the partially filled Ru $t_{2g}$ bands with different plasma frequencies and scattering rates. The high frequency broad absorption may be contributed by two interband transitions: from occupied Ru $t_{2g}$ states to empty $e_{g}$ bands and from the fully filled O 2p bands to unoccupied Ru $t_{2g}$ states.Comment: 4 pages, 6 figure

Lost in translation? The potential psychobiotic Lactobacillus rhamnosus (JB-1) fails to modulate stress or cognitive performance in healthy male subjects

Background: Preclinical studies have identified certain probiotics as psychobiotics a live microorganisms with a potential mental health benefit. Lactobacillus rhamnosus (JB-1) has been shown to reduce stress-related behaviour, corticosterone release and alter central expression of GABA receptors in an anxious mouse strain. However, it is unclear if this single putative psychobiotic strain has psychotropic activity in humans. Consequently, we aimed to examine if these promising preclinical findings could be translated to healthy human volunteers. Objectives: To determine the impact of L. rhamnosus on stress-related behaviours, physiology, inflammatory response, cognitive performance and brain activity patterns in healthy male participants. An 8 week, randomized, placebo-controlled, cross-over design was employed. Twenty-nine healthy male volunteers participated. Participants completed self-report stress measures, cognitive assessments and resting electroencephalography (EEG). Plasma IL10, IL1β, IL6, IL8 and TNFα levels and whole blood Toll-like 4 (TLR-4) agonist-induced cytokine release were determined by multiplex ELISA. Salivary cortisol was determined by ELISA and subjective stress measures were assessed before, during and after a socially evaluated cold pressor test (SECPT). Results: There was no overall effect of probiotic treatment on measures of mood, anxiety, stress or sleep quality and no significant effect of probiotic over placebo on subjective stress measures, or the HPA response to the SECPT. Visuospatial memory performance, attention switching, rapid visual information processing, emotion recognition and associated EEG measures did not show improvement over placebo. No significant anti-inflammatory effects were seen as assessed by basal and stimulated cytokine levels. Conclusions: L. rhamnosus was not superior to placebo in modifying stress-related measures, HPA response, inflammation or cognitive performance in healthy male participants. These findings highlight the challenges associated with moving promising preclinical studies, conducted in an anxious mouse strain, to healthy human participants. Future interventional studies investigating the effect of this psychobiotic in populations with stress-related disorders are required

Study of the impact of the post-MS evolution of the host star on the orbits of close-in planets. I. Sample definition and physical properties

Context: To date, more than 30 planets have been discovered around giant stars, but only one of them has been found to be orbiting within 0.6 AU from the host star, in direct contrast to what is observed for FGK dwarfs. This result suggests that evolved stars destroy/engulf close-in planets during the red giant phase. Aims: We are conducting a radial velocity survey of 164 bright G and K giant stars in the southern hemisphere with the aim of studying the effect of the host star evolution on the inner structure of planetary systems. In this paper we present the spectroscopic atmospheric parameters (\Teff, \logg, $\xi$, [Fe/H]) and the physical properties (mass, radius, evolutionary status) of the program stars. In addition, rotational velocities for all of our targets were derived. Methods: We used high resolution and high S/N spectra to measure the equivalent widths of many Fe{\sc\,i} and Fe{\sc\,ii} lines, which were used to derive the atmospheric parameters by imposing local thermodynamic and ionization equilibrium. The effective temperatures and metallicities were used, along with stellar evolutionary tracks to determine the physical properties and evolutionary status of each star. Results: We found that our targets are on average metal rich and they have masses between $\sim$\,1.0\,M$_\odot$ and 3.5\,M$_\odot$. In addition, we found that 122 of our targets are ascending the RGB, while 42 of them are on the HB phase.Comment: Accepted for publication in A&