From Koszul duality to Poincaré duality

We discuss the notion of Poincaré duality for graded algebras and its connections with the Koszul duality for quadratic Koszul algebras. The relevance of the Poincaré duality is pointed out for the existence of twisted potentials associated to Koszul algebras as well as for the extraction of a good generalization of Lie algebras among the quadratic-linear algebras.     

Vibration-rotation bands in ethane

The absorption spectrum of ethane was recorded at 0.014 cm^?1 resolution in the range 4500–6500 cm^?1 using a Fourier transform spectrometer and at room temperature. Eighteen bands could be identified and their type assigned. Upper state rotational constants are provided for the band at 5948.338 cm^?1 and Coriolis constants are obtained for most perpendicular bands. Vibrational assignments are suggested for the bands at 5948 cm^?1 (v7 + v10), 5914 cm^?1(v8 + v ₁₀+ v ₁₁), and 5852cm^?1 (v ₅+v ₁₀). All vibrational bands reported in the literature are gathered.     

UNSCHEDULED DNA SYNTHESIS: A QUANTITATIVE INDICATOR OF RESIDUAL IMMUNODETECTABLE PYRIMIDINE DIMERS IN HUMAN FIBROBLASTS AFTER ULTRAVIOLET-B IRRADIATION

We have addressed the question whether the level of UV-B induced DNA damage can be accurately assessed by the measurement of the rate of unscheduled DNA synthesis (UDS). Cultured human fibroblasts were irradiated with UV radiation at 290, 313 or 365 nm. The LD50 was 85 J/m2 at 290 nm, 4500 J/m2 at 313 nm, and 70 kJ/m2 at 365 nm. The analysis of UDS measurements indicate complete arrest of repair processes within 24 h after irradiation, irrespective of the dose (in the range 10-60 J/m2 at 290 nm, and 250-1000 J/m2 at 313 nm). Irradiation at 365 nm failed to yield detectable evidence of UDS. Incubation of irradiated cells with an antiserum directed against both 6-4 type and cyclobutane-type pyrimidine dimers shows a clear parallelism between the disappearance of the antibody-binding determinants and the variation of the rate of UDS vs time after the end of the irradiation. Thus it is concluded that in UV-B irradiated normal cultured human fibroblasts, the lack of UDS reflects the absence of immunodetectable pyrimidine dimers.     

Therapy burden, drug resistance, and optimal treatment regimen for cancer chemotherapy

Email: boldrini{at}ime.unicamp.brAuthor to whom correspondence should be addressed. Email: michel{at}Incc.br Three nonlinear models of tumour cell growth under continuousdelivery of cycle nonspecific anticancer agents are studied.A dynamical optimization problem with the objective of minimizingthe final level of tumour cells is posed for these mathematicalsetups. The simplest setup does not possess toxicity constraints,whereas the other setups contain a dynamical equation describingthe therapy burden as a toxicity criterion. In addition, thethird setting contains the dynamics of drug resistant cells.A discussion conceming the optimal strategies of the respectivemodels is performed.     

INDUCED OSCILLATIONS GENERATED BY PROTECTIVE THRESHOLD POLICIES IN THE MANAGEMENT OF EXPLOITED POPULATIONS

Abstract Management and conservation of exploited populations have been a central issue in theoretical and empirical studies. In this work, it is shown that threshold policies can induce cyclic behavior in an otherwise exploited stable population as a consequence of the combination of harvest pressure and excessively protective threshold densities. Moreover, the dynamical outcomes generated by these extremely protective policies may vary according to the initial densities. These results may be of significant concern in conservation as well as in management of exploited population.     

Orientational ordering in some nematogens deviating from the classical rod-shape

Several new laterally substituted liquid crystalline compounds have been synthesized. They have the same main core which contains four rings (two aromatic, two alicyclic) with two lateral substituents introduced on the same side of one of the inner rings. One of the substituents is a 4-X-benzyloxy group (X=CH3,CN,Cl) and the other is a hexyloxy chain. The presence of the lateral aromatic substituent makes these compounds deviate markedly from the classical rod-shape. However, a wide enantiotropic nematic phase is present for all the compounds. The order parameters of the chain and the para -disubstituted aromatic rings were obtained by using a 2D 13C NMR technique with variable angle spinning. The temperature dependence of the order parameters was estimated using 13C chemical shifts with slow spinning of the sample parallel to the magnetic field. The results indicate that the two lateral substituents are more or less folded back along the mesogenic core. Thus, the flexible lateral chain is found to be roughly aligned with the molecular long axis, whereas the para axis of the less flexible aromatic branch makes a considerable angle with the molecular long axis imposed by the core, substantially increasing the mean width of the molecule. The core ordering does not seem to be influenced by the type and position of the substituents. The folding back of the lateral chain and the substantial tilt of the lateral aromatic branch with respect to the core main axis are confirmed by the X-ray structure of a parent compound.     

Tau reconstruction, energy calibration and identification at ATLAS

Tau leptons play a central role in the LHC physics programme, in particular as an important signature in many Higgs boson and supersymmetry searches. They are further used in Standard Model electroweak measurements, as well as detector-related studies like the determination of the missing transverse energy scale. Copious backgrounds from QCD processes call for both efficient identification of hadronically decaying tau leptons, as well as large suppression of fake candidates. A solid understanding of the combined performance of the calorimeter and tracking detectors is also required. We present the current status of the tau reconstruction, energy calibration and identification with the ATLAS detector at the LHC. Identification efficiencies are measured in W ?? ??? events in data and compared with predictions from Monte Carlo simulations, whereas the misidentification probabilities of QCD jets and electrons are determined from various jet-enriched data samples and from Z ?? ee events, respectively. The tau energy scale calibration is described and systematic uncertainties on both energy scale and identification efficiencies discussed.     

Lattice Forces in Heavy Metal Picrates: Structural Characterization of Lead and Mercury Species

Structure determinations for the dimethylsulfoxide (dmso) solvate of lead(II) picrate (picrate = pic = 2,4,6-trinitrophenoxide), formally a centrosymmetric dimer, [Pb₂(dmso)₄(pic)₄], and for unsolvated mercury(I) picrate, a polymer of conventional mercurous dimers, [Hg₂(pic)₂] _n , show that, despite considerable differences in the form of the metal unit, there are remarkable similarities in the mode of coordination of the bridging picrate ligands. In both lattices, parallel arrays of picrate rings can be discerned but appear to be associated with short N…O, O…O or O…C contacts rather than C…C. In the Pb compound, there is also evidence of intramolecular contacts to dmso-S.     

COMPONENT ALLEE EFFECTS AND STAGE‐SPECIFIC PREDATION: A BRIEF INSIGHT INTO CONSERVATION AND BIOLOGICAL CONTROL ISSUES

In this paper, we propose a two‐stage structured population model subject to component Allee effects in fecundity and maturation, and with two disturbances (predation only and harvest and predation) acting on both stages. It is shown that this combination leads to a demographic Allee effect—a characteristic that could be exploited in pest biological control, but on the other hand, it represents a bane in conservation biology. The analysis is performed for disturbances with functional responses type 2 and 3, and the models show that they yield qualitatively similar results. This characteristic is discussed from the species conservation and biological control point of view, together with possible extensions of this work.     

Computation of Flashing Flows In Variable Cross-Section Ducts

A Finite-Volume scheme which enables computing fast transient single phase and two phase flows in variable cross section ducts is presented. The physical modelling relies on the Homogeneous Relaxation Model. The theoretical framework is briefly presented, together with the main ideas of a new approximate Riemann solver. Numerical results confirm the suitability of the present approach.