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Cystic fibrosis results from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel, ultimately leading to diminished transepithelial anion secretion and mucociliary clearance. CFTR correctors are therapeutics that restore the folding/trafficking of mutated CFTR to the plasma membrane. The large- conductance calcium-activated potassium channel ([BK.sub.Ca], [K.sub.Ca]1.1) is also critical for maintaining lung airway surface liquid (ASL) volume. Here, we show that the class 2 (C2) CFTR corrector VX-445 (elexacaftor) induces [K.sup.+] secretion across WT and F508del CFTR primary human bronchial epithelial cells (HBEs), which was entirely inhibited by the [BK.sub.Ca] antagonist paxilline. Similar results were observed with VX-121, a corrector under clinical evaluation. Whole-cell patch-clamp recordings verified that CFTR correctors potentiated [BK.sub.Ca] activity from both primary HBEs and HEK cells stably expressing the a subunit (HEK-BK cells). Furthermore, excised patch-clamp recordings from HEK-BK cells verified direct action on the channel and demonstrated a significant increase in open probability. In mouse mesenteric artery, VX-445 induced a paxilline- sensitive vasorelaxation of preconstricted arteries. VX-445 also reduced firing frequency in primary rat hippocampal and cortical neurons. We raise the possibilities that C2 CFTR correctors gain additional clinical benefit by activation of [BK.sub.Ca] in the lung yet may lead to adverse events through [BK.sub.Ca] activation elsewhere., Introduction Cystic fibrosis (CF) affects approximately 40,000 individuals in the United States and approximately 100,000 people worldwide (1, 2). The pathogenesis of CF is the result of mutations to the [...]

The objective of the present study was to compare a group-mediated cognitive behavioral (GMCB) physical activity intervention with traditional exercise therapy (TRAD) upon select social cognitive outcomes in sedentary knee osteoarthritis (knee OA) patients. A total of 80 patients (mean age = 63.5 years; 84% women) were recruited using clinic and community-based strategies to a 12-month, single-blind, two-arm, randomized controlled trial. Mobility-related self-efficacy, self-regulatory self-efficacy (SRSE), and satisfaction with physical function (SPF) were assessed at baseline, 3, and 12 months. Results of intent-to-treat 2 (Treatment: GMCB and TRAD) x 2 (Time: 3 and 12 month) analyses of covariance yielded significantly greater increases in SRSE and SPF (P < 0.01) relative to TRAD. Partial correlations revealed that changes in SRSE and SPF were significantly related (P < 0.05) to improvements in physical activity and mobility at 3 and 12-months. The GMCB intervention yielded more favorable effects on important social cognitive outcomes than TRAD; these effects were related to improvements in physical activity and mobility., Author(s): Brian C. Focht [sup.1] , Matthew J. Garver [sup.2] , Alexander R. Lucas [sup.3] , Steven T. Devor [sup.1] , Charles F. Emery [sup.1] , Kevin V. Hackshaw [sup.1] [...]

Neuropathic pain is a major, intractable clinical problem and its pathophysiology is not well understood. Although recent gene expression profiling studies have enabled the identification of novel targets for pain therapy (1-4), classical study designs provide unclear results owing to the differential expression of hundreds of genes across sham and nerve-injured groups, which can be difficult to validate, particularly with respect to the specificity of pain modulation (5). To circumvent this, we used two outbred lines of rats (6), which are genetically similar except for being genetically segregated as a result of selective breeding for differences in neuropathic pain hypersensitivity (7). SerpinA3N, a serine protease inhibitor, was upregulated in the dorsal root ganglia (DRG) after nerve injury, which was further validated for its mouse homolog. Mice lacking SerpinA3N developed more neuropathic mechanical allodynia than wild-type (WT) mice, and exogenous delivery of SerpinA3N attenuated mechanical allodynia in WT mice. T lymphocytes infiltrate the DRG after nerve injury and release leukocyte elastase (LE), which was inhibited by SerpinA3N derived from DRG neurons. Genetic loss of LE or exogenous application of a LE inhibitor (Sivelastat) in WT mice attenuated neuropathic mechanical allodynia. Overall, we reveal a novel and clinically relevant role for a member of the serpin superfamily and a leukocyte elastase and crosstalk between neurons and T cells in the modulation of neuropathic pain., A differential pain phenotype in rats with high and low pain sensitivity is apparent 3 d after injury (7). To identify genes that are associated with the induction of neuropathic [...]

The number of intermediate-conductance, [Ca.sup.2+]-activated [K.sup.+] channels (KCa3.1) present at the plasma membrane is deterministic in any physiological response. However, the mechanisms by which KCa3.1 channels are removed from the plasma membrane and targeted for degradation are poorly understood. Recently, we demonstrated that KCa3.1 is rapidly internalized from the plasma membrane, having a short half-life in both human embryonic kidney cells (HEK293) and human microvascular endothelial cells (HMEC-1). In this study, we investigate the molecular mechanisms controlling the degradation of KCa3.1 heterologously expressed in HEK and HMEC-1 cells. Using immunofluorescence and electron microscopy, as well as quantitative biochemical analysis, we demonstrate that membrane KCa3.1 is targeted to the lysosomes for degradation. Furthermore, we demonstrate that either overexpressing a dominant negative Rab7 or short interfering RNA-mediated knockdown of Rab7 results in a significant inhibition of channel degradation rate. Coimmunoprecipitation confirmed a close association between Rab7 and KCa3.1. On the basis of these findings, we assessed the role of the ESCRT machinery in the degradation of heterologously expressed KCa3.1, including TSG101 [endosomal sorting complex required for transport (ESCRT)-I] and CHMP4 (ESCRT-III) as well as VPS4, a protein involved in the disassembly of the ESCRT machinery. We demonstrate that TSG 101 is closely associated with KCa3.1 via coimmunoprecipitation and that a dominant negative TSG101 inhibits KCa3.1 degradation. In addition, both dominant negative CHMP4 and VPS4 significantly decrease the rate of membrane KCa3.1 degradation, compared with wild-type controls. These results are the first to demonstrate that plasma membrane-associated KCa3.1 is targeted for lysosomal degradation via a Rab7 and ESCRT-dependent pathway. endocytosis; Rab7; lysosomes; endosomal sorting complex required for transport doi: 10.1152/ajpcell.00120.2010.

The objective of this paper is to understand through parametric studies the effect of microstructural parameters, viz., the carbon nanotube (CNT) orientation with respect to the cutting direction, CNT loading, and level of dispersion within the matrix on the machinability of aligned CNT composites. To this end, a microstructure-based finite element machining model is used to simulate microstructures containing 1.5% and 6% by weight of CNTs. Microstructures with both uniform and nonuniform dispersions of CNTs are simulated. For each of these cases, CNTs having orientations of 0 deg, 45 deg, 90 deg, and 135 deg to the cutting direction are studied. The machining simulations were conducted using a positive rake tool Chip morphology, cutting forces, surface roughness, and surface/subsurface damages are the machinability measures used for comparison. The results of the parametric studies demonstrate that the CNT orientation, loading, and level of dispersion all play a critical role in dictating the machining response of aligned composites. The results further indicate that the surface morphology of the machined surface can be harnessed to produce the next generation of microfluidic devices. This application demonstrates the feasibility of designing the microstructure of CNT composites by taking into account both their engineering functionality and machinability. [DOI: 10.1115/1.4002495] Keywords: aligned CNT composites, micromachining, FEM models

Intermediate conductance, calcium-activated potassium channels are gated by the binding of intracellular [Ca.sup.2+] to calmodulin, a [Ca.sup.2+]-binding protein that is constitutively associated with the C terminus of the channel. Although previous studies indicated that the pore-lining residues along the C-terminal portion of $6 contribute to the activation mechanism, little is known about whether the nonluminal face of $6 contributes to this process. Here we demonstrate that the sulfhydral reagent, parachloromercuribenze sulfonate (PCMBS), modifies an endogenous cysteine residue predicted to have a nonluminal orientation ([Cys.sup.276]) along the sixth transmembrane segment (S6). Modification of [Cys.sup.276] manipulates the steady-state and kinetic behavior of the channel by shifting the gating equilibrium toward the open state, resulting in a left shift in apparent [Ca.sup.2+] affinity and a slowing in the deactivation process. Using a six-state gating scheme, our analysis shows that PCMBS slows the transition between the open state back to the third closed state. Interpreting this result in the context of the steady-state and kinetic data suggests that PCMBS functions to shift the gating equilibrium toward the open state by disrupting channel closing. In an attempt to understand whether the nonluminal face of S6 participates in the activation mechanism, we conducted a partial tryptophan scan of this region. Substituting a tryptophan for [Leu.sup.281] recapitulated the effect on the steady-state and kinetic behavior observed with PCMBS. Considering the predicted nonluminal orientation of [Cys.sup.276] and [Leu.sup.281], a simple physical interpretation of these results is that the nonluminal face of S6 forms a critical interaction surface mediating the transition into the closed conformation, suggesting the nonluminal C-terminal portion of S6 is allosterically coupled to the activation gate. doi/ 10.1085/jgp.201010430

Changes in neuronal activity are accompanied by the release of vasoactive mediators that cause microscopic dilation and constriction of the cerebral microvasculature and are manifested in macroscopic blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signals. We used two-photon microscopy to measure the diameters of single arterioles and capillaries at different depths within the rat primary somatosensory cortex. These measurements were compared with cortical depth-resolved fMRI signal changes. Our microscopic results demonstrate a spatial gradient of dilation onset and peak times consistent with 'upstream' propagation of vasodilation toward the cortical surface along the diving arterioles and 'downstream' propagation into local capillary beds. The observed BOLD response exhibited the fastest onset in deep layers, and the 'initial dip' was most pronounced in layer I. The present results indicate that both the onset of the BOLD response and the initial dip depend on cortical depth and can be explained, at least in part, by the spatial gradient of delays in microvascular dilation, the fastest response being in the deep layers and the most delayed response in the capillary bed of layer I. blood flow | cortical layer | hemodynamic | imaging | somatosensory doi/ 10.1073/pnas.1006735107

In this paper, a mechanical microscribing process is described that combines AFM probe-based microscribing with a five-axis microscale machine tool motion platform in order to achieve high scribing speeds, a large working volume, and the capability of cutting curvilinear patterns of grooves. An experiment is described that demonstrates groove formation, groove shape, and tool wear when long grooves are formed using multiple tool passes. A second more systematic experiment is described in which short-distance single-pass cutting tests were used to explore the effects of cutting speed, nominal tool load, and AFM probe mounting angle on groove geometry, tool wear, effective rake angle, and chip formation. Lastly, an experiment is described in which a long curvilinear groove is cut. It is shown that the most well-formed grooves were cut and acceptable tool wear was achieved, when using a high cutting speed, high nominal tool load, and low probe mounting angle. The capability of cutting grooves as long at 82 mm but with depths of only a few hundred nanometers, using a single tool pass at cutting speeds as high at 25 mm/min is demonstrated. [DOI: 10.1115/1.4001414]

The droplet behavior on a rotating surface has been studied to better understand the physics underlying atomized cutting fluid application. To this end, microturning experiments are carried out and the cutting performance evaluated for varying cutting fluids and at different droplet speeds. Microturning experiments indicate that a cutting fluid with low surface tension and low viscosity generates lower cutting temperatures, whereas a fluid with low surface tension and high viscosity generates lower cutting forces. Single-droplet impingement experiments are also conducted on a rotating surface using fluids with different surface tension and viscosity values. Upon impact, the droplet shape is observed to be a function of both the droplet speed and the surface speed. The spreading increases with increased surface speed owing to the tangential momentum added by the rotating surface. Spreading is observed to also increase with a decrease in fluid surface tension and does not change with the fluid viscosity. The evaporation rate is observed to increase for a rotating surface owing to convective heat transfer. Low surface tension and low viscosity are observed to increase the evaporation rate. It is concluded that a fluid with low surface tension and low viscosity is an effective coolant of the cutting zone, whereas a fluid with low surface tension and high viscosity is effective for lubrication. [DOI: 10.1115/1.4000859] Keywords: atomization, micro-machining, cutting-fluid, rotating surface, spreading, evaporation

Microfiltration is an in-process recycling method that shows great potential to extend fluid life and reduce bacterial concentrations in synthetic and semisynthetic metalworking fluids. The primary problem facing the use of microfiltration is membrane fouling, which is the blocking of membrane pores causing reduced flux. In this paper a fluid dynamic model of partial and complete blocking in sintered alumina membranes is developed that includes hydrodynamic, electrostatic, and Brownian forces. Model simulations are employed to study the impact of electrostatic and Brownian motion forces on the progression of partial blocking. The simulations also examine the effects of fluid velocity, particle size, and particle surface potential. The inclusion of electrostatic and Brownian forces is shown to significantly impact the progression of the partial blocking mechanism. The addition of a strong interparticle electrostatic force is shown to eliminate the partial blocking build-up of small particles due to the presence of the repulsive forces between the particles. As a result, the time to complete blocking of the test pore was lengthened, suggesting that flux decline is reduced in the presence of electrostatic forces. The Brownian motion is shown to have a large impact at low fluid velocities. The most effective parameter set is a low fluid velocity, small particle sizes, high microemulsion surface potential, and high membrane surface potential. [DOI: 10.1115/1.4000714]

The machinability of carbon nanotube (CNT)-reinforced polymer composites is studied as a function of CNT loading, in light of the trends seen in their material properties. To this end, the thermomechanical properties of the CNT composites with different loadings of CNTs are characterized. Micro-endmilling experiments are also conducted on all the materials under investigation. Chip morphology, burr width, surface roughness, and cutting forces are used as the machinability measures to compare the composites. For composites with lower loadings of CNTs (1.75% by weight), the visco-elastic/plastic deformation of the polymer-phase plays a significant role during machining, whereas, at loadings [greater than or equal to] 5% by weight, the CNT distribution and interface effects dictate the machining response of the composite. The ductile-to-brittle transition that occurs with an increase in CNT loading results in reduced minimum chip thickness values and burr dimensions in the CNT composite. The increase in thermal conductivity with the increase in CNT loading results in reduced number of adiabatic shear bands being observed on the chips and reduced thermal softening effects at high cutting velocities. Thus, overall, an increase in CNT loading appears to improve the machinability of the composite. [DOI: 10.1115/1.3123337] Keywords: CNT composites, micro-machining

The recycling of semisynthetic metalworking fluids (MWFs) using alumina membranes is significantly impacted by aggregated MWF microemulsions that cause partial and complete blocking of membrane pores. In this paper, computational fluid dynamic methods are employed to model both a portion of a sintered alumina membrane with tortuous pores and the microemulsions passing through it. Several particle size distributions, measured experimentally at various times through the membrane service life and under two different cross-flow velocities, were used to determine the particle sizes simulated in the flow. Simulated MWF particles smaller than the largest pore diameter were found to completely block the pore through the build-up of a network of particles that blocked smaller diameter inlets and outlets. The results demonstrate as well that significant membrane flux reduction can occur by partial blocking of pore inlets and outlets even in the absence of complete blocking. [DOI: 10.1115/1.2976149]

In this paper, the fouling of sintered [alpha]-alumina membranes by an uncontaminated semisynthetic metalworking fluid (MWF) is addressed. Experimental evidence of the form of flux reduction curves, scanning electron microscope images of the membranes, and MWF particle size measurements is used to identify two fouling mechanisms, pore blocking and partial pore blocking, as the major contributors to flux decline. A probability-based mechanistic model is developed based on the time-dependent particle size distribution and membrane pore sizes. The model is fitted to experimental data from two commonly used membrane pore sizes with good agreement. Partial blocking is shown to be a predominant first step in the pore blocking mechanism in microfiltration of semisynthetic MWFs due to the tortuous nature of the pores present in sintered ceramic membranes. [DOI: 10.1115/1.2953234] Keywords: microfiltration, metalworking fluids, cutting fluids, membrane fouling

A microstructure-level finite element machining model has been developed to simulate the machining of carbon nanotube (CNT) reinforced polymer composites. The model integrates a failure model with a previously developed microstructure-based material model. The competition between ductile and brittle modes of failure in the polymer phase (polycarbonate) is captured by implementing the Gearing and Anand failure model calibrated at different temperatures. The CNT phase is given a simple strain-to-failure criterion. The proposed machining model has been validated at different orthogonal machining conditions for the plain polycarbonate and for composites with two different percentage loadings of CNTs. On an average, the model is seen to successfully predict the cutting forces with an accuracy of 8% and the thrust forces with an accuracy of 13.4% for all the materials. The machining model also predicts the continuous chip morphology and formation of adiabatic shear bands in plain polycarbonate and for composites with lower loadings of CNTs. On an average, the chip thicknesses are predicted within an accuracy of 14% for plain polycarbonate and 10% for the CNT composites. [DOI: 10.1115/1.2917378] Keywords: carbon nanotube composites, machining model

An atomization-based cutting fluid application system is developed for micro-end milling. The system was designed to ensure spreading of the droplets on the workpiece surface based on the analysis of the atomized droplet impingement dynamics. The results of the initial experiments conducted to examine the viability of the system show that the cutting forces are lower and tool life is significantly improved with the atomized cutting fluids when compared to dry and flood cooling methods. Also, application of atomized cutting fluid is found to result in good chip evacuation and lower cutting temperature. Experiments were also conducted to study the effect of fluid properties on cutting performance, and the results show that cutting fluids with lower surface tension and higher viscosity perform better in terms of cutting forces. [DOI: 10.1115/1.2738961]

The microstructure-level finite element machining model developed in Part I of this paper is used to perform a detailed analysis of the failure mechanisms that occur while machining the carbon nanotube (CNT) reinforced polycarbonate composites. The chip formation in plain polycarbonate (PC) is seen to be influenced by the ductile failure mode. For the composite containing 1.75% by weight of CNTs (Composite A), the polymer fails in the ductile mode. The presence of CNTs is seen to result in CNTs protruding from the machined surface and subsurface damage. The low thermal conductivity of the polymer phase is seen to result in the formation of adiabatic shear bands in plain PC and Composite A. As the CNT loading is increased to 5% by weight, the failure in the polymer phase is seen to be predominantly brittle in nature. The presence of the larger percentage of CNTs is also seen to offset the formation of adiabatic shear bands. The machining model has also been used to successfully predict the machining behavior of CNT composites with tailored microstructures. Simulation experiments with varying CNT alignment, aspect ratio, percentage loading, and cutting velocity were conducted to study the effects of these factors on cutting forces. The results show that the machining model in combination with the material model is an effective tool to design CNT composites with emphasis both on the mechanical properties and machinability. [DOI: 10.1115/1.2927431] Keywords: carbon nanotube composites, machining model

A continuum-based microstructure-level material model for simulation of polycarbonate carbon nanotube (CNT) composite machining has been developed wherein polycarbonate and CNT phases are modeled separately. A parametrization scheme is developed to characterize the microstructure of composites having different loadings of carbon nanotubes. The Mulliken and Boyce constitutive model [2006, 'Mechanics of the Rate Dependent Elastic Plastic Deformation of Glassy Polymers from Low to High Strair Rates,' Int. J. Solids Struct., 43(5), pp. 1331-1356] for polycarbonate has been modified and implemented to capture thermal effects. The CNT phase is modeled as a linear elastic material. Dynamic mechanical analyzer tests are conducted on the polycarbonate phase to capture the changes in material behavior with temperature and strain rate. Compression tests are performed over a wide range of strain rates for model validation. The model predictions for yield stress are seen m be within 10% of the experimental results for all the materials tested. The model is used to study the effect of weight fraction, length, and orientation of CNTs on the mechanical behavior of the composites. [DOI: 10.1115/1.2917564]

A piezoelectrically driven, submicron XY-positioning stage with multiprocess capability is developed and then integrated into two micro/nanoscale manufacturing processes to improve their performance. The design is based on the HexFlex[TM] mechanism but is modified to improve structural robustness using a combination of factorial design, linear programming, and finite element analysis. Performance analysis reveals travel ranges of 16 [micro]m (X-axis) and 8 [micro]m (Y-axis), positioning accuracies of 87 nm (X-axis) and 92 nm (Y-axis), and overall stiffnesses of 32 N/ [micro]m (X-axis) and 36 N/ [micro]m (Y-axis). A comparison of microfluidic channels manufactured with a micromachine tool (mMT) alone and with the stage stacked on the mMT shows an improvement in feature accuracy from 870 nm to 170 nm. The stage is integrated with an electrochemical deposition setup. Nanowire structures with sharp angles are fabricated. The diameter of these nanowires shows an improvement in uniformity by decreasing the standard deviation of diameter variation from 2.088 [micro]m to 0.009 [micro]m. [DOI: 10.1115/1.2917315] Keywords: precision positioning, flexure stage, microscale machining, electrochemical deposition, piezoelectric actuator

Kinematic couplings have been used to create palletized system for part transfer in a microfactory. While kinematic couplings provide high repeatability, calibration is needed to achieve high interchangeability accuracy. In this paper, a generalized artifact-based methodology for pallet calibration and workpiece registration is developed. This calibration method uses the microfactory machines to both machine and measure artifacts to estimate the interchangeability errors. The error sources affecting the accuracy of calibration are analyzed and techniques are suggested to reduce these errors. Finally, the methodology is applied and validated for a specific microfactory application. [DOI: 10.1115/1.2917289]

An acoustic emission-based touch-off detection system has been developed to determine contact between a rotating microtool and a workpiece surface with micron-level accuracy. The system has been implemented on an existing three-axis microscale machine tool. The system has been tested with microendmills as small as 50 [micro]m in diameter and microdrills as small as 254 [micro]m in diameter. The accuracy of the system has been found to depend on tool geometry and workpiece surface characteristics and is generally on the order of 1 [micro]m. An analytical model has been constructed to predict touch-off detection error. The calibrated model has been shown to predict surface overshoot and undershoot trends quite well. Simulations have shown that touch-off error is dominated by part surface roughness. [DOI: 10.1115/1.2917285]

A model to predict failure of coated WC-Co grades due to chipping in intermittent cutting via microstructure-level finite element machining process simulation is presented and applied to various coated WC-Co tools. Coated tools were examined for the characterization and simulation of their microstructures. Model predictions of failure due to chipping for coated WC-Co systems were validated by continuous machining tests. In order to simulate cyclic loading conditions during intermittent cutting, mechanical and thermal boundary conditions were applied during cutting phases and removed during noncutting phases. Interrupted turning experiments were conducted to validate the model and the results showed that the predictions agreed well with the observations from the experiments. The paper includes the application of this model to a problem of WC-Co grade design. [DOI: 10.1115/1.2738507]

A cutting noise prediction model is developed to relate the cutter-workpiece vibrations to the sound pressure field around the cutter in the high-speed face-milling process. The cutter-workpiece vibration data are obtained from a dynamic mechanistic face-milling force simulation model. The total noise predicted, based on both cutting noise and aerodynamic noise prediction, compares well to the noise observed experimentally in the face-milling process. Using the model, the effects of various machining and cutter geometry parameters are studied. It is shown that cutter geometry, machine dynamics, and cutting speed all play important roles in determining overall noise in face milling. [DOI: 10.1115/1.2716702]

This paper presents the development of models that describe the surface-generation process for microendmilling. The surface-generation models for the sidewall and floor surfaces consist of deterministic and stochastic models. In the sidewall surface-generation model, the deterministic model characterizes the surface topography generated from the relative motion between the major cutting edge and the workpiece material. The model includes the effects of the process kinematics, dynamics, tool edge serration, and process faults (e.g., tool tip runout). The stochastic model predicts the increased surface roughness generated from ploughing due to the significant tool edge radius effect. In the floor surface-generation model, the deterministic model characterizes the three-dimensional surface topography over the entire floor surface and considers the effects of the minimum chip thickness, the elastic recovery, and the transverse vibration. The variation of the ploughing amount across the swept arc' of the cutter due to the varying chip load conditions is considered in the stochastic model. [DOI: 10.1115/1.2716705]

The surface-generation models for the microendmilling process developed in Part I (Liu, DeVor, and Kapoor, 2007, J. Manuf Sci. Eng., 129(3), pp. 453-460) are experimentally calibrated and validated. Partial immersion peripheral downmilling and full-immersion slotting tests are performed over a wide range of feed rates (0.25-12 [micro]m/flute) using two tools with different edge radii (3 [micro]m and 2 [micro]m) and runout levels (2 [micro]m and 3 [micro]m) for the investigation of sidewall and floor surface generation, respectively. The deterministic models are validated using large feed-rate tests with errors within 18% for both sidewall and floor surfaces. For low feed-rate tests, the stochastic portion of the surface roughness data are determined from the observed roughness data and the validated deterministic model. The stochastic models are then calibrated and validated using independent data sets. The combination of the deterministic and stochastic models predicts the total surface roughness within 15% for both the sidewall and floor surface over a range of feed rates. The models are then used to simulate micromachined surfaces under a variety of conditions to gain a deeper understanding of the effects of tool geometry (edge radius and edge serration), process conditions, tool tip runout, process kinematics and dynamics on the machined surface roughness. [DOI: 10.1115/1.2716706]

We examined mitochonchrial DNA (mtDNA) haplogroup and haplotype diversity in 188 individuals from three Chibchan (Kogi, Arsario, and Ijka) populations and one Arawak (Wayuu) group from northeast Colombia to determine the biological relationship between lower Central American and northern South American Chibchan speakers, mtDNA haplogroups were obtained for all individuals and mtDNA HVS-I sequence data were obtained for 110 samples. Resulting sequence data were compared to 16 other Caribbean, South, and Central American populations using diversity measures, neutrality test statistics, sudden and spatial mismatch models, intermatch distributions, phylogenetic networks, and a multidimensional scaling plot. Our results demonstrate the existence of a shared maternal genetic structure between Central American Chibchan, Mayan populations and northern South American Chibchan-speakers. Additionally, these results suggest an expansion of Chibchan-speakers into South America associated with a shift in subsistence strategies because of changing ecological conditions that occurred in the region between 10,000-14,000 years before present. KEY WORDS Colombia; Ijka; Kogi; Arsario; Wayuu; Chibcha

T cell receptor engagement results in the reorganization of intracellular and membrane proteins at the T cell-antigen presenting cell interface forming the immunological synapse (IS), an event required for [Ca.sup.2+] influx. KCa3.1 channels modulate [Ca.sup.2+] signaling in activated T cells by regulating the membrane potential. Nothing is known regarding KCa3.1 membrane distribution during T cell activation. Herein, we determined whether KCa3.1 translocates to the IS in human T cells using YFP-tagged KCa3.1 channels. These channels showed electrophysiological and pharmacological properties identical to wild-type channels. IS formation was induced by either anti-CD3/CD28 antibody-coated beads for fixed microscopy experiments or Epstein-Barr virus-infected B cells for fixed and live cell microscopy. In fixed microscopy experiments, T cells were also immunolabeled for F-actin or CD3[epsilon], which served as IS formation markers. The distribution of KCa3.1 was determined with confocal and fluorescence microscopy. We found that, upon T cell activation, KCa3.1 channels localize with F-actin and CD3[epsilon] to the IS but remain evenly distributed on the cell membrane when no stimulus is provided. Detailed imaging experiments indicated that KCa3.1 channels are recruited in the IS shortly after antigen presentation and are maintained there for at least 15-30 min. Interestingly, pretreatment of activated T cells with the specific KCa3.1 blocker TRAM-34 blocked [Ca.sup.2+] influx, but channel redistribution to the IS was not prevented. These results indicate that KCa3.1 channels are a part of the signaling complex that forms at the IS upon antigen presentation. T cell activation; ion channels; membrane distribution

Aerodynamic noise generated in high speed face milling cutters is usually much higher than the noise exposure limit set by OSHA. Experiments were conducted on two different face milling cutters to understand the aerodynamic noise generation in face milling cutters. It is observed that dipole sources of noise are most important in determining the noise generation in rotating face milling cutters. The aerodynamic noise spectrum consists of discrete tones at the rotational frequency and a broad range of higher frequencies, with the broadband spectrum contributing significantly to overall noise. A mathematical model based on the Ffowcs Williams-Hawkings Equation is used to predict (un-weighted) aerodynamic noise. The noise predicted compares well with the experimental observations. The cutter gullet shape was found to be an important factor in determining broadband noise. [DOI: 10.1115/1.2335861]

Membrane microfiltration is a promising technology that has been shown to extend metalworking fluid (MWF) life by eliminating contaminants while allowing the fluid to stay in use. However, the efficacy of this technology is compromised by the clogging of the filter pores in a process known as membrane fouling. In this paper the fouling issue is addressed by the development of a semi-synthetic MWF specifically designed to not foul microfiltration membranes. The composition of the designed MWF is discussed and compared with a commercial MWF. Cross-flow microfiltration fouling tests were carried out in low-pressure, high-velocity conditions on ceramic [alpha]-alumina membranes. Several common MWF components are shown not to be factors of membrane fouling on these membranes. The flux of the designed fluid was found to reach an immediate steady state at about twice the value of the steady-state flux of the tested commercial fluid. Scanning electron microscope imaging was used to further evaluate membrane fouling by each fluid. The machining capabilities of the designed fluid were examined in terms of cutting forces and machining temperature. [DOI: 10.1115/1.2401207] Keywords: microfiltration, membrane fouling, metalworking fluids

In Part II of this paper, experimental and analytical methods' have been developed to estimate the values of the process faults defined in Part I of this paper. The additional faults' introduced by the microend mill design are shown to have a significant influence on the total net runout of the microend mill. The dynamic model has been validated through microend milling experiments. Using the dynamic model, the effects of minimum chip thickness and elastic recovery on micraend milling stability have been studied over a range of feed rates for which the cutting mechanisms vary from ploughing-dominated to shearing'-dominated. The minimum chip thickness effect is found to cause feed rate dependent instability at low feed rates, and the range of unstable feed rates depends on the axial depth of cut. The effects of process faults on microend mill vibrations have also been studied and the influence of the unbalance from the faults is found to be significant as spindle speed is increased. The stability characteristics due to the regenerative effect have been studied. The results show that the stability lobes from the second mode of the microend mill, which are generally neglected in macroscale end milling, affect the microend mill stability significantly. [DOI: 10.1115/1.2335854]

In microend milling, due to the comparable size of the edge radius to chip thickness, chip formation mechanisms are different. Also, the design of microend mills with features of a large shank, taper, and reduced diameter at the cutting edges introduces additional dynamics and faults or errors at the cutting edges. A dynamic microend milling cutting force and vibration model has been developed to investigate the microend milling dynamics caused by the unique mechanisms of chip information as well as the unique microend mill design and its associated fault system. The chip thickness model has been developed considering the elastic-plastic nature in the ploughing process. A slip-line field modeling approach is taken for a cutting force model development that accounts for variations in the effective rake angle and dead metal cap. The process fault parameters associated with microend mills have been defined and their effects on chip load have been derived. Finally, a dynamic model has been defined developed considering the effects of both the unique microend mill design and fault system factors that become significant at high spindle speeds including rotary inertia and gyroscopic moments. [DOI: 10.1115/1.2193546]

A model to predict tool failure due to chipping in machining via the microstructure-level finite element cutting process simulation is presented and applied to a wide variety of WC-Co tool materials. The methodology includes the creation of arbitrary microstructures comprised of WC and Co phases to simulate various grades of WC-Co alloys. Equivalent stress, strain, and strain energy are then obtained via orthogonal microstructure-level finite element machining simulations. A model was developed to predict the occurrence of tool failure based on the mixed mode fracture criterion. Turning experiments were conducted to validate the model and the results showed that the model predictions agree well with the observations from the experiments. The model was then employed to study the effects of microstructural parameters and feedrate on chipping and failure. [DOI: 10.1115/1.2194233]

The native peoples of Gorno Altai in southern Siberia represent a genetically diverse population and have been of great interest to anthropological genetics. In particular, the southern Altaian population is argued to be the best candidate for the New World ancestral population. In this study we sampled Altai-Kizhi from the southern Altaian village of Mendur-Sokkon, analyzed mtDNA RFLP markers and HVS-I sequences, and compared the results to other published mtDNA data from Derenko et al. (2003) and Shields et al. (1993) encompassing the same region. Because each independent study uses different sampling techniques in characterizing gene pools, in this paper we explore the accuracy and reliability of evolutionary studies on human populations. All the major Native American haplogroups (A, B, C, and D) were identified in the Mendur-Sokkon sample, including a single individual belonging to haplogroup X. The most common mtDNA lineages are C (35.7%) and D (13.3%), which is consistent with the haplogroup profiles of neighboring Siberian groups. The Mendur-Sokkon sample exhibits depressed HVS-I diversity values and neutrality test scores, which starkly differs from the Derenko et al. (2003) data set and more closely resembles the results for neighboring south Siberian groups. Furthermore, the multidimensional scaling plot of DA genetic distances does not cluster the Altai samples, showing different genetic affinities with various Asian groups. The findings underscore the importance of sampling strategy in the reconstruction of evolutionary history at the population level. KEY WORDS: ALTAI, SIBERIA, RFLP, mtDNA, MOLECULAR ANALYSIS., To identify differences among various samples from the same geographic area and to investigate the effect of independent sampling on the reconstruction of human evolutionary history, we examined multiple data [...]

Rapid eye movement (REM) sleep consists of a dreaming state in which there is activation of the cortical and hippocampal electroencephalogram (EEG), rapid eye movements, and loss of muscle tone. Although REM sleep was discovered more than 50 years ago, the neuronal circuits responsible for switching between REM and non-REM (NREM) sleep remain poorly understood. Here we propose a brainstem flip-flop switch, consisting of mutually inhibitory REM-off and REM-on areas in the mesopontine tegmentum. Each side contains GABA ([gamma]-aminobutyric acid)-ergic neurons that heavily innervate the other. The REM-on area also contains two populations of glutamatergic neurons. One set projects to the basal forebrain and regulates EEG components of REM sleep, whereas the other projects to the medulla and spinal cord and regulates atonia during REM sleep. The mutually inhibitory interactions of the REM-on and REM-off areas may form a flip-flop switch that sharpens state transitions and makes them vulnerable to sudden, unwanted transitions--for example, in narcolepsy. Asleep in the blink of an eye Rapid eye movement (REM) sleep is a dreaming state in which the brain is highly active. The mechanism responsible for switching between REM and non-REM sleep (also called slow-wave sleep, when cortical activity is slow) is poorly understood. Now, based on detailed anatomy and lesion experiments, Lu et al. have identified brainstem regions that control the transition from REM to non-REM sleep. The REM-off and REM-on areas are mutually inhibitory. This appears to produce a flip-flop switch relationship that could explain many of the properties of the abrupt switching into and out of REM states seen in sleep disorders such as narcolepsy., Author(s): Jun Lu [sup.1] , David Sherman [sup.1] , Marshall Devor [sup.1] [sup.2] , Clifford B. Saper [sup.1] Author Affiliations: (1) Department of Neurology and Program in Neuroscience, Harvard Medical [...]

In micromachining, the uncut chip thickness is comparable or even less than the tool edge radius and as a result a chip will not be generated if the uncut chip thickness is less than a critical value, viz., the minimum chip thickness. The minimum chip thickness effect significantly affects machining process performance in terms of cutting forces, tool wear, surface integrity, process stability, etc. In this paper, an analytical model has been developed to predict the minimum chip thickness values, which are critical for the process model development and process planning and optimization. The model accounts for the effects of thermal softening and strain hardening on the minimum chip thickness. The influence of cutting velocity and tool edge radius on the minimum chip thickness has been taken into account. The model has been experimentally validated with 1040 steel and Al6082-T6 over a range of cutting velocities and tool edge radii. The developed model has then been applied to investigate the effects of cutting velocity and edge radius on the normalized minimum chip thickness for various carbon steels with different carbon contents and Al6082-T6. [DOI: 10.1115/1.2162905]

A trigger probe measurement system and measurement methodology are developed for kinematic self-calibration of micro/meso-scale machine tools (mMTs). The trigger probe detects the contact between a spindle-mounted stylus and a table-mounted planar artifact. The trigger probe system is small enough to be easily mounted on an mMT. The measurement methodology is divided into off-machine and on-machine measurements. The off-machine measurements are only needed for the first calibration. Recalibration requires only the on-machine measurements to be repeated, thereby reducing recalibration time. The measurement system and methodology are implemented with existing kinematic modeling, error parameter estimation, and compensation techniques for the experimental calibration of a three-axis mMT. The measurement system error is evaluated and experimentally measured. Cutting tests are used to validate the performance of the calibration methodology.

The machinability of a polycarbonate nanocomposite containing multiwalled carbon nanotubes is investigated and contrasted with its base polymer and with a conventional carbon fiber composite. The material microstructures are characterized using transmission electron and scanning electron microscopy methods. Micro-endmilling experiments are conducted on the three materials. Chip morphology, machined surface characteristics, and the nature of the cutting forces are employed as machinability measures for comparative purposes. Polycarbonate chips are seen to transition from being discontinuous to continuous as the feed-per-tooth (FPT) increases, while, at all FPT values the nanocomposite is seen to form comparatively thicker continuous chips. The nanocomposite and the carbon fiber composite are seen to have the lowest and the highest magnitudes, respectively, for both the surface roughness and cutting forces. Shearing along the nanotube-polymer interface and better thermal conductivity are speculated to be the mechanisms responsible for the observations seen in the nanocomposite. [DOI: 10.11151/1.2137753]

A survey of the genomic context of more than 300 human microRNA (miRNA) loci revealed that two primate-specific miRNAs, miR-220 and miR-492, each lie within a processed pseudogene. It appears that, while processed pseudogenes are good candidates for miRNA incubators, it is unlikely that more than a very small percentage of new miRNAs arise this way.

The mtDNA variation of 198 Aleuts, as well as North American and Asian populations drawn from the literature, were analyzed to reconstruct the Aleuts' genetic prehistory and to investigate their role in the peopling of the Circumarctic region. From median-joining network analysis, three star-like clusters were identified in the Aleuts within the following subhaplogroups: A3, A7 (an Aleut-specific subclade of A3), and D2. Mismatch analyses, neutrality test scores, and coalescent time estimates for these three components provided evidence of two expansion events, one occurring at approximately 19,900 B.P. and the other at 5,400 B.P. Based on these findings and evidence from the archaeological data, four general models for the genetic prehistory of the Aleutian Island chain are proposed: 11 biological continuity involving a kin-structured peopling of the archipelago; 2) intrusion and expansion of a non-native biface-producing population dominated by subhaplogroup D2; 3) amalgamation of Arctic Small Tool tradition peoples characterized by D2 with an older Anangula substratum; and 41 biological continuity with significant gene flow from neighboring populations of the Alaskan mainland and Kodiak Island. The Aleut mtDNAs are consistent with the Circumarctic pattern by the fixation of A3 and D2, and the exhibition of depressed diversity levels relative to Amerind and Siberian groups. The results of this study indicate a broad postglacial reexpansion of Na-Dene and Esko-Aleuts from reduced populations within northern North America, with D2 representing a later infusion of Siberian mtDNAs into the Beringian gene pool. KEY WORDS Aleuts; mtDNA; mismatch analysis; reduced median network analysis

The form tapping process typically yields unfinished threads known as split crests. Thread quality can be greatly improved by reducing the size and severity of split crest formation. This paper develops a finite element model to simulate form tapping with an eye towards the reduction of split crests. The model is validated against linear scratch experiments, and simulations are compared to actual tapping. The effects of various tap design parameters and tapping process conditions on the formation of split crests are investigated to strive toward an optimal tap design. [DOI: 10.1115/1.2117427]

In form tapping, the generation of unfinished thread forms results in the appearance of split crests. An experimental technique is developed to study the nature of split crest formation. Custom tools are modeled after tap tooth geometry to perform the forming process in a vertical milling machine. Single-tooth experiments replicate the initial deformation stages and determine the tap geometry and tapping process parameters that significantly affect ridge size and shape. This method is then expanded to consider two axially consecutive tap teeth and the interaction of consecutive ridges to create the final thread form. It is found that certain tap geometrical characteristics are important to the final thread form and, therefore, determine the size and shape of the resulting split crest. [DOI: 10.1115/1.1951784]

This paper describes an algorithmic strategy to facilitate the generation of multicomponent software tools for computer-aided manufacturing (CAM) and virtual manufacturing (VM). Components that are often used to build CAM and VM applications include a wide range of domain-specific knowledge sources and also more general utility components with often very heterogeneous characteristics. The identification of a suitable and compatible set of these components is the first and arguably most important step during the development process of any CAM or VM application, This paper presents an algorithmic strategy that automates this development step by solving a time-expanded network problem, referred to as the component set identification (CSI) problem. A definition of the CSI problem, a mathematical formulation, a solution procedure, and some computational results are presented. Finally, an application to predict hole quality in drilling is used to illustrate the functionality of the proposed algorithmic strategy. [DOI: 10.1115/1.1954792] Keywords: Computer-Aided Manufacturing, Virtual Manufacturing, Information Integration, Integer Programming, Component Set Identification Problem

Heat sensitivity shows considerable functional variability in humans and laboratory animals, and is fundamental to inflammatory and possibly neuropathic pain. In the mouse, at least, much of this variability is genetic because inbred strains differ robustly in their behavioral sensitivity to noxious heat. These strain differences are shown here to reflect differential responsiveness of primary afferent thermal nociceptors to heat stimuli. We further present convergent behavioral and electrophysiological evidence that the variable responses to noxious heat are due to strain-dependence of CGRP expression and sensitivity. Strain differences in behavioral response to noxious heat could be abolished by peripheral injection of CGRP, blockade of cutaneous and spinal CGRP receptors, or long-term inactivation of CGRP with a CGRP-binding Spiegelmer. Linkage mapping supports the contention that the genetic variant determining variable heat pain sensitivity across mouse strains affects the expression of the Calca gene that codes for CGRP[alpha]. calcitonin gene-related peptide | genetic | Calca | nociceptors | pain

This paper proposes an analytical approach to detect depth-of-cut variations based on the cutting-force shape characteristics in end milling. Cutting forces of a single-flute end mill are analyzed and classified into three types according to their shape characteristics. Cutting forces of a multiple-flute end mill are then classified by considering both the cutting types of the corresponding single-flute end mill and the degree of overlap of successive flutes in the cut. Force indices are extracted from the cutting forces and depth-of-cut variations are detected based on the changes of the force shape characteristics via the force indices in an end-milling process. The detection methodology is validated through cutting experiments. [DOI: 10.1115/1.1947207]

Laser speckle contrast imaging is becoming an established method for full-field imaging of cerebral blood flow dynamics in animal models. The sensitivity and noise in the measurement of blood flow changes depend on the camera exposure time. The relation among sensitivity, noise, and camera exposure time was investigated experimentally by imaging the speckle contrast changes in the brain after electrical forepaw stimulation in rats. The sensitivity to relative changes in speckle contrast was found to increase at longer exposure times and to reach a plateau for exposure times greater than approximately 2 ms. However, the speckle contrast noise also increases with exposure time and thus the contrast-to-noise ratio was found to peak at an exposure time of approximately 5 ms. Our results suggests that ~5 ms is an optimal exposure time for imaging of stimulus-induced changes in cerebral blood flow in rodents. OCIS codes: 120.6150, 170.3880, 170.1650.

Accurate interpretation of functional MRI (fMRI) signals requires knowledge of the relationship between the hemodynamic response and the neuronal activity that underlies it. Here we address the question of coupling between pre- and postsynaptic neuronal activity and the hemodynamic response in rodent somatosensory (Barrel) cortex in response to single-whisker deflection. Using full-field multiwavelength optical imaging of hemoglobin oxygenation and electrophysiological recordings of spiking activity and local field potentials, we demonstrate that a point hemodynamic measure is influenced by neuronal activity across multiple cortical columns. We demonstrate that the hemodynamic response is a spatiotemporal convolution of the neuronal activation. Therefore, positive hemodynamic response in one cortical column might be explained by neuronal activity not only in that column but also in the neighboring columns. Thus, attempts at characterizing the neurovascular relationship based on point measurements of electrophysiology and hemodynamics may yield inconsistent results, depending on the spatial extent of neuronal activation. The finding that the hemodynamic signal observed at a given location is a function of electrophysiological activity over a broad spatial region helps explain a previously observed increase of local vascular response beyond the saturation of local neuronal activity. We also demonstrate that the oxy- and total-hemoglobin hemodynamic responses can be well approximated by space-time separable functions with an antagonistic center-surround spatial pattern extending over several millimeters. The surround 'negative' hemodynamic activity did not correspond to observable changes in neuronal activity. The complex spatial integration of the hemodynamic response should be considered when interpreting fMRI data. Barrel cortex | blood oxygenation | intrinsic signals | optical imaging

An oblique cutting model is developed to predict the thrust and torque created by the chisel edge of a drill with an arbitrary point geometry. The chisel edge geometry is modeled using a mathematical representation of the flank grinding parameters and the flute geometry. The varying cutting angles at the chisel edge are determined and used to calculate the force contribution of each element using a mechanistic modeling approach. The model is validated for three commercial point geometries--the conical, helical and Racon[R] drill points. Model simulations match experimental data well for the geometries tested and show a marked improvement over the orthogonal cutting model [DOI: 10.1115/1.1826076]

The ribonuclease (RNase) A gene family is the only vertebrate-specific superfamily known to encode proteins with enzymatic function (Lander et al. 2001). To date, eight members of the superfamily have […]

In Part II of this paper, a cutting force model for the micro-endmilling process is developed. This model incorporates the minimum chip thickness concept in order to predict the effects of the cutter edge radius on the cutting forces. A new chip thickness computation algorithm is developed to include the minimum chip thickness effect. A slip-line plasticity force model is used to predict the force when the chip thickness is greater than the minimum chip thickness, and an elastic deformation force model is employed when the chip thickness is less than the minimum chip thickness. Orthogonal, microstructure-level finite element simulations are used to calibrate the parameters of the force models for the primary metallurgical phases, ferrite and pearlite, of multiphase ductile iron workpieces. The model is able to predict the magnitudes of the forces for both the ferrite and pearlite workpieces as well as for the ductile iron workpieces within 20%.

This paper provides a comprehensive review of the literature, mostly of the last 10-15 years, that is enhancing our understanding of the mechanics of the rapidly growing field of micromachining. The paper focuses on the mechanics of the process, discussing both experimental and modeling studies, and includes some work that, while not directly focused on micromachining, provides important insights to the field. Experimental work includes the size effect and minimum chip thickness effect, elastic-plastic deformation, and microstructure effects in micromachining. Modeling studies include molecular dynamics methods, finite element methods, mechanistic modeling work, and the emerging field of multiscale modeling. Some comments on future needs and directions are also offered.