Selection of microalgal growth model for describing specific growth rate-light response using extended information criterion

The effects of light intensity and carbon dioxide (CO2) concentration on the growth of the highly CO2-tolerant green alga Chlorococcum littorale were studied in batch cultures. Four mathematical representations were compared for the specific growth rate-light response curve: a rectangular hyperbolic function, Steele's exponential function, a Poisson function and a hyperbolic tangent function. The hyperbolic tangent function, which is commonly used for representing the photosynthesis-light relationship, gave the best fit as evaluated by the extended information criterion (EIC). EIC proved to be applicable as a criterion to this kind of nonlinear model selection problem. Carbon dioxide, the sole carbon source for photoautotrophic growth of this alga, inhibited the growth rate at concentrations higher than pCO2 of 0.02. A substrate inhibition model was successfully used to simulate the relationship between the specific growth rate and CO2 response.     

Transport Properties of Se/As2Se3 Nanolayer Superlattice Fabricated Using Rotational Evaporation

Since their proposal by Esaki, superlattices have been observed to have fascinating features such as quantum size effects, negative differential resistance, and sequential resonant tunneling. However, the technology threshold for fabricating superlattices is high, requiring methods like molecular beam epitaxy (MBE) and atomic layer deposition (ALD), among others, even for amorphous materials. Thus, the desirable features from superlattices have not been extensively utilized. It is shown that superlattices of Se and As₂Se₃ (superlattice‐Se), fabricated using rotational evaporation, exhibit sequential tunneling, a typical superlattice feature. From current–voltage measurements of the superlattice deposited on n‐type Si, oscillations in the characteristics are observed. Using models of reverse‐biased Schottky barriers, the observations are explained as tunneling in sequence from superlattice minibands. The superlattice‐Se also shows carrier blocking, with a resistivity of the order of 10¹² Ω cm in dark conditions at room temperature, despite the low resistivity (≈10 Ω cm) of the n‐type Si substrate. When the Si is illuminated, the device shows higher detectivity for weaker signals compared to higher illumination. The ease of fabrication, and the blocking and amplifying capabilities make superlattice‐Se an interesting “add‐on” structure to improve conventional photodetector materials such as Si or Ge, which have issues with dark currents at room temperature.     

An LMI approach to observer-based guaranteed cost control

This article presents a design method for an observer-based guaranteed cost controller for a class of uncertain linear systems, in which full state variables cannot be measured. The perturbations are assumed to be described by structural uncertainties. The linear matrix inequality (LMI) approach is applied to design the observer-based controller. The controller and observer gains are obtained by solving the LMI optimization and feasibility problems, respectively. A numerical example shows the potential of the proposed method. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

A scintillation response and an ionization yield in pure xenon and mixtures of it with methane

The scintillation response to an α source (²⁴¹Am) and the ionization yield in pure gaseous xenon and its mixtures with 0.2–2% of methane were measured at a pressure of 26 atm and different values of reduced electric field E/N. Both light and ionization yields in xenon were shown to decrease with increasing percentage of methane.     

Immunological features of patients with primary biliary cirrhosis (PBC) overlapping systemic sclerosis: a comparison with patients with PBC alone

Mutations within exons 16 and 17 of the beta-amyloid precursor protein (APP) gene were the first known cause of familial Alzheimer's disease. These mutations are rare and have been reported in a handful of families exhibiting autosomal dominant inheritance of Alzheimer's disease with age of onset around 50 years. In vitro and in vivo studies have demonstrated that each of these mutations alters proteolytic processing of APP, resulting in an increase in the production of A beta 42, a highly fibrillogenic peptide, that spontaneously aggregates and deposits in the brain. Transgenic mice carrying a mutant human APP gene also show age-dependent beta-amyloid (A beta) deposition in the brain. The rate of deposition in these mice can be modified by apolipoprotein E expression.     

Ribulose-1,5-bisphosphate carboxylase/oxygenase from thermophilic red algae with a strong specificity for CO2 fixation

Strongly carboxylase-specific ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) was found in Galdieria partita and Cyanidium caldarium (Cyanidiophyceae). The relative specificity, VcKo/VoKc, of Galdieria and Cyanidium RuBisCO was 238 and 222, respectively; 2.4 to 2.5-fold that of higher plant RuBisCOs. The apparent Km of RuBisCO from the thermophilic red algae for CO2 was 6 to 7 microM and the smallest of the values reported so far for other RuBisCOs. The pre-rhodophyte Porphiridium purpureum, which lives at moderate temperatures, had RuBisCO with the relative specificity value of 144. A large difference (5.2 kcal x mol(-1)) in the activation energies between the carboxylase and oxygenase activities in Galdieria RuBisCO was a cause of the strong specificity for the carboxylase activity.     

Mature type of skin collagen crosslink, histidinohydroxylysinonorleucine, is significantly increased in the skin of systemic sclerosis patients

We describe a case of Takayasu's arteritis discovered at the early systemic phase. Ultrasonography and computed tomography show thickening of the walls of the superior mesentery and common carotid arteries despite normal findings on angiography. Diagnosis was confirmed by arterial biopsy. We emphasize the importance of noninvasive vascular investigation to support the diagnosis of Takayasu's arteritis.