基于拉格朗日模型的CO2气固两相圆管内突扩流动沉积特性分析

CO2在通过安全阀的排放过程中,形成的固体CO2在安全阀下游管道突扩处沉积,导致管路的堵塞和冻结,危害被保护系统的安全.为了寻求减少固体CO2在安全阀下游管道突扩处的沉积量和进一步避免管道堵塞的方法,利用拉格朗日模型对CO2气固两相紊流在突扩管内的流动和沉积特性进行计算,通过比较沉积率计算值与实验值,验证了计算结果的合理性;利用该模型分析了各种流动参数对流动和沉积特性的影响.结果表明,通过安全阀开启排放过程中生成的固体颗粒直径尽可能远离颗粒回流量的峰值区域(即颗粒直径0.04~0.07 mm,St数为3.2~9.8的区域),可以降低固体CO2的沉积量,从而避免管道的堵塞和冻结.具体可以通过设计适当的安全阀开启时最小流通截面面积做到.     

Time series forecasting using robust regression

The method of ordinary least squares (OLS) and generalizations of it have been the mainstay of most forecasting methodologies for many years. It is well-known, however, that outliers or unusual values can have a large influence on least-squares estimators. Users of automatic forecasting packages, in particular, need to be aware of the influence that outlying data values can have on statistical analyses and forecasting results. Robust methods are available to modify least-squares procedures so that outliers have much less influence on the final estimates; yet these formal methods have not found their way into general forecasting procedures. This paper provides a case study in which classical least-square-estimation procedures are complemented with a robust alternative to enhance statistical fit criteria and improve forecasting performance. The study suggests that much can be gained in understanding the nature of outliers and their influence on forecasting performance by performing a robust regression in addition to OLS.     

Beziehungen zwischen phagozytierenden,virusinfizierten Myeloblasten des Huhnes in vitro und den «gray bodies»

Summary The so-called gray bodies in chicken myeloblasts infected with the myeloblastose virus are phagocytized cell debris. Some difficultues concerning this virus-cell-system are pointed out.

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Die Arbeit wurde unterstützt durch Research grant No. C-4572 an die Duke University von National Cancer Institute, National Institutes of Health, Public Health Service, durch Grant No. E-84A von der American Cancer Society, Inc. und durch den Dorothy Beard Research Fund.     

On The Impossibility Of Empirical Controls Of Scientific Theories – From The Point Of View Of A Psychologist

Standard considerations of philosophy of science are reformulated in psychological terms and arguments, suggesting a fundamental change in life perspective: subjective experiences or introspective data are subject to motivational biases and therefore not admitted as objective empirical facts in science, However, we never experience objects or events of the external world, i.e., so called objective facts, but exclusively subjective percepts or mental events. They are merely assumed to, but may or may not be accurate or distorted mental representations of objects or events of an external world. Accordingly, the latter are theoretical constructs, i.e., constructs of the fictitious but most successful predictive (implicit) theory, called external world, which seems to be constructed from regularities observed in mental events and serves as a reference fiction for, erroneously called empirical, tests of predictions of scientific theories.Relevant Publication: Micko, H.C.: 2001, Psychologie: Von der Geistes – zur Naturwissenschaft – und weiter wohin? Erkenntnistheoretische Erwägungen vor und nach dem Aufkommen des philosophischen Konstruktivismus. Ztschr. f. Psychologie, 209: 54–68.     

A specific requirement for PDGF-C in palate formation and PDGFR-alpha signaling

PDGF-C is a member of the platelet-derived growth factor (PDGF) family, which signals through PDGF receptor (PDGFR) alphaalpha and alphabeta dimers. Here we show that Pdgfc(-/-) mice die in the perinatal period owing to feeding and respiratory difficulties associated with a complete cleft of the secondary palate. This phenotype was less severe than that of Pdgfra(-/-) embryos. Pdgfc(-/-) Pdgfa(-/-) embryos developed a cleft face, subepidermal blistering, deficiency of renal cortex mesenchyme, spina bifida and skeletal and vascular defects. Complete loss of function of both ligands, therefore, phenocopied the loss of PDGFR-alpha function, suggesting that both PDGF-A and PDGF-C signal through PDGFR-alpha to regulate the development of craniofacial structures, the neural tube and mesodermal organs. Our results also show that PDGF-C signaling is a new pathway in palatogenesis, different from, and independent of, those previously implicated.     

Experimental demonstration of five-photon entanglement and open-destination teleportation

Quantum-mechanical entanglement of three or four particles has been achieved experimentally, and has been used to demonstrate the extreme contradiction between quantum mechanics and local realism. However, the realization of five-particle entanglement remains an experimental challenge. The ability to manipulate the entanglement of five or more particles is required for universal quantum error correction. Another key process in distributed quantum information processing, similar to encoding and decoding, is a teleportation protocol that we term 'open-destination' teleportation. An unknown quantum state of a single particle is teleported onto a superposition of N particles; at a later stage, this teleported state can be read out (for further applications) at any of the N particles, by a projection measurement on the remaining particles. Here we report a proof-of-principle demonstration of five-photon entanglement and open-destination teleportation (for N = 3). In the experiment, we use two entangled photon pairs to generate a four-photon entangled state, which is then combined with a single-photon state. Our experimental methods can be used for investigations of measurement-based quantum computation and multi-party quantum communication.     

Genetic analysis of the mouse brain proteome

Proteome analysis is a fundamental step in systematic functional genomics. Here we have resolved 8,767 proteins from the mouse brain proteome by large-gel two-dimensional electrophoresis. We detected 1,324 polymorphic proteins from the European collaborative interspecific backcross. Of these, we mapped 665 proteins genetically and identified 466 proteins by mass spectrometry. Qualitatively polymorphic proteins, to 96%, reflect changes in conformation and/or mass. Quantitatively polymorphic proteins show a high frequency (73%) of allele-specific transmission in codominant heterozygotes. Variations in protein isoforms and protein quantity often mapped to chromosomal positions different from that of the structural gene, indicating that single proteins may act as polygenic traits. Genetic analysis of proteomes may detect the types of polymorphism that are most relevant in disease-association studies.     

Ordering and manipulation of the magnetic moments in large-scale superconducting pi-loop arrays

The phase of the macroscopic electron-pair wavefunction in a superconductor can vary only by multiples of 2pi when going around a closed contour. This results in quantization of magnetic flux, one of the most striking demonstrations of quantum phase coherence in superconductors. By using superconductors with unconventional pairing symmetry, or by incorporating pi-Josephson junctions, a phase shift of pi can be introduced in such loops. Under appropriate conditions, this phase shift results in doubly degenerate time-reversed ground states, which are characterized by the spontaneous generation of half quanta of magnetic flux, with magnitude 1/2 Phi(0)(Phi(0) = h/2e = 2.07 x 10(-15) Wb) (ref. 7). Until now, it has only been possible to generate individual half flux quanta. Here we report the realization of large-scale coupled pi-loop arrays based on YBa2Cu3O7-Au-Nb Josephson contacts. Scanning SQUID (superconducting quantum interference device) microscopy has been used to study the ordering of half flux quanta in these structures. The possibility of manipulating the polarities of individual half flux quanta is also demonstrated. These pi-loop arrays are of interest as model systems for studying magnetic phenomena--including frustration effects--in Ising antiferromagnets. Furthermore, studies of coupled pi-loops can be useful for designing quantum computers based on flux-qubits with viable quantum error correction capabilities.     

An NS3 protease inhibitor with antiviral effects in humans infected with hepatitis C virus

Hepatitis C virus (HCV) infection is a serious cause of chronic liver disease worldwide with more than 170 million infected individuals at risk of developing significant morbidity and mortality. Current interferon-based therapies are suboptimal especially in patients infected with HCV genotype 1, and they are poorly tolerated, highlighting the unmet medical need for new therapeutics. The HCV-encoded NS3 protease is essential for viral replication and has long been considered an attractive target for therapeutic intervention in HCV-infected patients. Here we identify a class of specific and potent NS3 protease inhibitors and report the evaluation of BILN 2061, a small molecule inhibitor biologically available through oral ingestion and the first of its class in human trials. Administration of BILN 2061 to patients infected with HCV genotype 1 for 2 days resulted in an impressive reduction of HCV RNA plasma levels, and established proof-of-concept in humans for an HCV NS3 protease inhibitor. Our results further illustrate the potential of the viral-enzyme-targeted drug discovery approach for the development of new HCV therapeutics.     

The Wnt/beta-catenin pathway regulates cardiac valve formation

Truncation of the tumour suppressor adenomatous polyposis coli (Apc) constitutively activates the Wnt/beta-catenin signalling pathway. Apc has a role in development: for example, embryos of mice with truncated Apc do not complete gastrulation. To understand this role more fully, we examined the effect of truncated Apc on zebrafish development. Here we show that, in contrast to mice, zebrafish do complete gastrulation. However, mutant hearts fail to loop and form excessive endocardial cushions. Conversely, overexpression of Apc or Dickkopf 1 (Dkk1), a secreted Wnt inhibitor, blocks cushion formation. In wild-type hearts, nuclear beta-catenin, the hallmark of activated canonical Wnt signalling, accumulates only in valve-forming cells, where it can activate a Tcf reporter. In mutant hearts, all cells display nuclear beta-catenin and Tcf reporter activity, while valve markers are markedly upregulated. Concomitantly, proliferation and epithelial-mesenchymal transition, normally restricted to endocardial cushions, occur throughout the endocardium. Our findings identify a novel role for Wnt/beta-catenin signalling in determining endocardial cell fate.