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Aim To compare the accuracy of predicting an in-hospital fatal outcome for models based on current machine-learning technologies in patients with ischemic heart disease (IHD) after coronary bypass (CB) surgery.Material and methods A retrospective analysis of 866 electronic medical records was performed for patients (685 men and 181 women) who have had a CB surgery for IHD in 2008–2018. Results of clinical, laboratory, and instrumental evaluations obtained prior to the CB surgery were analyzed. Patients were divided into two groups: group 1 included 35 (4 %) patients who died within the first 20 days of CB, and group 2 consisted of 831 (96 %) patients with a beneficial outcome of the surgery. Predictors of the in-hospital fatal outcome were identified by a multistep selection procedure with analysis of statistical hypotheses and calculation of weight coefficients. For construction of models and verification of predictors, machine-learning methods were used, including the multifactorial logistic regression (LR), random forest (RF), and artificial neural networks (ANN). Model accuracy was evaluated by three metrics: area under the ROC curve (AUC), sensitivity, and specificity. Cross validation of the models was performed on test samples, and the control validation was performed on a cohort of patients with IHD after CB, whose data were not used in development of the models.Results The following 7 risk factors for in-hospital fatal outcome with the greatest predictive potential were isolated from the EuroSCORE II scale: ejection fraction (EF) Conclusion The use of current machine-learning technologies allowed developing a novel algorithm for selection of predictors and highly accurate models for predicting an in-hospital fatal outcome after CB.

The theory of Bloch electron dynamics for carriers in homogeneous electric and magnetic fields of arbitrary time dependence is developed in the framework of the Liouville equation. The Wigner distribution function (WDF) is determined from the single particle density matrix in the ballistic regime, i.e., collision effects are excluded. The single particle transport equation is established with the electric field described in the vector potential gauge, and the magnetic field is treated in the symmetric gauge. The general approach is to employ the accelerated Bloch state representation (ABR) as a basis so that the dependence upon the electric field, including multiband Zener tunneling, is treated exactly. In the formulation of the WDF, we transform to a new set of variables so that the final WDF is gauge invariant and is expressed explicitly in terms of the position, kinetic momentum, and time. The methodology for developing the WDF is illustrated by deriving the exact WDF equation for free electrons in homogeneous electric and magnetic fields. The methodology is then extended to the case of electrons described by an effective Hamiltonian corresponding to an arbitrary energy band function. In treating the problem of Bloch electrons in a periodic potential, the methodology for deriving the WDF reveals a multiband character due to the inherent nature of the Bloch states. In examining the single-band WDF, it is found that the collisionless WDF equation matches the equivalent Boltzmann transport equation to first order in the magnetic field. These results are necessarily extended to second order in the magnetic field by employing a unitary transformation that diagonalizes the Hamiltonian using the ABR to second order. The work includes a discussion of the multiband WDF transport analysis and the identification of the combined Zener-magnetic field induced tunneling., Comment: 23 pages

SVX4 is the new silicon strip readout IC designed to meet the increased radiation tolerance requirements for Run IIb at the Tevatron collider. Devices have been fabricated, tested, and approved for production. The SVX4 design is a technology migration of the SVX3D design currently in use by CDF. Whereas SVX3D was fabricated in a 0.8-/spl mu/m radiation-hard process, SVX4 was fabricated in a standard 0.25-/spl mu/m mixed-signal CMOS technology using the "radiation tolerant by design" transistor topologies devised by the CERN RD49 collaboration. The specific cell layouts include digital cells developed by the ATLAS Pixel group, and full-custom analog blocks. Unlike its predecessors, the new design also includes the necessary features required for generic use by both the CDF and D0 experiments at Fermilab. Performance of the IC includes >20 MRad total dose tolerance, and /spl sim/2000 e-rms equivalent input noise charge with 40-pF input capacitance, when sampled at 132-ns period with an 80-ns preamp risetime. At the nominal digitize/readout rate of 106/53 MHz, the 9 mm/spl times/6.3 mm die dissipates /spl sim/2 mW/channel average at 2.5 V. A review of typical operation, details of the design conversion process, and performance measurements are covered.

CMOS monolithic active pixel sensors are currently being established as the technology of choice for new generation digital imaging systems in Transmission Electron Microscopy (TEM). A careful sensor design that couples μm-level pixel pitches with high frame rate readout and radiation hardness to very high electron doses enables the fabrication of direct electron detectors that are quickly revolutionizing high-resolution TEM imaging in material science and molecular biology. This paper will review the principal characteristics of this novel technology and its advantages over conventional, optically-coupled cameras, and retrace the sensor development driven by the Transmission Electron Aberration corrected Microscope (TEAM) project at the LBNL National Center for Electron Microscopy (NCEM), illustrating in particular the imaging capabilities enabled by single electron detection at high frame rate. Further, the presentation will report on the translation of the TEAM technology to a finer feature size process, resulting in a sensor with higher spatial resolution and superior radiation tolerance currently serving as the baseline for a commercial camera system.

This paper presents the characterization of a CMOS monolithic pixel sensor prototype optimized for direct detection in Transmission Electron Microscopy (TEM). The sensor was manufactured in a deep-submicron commercial CMOS process and features pixels of 5 μ m pitch. Different pixel architectures have been implemented in the test chip, and the best performing architecture has been selected from a series of tests performed with 300 keV electrons. Irradiation tests to high electron doses have also been performed in order to estimate device lifetime.

Aim The aim of this study was to determine the number of successful establishments of the invasive Argentine ant outside native range and to see whether introduced supercolonies have resulted from single or multiple introductions. We also compared the genetic diversity of native versus introduced supercolonies to assess the size of the propagules (i.e. the number of founding individuals) at the origin of the introduced supercolonies. Location Global. Methods We used mitochondrial DNA (mtDNA) markers and microsatellite loci to study 39 supercolonies of the Argentine ant Linepithema humile covering both the native (n = 25) and introduced range (n = 14). Results Data from three mitochondrial genes and 13 nuclear microsatellites suggest that the introduced supercolonies studied originated from at least seven founding events out of the native area in Argentina (primary introductions). The distribution of mtDNA haplotypes also suggests that supercolonies in the introduced range each derive from a single source supercolony and that one of these source supercolonies has been particularly successful, being the basis of many introduced populations spread across the world. Comparison of the genetic diversity of supercolonies based on the five most diverse loci also revealed that native and introduced supercolonies have greatly overlapping ranges of diversity, although the genetic diversity is on average less in introduced than in native supercolonies. Main conclusions Both primary introductions (from the native range) and secondary introductions (from sites with established invasive supercolonies) were important in the global expansion of the Argentine ant. In combination with the similar social organization of colonies in the native and introduced range, this indicates that invasiveness did not evolve recently as a unique and historically contingent event (e.g. reduction of genetic diversity) in this species. Rather, native L. humile supercolonies have characteristics that make them pre-adapted to invade new - and in particular disturbed - habitats when given the opportunity. These results have important implications with regard to possible strategies to be used to control invasive ants.

A method is discussed for the determination of single particle atomic expectation values, (W), accurate to 0(δ2) if an approximate wave function, Ψ0T, correct to 0(δ) is employed. The technique involves writing the expectation values as a functional of Ψ0T, the Hamiltonian, and a subsidiary function which is the solution of a differential equation, derived from certain self-consistency considerations, involving both W and Ψ0T. Analytic calculations for , n = 2, 1, - 1, -2, and the electron density at the origin p(0) have been performed for the ground state of the helium isoelectronic sequence using energy-optimized simple products of hydrogenic states as the approximate wave function. For 1 ≤ Z ≥ 8, our results have an accuracy equivalent to a Hartree-Fock calculation when compared to both the results of Pekeris and a 204 term variational perturbation treatment. The least accurate of our results are for which for He and Li+ are in error by 1% and 0.3% respectively and in all cases this error is further diminished with each increase in the atomic number.

The analytical method developed by the authors for the determination of the expectation value of single-particle operators W = Σi W(ri) correct to second order is employed to obtain an analytic expression for the coherent atomic scattering factor F(k) for the ground state of the helium isoelectronic sequence valid for all values of momentum transfer. The trial wave function ϕot employed is an energy minimized Hartree product of hydrogenic states. For helium the results for the form factor are within 1.2% of the highly accurate values calculated using a 120 parameter configuration interaction wave function and have an accuracy equivalent to that of an analytical Hartree-Fock treatment. This error is further reduced as the atomic number is increased. The calculations are extended to the infinite momentum transfer range and the accuracy of the results are studied in this limit by employing the Kato electron-nucleus cusp condition for the exact ground state wave function of two-electron atomic systems. We observe that in the infinite momentum transfer limit our results for helium are in error by 0.57% and that this error is further diminished for each successive element of the isoelectronic sequence. In addition, we note that the cusp condition is exactly satisfied and is independent of the variational parameter employed in the trial wave function.

Analyses of population genetic variation in invasive species can provide information on the history of the invasions, breeding systems, and gene flow patterns. We surveyed genetic variation in both social forms of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), throughout the species' introduced range in the United States, to learn how the unique breeding biology of each form shapes genetic structure at various scales, to discern genetic footprints of the invasion process, and to reconstruct the origin and spread of each form. Consistent with more limited earlier studies, our analyses revealed significant local mitochondrial DNA (mtDNA) differentiation in the polygyne (multiple colony queens) but not in the monogyne (single colony queen) social form as well as pronounced mtDNA differentiation coupled with weaker nuclear differentiation between sympatric populations of the two forms. At a larger scale, we found no mtDNA but significant nuclear regional differentiation. In general, populations were most similar to other populations of the same social form at their mtDNA genomes. These higher level patterns of structure are consistent with the spread of the ant by long-distance, human-mediated dispersal, with subfounder populations of each form typically established by queens of the same form. Bayesian analyses showed that study populations most distant from the claimed site of entry, Mobile, AL, have diverged most from the hypothetical founder population, consistent with an invasion scenario in which the ants spread outward from Mobile through repeated subfounder events. Several lines of evidence raise the possibility of secondary introductions of S. invicta into the United States.

The gene Gp-9 is believed to have a major effect on colony social organization in fire ants, with the presence of b-like alleles in a colony associated with multiple-queen (polygyne) organization. Queens and workers of polygyne Solenopsis invicta homozygous for the b-like allele designated b suffer reduced viability compared to other genotypes, and bb queens do not survive to become egg-layers. Thus, the b allele effectively acts as a recessive lethal. This allele differs from the remaining b-like alleles (designated b'), as well as all other Gp-9 alleles, by encoding a lysine at position 151 in the protein product, suggesting that this substitution is responsible for its deleterious effects. We tested this hypothesis by comparing frequencies of b'b' and bb homozygotes, first in queens of Solenopsis richteri and S. invicta, then in S. invicta workers from populations polymorphic for the two b-like alleles. We found that almost 20% of S. richteri queens were b'b' homozygotes, compared to the virtual absence of bb homozygotes among S. invicta queens, and that 5-18% of S. invicta workers bore genotype b'b', compared to the apparent lack of bb workers in the same populations. While we cannot entirely rule out involvement of other genes in complete gametic disequilibrium with Gp-9, our data are consistent with the hypothesis that the Lys(151) residue in GP-9 protein confers the deleterious effects of the b allele in homozygous condition, possibly by impairing the protein's function through interference with ligand binding/release or hindrance of dimer formation.

Kinship among group members has long been recognized as a main factor promoting the evolution of sociality and reproductive altruism, yet some ants have an extraordinary social organization, called unicoloniality, whereby individuals mix freely among physically separated nests. This type of social organization is not only a key attribute responsible for the ecological dominance of these ants, but also an evolutionary paradox because relatedness between nestmates is effectively zero. Recently, it has been proposed that, in the Argentine ant, unicoloniality is a derived trait that evolved after its introduction into new habitats. Here we test this basic assumption by conducting a detailed genetic analysis of four native and six introduced populations with five to 15 microsatellite loci and one mitochondrial gene. In contrast to the assumption that native populations consist of family-based colonies with related individuals who are aggressive toward members of other colonies, we found that native populations also form supercolonies, and are effectively unicolonial. Moreover, just as in introduced populations, the relatedness between nestmates is not distinguishable from zero in these native range supercolonies. Genetic differentiation between native supercolonies was very high for both nuclear and mitochondrial markers, indicating extremely limited gene flow between supercolonies. The only important difference between the native and introduced populations was that supercolonies were several orders of magnitude smaller in the native range (25-500 m). This size difference has important consequences for our understanding of the evolution and stability of unicolonial structures because the relatively small size of supercolonies in the native range implies that competition can occur between supercolonies, which can act as a break on the spread of selfish mutants by eliminating supercolonies harboring them.

The main building block and readout unit of the planned CDF Run IIb silicon detector is a "stave," a highly integrated mechanical, thermal, and electrical structure. One of its characteristic features is a copper-on-Kapton flexible cable for power, high voltage, data transmission, and control signals that is placed directly below the silicon microstrip sensors. The dense packaging makes deadtime-less operation of the stave a challenge since coupling of bus cable activity into the silicon sensors must be suppressed efficiently. The stave design features relevant for deadtime-less operation are discussed. The electrical performance achieved with stave prototypes is presented.

Fermilab plans to deliver 5-15 fb(-1) of integrated luminosity to the CDF and D0 experiments. The current inner silicon detectors at CDF (SVXIIa and L00) will not tolerate the radiation dose associated with high-luminosity running and will need to be replaced. A new readout chip (SVX4) has been designed in radiation-hard 0.25 mum, CMOS technology. Single-sided sensors are arranged in a compact structure, called a stave, with integrated readout and cooling svstems. This paper describes the general design of the Run IIb system, testing results of prototype electrical components (staves), and prototype silicon sensor performance before and after irradiation. (C) 2003 Elsevier B.V. All rights reserved.

A major distinction in the social organization of ant societies is the number of reproductive queens that reside in a single colony. The fire ant Solenopsis invicta exists in two distinct social forms, one with colonies headed by a single reproductive queen and the other containing several to hundreds of egg-laying queens. This variation in social organization has been shown to be associated with genotypes at the gene Gp-9. Specifically, single-queen colonies have only the B allelic variant of this gene, whereas multiple-queen colonies always have the b variant as well. Subsequent studies revealed that Gp-9 shares the highest sequence similarity with genes encoding pheromone-binding proteins (PBPs). In other insects, PBPs serve as central molecular components in the process of chemical recognition of conspecifics. Fire ant workers regulate the number of egg-laying queens in a colony by accepting queens that produce appropriate chemical signals and destroying those that do not. The likely role of GP-9 in chemoreception suggests that the essential distinction in colony queen number between the single and multiple-queen form originates from differences in workers' abilities to recognize queens. Other, closely related fire ant species seem to regulate colony social organization in a similar fashion.

Little is known about the genetic foundations of colony social organization. One rare example in which a single major gene is implicated in the expression of alternative social organizations involves the presumed odorant-binding protein gene Gp-9 in fire ants. Specific amino acid substitutions in this gene invariably are associated with the expression of monogyny (single queen per colony) or polygyny (multiple queens per colony) in fire ant species of the Solenopsis richteri clade. These substitutions are hypothesized to alter the abilities of workers to recognize queens and thereby regulate their numbers in a colony. We examined whether these same substitutions underlie the monogyny/polygyny social polymorphism in the distantly related fire ant S. geminata. We found that Gp-9 coding region sequences are identical in the polygyne and monogyne forms of this species, disproving our hypothesis that one or a few specific amino acid replacements in the protein are necessary to induce transitions in social organization in fire ants. On the other hand, polygyne S. geminata differs genetically from the monogyne form in ways not mirrored in the two forms of S. invicta, a well-studied member of the S. richteri clade, supporting the conclusion that polygyny did not evolve via analogous routes in the two lineages. Specifically, polygyne S. geminata has lower genetic diversity and different gene frequencies than the monogyne form, suggesting that the polygyne form originated via a founder event from a local monogyne population. These comparative data suggest an alternative route to polygyny in S. geminata in which loss of allelic variation at genes encoding recognition cues has led to a breakdown in discrimination abilities and the consequent acceptance of multiple queens in colonies.

Polygyne (multiple queen) colony social organization in the Þre ant Solenopsis invicta Buren is always associated with the presence of a particular class of alleles at the gene Gp-9. We used diagnostic polymerase chain reaction assays capable of distinguishing these alleles to determine the location of polygyne populations in the native South American range of this species. We found that polygyny occurs in a mosaic pattern with respect to the more common monogyne (single queen) social form, a pattern superÞcially similar to that seen in the introduced range in the United States. However, polygyny appears to be relatively restricted in its geographical prevalence in the native range compared with the introduced range. This difference may stem from higher dispersal rates in the introduced range, which are associated with greater opportunities for human-mediated transport of mated queens or colony fragments. On the basis of our distributional data and results from other studies, the southern part of the native range of S. invicta, particularly northeastern Argentina, is emerging as the most likely geographic source of the founders of the U.S. population.

Screens of a library of genomic DNA made during a recent study of the fire ant Solenopsis invicta revealed the presence of three distinct types of transposable elements (TEs). Two of the recovered sequences showed a high similarity to long-terminal repeat (LTR) retrotransposons, while the third showed a high homology to mariner elements. To investigate the distribution and relationships of mariners in related ants, we PCR-amplified these elements from additional Solenopsis species. Phylogenetic analyses showed that they form a single group within the mauritiana subfamily that is part of a larger clade derived from hymenopteran species. We also present partial sequence data for the two LTR-retrotransposons and describe their phylogenetic affinities.

Details concerning the design, fabrication and performance of the STAR Barrel Electromagnetic Calorimeter are presented.

We present a compact, configurable scintillation camera employing a maximum of 16 individual 64-pixel imaging modules resulting in a 1024-pixel camera covering an area of 9.6 cm/spl times/9.6 cm. The 64-pixel imaging module consists of optically isolated 3 mm/spl times/3 mm/spl times/5 mm CsI(Tl) crystals coupled to a custom array of Si p-i-n photodiodes read out by a custom integrated circuit (IC). Each imaging module plugs into a readout motherboard that controls the modules and interfaces with a data acquisition card inside a computer. For a given event, the motherboard employs a custom winner-take-all IC to identify the module with the largest analog output and to enable the output address bits of the corresponding module's readout IC. These address bits identify the "winner" pixel within the "winner" module. The peak of the largest analog signal is found and held using a peak detect circuit, after which it is acquired by an analog-to-digital converter on the data acquisition card. The camera is currently operated with four imaging modules in order to characterize its performance. At room temperature, the camera demonstrates an average energy resolution of 13.4% full-width at half-maximum (FWHM) for the 140-keV emissions of /sup 99m/Tc. The system spatial resolution is measured using a capillary tube with an inner diameter of 0.7 mm and located 10 cm from the face of the collimator. Images of the line source in air exhibit average system spatial resolutions of 8.7- and 11.2-mm FWHM when using an all-purpose and high-sensitivity parallel hexagonal holes collimator, respectively. These values do not change significantly when an acrylic scattering block is placed between the line source and the camera.

An integrated circuit (IC) providing 64 channels of low-noise signal processing electronics in an 8/spl times/8 pixel arrangement has been developed as part of an integrated silicon detector array for high count-rate X-ray spectroscopy applications. Each pixel features low-noise charge integration, programmable peaking time and gain, and an output driver. The 8/spl times/8 pixel IC builds upon our previous development of the XPS chip, a 1-dimensional (1-D) preamplifier-shaper IC for linear silicon detector arrays. The new pixel design features significant improvements to the shaper and output driver stages, including digital peaking time and gain selection, and a low-power charge driver/receiver design. When operated with a cooled, low-capacitance silicon detector, an energy resolution of /spl sim/210 eV FWHM was obtained for 5.89 keV X-rays. The power dissipation is /spl sim/6 mW per pixel at a supply voltage of 3.3 V.

One of the greatest challenges in robotics is to create machines that are able to interact with unpredictable environments in real time. A possible solution may be to use swarms of robots behaving in a self-organized manner, similar to workers in an ant colony. Efficient mechanisms of division of labour, in particular series-parallel operation and transfer of information among group members, are key components of the tremendous ecological success of ants. Here we show that the general principles regulating division of labour in ant colonies indeed allow the design of flexible, robust and effective robotic systems. Groups of robots using ant-inspired algorithms of decentralized control techniques foraged more efficiently and maintained higher levels of group energy than single robots. But the benefits of group living decreased in larger groups, most probably because of interference during foraging. Intriguingly, a similar relationship between group size and efficiency has been documented in social insects. Moreover, when food items were clustered, groups where robots could recruit other robots in an ant-like manner were more efficient than groups without information transfer, suggesting that group dynamics of swarms of robots may follow rules similar to those governing social insects.

Teams with up to 12 real robots were given the mission to maintain the energy stocked in their nest by collecting food-items. To achieve this mission efficiently, we implemented a simple and decentralised task allocation mechanism based on individual activation-thresholds, i.e. the energy level of the nest under which a given robot decides to go collect food-items. The experiments show that such a mechanism — already studied among social insects — results in an efficient dynamical task allocation even under the noisy conditions prevailing in real experiments. Experiments with different team sizes were carried out to investigate the effect of team size on performance and risk of mission failure.

A large microsatellite survey of fire ants of both social forms (monogyne and polygyne) from both the native and introduced ranges (Argentina and the U.S.A.) revealed surprisingly high levels of triploidy (12%) in non-reproductive females from an introduced polygyne population in Georgia, U.S.A. Triploid females were not detected among reproductive (egg-laying) queens from this population, among females from monogyne populations in the introduced range or among females of either social form from the native range. The results of complementary analyses with allozyme markers were highly concordant with the individual microsatellite ploidy designations and confirmed the general patterns in the distribution of triploidy observed with microsatellites. Triploidy in the Georgia polygyne population is hypothesized to be linked to the high frequency of diploid males in this population; although most such males are sterile, 2.4% were found to possess functional reproductive tracts and presumably produce diploid sperm. Mating of such males with polygyne queens is expected to give rise to triploid females at levels close to those observed. Diploid males are absent in monogyne populations and uncommon in the introduced range, thus explaining the lack of triploid females in samples from these sources. The absence of triploid reproductive queens in the Georgia polygyne population may result from subviability of triploid queens or execution of such queens by workers. Our results suggest that triploid females of social Hymenoptera may be more common than appreciated and are most likely to be found in populations with substantial numbers of fertile diploid males.

Populations with diploid and triploid individuals co-occur in various plant and animal species, but detecting their relative frequencies is problematic. Microsatellite markers can be used to detect triploids that have three distinct alleles at a given locus, but cannot identify triploids that are partially or fully homozygous (i.e., possessing two or three copies of the same allele). Detection of partially homozygous triploids is sometimes possible with allozymes if no dosage compensation occurs. However, the inference of triploidy from uneven band intensities is not always reliable, making it difficult to estimate the actual proportion of triploids in a population. We present an iterative mathematical procedure for estimating the overall proportion of triploids from allozyme and microsatellite data. This method also estimates corrected allele frequencies by accounting for potentially hidden cases of homozygosity occurring in triploid individuals with multiple copies of an allele.

The theory of Bloch electron dynamics in spatially homogeneous electric fields of arbitrary strength and time dependence is presented. In the formalism, the electric field is described through the use of the vector potential, and the instantaneous eigenstates of the Hamiltonian are used as basis stated to depict the Bloch dynamics and quantum properties. This approach leads to a natural indication of high- and low-filed limits, and allows for the inclusion of general band-structure effects and multiband coupling in the quantum dynamics. A variety of dc electric field effects, such as Bloch oscillations, Zener tunneling, and localization, and ac electric field effects, such as interband absorption, and phonon-assisted transport, will be discussed.

The value of Becke's exact-exchange-mixing parameter is determined by purely theoretical considerations by requiring that the ionization energy theorem (−ϵm=I) be satisfied as closely as possible. This method is applied to the case in which the density functional theory approximation to the exchange–correlation energy functional is given by the local spin density approximation with Perdew–Zunger self-interaction correction, which leads to the correct−1/r long-range behavior of the exchange– correlation potential and consequently to accurate highest occupied orbital energy eigenvalues, ϵm. Employing this approach on atoms with Z≤20 self-consistent optimized-effective potential calculations results in the determination of the mixing parameter, which is in good agreement with that of Becke, and the resulting calculations of the ionization potentials and electron affinities for these atoms are on average within 0.10 eV of the experimental results. In addition, the resulting correlation potential for both neon and argon exhibits a positive bump in the region of maximum density of the highest lying p states. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 255–264, 1998

We describe genetic structure at various scales in native populations of the fire ant Solenopsis invicta using two classes of nuclear markers, allozymes and microsatellites, and markers of the mitochondrial genome. Strong structure was found at the nest level in both the monogyne (single queen) and polygyne (multiple queen) social forms using allozymes. Weak but significant microgeographic structure was detected above the nest level in polygyne populations but not in monogyne populations using both classes of nuclear markers. Pronounced mitochondrial DNA (mtDNA) differentiation was evident also at this level in the polygyne form only. These microgeographic patterns are expected because polygyny in ants is associated with restricted local gene flow due mainly to limited vagility of queens. Weak but significant nuclear differentiation was detected between sympatric social forms, and strong mtDNA differentiation also was found at this level. Thus, queens of each form seem unable to establish themselves in nests of the alternate type, and some degree of assortative mating by form may exist as well. Strong differentiation was found between the two study regions usinga all three sets of markers. Phylogeographic analyses of the mtDNA suggest that recent limitations on gene flow rather than longstanding barriers to dispersal are responsible for this large-scale structure.

The integral equation for the optimized effective potential (OEP) is utilized in a compact form from which an accurate OEP solution for the spin-unrestricted exchange-correlation potential, Vxcσ, is obtained for any assumed orbital-dependent exchange-correlation energy functional. The method extends beyond the Krieger-Li-Iafrate (KLI) approximation toward the exact OEP result. The compact nature of the OEP equation arises by replacing the integrals involving the Green's function terms in the traditional OEP equation by an equivalent first-order perturbation theory wavefunction often referred to as the "orbital shift" function. Significant progress is then obtained by solving the equation for the first order perturbation theory wavefunction by use of Dalgarno functions which are determined from well known methods of partial differential equations. The use of Dalgarno functions circumvents the need to explicitly address the Green's functions and the associated problems with "sum over states" numerics; as well, the Dalgarno functions provide ease in dealing with inherent singularities arising from the origin and the zeros of the occupied orbital wavefunctions. The Dalgarno approach for finding a solution to the OEP equation is described herein, and a detailed illustrative example is presented for the special case of a spherically symmetric exchange-correlation potential. For the case of spherical symmetry, the relevant Dalgarno function is derived by direct integration of the appropriate radial equation while utilizing a user friendly method which explicitly treats the singular behavior at the origin and at the nodal singularities arising from the zeros of the occupied states. The derived Dalgarno function is shown to be an explicit integral functional of the exact OEP Vxcσ, thus allowing for the reduction of the OEP equation to a self-consistent integral equation for the exact exchange-correlation potential; the exact solution to this integral equation can be determined by iteration with the natural zeroth order correction given by the KLI exchange-correlation potential. Explicit analytic results are provided to illustrate the first order iterative correction beyond the KLI approximation. The derived correction term to the KLI potential explicitly involves spatially weighted products of occupied orbital densities in any assumed orbital-dependent exchange-correlation energy functional; as well, the correction term is obtained with no adjustable parameters. Moreover, if the equation for the exact optimized effective potential is further iterated, one can obtain the OEP as accurately as desired.

We have investigated the accuracy of the local-spin-density approximation with orbital-density-dependent self-interaction correction (LSDSIC) as proposed by Perdew and Zunger within a Kohn-Sham approach in which electrons with a given spin projection all move in a single optimized effective potential (OEP). We have also studied the accuracy of the Krieger-Li-Iafrate (KLI) approximation to the OEP for the same energy functional in order to assess its applicability to systems in which the integral equation for the OEP cannot be reduced to a one-dimensional problem, e.g., molecules. Self-consistent Kohn-Sham LSDSIC calculations have been performed for atoms with atomic number Z=1--20 in the exchange-only case for the total energy, the highest-occupied orbital energy ${\mathrm{\ensuremath{\epsilon}}}_{\mathit{m}}$, and the expectation value of ${\mathit{r}}^{2}$. In addition, the structure of the resulting exchange potential is examined and compared with the exact exchange-only density-functional theory (OEP method with Hartree-Fock exchange-energy functional) results. Furthermore, we display ${\mathrm{\ensuremath{\epsilon}}}_{\mathit{m}}$, the ionization potential I, and the electron affinity A when both exchange and correlation energy effects are included. Finally, we also consider the results of evaluating the LSDSIC energy functional by employing the exact (in the central-field approximation) single particle orbitals as proposed by Harrison. We find that the LSDSIC energy functional generally leads to calculated values that are superior to those provided by the LSD approximation and that the KLI approximation yields results in excellent agreement with the corresponding exact OEP results for this energy functional. In particular, quantities strongly related to the behavior of the valence electrons are nearly identical in both the OEP and KLI calculations, i.e., the difference between the 〈${\mathit{r}}^{2}$〉 and ${\mathrm{\ensuremath{\epsilon}}}_{\mathit{m}}$ is less than 0.2% on average, while the difference between the calculated I is less than 0.2 millihartree on average with the corresponding difference of only 0.1 millihartree for A. \textcopyright{} 1996 The American Physical Society.

Available approximations to Exc[{nσ}], the exchange-correlation energy functional of spin-density-functional theory, do not include self-interaction corrections (SIC). This leads to Kohn–Sham (KS) potentials, Vxcσ, that fail to satisfy some important analytic properties known to be exhibited by the exact potential. To resolve these difficulties, we consider a KS theory for orbital-dependent exchange-correlation energy functionals that explicitly includes SIC. Recent work by Krieger, Li, and lafrate (KLI), which considers the analytic properties of the spin-polarized optimized effective potentials (OEP), V, i.e., the KS potentials corresponding to Exc = Exc[{ϕiσ,}], is reviewed as well as the properties of VxcσKLI, an easily calculated approximation to the exact result which, unlike Vxcσ0, can be employed for systems of arbitrary symmetry. In addition, we compare the results of the exact and approximate OEP calculation of the properties of the ground state of atoms and singly charged negative ions in the exchange-only case in which Ex = ExHF [{ϕiσ}] where HF = Hartree–Fock. We conclude that V maintains most of the important analytic properties of V, and provides an excellent numerical approximation to the exact result. We also give detailed consideration to the calculation of the ionization potential, I, and the electron affinity, A, in the exchange-only approximation for atoms with Z ≤ 20. We find that the KLI results for both I and A are always within 0.1 milli-au of the exact KS results, whereas both the local spin density (LSD) approximation and the Becke exchange only energy functional lead to deviations which on average are two orders of magnitude larger and significantly exceed the criterion for quantum chemistry accuracy. Finally, using the KLI method for orbital dependent Exc, we compare the KS results for I and A for Z ≤ 20 with the experimental values by employing various approximations for Exc[{ϕiσ] including: (1) HF exchange with LSD correlation with SIC, (2) LSD approximation for exchange and correlation with SIC, (3) the conventional spin density LSD approximation, and (4) the Becke exchange-energy functional with LSD correlation. In addition, we examine how closely the ionization theorem for ∈m, the energy eigenvalue for the highest occupied orbital, is satisfied in these approximations. © 1995 John Wiley & Sons, Inc.

A first prototype of the SVX4 readout IC with enclosed transistor layout for radiation tolerance has been fabricated in a commercial 0.25 μm bulk CMOS process. The SVX4 is intended to instrument the CDF and D0 Run IIB silicon strip detector upgrades at Fermilab. The design and test results are discussed.

This work presents the design and characterization of a monolithic active pixel sensor manufactured in a commercial 65 nm CMOS process. The chip is the first prototype of our third generation development of CMOS pixel sensors as direct detectors for Transmission Electron Microscopy, and follows previous designs manufactured in 0.35 μm and 0.18 μm processes. The sensor features square pixels of 2.5 μm pitch, arrayed on a 400×400 pixel matrix and subdivided in four sections implementing different layouts for the charge collecting diode and the readout transistors. The paper will present results from the characterization performed in the laboratory and in an electron microscope, including the evaluation of the sensor performance after irradiation to a 200 Mrad dose, and compare them to those obtained on the previous sensors.

Because of the inherent moisture and large particle size of wood used in the Forest Products Industry, there has been regional interest in exploring the feasibility of processing wood, cellulose, and other such related materials using microwave dielectric-loss heating. A research project was undertaken in the late 1970’s to determine the important variables altering the rate of microwave-induced reactions of this polymeric material. The research presented dates from that period. Reaction proudcts were measured in detail and some optimization of the coupling of the microwave energy to the large particles was studied. Results and principal findings at the time of the study are presented in this paper as well as two papers by the author in the cited literature. Suggestions for future directions for this type of study are also presented.

This work presents the development of radiation-hard CMOS monolithic pixel sensors as direct electron detectors for high resolution, fast dynamic imaging in Transmission Electron Microscopy. The R&D path from small scale prototypes to megapixel, reticle size sensors manufactured in 0.35 and 0.18 µm commercial CMOS processes is briefly reviewed. Design challenges and solutions are highlighted, with reporting on the achieved imaging performance and radiation hardness of sensors that can ultimately achieve readout rates as high as 6.4 gigapixels/s. Further, we will report on the latest search for an improved pixel architecture and layout, and introduce the evaluation of a first prototype sensor manufactured in a 65 nm CMOS process.

A 1M- and a 4M-pixel monolithic CMOS active pixel sensor with 9.5x9.5 micron^2 pixels have been developed for direct imaging in transmission electron microscopy as part of the TEAM project. We present the design and a full characterisation of the detector. Data collected with electron beams at various energies of interest in electron microscopy are used to determine the detector response. Data are compared to predictions of simulation. The line spread function measured with 80 keV and 300 keV electrons is (12.1+/-0.7) micron and (7.4+/-0.6) micron, respectively, in good agreement with our simulation. We measure the detection quantum efficiency to be 0.78+/-0.04 at 80 keV and 0.74+/-0.03 at 300 keV. Using a new imaging technique, based on single electron reconstruction, the line spread function for 80 keV and 300 keV electrons becomes (6.7+/-0.3) micron and (2.4+/-0.2) micron, respectively. The radiation tolerance of the pixels has been tested up to 5 Mrad and the detector is still functional with a decrease of dynamic range by ~30%, corresponding to a reduction in full-well depth from ~39 to ~27 primary 300 keV electrons, due to leakage current increase, but identical line spread function performance., 19 pages, 14 figures, submitted to Nuclear Instruments and Methods A

Exchange-only calculations using the optimized effective potential method and the method developed recently by Krieger, Li and Iafrate are performed for negative ions of alkalis, halogens and those with incomplete 2p and 3p shells. Comparisons are made with the results of Hartree—Fock as well as with those obtained by using the method proposed by Harbola and Sahni.

Using simple physical arguments, a local spin-polarized exchange potential, Vxσ, is constructed from the single-particle Hartree–Fock (HF) potentials (generalized Slater method) that reduces to the usual Kohn–Sham (KS) result in the uniform gas limit. Numerical results for 10 closed subshell atoms demonstrate that the total energy calculated employing this Vxσ is closer to the exact KS results than those of other standard exchange approximations with electron densities and highest occupied orbital eigenvalues that closely approximate the HF results.

The $g$ factors and mean lifetimes of several short-lived low-lying states in ${}_{30}^{70}$${\mathrm{Zn}}_{40}$ have been measured using the techniques of projectile Coulomb excitation in inverse kinematics combined with transient magnetic fields and the Doppler-shift attenuation method. The present results have been interpreted within the framework of large-scale shell-model calculations that include the ${g}_{9/2}$ orbital.

This paper presents a new approach to identify the important aspects of packaging. The approach uses experimentally designed concepts dealing with packages, their uses, and their benefits. The concepts comprise "elements," which are short words, pictures, and video clips (short videos lasting 3 to 5 s), combined by an experimental design and presented to the consumer on a computer screen. The consumer rates each combination on acceptance and expected performance. The computer acquires the ratings just after presenting the concept stimulus. The resulting database, comprising concept elements and consumer responses, is analyzed by dummy variable regression analysis to reveal which specific elements drive each consumer-rated attribute, respectively. The results of the analysis yield a model that allows the developer to "optimize" the package concept in order to maximize acceptance and/or to communicate different end benefits while so doing. The paper illustrates the method by an experiment with "baby wipes" (premoistened towelettes).

Lifetimes and g‐factors have been measured for short‐lived low‐lying states in 70Zn using the techniques of projectile Coulomb excitation in inverse kinematics combined with transient magnetic fields and the Doppler‐Shift‐Attenuation‐Method (DSAM). While the g(21+) value was redetermined and found to be consistent with the literature values, all other data are new. The main goal is a better understanding of the influence of the v(g9/2) orbital in this region of the nuclear chart.

The optimized-effective-potential (OEP) method and a method developed recently by Krieger, Li, and Iafrate (KLI) are applied to the band-structure calculations of noble-gas and alkali halide solids employing the self-interaction-corrected (SIC) local-spin-density (LSD) approximation for the exchange-correlation energy functional. The resulting band gaps from both calculations are found to be in fair agreement with the experimental values. The discrepancies are typically within a few percent with results that are nearly the same as those of previously published orbital-dependent multipotential SIC calculations, whereas the LSD results underestimate the band gaps by as much as 40%. As in the LSD---and it is believed to be the case even for the exact Kohn-Sham potential---both the OEP and KLI predict valence-band widths which are narrower than those of experiment. In all cases, the KLI method yields essentially the same results as the OEP.

The g factor of the 2 1 + state in 132 52 Te, E ( 2 1 + ) = 0.9739 MeV , τ = 2.6 ps , was measured by the transient field technique applied to a radioactive beam. The development of an experimental approach necessary for work in radioactive beam environments is described. The result g = 0.28 ( 15 ) agrees with the previous measurement by the recoil-in-vacuum technique, but here the sign of the g factor is measured as well.