Does immigration induce “native flight” from public schools?

For more than a century, parents in Denmark could enroll their children into privately operated “free schools.” Results from this study indicate an increase in native Danes’ propensity to enroll their children in free schools as the share of children with immigrant background becomes larger in their municipality of residence. The effect is most pronounced in small, and medium-sized municipalities, while it seems absent in larger municipalities. The study explores changes in the immigrant population in Danish municipalities 1992–2004, a period marked by a substantial influx of refugees, where a state-sponsored placement policy restricted their initial choice of residence.     

Identification,Synthesis, and Behavioral Activity of 5,11-Dimethylpentacosane,A Novel Sex Pheromone Component of the Greater Wax Moth,Galleria Mellonella (L.)

The greater wax moth, Galleria mellonella (L.), is a serious and widespread pest of the honeybee, Apis mellifera L. In contrast to most moths, for which long-range mate finding is mediated by female-produced sex pheromones, G. mellonella males attract conspecific females over long distances by emitting large amounts of a characteristic scent in combination with bursts of ultrasonic calls. The male scent for this species was previously identified as a blend of nonanal and undecanal. When these compounds were bioassayed, characteristic short-range sexual behavior, including wing fanning, was triggered in conspecific females, but the aldehyde blend failed to elicit attraction over longer distances. We identified, via analysis and synthesis, a third male-specific compound, 5,11-dimethylpentacosane. We show that it acts as a behavioral synergist to the aldehydes. In wind tunnel experiments, very few female moths responded to the aldehyde blend or to 5,11-dimethylpentacosane tested separately, but consistently showed orientation and source contact when a combination of all three compounds was applied. The level of attraction to the three-component mixture was still lower than that to male extract, indicating that the composition of compounds in the synthetic blend is suboptimal, or that additional pheromone components of G. mellonella are yet to be identified. The identification of 5,11-dimethylpentacosane is an important step for the development of an efficient long-range attractant that will be integrated with other environmentally safe strategies to reduce damage to beehives caused by wax moths.     

The Impact of Early Saliva Interaction on Dental Implants and Biomaterials for Oral Regeneration: An Overview

The presence of saliva in the oral environment is relevant for several essential health processes. However, the noncontrolled early saliva interaction with biomaterials manufactured for oral rehabilitation may generate alterations in the superficial properties causing negative biological outcomes. Therefore, the present review aimed to provide a compilation of all possible physical–chemical–biological changes caused by the early saliva interaction in dental implants and materials for oral regeneration. Dental implants, bone substitutes and membranes in dentistry possess different properties focused on improving the healing process when in contact with oral tissues. The early saliva interaction was shown to impair some positive features present in biomaterials related to quick cellular adhesion and proliferation, such as surface hydrophilicity, cellular viability and antibacterial properties. Moreover, biomaterials that interacted with contaminated saliva containing specific bacteria demonstrated favorable conditions for increased bacterial metabolism. Additionally, the quantity of investigations associating biomaterials with early saliva interaction is still scarce in the current literature and requires clarification to prevent clinical failures. Therefore, clinically, controlling saliva exposure to sites involving the application of biomaterials must be prioritized in order to reduce impairment in important biomaterial properties developed for rapid healing.     

The Effect of processing on the content and composition of free sterols and sterol esters in soybean oil

The content and composition of free sterols and sterol esters in crude soybean oil and in oils from different stages of two continuous refining systems were determined. The sterols were isolated by preparative thin layer chromatography and analyzed by gas chromatography with cholesterol as an internal standard. The free sterols in one of the degummed oils amounted to 3.1 mg/g and were diminished to 1.8 mg/g oil by the De Laval Short-Mix refining process. The content of free sterols of the other degummed oil was reduced from 3.4 to 1.6 mg/g oil by the Zenith process. The greatest reduction of sterol content was caused by the treatment with bleaching earth. The sterol esters accounted for 0.6 mg/g of the degummed oil, and only very small changes were observed during the processes. However, changes in the composition of fatty acids of the sterol esters were found. These changes might indicate a selective deacylation of sterol esters or an interesterification during the refining processes. The composition of sterols in free and esterified form were different. Campesterol, stigmasterol and sitosterol were obtained in both free and esterified form, but Δ7 stigmasterol was only found in esterified form. Only small changes in the percentage distribution of the sterols occurred during the processes. Present adress Food Technology Division, ALFA-LAVAL,S-14700 Tumba, Sweden     

PEPT study of particle cycle and residence time distributions in a Wurster fluid bed

Particle cycle and residence time distributions are critical factors in determining the coating quality in the Wurster process. Positron emission particle tracking experiments are performed to determine the cycle and residence times of particles in different regions of a Wurster fluid bed. The results show that particles tend to recirculate in and sneak out below from the Wurster tube. The experiments also show that a larger batch size leads to a shorter cycle time and a narrower cycle time distribution (CTD). It is possible to avoid recirculations and obtain a shorter cycle time and a narrower CTD by selecting the operating conditions appropriately or via equipment design. Experiments using binary mixtures of particles with a diameter ratio of 1.5 show that large particles have a longer cycle time than small particles and that the cycle time is shorter for mixtures with approximately equal amounts of small and large particles. © 2014 American Institute of Chemical Engineers AIChE J, 61: 756–768, 2015     

A readout IC for an uncooled microbolometer infrared FPA with on-chip self-heating compensation in 0.35 μm CMOS

This paper describes a readout integrated circuit architecture for an infrared focal plane array intended for infrared network-attached video cameras in surveillance applications. The focal plane array consists of 352 × 288 uncooled thin-film microbolometer detectors with a pitch of 25 μm, enabling ambient temperature operation. The circuit features a low-noise readout path, detector resistance mismatch correction and a non-linear ramped current pulse scheme for the electrical biasing of the detectors in order to relax the dynamic range requirement of amplifiers and the ADC in the readout channel, imposed by detector process variation and self-heating during readout. The design is implemented in a 0.35-μm standard CMOS process and two versions of a smaller 32 × 32-pixel test chip have been fabricated and measured for evaluation. The latest test chip achieves a dynamic range of 97 dB and an input-referred RMS noise voltage of 6.4 μV yielding an estimated NETD value of 26 mK with f/1 optics. At a frame rate of 60 FPS the chip dissipates 170 mW of power from a 3.4 V supply.     

Ecological effects of river regulation on mammals and birds: A review

Although most of the world's river systems are regulated, the effects of river regulation on mammals and birds are little known. In fact, speculations are more common than empirical data. A review of this topic is presented, emphasizing northern rivers where most impacts have been described. Effects are related to the major causes of change. It is concluded that the two most disastrous effects of river regulation on mammals and birds are the permanent inundation of vast areas of land, and the disruption of the seasonal flood regime along the river. The design of future investigations to improve our knowledge is considered.     

Oxidation behaviour of a Mo(Si,Al)2 based composite at 1500 °C

The oxidation of a Mo(Si,Al)₂ composite is investigated at 1500 °C in dry air using exposure times from 1 to 1000 h. Cross sections are examined with Scanning Electron Microscopy (SEM) and the phase composition is analyzed by X-ray diffraction (XRD). The material forms a continuous and protective alumina layer, the growth of the alumina layer following parabolic kinetics. Immediately below the scale Mo(Si,Al)₂ is replaced by a Mo₅(Si,Al)₃ layer due to the flux of aluminum to the scale. The Al concentration in the Mo(Si,Al)₂ phase in the underlying substrate decreases from 27% before exposure to 16–17% after 1000 h. The continuous alumina layer becomes covered by a top layer consisting of alumina grains embedded in a viscous melt with approximate composition 7 Na₂O–15 Al₂O₃–78 SiO₂. With time, sodium is volatilized from the melt and the top scale layer transforms to a mixture of alumina, mullite and silica melt.     

Solving House Allocation Problems with Risk-Averse Agents

This paper solves the fair and optimal house allocation problem (Sun and Yang, Econ Lett 81:73–79, 2003) when the agents preferences are represented by nonlinear utility functions using techniques for global mixed integer nonlinear optimization. A small simulation study indicates that if quasi-linear specifications are adopted as approximations to nonlinear utility functions and if the fair and optimal allocation is identified based on this approximation, then the prices are typically higher on average and the resulting allocation is typically non-fair.