cssi/SciSciGPT-SciSciNet huggingface dataset:
Cell fates and fusion in the C. elegans vulval primordium are regulated by the EGL-18 and ELT-6 GATA factors -- apparent direct targets of the LIN-39 Hox protein.

Development of the vulva in C. elegans is mediated by the combinatorial action of several convergent regulatory inputs, three of which, the Ras, Wnt and Rb-related pathways, act by regulating expression of the lin-39 Hox gene. LIN-39 specifies cell fates and regulates cell fusion in the mid-body region, leading to formation of the vulva. In the lateral seam epidermis, differentiation and cell fusion have been shown to be regulated by two GATA-type transcription factors, ELT-5 and -6. We report that ELT-5 is encoded by the egl-18 gene, which was previously shown to promote formation of a functional vulva. Furthermore, we find that EGL-18 (ELT-5), and its paralogue ELT-6, are redundantly required to regulate cell fates and fusion in the vulval primordium and are essential to form a vulva. Elimination of egl-18 and elt-6 activity results in arrest by the first larval stage; however, in animals rescued for this larval lethality by expression of ELT-6 in non-vulval cells, the post-embryonic cells (P3.p-P8.p) that normally become vulval precursor cells often fuse with the surrounding epidermal syncytium or undergo fewer than normal cell divisions, reminiscent of lin-39 mutants. Moreover, egl-18/elt-6 reporter gene expression in the developing vulva is attenuated in lin-39(rf) mutants, and overexpression of egl-18 can partially rescue the vulval defects caused by reduced lin-39 activity. LIN-39/CEH-20 heterodimers bind two consensus HOX/PBC sites in a vulval enhancer region of egl-18/elt-6, one of which is essential for vulval expression of egl-18/elt-6 reporter constructs. These findings demonstrate that the EGL-18 and ELT-6 GATA factors are essential, genetically redundant regulators of cell fates and fusion in the developing vulva and are apparent direct transcriptional targets of the LIN-39 Hox protein.
Characterization of Al wire wedge bonding in power electronics package

Heavy Al wire wedge bonding is a dominant technique for power packages with high voltage. The parameters that impact the wedge bonding quality are mainly bonding process related and material related. Possible failure modes for wire bonding are non-stick of bond wire to the pad, die surface cratering or peeling of pad metallization, and wire break. In this paper, the dielectric damage under the top metal of the silicon die is investigated during the Al wire wedge bonding process for a power module package with 20 mil Al bond wires. FEA 3-D modeling is conducted to simulate the wedge bonding process. The high compressive stress in the dielectric layer is determined to cause the dielectric damage, by comparing the FEA simulation results and practical FA analysis results. To shorten the simulation time, DoEs with FEA 2-D models are performed to study the impact of bonding parameters, thickness of top metal and barrier metal of silicon die, and die tilt. With the guidance of the FEA simulation results, some practical tests are performed for the same parameters. The samples are further analyzed for cross sectional measurements by SEM, chemical etching/de-cap analysis. It is found that the FA results match well with the FEA modeling results.
Mental control after dysphoria: Evidence of a suppressed, depressive bias

Previous research has generally failed to find persistent negative thinking following a depressive episode, suggesting that negative thoughts may simply be by-products of the emotional disturbance. The present research examined the idea that a persistent depressive bias does exist, but it is obscured by thought suppression. Mental control theory suggests that suppressed thoughts can be detected by assessing cognition before the effortful process of distraction is implemented. To test this prediction, formerly dysphoric, chronically dysphoric, and nondysphoric control groups interpreted audio recordings of words—some of which included homophones with emotional alternatives relevant to depression (e.g., weak/week). Participants wrote down each word either immediately or after a 10-sec delay. Although formerly dysphoric individuals did not display a depressive bias in the delayed condition, their immediate responses revealed a depressive bias. As predicted, the emergence of a negative bias was associated with high levels of chronic thought suppression.
MO‐D‐BRB‐06: Effect of Spine Hardware on Intensity Modulated Spinal Sterotactic Radiosurgery Treatment Planning

Purpose: To evaluate the dosimetric effect of spine hardware on intensity modulated spinal sterotactic radiosurgery (IMSRT) treatment planning in Pinnacle. Methods: Monte Carlo(MC) modeling of a clinical 6 MV photon beam was validated with measured Percentage depth dose (PDD) and cross profile for various field sizes. Once validated, MC simulation was used to study the dosimetric effect of a 5‐mm diameter Titanium rod in water for field sizes 2×2, 3×3 and 5×5 cm2. We used MC results to benchmark the Pinnacle treatment planning system on heterogeneity calculations for Titanium rods by overriding the titanium density (4.5 g/cm3) from the default CT‐Density LUT value of 1.75 g/cm3. Finally, Pinnacle was used to study the dosimetric effect of metal implant in IMSRT plan by evaluating the DVH difference between a hardware density of 1.75 and 4.5. In the study, spine hardware was auto contoured and verified with DCR in multiple beam angles. Results: Pinnacle's heterogeneity calculation for titanium rods are accurate when relative electronic density of 4.5 is used based on our benchmark tests using MC simulations. Overriding the hardware density from 1.75 to 4.5 decreases the dose to the part of the target that is blocked by the hardware, which reduces the target volume that receives the prescribed dose. For the 7 cases we evaluated, the reduction of target volume receiving the prescription dose can be as high as 15% with most cases around 4%. The dosimetric effect of the hardware on critical structures, such as cord, is minimal. Conclusions: Our results showed metal implants can cause significant dose perturbations in spine SBRT. Beam angle selection should minimize the presence of the metal hardware in the beam path. Appropriate density values should be used for the hardware to improve the dose calculation accuracy.
Iron-mediated redox modulation in neural plasticity.

The role of iron in brain physiology has focused on the neuropathological, effects due to iron-induced oxidative stress. However, our recent work has established a physiological relationship between the iron-mediated oxidative modification and normal neuronal function. Our results obtained from hippocampal neurons, suggest that iron-generated reactive species oxygen (ROS) are involved in calcium signaling initiated by stimulation of NMDA receptors. This signal is amplified by ryanodine receptors (RyR), a redox- sensitive calcium channel, allowing the phosphorylation and nuclear translocation of ERK1/2. Furthermore, using electrophysiological approaches, we showed that iron is required for basal synaptic transmission and full expression of long-term potentiation, a type of synaptic plasticity. Our data combined suggest that the oxidative effect of iron is critical to activate processes that are downstream of NMDAR activation. Finally, due to the high reactivity of DNA with iron-generated ROS, we hypothesiz...
Identification and Characterization of an Ecto-(lyso)phosphatidic Acid Phosphatase in PAM212 Keratinocytes

Intact PAM212 keratinocytes were found to preferentially degrade exogenous phosphatidic acids (PA) containing short fatty acid chains. The product of this degradation was inorganic phosphate (Pi), suggesting that the enzyme was a phosphatase. Systematic studies using enzymatically synthesized PA and lysophosphatidic acid (lysoPA) demonstrated that the sn-2 fatty acid chain length was the determining factor for suitability of PA as substrate for this cell-associated enzyme. Thus 1-acyl-2-lyso-PA provided the best substrate for this enzyme while long-chain PA were poor substrates. The enzyme was effectively inhibited by NaF and Na3VO4, but was insensitive to inhibitors of alkaline phosphatase or other nonspecific phosphatases. The enzyme activity was solubilized from intact cells by proteinases, such as trypsin and papain, and the reaction product Pi was distributed exclusively in the extracellular medium, suggesting that this (lyso)PA phosphatase is an ectoenzyme. These results unequivocally demonstrated the presence of a (lyso)PA phosphatase located at the cell surface. This novel ectoenzyme may provide a mechanism for the inactivation of the potent bioactive phospholipid, lysoPA.
Variable density fluid reactor network synthesis—Construction of the attainable region through the IDEAS approach

Abstract In this work, the I nfinite D imE nsionA l S tate-space (IDEAS) method and the associated Shrink-wrap algorithm are shown to be applicable to variable density fluid (VDF) reactor network synthesis (RNS). To this end, mathematical models for variable density fluid continuous stirred tank reactors (CSTR) and plug flow reactors (PFR) are shown to give rise to linear operators within the IDEAS framework. Using IDEAS, a variety of convex (linear) objective functions, such as maximization of concentration, yield, selectivity, or economic considerations like minimization of total reactor volume, or attainable region construction can be handled by linear programming. To demonstrate the effectiveness of the proposed method, three reactor network synthesis case studies involving gas phase reactions are presented.
Reliable External Actuation for Full Reachability in Robotic Modular Self-reconfiguration

External actuation in self-reconfigurable modular robots promises to allow modules to shrink down in size. Synchronous external motions promise to allow fast convergence and assembly times. XBot is a modular system that uses synchronous external actuation, but has a limited range of reachable configurations stemming from a single motion primitive of a module rotating about another. This paper proposes to extend the motion primitives by using moves with two modules swinging in a dynamic chain. The feasibility of these motion primitives is proven experimentally. A parameterization of the external actuation motion profiles is explored to define a space of physically valid motion profiles. The larger the space, the more robust the motion primitives will be to inexact initial conditions and to imprecision in the external actuation mechanisms. In addition, this paper proves that a configuration of XBot meta-modules can reach any configuration using just these motion primitives.
An operator inequality and matrix normality

Abstract Let A be a bounded linear operator on a Hilbert space H; denote |A| = (A ∗ A) 1 2 and the norm of x ϵ H by ‖x‖. It is proved that |(Au, v)|≤⦀A| a u‖ ⦀A ∗ | 1−a ‖ ∀u, v ϵ H for any 0 |(Au, v)|≤(|A|u, u) 1 2 (|A ∗ |v,v) 1 2 ∀u, v ϵ H. When H is of finite dimension, it is shown that A must be a normal operator if it satisfies |(Au, u)|≤(|A|u, u) a (|A ∗ |u, u) 1−a ∀u ϵ H for some real number α ≠ 1 2 .
Evolution of an initially columnar vortex terminating normal to a no-slip wall

The early evolution of an initially columnar vortex normal to a solid wall was examined. The vortex was generated by a pair of flaps in a water tank. Detrimental effects from the wall during the vortex generation were avoided by producing the vortex normal to a free surface and subsequently bringing a horizontal plate into contact with the surface. Digital particle image velocimetry (DPIV) measurements of the velocity and vorticity, together with laser induced fluorescence (LIF) visualizations, in a meridional plane revealed a toroidal structure with the appearance of an axisymmetric vortex breakdown bubble. Agreement was found between the measurements and numerical simulations of the axisymmetric Navier–Stokes equations. The results show that the flow in the effusive corner region is dominated by a Bodewadt-type spatially oscillatory boundary layer within the core region and a potential-like vortex boundary layer at large radii. The toroidal structure results from the interaction between these two boundary layers, leading to the roll up of a dominant shear layer within the Bodewadt structure, and does not develop from the columnar vortex itself.
Biological effects on swine and primates due to power frequency and radio frequency radiation

Abstract This paper presents and discusses two important sets of experiments designed to examine the effects of 60 Hz power line frequency radiation on swine and the effects of higher frequency radiation (2.46 and 9.3 GHz) on primates. The basic electromagnetic field equations that apply to field intensity calculations are reviewed. Physical facilities designed to carry out these experiments are described and detailed. Second-generation pigs born and raised inside the right-of-way of 345 kV lines show no observable effects due to their exposure to the HV line's field of influence. These pigs were continually exposed to an electric field of 3.5 − 4.2 kV m −1 , which was the maximum measured and calculated inside the right-of-way. No statistical difference between the control and exposed groups in the rate of pregnancy, litter size, average birth weight and average gain per pig was observed. No malformation was observed in either group. Monkeys exposed to microwave radiation at 2.4 and 9.3 GHz, with a peak power of 40 kW and an average power density of 150 mW cm −2 at the locus of the monkey's head, showed no observable ill effects. In particular, no occular injury was found in the irradiated monkeys. The exposed groups were compared with control animals with respect to social and sexual behavior and were found to be normal in these respects. The fecundity of the exposed animals was the same as that of the controls. Hematological examinations of control and exposed groups showed no significant differences.
Water intake during the development of renal hypertension (2K-1C) in mice.

Abstract SANTOS, C. M., R. F. JOHNSON, T. G. BELTZ, R. L. THUNHORST AND A. K. JOHNSON. Water intake during the development of renal hypertension (2K-1C) in mice. PHYSIOL BEHAV XX(X) XXX-XXX, 2005.-For both practical and methodological reasons, mice have been the most widely employed species for development of transgenic and gene knockin and knockout animals. However, basic behavioral and physiology control and regulatory mechanisms in mice are not well characterized. To broaden our understanding of the processes maintaining body fluid and blood pressure homeostasis in the mouse, the objectives of this study were to evaluate voluntary water, and sodium intakes during the development of renal hypertension and to examine the relationship between hypertension and the quantities of water and salt ingested. In male, C57BL/6J mice, two-kidney, one-clip renal hypertension (2K-1C) was induced, and water and 1.8% NaCl intakes were monitored for 2 weeks. At the end of this period, all animals received arterial catheters for direct recording of blood pressure. The mice that received renal artery clips were sorted into hypertensive (152 ± 4 mm Hg) and normotensive (122 ± 2 mm Hg) groups and were compared to control (117 ± 4 mm Hg) animals that underwent a sham renal clipping procedure. Hypertensive 2K-1C animals had significantly elevated water intake compared to control animals. On most of the postsurgical days, the normotensive 2K-1C animals did not display increased water intake in comparison to the control group. No significant effect was detected for 1.8% saline intake between any of the pairs of groups. In summary, the reduction of blood flow to a single kidney in the 2K-1C model of renal hypertension induces high blood pressure accompanied by sustained hyperdipsia in the mouse.
Evidence That Testosterone Can Suppress Pituitary Gonadotropin Secretion Independently of Peripheral Aromatization

Testosterone (T) was given to normal men with and without the concomitant administration of the aromatase inhibitor, α1-testolactone (Teslac), to examine the role of peripheral aromatization of T in gonadotropin regulation. When T was administered alone by continuous iv infusion (15 mg/day for 4 days), serum T increased 3-fold (P <0.01) and estradiol (E) increased by 50% (P < 0.01). These changes were associated with a 50% decrease in serum LH and FSH concentrations (P < 0.01). When T was infused into men taking Teslac (2000 mg/day), serum T levels doubled (P < 0.01), but E levels did not change (13.4 ± 1.5 vs. 13.5 ± 1.0 pg/ml; P = NS). This pattern of plasma steroids, increased T and unchanged E, was also associated with significantly decreased serum LH and FSH concentrations (14.5 ± 0.4 vs. 8.0 + 0.4 mlU/ml and 9.9 ± 2.5 vs. 5.8 ± 0.1 mlU/ml, respectively; P < 0.01). These data support the hypothesis that T or one of its metabolites can modulate LH and FSH secretion independently of peripheral aromatiz...
Electronic Discrimination of the Effective Thickness of Proportional Counters

We developed and tested a new method of electronic discrimination of the effective thickness of proportional counters and applied this method in a proportional counter camera to adjust its effective aperture, i.e., the combination of counter efficiency and spatial resolution without changing the pinhole aperture, the collimator, or the distance between the subject and camera. The discriminator virtually divides the thickness of the electron drift volume of the camera into two regions and separates the photons detected in each region. Thus, two sets of data are acquired and displayed simultaneously during an exposure: one with good spatial resolution ( 50% for 60-keV photons) but poorer resolution (~5 mm fwhm) using all detected photons. Simultaneous acquisition of two sets of data with different apertures reduces the exposure time in applications, such as nuclear medicine, where a sequence of images often is required to select the optimum aperture for different portions of radioisotope distribution images.
Cultural identities and practices of community

Abstract How can people from different cultures collaborate effectively? How can we imagine joint futures when we come from radically different background? Is cultural diversity an asset or a hindrance to effective collaboration? Is celebrating cultural diversity enough? This essay explores these questions by discussing the problems of convergence and diversity in communities as they relate to possible futures. It examines some examples of successful collaborative ventures, raises numerous problems and questions, and suggests that cultures always reinvent traditions. We can learn to practice community if we learn to practice difference.
Electro-optic search for critical divergence of the charge-density-wave diffusion constant at the onset of depinning

We have used electroreflectance measurements to study charge-density-wave (CDW) polarization dynamics at voltages near the CDW depinning onset $({V}_{\mathrm{on}})$ in the quasi-one-dimensional conductor ${\mathrm{K}}_{0.3}\mathrm{Mo}{\mathrm{O}}_{3}$ (``blue bronze''). For low voltages, where the phase-slip rate is low, it is expected that the polarization relaxation time should be inversely proportional to the CDW diffusion constant, which is expected to diverge at ${V}_{\mathrm{on}}$. At $T=78\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, we observe saturation of the relaxation time at low voltages, suggesting that we are in the low phase-slip limit and allowing us to estimate the noncritical value of the CDW diffusion constant $\mathrm{D}(\ensuremath{\infty})\ensuremath{\sim}0.02\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{2}∕\mathrm{s}$, consistent with the measured phason velocity. At other temperatures, the relaxation time increases with decreasing voltage even at the lowest voltages we could measure. In no case do we observe the expected ``critical speeding up,'' setting an upper limit on the critical region of ${\ensuremath{\mid}V∕{V}_{\mathrm{on}}\ensuremath{-}1\ensuremath{\mid}}_{\text{critical}}l0.06$.
Accumulation of elemental gold on the alga Chlorella vulgaris

Abstract The accumulation of Au(0) by lyophilized preparations of the alga Chlorella vulgaris has been investigated. Gold is bound to the algae upon suspending dried algal cells in solutions containing hydrogen tetrachloroaurate (III). Relative amounts of ionic and atomic algal-bound gold were determined by thiourea extraction. It was found that the amount of algal-bound atomic gold produced from ionic gold increased with time. The effect of algal-bound gold concentration on the rate and extent of gold reduction was observed. It is suggested that at least three different classes of sites are available for gold binding and reduction. The effect of Au(0) accumulation on the binding ability of gold-bound algae was also investigated, and an apparent enhancement of gold binding ability is reported.
A Public Economy Approach to Education: Choice and Co-Production

This paper represents the development of a theoretical framework that can be used to analyze, reform, and design institutional arrangements for the provision and production of educational services. We examine current dichotomous debate over policy and reform proposals for education (hierarchical organization of schools versus market competition between schools) and question whether the nature of the puzzles associated with the provision and production of education warrant such attempts to dichotomize and search for a single, "best" solution. We show the chain of choices potentially affecting educational performance and analyze the institutional incentives and problems of both providing and producing education. We evaluate the likelihood of alternative institutional regimes exacerbating or ameliorating these provision and production problems and argue that one might think of alternative institutional arrangements as being sets of experiments-each having diverse potential for success and failure in overcoming perverse institutional incentives associated with education, but no one institutional design representing the "one best solution."
On the use of the compression split Hopkinson pressure bar to high strain rate

La reponse en compression d'un cuivre, d'un acier et d'alliages de tungstenes a ete obtenue a l'aide de barres d'Hopkinson (split Hopkinson pressure bar) pour des vitesses de deformation variant de 3 × 10 3 a 7 × 10 3 s −1 . L'hypothese de deformation a vitesse constante a ete examinee a l'aide de jauges de contrainte placees sur l'echantillon. Au debut de la deformation plastique, des vitesses de deformation pres de la face avant de l'echantillon superieures a la vitesse de deformation conventionnelle ont ete observees. Cette discontinuite fut confirme a l'aide de la simulation numerique utilisant un hydrocode d'un essai conduit a 7160 s −1
Tensile deformation of fcc Ni as described by an EAM potential

We present the results of a large-scale atomistic study of tensile deformation in a virtual fcc polycrystalline sample with columnar grain structure and a [110] texture. The atomic interaction was described by a volume-dependent central interatomic potential based on first principle calculations and experimental data for fcc Ni. The sample contained nine grains of 40 nm average size, created using a Voronoi construction with a common [110] axis, so that the grain boundaries were all pure tilt with random misorientation angles and crystallographic orientation of the grain boundary plane. We report the stress–strain behavior of the sample and the particular details of dislocation emission and dislocation interaction. Different grain boundaries acted as emission sites at different stresses due to their different local structure and orientation with respect to the applied stress. It was found that boundaries close to a twin misorientation can emit dislocations easily and become closer to the twin misorientati...
Immunoprecipitation of ATP synthetase from beef heart mitochondria.

Summary Antibody against chloroform-treated beef heart mitochondrial F 1 ATPase has been raised in rabbits. The purified antibody inhibits ATPase activity in soluble and membrane bound F 1 ATPase. It immunoprecipitates the entire ATP synthetase complex (F 1 ATPase plus membrane sector) from mitochondria. The polypeptide profile of the immunoprecipitate is similar to that of oligomycin-sensitive ATPase purified according to Berden and Voorn-Brouwer (Biochim. Biophys. Acta 501 , 424–439, 1978).
Localization of galactinol, raffinose, and stachyose synthesis in Cucurbita pepo leaves.

The biochemical pathway of stachyose synthesis was localized by immunocytochemical and 14C-labeling techniques in mature Cucurbita pepo L. leaves. Galactinol synthase (GaS; EC 2.4.1.123), the first unique enzyme in this pathway, was immunolocalized within the intermediary cells of minor veins in conventionally fixed and cryo-fixed, resin-embedded sections using polyclonal anti-GaS antibodies and protein A-gold. Intermediary cells are specialized companion cells with extensive symplastic connections to the bundle sheath. Gold particles were not seen over the non-specialized companion cells of larger veins or over intermediary cells in young leaves prior to the sink-source transition. In another approach to localization, radiolabel was measured in isolated mesophyll tissue and whole tissue of leaves that were lyophilized following a 90-s exposure to 14CO2. Mesophyll, obtained by abrasion of the leaf surface, contained labeled sucrose, galactinol, raffinose and stachyose. However, the latter three labeled compounds constituted a smaller proportion of the neutral fraction than in whole-tissue samples, which also contained minor veins. We conclude that synthesis of galactinol, raffinose, and stachyose occurs in both mesophyll and intermediary cells, predominantly the latter.
Selective modification of rabbit liver fructose bisphosphatase

Abstract Chemical modification of rabbit liver fructose 1,6-bisphosphatase by 5,5′-dithiobis-(2-nitrobenzoic acid) results in thiolation of four highly reactive sulfhydryl groups and a diminished sensitivity to AMP inhibition but not loss of enzyme activity. Ethoxyformylation of the histidine groups of fructose 1,6-bisphosphatase does not result in a sharp loss of activity until at least 4 or 5 of the 13 residues have reacted. Exhaustive formylation does abolish the enzyme's activity. These four most reactive sulfhydryl groups and the one or two least easily modified histidine moieties (those responsible for activity) can be protected against modification by fructose-1,6-P 2 and to a lesser extent by fructose-6-P. The binding of fructose-1,6-P 2 to fructose 1,6-bisphosphatase, however, depends on the presence of structural metal ion since EDTA which removes all endogenous Zn 2+ from the protein prevents binding of fructose-1, 6-P 2 to the enzyme.
Experimental changes in mineral content of juvenile mouse femora.

Juvenile laboratory mice were exposed to hypergravity (8 g), burrowing exercise, swimming to exhaustion, an anabolic steroid, and swimming and an anabolic steroid for 30 days to determine the variability of skeletal mineralization during growth. Changes in mineralization were correlated with changes in bending strength. Experimental mouse femora were loaded to failure in a cantilever beam configuration to determine bending strength, and ashed to determine total mineral content. Between experimental groups, mineral content ranged from 66.0 to 71.2% with the greatest change from the control being a 4.7% decrease in mineralization in the male swimming exercise group (P<0.001). Within two age-matched experiments, the first showed that the group with the greatest decrease in mineralization also had the greatest reduction in bending strength (P<0.001). The second age-matched experiment showed that the group with the greatest reduction in mineralization had bending strength greatly reduced (P<0.001). However, in this experiment, the weakest femora were in the anabolic steroid group that did not have the mineral content reduced. We conclude that (1) mineralization of juvenile mouse femora is extremely variable given varied conditions of exercise or loading; (2) mineralization of normal bone is decreased more often and to a greater extent than increased from normal exercise controls; (3) the decrease in mineralization seen here can decrease bending strength; and (4) the decrease in mineralization seen was not caused by a decrease in mechanical loading but was probably due to a corticosterone-mediated psychological stress response. Therefore, two variables were indicated, one anabolic (mechanical loading) and one catabolic (corticosterone).
A simple method for measuring nitrogen fixation by cell-free enzyme preparations of Clostridium pasteurianum.

Summary A simple, rapid method for measuring nitrogen fixation by cell-free enzyme preparations has been devised. The method comprises the measurement of the ammonia produced during nitrogen fixation and can detect from 3 to 5 μ g nitrogen fixed. The validity of using this technique as a means of measuring nitrogen fixation has been verified by comparing its results with those of similar ones measuring N 15 incorporation.
The Veil of Black: (Un)Masking the Subject of African-American Modernism's Native Son

Entering the master's book: what logic or desire governs the slave's movement into the New World order's privileged site of meaning, power, and presence? Does the slave's coming-into-language mark a moment of possession by anterior systems of signification or of self-apprehension? Does he assume the master's position subversively (thereby preparing some larger upheaval or displacement), or is he inexorably contained in a space already overwritten by a discourse that denies him agency, subjectivity, voice? Somewhere between repetition and irony, representation and parody, incorporation and appropriation, imitation and critique, the slave's writing begins in specular relation to an antagonist that seeks his permanent enclosure. Like the young Ben Franklin earnestly copying-out the cheerful pieties of Addison's Spectator in order to become a "tolerable English writer" (Franklin, 1950:19-20), Douglass might at first seem to accept at face value the master's book as the source and limit of self-understanding, as an exalted scene-of-instruction submission to which yields the signature of authenticity. But just as Franklin cagily inserts acknowledgment of his having altered and "improved" Addison's "method" even as he worked diligently to "correct" his own "faults" in replicating key passages, so Douglass's "hand" the same hand that the master would force to work nigh-unto-death in the fields; to be bound in preparation for brutal whip
Machine vision feedback for on-line correction of manufacturing processes: a control formulation

Abstract We study machine vision post-inspection of productsfor automatic correction of manufacturing processes.The general question is posed as a "discrete-event" stochastic control problem with the camera as the feedback sensor. The physical models employed yieldinsight into design procedures for robustness. 1 Introduction We consider the use of machine vision for the post-inspection of manufactured products and on-line cor-rection of the fabrication process. The scenario con-sists of an assembly line of repetitively manufacturedproducts, followed by an inspection of each with adigital camera. The goal is to feedback product er-ror information to adapt the manufacturing processto improve the quality of subsequent products. SeeFigure 1. Figure 1: Machine Vision Feedback for On-Line Correction To facilitate engineering design, a mathematical description, based on the physics of the problem, isdeveloped. This is divided into three tasks: 1. Finding a precise mathematical description of
Huntite Flowstone in Carlsbad Caverns, New Mexico

Huntite flowstone has recently been discovered in Carlsbad Caverns. This flowstone occurs as a thin, white layer of microcrystals (approximately 1 to 60 micrometers in diameter) which appears buckled and crinkled. The huntite is believed to be precipitating directly from magnesium-rich solutions rather than forming by alteration of preexisting minerals.
Improving Assignment Preference Through Interspersing Additional Problems: Brief Versus Easy Problems

College students were exposed to a control mathematics assignment containing 16 three-digit by two-digit multiplication (3×2) problems and two experimental assignments that contained 16 equivalent 3×2 problems and six additional interspersed problems. On one experimental assignment, 4-digit plus 4-digit problems (4+4) were interspersed. On the other experimental assignment, 2-digit divided by 1-digit with whole number answers problems (2/1) were interspersed. When given a choice, significantly more students choose the 2/1 assignment over the control and 1+4 assignment. Students also ranked the 2/1 sheet as requiring less time to complete than the control or 4+4 assignment but no differences were found on assignment difficulty rankings between the 4+4 and 2/1 assignments. No differences were found on accuracy levels or rates of responding on the target 3×2 problems across assignments. Results showed that interspersing additional problems that take relatively less time to complete may be more important for altering student preference for assignments than interspersing easier problems. Discussion focuses on schedules of reinforcement and resource efficient procedures for increasing student preference for assignment without compromising curricula integrity.
From operational semantics to abstract machines: preliminary results

The operational semantics of functional programming languages is frequently presented using inference rules within simple meta-logics. Such presentations of semantics can be high-level and perspicuous since meta-logics often handle numerous syntactic details in a declarative fashion. This is particularly true of the meta-logic we consider here, which includes simply typed l-terms, quantification at higher types, and b-conversion. Evaluation of functional programming languages is also often presented using low-level descriptions based on abstract machines: simple term rewriting systems in which few high-level features are present. In this paper, we illustrate how a high-level description of evaluation using inference rules can be systematically transformed into a low-level abstract machine by removing dependencies on high-level features of the meta-logic until the resulting inference rules are so simple that they can be immediately identified as specifying an abstract machine. In particular, we present in detail the transformation of two inference rules specifying call-by-name evaluation of the untyped l-calculus into the Krivine machine, a stack-based abstract machine that implements such evaluation. The initial specification uses the meta-logic's b-conversion to perform substitutions. The resulting machine uses de Bruijn numerals and closures instead of formal substitution. We also comment on a similar construction of a simplified SECD machine implementing call-by-value evaluation. This approach to abstract machine construction provides a semantics-directed method for motivating, proving correct, and extending such abstract machines.
Ultrastructural study of the muscle cell surface

In human muscle fibers and using tannic acid—glutaraldehyde fixation and freeze-fracture deepetch rotary replication, trabecular structures connecting the basal lamina to the outer leaflet of the muscle plasma membrane were observed. The trabeculae were noted at all levels of the sarcomere in regions away from the myotendinous junction. It is suggested that trabecular structures connecting the basal lamina to the plasma membrane may be a universal feature of the muscle cell surface.
Determining molecular weight distributions of antigen–antibody complex by quasi‐elastic light scattering

Physiological properties of soluble antigen-antibody (Ag-Ab) complexes depend in part on the size of the complexes. In previous work, the size distribution and structure of model Ag-Ab complexes were determined by electron microscopy. In this study, we used constrained regularization analysis of quasi-elastic light scattering data to estimate molecular weight distributions of model Ag-Ab complexes. A conformational model was necessary to determine appropriate correlations between molecular weight and diffusion coefficient, and to estimate particle structure factors. Porod-Kratky theory proved to be an adequate conformational model for these purposes. The molecular weight distributions determined by constrained regularization compared favorably with distributions obtained either by electron microscopy or by thermodynamic modeling.
Specific adsorption of plant viruses by antibodies coupled to a solid matrix.

Abstract Serologically specific, solid immunoadsorbents for plant viruses were prepared by coupling antibodies to diazotized p -aminobenzylcellulose (PAB). The best conditions for the coupling reaction were pH 5.0, 0.01 M sodium acetate buffer, 0.006 ionic strength for 27 hours at 4 °C. Unfractionated tobacco mosaic (TMV) antiserum, coupled to diazotized PAB, rapidly bound TMV in 0.01 M sodium ethylenediamine tetraacetate (EDTA), pH 8.0, containing 0.15 M NaCl. TMV in phosphate, borate, and glycine buffers was also bound by the conjugated antibodies, but it aggregated more in these buffers than in EDTA. Nonspecific binding of TMV by normal serum proteins was due to weak bonds, while specific binding by antibodies depended on stronger bonds at a limited number of sites. Rate studies suggested that specific binding was a first-order reaction. Frontal analysis of effluents from chromatographic columns packed with immunoadsorbent indicated that TMV was specifically bound by PAB-TMV antibody, and that only a small amount was adsorbed nonspecifically by PAB normal serum or PAB-southern bean mosaic virus antiserum conjugates. Effluents were analyzed by ultraviolet absorption and infectivity assays. Southern bean mosaic virus was freed from a mixture containing TMV by passing it through columns containing PAB-TMV antibody and vice versa. The virus was rapidly eluted from the immunoadsorbent by solutions at pH 2.5–3.0. Elution was more complete from columns than from batches containing the conjugate-antigen complex.
Endogenous burst-organizing potentials in two classes of neurons in the lobster cardiac ganglion respond differently to alterations in divalent ion concentration

1. Crustacean cardiac ganglion neurons generate endogenous burst-organizing potentials termed ‘driver potentials’. In the five motorneurons (‘large cells’) in the system these are slow local potentials with the depolarizing current carried by calcium ions. The existence of similar endogenous potentials in the second class of neurons in the ganglion, the four small ‘pacemaker’ cells, has been postulated primarily on the basis of indirect evidence. The results presented here show that burst-generating mechanisms in the pacemaker neurons and motorneurons respond differently to alterations in the ionic content of the medium, and suggest that driver potentials have different ionic bases in the two cell types. 2. Bursting in isolated lobster (Homarus americanus) cardiac ganglia persists in altered form in salines containing high levels of manganese (Fig. 1) or reduced calcium (Figs. 3, 4). Both of these ionic alterations suppress driver potentials generated by the motorneurons (Fig. 2). Bursts generated in low-calcium salines were of very long duration. 3. In low-calcium salines the long-duration bursts resulted from prolonged and intensified discharge of the small pacemaker neurons; motorneuron activity was suppressed as would be predicted from blockade of the large cell driver potentials. These conclusions derive from the use of ligatured preparations, in which a large cell group was functionally isolated from the rest of the ganglion (Fig. 5); from two-pool preparations in which the two classes of cells were perfused independently in different ionic media (Fig. 6); and from ganglia in which one or the other cell type was silenced by selective application of tetrodotoxin (Figs. 7, 8). 4. These experiments support the idea that driver potentials in the motorneurons are primarily based on inflow of calcium ions, but that a significant proportion of the inward current responsible for the driver potentials in the small pacemaker neurons is carried by an ion other than calcium. 5. The results support current models for the roles of endogenous properties and network interactions in determining the pattern of impulse production by the motorneurons; however, the synaptic mechanisms by which the pacemakers influence the motorneurons, which has previously been thought to be mainly chemical in lobsters, appears to contain a significant electrical component.
New Value: Keeping It Real

Many parts of the world now swim in a sea of complex products that do not necessarily improve the overall quality of our lives. From cell phones to baby strollers, we have overloaded our designed environment with hyper-functional products that often leave us searching for simpler, straighter forward product offerings. In a product landscape that more often than not equates complexity with sophistication; our ever-increasingly complex modern society has allowed faux conveniences to outweigh the tangible realness of our experiences. The look and feel of products has often become complex and complicated – and this is often highlighted as a positive thing. We are less likely to encounter simple, intuitive, and usable products geared toward the individual. To avoid this trap, one would need to apply a filter that would govern the intake of certain products to only those that are seen as adding true value to our lives. It is necessary to appeal to people’s emotions, and carry cultural richness and authenticity back to the forefront while embracing the power of cur-rent and future technologies. Design has tremendous power and the versatility necessary to bring about this positive change.
Theory of damped Bloch waves in elastic media

We present a theory for Bloch wave propagation in damped elastic media. We expand the eigenvalue problem governing the dispersion relation using a set of Bloch mode eigenvectors at each wave-vector point. With the assumption of Rayleigh damping, this decomposition allows us to derive the band structure in the Brillouin zone. The damping ratio corresponding to each Bloch mode is also generated. We show that damping qualitatively alters the shape of the dispersion curves. Damping also results in a branch-overtaking phenomenon that has a significant effect on band gaps. As the damping is increased, a band-gap size can drop abruptly.
Statistical methods for sensitivity and performance analysis in computer experiments

We describe statistical methods for sensitivity and performance analysis of complex computer simulation experiments. Graphical methods, such as trellis plots, are suggested for exploratory analysis of individual or aggregate performance metrics, conditional on different experiment inputs. More formal statistical methods, such as analysis of variance based methods and regression tree analysis, are used to determine variables having substantive influence on the experimental results and to investigate the structure of the underlying relationship between inputs and outputs. The methods are discussed in relation to a supply chain model of the textile manufacturing process having many possible input and output variables of interest and for a computer model used to describe the flow of material in an ecosystem.
Paper: Future computer technology for large power system simulation

A true technological explosion has taken place in the computer hardware industry in the last few years. Words such as parallel processing, vector processors, array processors, pipelined machines, 'number crunching', and megaflops (Millions of FLoating-point OPerations per Second) are heard regularly. Computer manufacturers have responded to the needs of specific groups requiring, above all else, high speed arithmetic capability. The result is a host of new machines which are called in this paper 'vector processors'. This paper will assess the applicability of vector processors to power flow and transient stability simulation programs and will indicate how these programs should be organized to run efficiently on these new machines. The approach taken will be to survey the entire class of vector processors available now and in the near future, to attempt to raise the reported low efficiency of sparsity-coded programs for large vector processors by reorganizing their sparse structure.
Hypnosis, context effects, and the recall of early autobiographical memories.

Abstract This study found that attempts to recall earliest memories were strongly influenced by the testing context. It showed that a brief 3-minute self-hypnosis experience, coupled with the insinuation that hypnosis improves memory, resulted in earlier autobiographical memory reports (M = 29.5 months) than instructions for relaxation (M = 37.9 months) or counting/visualization (M = 48.9 months). Inquiries about earliest memories across 5 age ranges showed that the hypnotic context resulted in a higher proportion of participants reporting a memory at or before 12, 24, 36, 48, and 60 months of age. Nearly 40% of the “hypnotized” participants reported a memory for an event that reportedly occurred at or before 12 months of age. A brief discussion of context effects and demand characteristics associated with hypnosis and memory follows.
An Ablation Parameter Study and Micromachining of NiTi Based Shape Memory Alloy Using Femtosecond Laser

The use of femtosecond lasers for the micromachining of engineering materials with micro and submicron size features is slowly but steadily increasing. This increase though presents challenges in understanding the interaction mechanism of femtosecond laser pulses with a material and defining process parameters for quality machining. This manuscript will present the setup for a 3DOF femtosecond laser microfabrication (FLM) system and its use in studying the ablation (single and multi shot) characteristics and incubation coefficient of nickel-titanium (NiTi) shape memory alloy. Understanding of these characteristics could allow for the identification of new applications of smart materials in the macro, micro, nano and MEMS domains.Copyright © 2007 by ASME
A Continuous Spectrophotometric and Fluorometric Assay for Protein Tyrosine Phosphatase Using Phosphotyrosine-Containing Peptides

Abstract Two continuous assays for protein tyrosine phosphatases (PTPases) have been developed using phosphotyrosine containing peptide substrates. These assays are based on the marked differences in the spectra of the peptide before and after the removal of the phosphate group. The increase in the absorbance at 282 nm or the fluorescence at 305 nm of the peptide upon the action of PTPase can be followed continuously and the resulting progress curve (time course) can be analyzed directly using the integrated form of the Michaelis-Menten equation. The procedure is convenient and efficient, since both k cat and Km values can be obtained in a single run. The difference absorption coefficient (Δepsi) at 282 nm is relatively insensitive to the pH of the reaction media. These techniques were applied to two homogeneous recombinant PTPases employing six phosphotyrosine-containing peptides. Km and k cat values obtained from the progress curve analysis were similar to those determined by the traditional initial rate inorganic phosphate assay. The peptides corresponding to autophosphorylation sites in Neu, p56lck, and p60src proteins show distinct behavior with the Yersinia PTPase, Yop51*, and the mammalian PTPase (PTP1U323). In both cases, the k cat values were relatively constant for all the peptides tested whereas the Km values were very sensitive to the amino acid sequence surrounding the tyrosine residue, especially in the case of Yop51*. Thus, both Yop51* and PTP1U323 show differential recognition of the phosphotyrosyl residues in the context of distinct primary structure of peptide substrates.