Two-dimensional packing with conflicts

We study the two-dimensional version of the bin packing problem with conflicts. We are given a set of (two-dimensional) squares V = {1, 2, . . . ,n} with sides and a conflict graph G = (V, E). We seek to find a partition of the items into independent sets of G, where each independent set can be packed into a unit square bin, such that no two squares packed together in one bin overlap. The goal is to minimize the number of independent sets in the partition. This problem generalizes the square packing problem (in which we have ) and the graph coloring problem (in which s _i = 0 for all i = 1,2, . . . , sn). It is well known that coloring problems on general graphs are hard to approximate. Following previous work on the one-dimensional problem, we study the problem on specific graph classes, namely, bipartite graphs and perfect graphs. We design a -approximation for bipartite graphs, which is almost best possible (unless P = NP). For perfect graphs, we design a 3.2744-approximation. An extended abstract version of this paper has appeared in Proceedings of the 16th International Symposium on Fundamentals of Computation Theory (FCT 2007), pp 288–299. Rob van Stee was supported by the Alexander von Humboldt Foundation.     

Measurements of Morphology Changes of Fractal Soot Particles using Coating and Denuding Experiments: Implications for Optical Absorption and Atmospheric Lifetime

Mobility-selected fractal and non-fractal soot particles (mobility diameters d _m = 135 to 310 nm) were produced at three controlled fuel equivalence ratios (φ = 2.1, 3.5, and 4.5) by an ethylene/oxygen flame. Oleic acid (liquid) and anthracene (solid) coatings were alternately applied to the particles and removed. Simultaneous measurements with an Aerodyne aerosol mass spectrometer and a scanning mobility particle sizer yielded the particle mass, volume, density, composition, dynamic shape factor, fractal dimension, surface area, and the size and number of the primary spherules forming the fractal aggregate. For a given φ, the diameters of the primary spherules are approximately the same, independent of d _m (15 nm, 35 nm, and 55 nm for φ = 2.1, 3.5, and 4.5, respectively). As the coating thickness on a particle increases, the dynamic shape factor decreases but d _m remains constant until the particle reaches a spherical (for oleic acid) or non-fractal but irregular (for anthracene) shape. Under some conditions, liquid oleic acid coating causes the internal BC framework to rearrange into a more compact configuration. The surface area of fractal particles is up to 2.4 times greater than that of a sphere with the same d _m . Using the surface area determinations, the time for a fractal particle to obtain a monolayer of coating material is compared to that of spheres. If it is assumed that the fractal particle is a sphere with the same d _m as the fractal particle, the monolayer coating time is underestimated by a factor of up to 1.7.     

Validating a Distinction Between Primary and Secondary Psychopathy With Measures of Gray's BIS and BAS Constructs.

Investigators commonly distinguish between primary and secondary psychopathy (H. Cleckley, 1976; D.T. Lykken, 1995), though there is a lack of consensus regarding the best means to achieve this distinction. To address the validity of using R. D. Hare's (2003) Psychopathy Checklist and the G. Welsh (1956) Anxiety Scale for this purpose, the authors used 2 measures of J. A. Gray's (1987) behavioral inhibition system/behavioral activation system (BIS/BAS). Following D. T. Lykken (1995) and D. C. Fowles (1980), the authors hypothesized that primary psychopathy would be associated with a weak BIS and a normal BAS, whereas secondary psychopathy would be associated with a strong BAS and a normal BIS. Results for primary psychopathy were as predicted. Results for secondary psychopathy clearly supported the strong BAS prediction but provided mixed support for the normal BIS prediction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The formation of MgZnO luminescent ceramics

Mg_xZn_1−xO is a promising alloy system with UV-tunable bandgap. The alloy can have the hexagonal or cubic structure depending on the composition x and growth conditions. We present studies of the optical and material properties of Mg_0.1Zn_0.9O and Mg_0.6Zn_0.4O sintered ceramics. The rationale for choosing these compositions is that alloys of both the wurtzite and the cubic phases, respectively, can be investigated. To study the alloying dynamics for the optimization of light emission, the properties as a function of annealing temperature in the range of 600–1,100 °C were investigated via micro-photoluminescence, X-ray diffraction, and imaging techniques. For the Mg_0.1Zn_0.9O it was found that a threshold temperature of ~900 °C is required in order to initiate the formation of the solid solution with the wurtzite structure. At the elevated temperature regime, the photoluminescence energy for this ceramic sample shifted from 3.25 to 3.5 eV, while the ceramic retained the wurtzite structure. The Mg_0.6Zn_0.4O was found to have a sequence of phases: initially the alloy formed with the wurtzite structure, and then a transition into the NaCl cubic structure took place. Similar to the Mg_0.1Zn_0.9O, a threshold temperature of ~900 °C was required in order to initiate the alloying process. At that temperature regime an alloy was formed with the wurtzite structure, and its photoluminescence energy was ~3.25 eV. At ~1,100 °C the alloy was found to undergo a phase transition from wurtzite to cubic structure. The photoluminescence energy at that temperature was considerably shifted into the UV-range of 4 eV.     

Ultra performance liquid chromatography isotope dilution tandem mass spectrometry for the absolute quantification of proteins and peptides

A selective, rapid, and sensitive 12.7-min ultra performance liquid chromatography-isotope dilution tandem mass spectrometry (UPLC-ID/MS/MS) method was developed and compared to conventional high-performance liquid chromatography-isotope dilution tandem mass spectrometry (HPLC-ID/MS/MS) for the absolute quantitative determination of multiple proteins from complex matrixes. The UPLC analysis was carried out on an Acquity UPLC ethylene-bridged hybrid (BEH) C18 reversed-phase column (50 x 2.1 mm i.d., 1.7-microm particle size) with gradient elution at a flow rate of 300 microL/min. For the HPLC separation, a similar gradient profile on a reversed-phase C18 column with dimensions of 150 x 1.0 mm at a flow rate of 30 microL/min was utilized. The aqueous and organic mobile phases were 0.1% formic acid in water and acetonitrile, respectively. Detection was performed on a triple-quadrupole mass spectrometer operated in the multiple reaction monitoring mode. Linear calibration curves were obtained in the concentration range of 10-90 fmol/microL. Relative standard deviation values equal to or less than 6.5% were obtained by the UPLC-ID/MS/MS method, thus demonstrating performance equivalent to conventional HPLC-ID/MS/MS for isotope dilution quantification of peptides and proteins. UPLC provides additional dimensions of rapid analysis time and high-sample throughput, which expands laboratory emergency response capabilities over conventional HPLC.     

The second ACTRIS inter-comparison (2016) for Aerosol Chemical Speciation Monitors (ACSM): Calibration protocols and instrument performance evaluations

This work describes results obtained from the 2016 Aerosol Chemical Speciation Monitor (ACSM) intercomparison exercise performed at the Aerosol Chemical Monitor Calibration Center (ACMCC, France). Fifteen quadrupole ACSMs (Q_ACSM) from the European Research Infrastructure for the observation of Aerosols, Clouds and Trace gases (ACTRIS) network were calibrated using a new procedure that acquires calibration data under the same operating conditions as those used during sampling and hence gets information representative of instrument performance. The new calibration procedure notably resulted in a decrease in the spread of the measured sulfate mass concentrations, improving the reproducibility of inorganic species measurements between ACSMs as well as the consistency with co-located independent instruments. Tested calibration procedures also allowed for the investigation of artifacts in individual instruments, such as the overestimation of m/z 44 from organic aerosol. This effect was quantified by the m/z (mass-to-charge) 44 to nitrate ratio measured during ammonium nitrate calibrations, with values ranging from 0.03 to 0.26, showing that it can be significant for some instruments. The fragmentation table correction previously proposed to account for this artifact was applied to the measurements acquired during this study. For some instruments (those with high artifacts), this fragmentation table adjustment led to an “overcorrection” of the f44 (m/z 44/Org) signal. This correction based on measurements made with pure NH₄NO₃, assumes that the magnitude of the artifact is independent of chemical composition. Using data acquired at different NH₄NO₃ mixing ratios (from solutions of NH₄NO₃ and (NH₄)₂SO₄) we observe that the magnitude of the artifact varies as a function of composition. Here we applied an updated correction, dependent on the ambient NO₃ mass fraction, which resulted in an improved agreement in organic signal among instruments. This work illustrates the benefits of integrating new calibration procedures and artifact corrections, but also highlights the benefits of these intercomparison exercises to continue to improve our knowledge of how these instruments operate, and assist us in interpreting atmospheric chemistry.     

Improved Results for a Memory Allocation Problem

We consider a memory allocation problem. This problem can be modeled as a version of bin packing where items may be split, but each bin may contain at most two (parts of) items. This problem was recently introduced by Chung et al. (Theory Comput. Syst. 39(6):829–849, 2006). We give a simple \frac32\frac{3}{2} -approximation algorithm for this problem which is in fact an online algorithm. This algorithm also has good performance for the more general case where each bin may contain at most k parts of items. We show that this general case is strongly NP-hard for any k≥3. Additionally, we design an efficient approximation algorithm, for which the approximation ratio can be made arbitrarily close to \frac75\frac{7}{5} .     

Influence of assay conditions on the in vitro hindgut digestibility of dry matter

In vitro assays have been developed to predict dry matter digestibility (DMD) in the human colon, but there is little information on the effect of assay variables. The effect of altering pH, duration of incubation, presence of shaking during incubation and the concentration of faecal inoculum or digestive enzymes on DMD was investigated for three in vitro hindgut digestibility assays. Three mixed human diets varying in the type and ratio of soluble and insoluble dietary fibre were used as substrates. The pH, duration of incubation and the concentration of inoculum relative to substrate significantly (P > 0.05) affected predicted DMD for the two in vitro methods employing faecal inocula. The method using synthetic enzymes showed little sensitivity to alteration of assay variables and gave highly variable results and for this reason was not pursued further. Shaking did not affect (P > 0.05) digestibility for any method or diet. The different methods led to large differences in predicted hindgut DMD within each of the three diets. In vitro hindgut digestibility assay variables need to be optimised and the predicted DMD data validated against in vivo data.     

漂泊的办公桌：一个穿越现代性的包豪斯物件

沃尔特·格罗皮乌斯（Walter Gropius）在德国包豪斯学校的办公桌是一个特殊的物件：它由格罗皮乌斯亲自设计,是1923年包豪斯魏玛的校长办公室空间构成的一部分,却经历了从魏玛（Weimar）到德绍（Dessau）、从德国到美国的场景置换。本文回溯办公桌迁移的旅程,探究其作为一个象征物件,所反映出的现代主义和现代性思想的演变。书桌成为一个媒介符号,其所在的空间场景的变换,指向以包豪斯为中心的现代生活方式的演变。本文关注书桌迁徙的旅程中几个重要年代节点：1923年的魏玛、1925年的德绍和1938年的林肯,由一个贴着“包豪斯”标签的物件出发,探寻现代性演变的历史路径。     

Catalytic relationships between type I and type II iterative polyketide synthases: The Aspergillus parasiticus norsolorinic acid synthase

Norsolorinic acid synthase (NSAS) is a type I iterative polyketide synthase that occurs in the filamentous fungus Aspergillus parasiticus. PCR was used to clone fragments of NSAS corresponding to the acyl carrier protein (ACP), acyl transferase (AT) and beta-ketoacyl-ACP synthase (KS) catalytic domains. Expression of these gene fragments in Escherichia coli led to the production of soluble ACP and AT proteins. Coexpression of ACP with E. coli holo-ACP synthase (ACPS) let to production of NSAS holo-ACP, which could also be formed in vitro by using Streptomyces coelicolor ACPS. Analysis by mass spectrometry showed that, as with other type I carrier proteins, self-malonylation is not observed in the presence of malonyl CoA alone. However, the NSAS holo-ACP serves as substrate for S. coelicolor MCAT, S. coelicolor actinorhodin holo-ACP and NSAS AT domain-catalysed malonate transfer from malonyl CoA. The AT domain could transfer malonate from malonyl CoA to NSAS holo-ACP, but not hexanoate or acetate from either the cognate CoA or FAS ACP species to NSAS holo-ACP. The NSAS holo-ACP was also active in actinorhodin minimal PKS assays, but only in the presence of exogenous malonyl transferases.