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Background: Sarcopenia, reduced skeletal muscle mass, is associated with frailty, injuries, and mortality. The purpose of this study was to evaluate the impact of computed tomography–determined sarcopenia on surgical complications and outcomes after resection of non-small cell lung cancer.Methods: For a total 272 non-small cell lung cancer patients that underwent surgery between 2011 and 2016, cross-sectional area of muscle at the third lumbar vertebra (L3) was retrospectively measured using preoperative chest computed tomography images. Sarcopenia was defined as an L3 muscle index of <55 cm2/m2for men and of <39 cm2/m2for women. Clinical characteristics, postoperative complications, disease-free survival, and overall survival of patients with or without sarcopenia were compared.Results: A total of 60.3% (n= 164) were male, and mean patient age was 62.9 ± 9.6 years. The prevalence of sarcopenia was 22.4% for all study subjects, 32.9% for men, and 6.5% for women. No significant difference was observed between patients with or without sarcopenia in terms of intensive care unit or hospital stay (p= 0.502 and p= 0.378, respectively), and the presence of sarcopenia was not associated with postoperative complications. Furthermore, no significant difference was observed between the 3-year disease-free survival rate (74.3% vs 66.7%, p= 0.639) or 3-year overall survival rate (83.9% vs 87.7%, p= 0.563) of patients with or without sarcopenia.Conclusion: Sarcopenia as determined by preoperative computed tomography does not appear to have a negative impact on surgical outcome or overall survival for resected non-small cell lung cancer patients.

InSb nanostructures embedded in InAs and InAsSb matrices were grown on InAs (001) and GaAs (001) substrates by molecular beam epitaxy. The diameter and height of InSb quantum dots (QDs) on InAs with 2ML-InSb coverage grown by Stranski-Krastanov (S-K) are ~36.8 nm and ~3.1 nm, respectively. The density of QDs is ~2.5×1010cm-2. The size distribution of InSb QDs on InAs with 2ML-InSb coverage grown by migration enhanced epitaxy (MEE) was larger than that of its S-K counterpart. Unique InSb quantum dashes (Q-dashes) on InAsSb elongated along two directions were found on an AlSb-buffered GaAs substrate. InSb Q-dashes grown by migration enhanced epitaxy (MEE) were ~159 nm in length, ~63 nm in width, and ~11 nm in height. A large reduction of volume of InSb structures between those in the matrix and those on the surface was found. Threading disl°Cations resulting from the Q-dash structures were also observed. This may be attributed to As-Sb exchange.

We have grown GaAs quantum dots (QDs) in Al0.3Ga0.7As matrix by droplet epitaxy for application in single photon sources. This growth method enables the formation of QDs without strain, with emission wavelengths of around 700 nm within the optimal detection range of cost effective silicon detector, and with reduced surface density of several tens to a few QDs per m2for easier isolation of single QDs. The optical properties of QDs were envisaged by exciton and biexciton emission peaks identified from power dependent and time-resolved micro-photoluminescence (-PL) measurements. The possibility of fabricating photonic crystal (PC) resonator including a single QD was shown by obtaining precise spectral and spatial information from a few QDs in a mesa structure, utilizing cathodoluminescence (CL) measurements.

The nonpoint source (NPS) control facilities as best management practices (BMPs) were installed to manage NPS pollution in Korean and determining the pollutant reduction loads of BMPs is important to abide by the Korean total maximum daily load (TMDL). However, there are some inadequacies in the methodology to estimate the NPS reduction loads because of uncertainties in rainfall and runoff characteristics. For that reason, a Storm water management model (SWMM) model was used to eliminate uncertainties and to estimate more appropriate reduction loads. In this study, the annual total reduction load (ATRL) method was suggested to calculate annual reduction loads using a SWMM model for appropriate NPS pollution control in the TMDL. Also regression of EMCs (ROE) method was suggested to calculate the annual average removal efficiency (RE) compared to the four different methods, namely, the efficiency ratio (ER), summation of loads (SOL), regression of loads (ROL), and rainfall of frequency method (ROF). Therefore, the ROE method was suggested as the appropriate method to determine the average REs of the BMPs. Also the ATRL method was suggested as the appropriate method to determine the reduction load compared to the existing method in the Korean TMDL. This study provides a SWMM model to standardize BMPs data analysis. The SWMM model can be used to determine the RE and reduction loads of NPS pollution due to the implementation of BMPs and to complement their uncertainties in the TMDL.

Replacement of dopant P by Si in LiF:Mg,Cu,P has provided an improved LiF:Mg,Cu,Si TLD material. Responses of indigenously developed Korean NaturalLiF:Mg,Cu,Si. 6LiF:Mg,Cu,Si and 7LiF:Mg,Cu,Si TLDs to gamma rays and neutrons were evaluated and compared with the commercially available LiF based TLDs. The intrinsic gamma ray sensitivity of NaturalLiF:Mg,Cu,Si was found to be the highest among the studied TLDs. The gamma ray sensitivities of 6LiF:Mg,Cu,Si and 7LiF:Mg,Cu,Si were about 27 and 32 times higher than that of Harshaw LiF:Mg,Ti. The relative neutron sensitivities (ratio of TL/mGy to neutron and gamma rays) of 6LiF TLDs doped with Mg,Cu,P and Mg,Cu,Si were about the same but lower than that of Harshaw 6LiF:Mg,Ti (TLD-600) due to the difference in their LET dependences. The high intrinsic TL sensitivity of 6LiF:Mg,Cu,Si outweighs the higher relative neutron sensitivity of TLD-600. In the testing following ANSI criteria, the performance quotient of the pairs of 6LiF:Mg,Cu,Si / 7LiF:Mg,Cu,Si held in Harshaw neutron TLD badge holders for the dosimetry in the mixed field of neutron and gamma rays was found to be less than 0.1 as against the maximum permitted value of 0.4.

The fabrication of transparent, flexible, and optically homogeneous magnetic composites containing ferrite (Fe3O4) nanoparticles, liquid crystals (LCs), and siloxane backbones is reported. The transparent magnets are achieved by covalently bonding LCs to the siloxane backbones and then linking them to dopamine‐functionalized ferrite nanocrystals. They exhibit simultaneous high transparency and strong magnetic properties. A remarkable feature of these films is that the surface morphology of the LC‐attached ferrite films can be tuned by an external magnetic field, demonstrating a striped surface in the direction of the field. We show that the LC‐attached film can act as an alignment layer to orient LCs, enabling the development of LC alignment surfaces on the basis of these nanomagnet–LC polymer composites.

We have investigated the electronic structures and magnetic properties of free-standing Fe−Co nanowires by density functional theory (DFT) calculations using ultrasoft pseudopotential plane wave method. We have considered the free-standing Fe(1-x)Cox nanowires with centered-staggered triangle and square structures. The optimized lattice constants obtained by total energy calculation are slightly longer than those of the experimental results and the variation of magnetic moments with Co concentration is similar to the Slater-Pauling curve. The spin-polarized density of states (DOS) of Fe0.8Co0.2 nanowire reveals a nearly half-metallic character. We have found the coercivity estimated by the chain-of-spheres model is consistent with the experimental results for Fe−Co nanowire arrays fabricated in porous templates.

The magnetic properties of V and Fe at the interface in V/Fe(110) are investigated theoretically by using the all-electron full-potential linearized augmented plane wave (FLAPW) method within the generalized gradient approximation (GGA) for exchange and correlation. In order to take into account both interface and surface magnetic properties, we considered 2 V monolayers on Fe(110) substrate. The cal- culated magnetic moments for V and Fe layers exhibit the induced magnetic moments in V couple antiferromagnetically to the Fe one, which is in agreement with other theoretical and experimental results for Fe/V/Fe(110) trilayers. The interface V layer has larger magnetic moment than the surface one, which indicates that the induced V magnetic moment is mainly located at the interface and the surface has nearly no effect to the V/Fe(110). The calculated magnetic moment for interface Fe exhibits slightly reduced value compared with the calculated bulk moment, which is consistent with previous results for Fe/V(110) and implies that there is strong hybridization between the V and Fe layers at the interface. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

This study presents photodissociation branching ratio data for clusters formed by solvation of Sr⁺ with CH3OD molecules. The primary photoproducts in clusters with one to four solvent molecules are evaporative ligand loss, C−O bond cleavage to form SrOD⁺, and O−D bond cleavage, forming SrOCH3⁺. Careful analysis of the mass spectra of products and unphotolyzed parent ions as a function of laser fluence shows that clusters that lose a single solvent molecule may absorb additional photons, undergoing subsequent solvent evaporation and chemical reaction. Cluster ions formed by loss of one or more solvent molecules are vibrationally excited, and their subsequent photolysis products reveal strong enhancement of reactive channels involving D-atom loss and C−O bond cleavage relative to cold clusters produced directly by supersonic expansion. In addition to determining branching ratios for the products of vibrationally excited clusters, the study reveals that these hot clusters also have dissociation spectra that are strongly red-shifted relative to their cold counterparts.

This study presents photodissociation data on the mass-selected clusters Sr⁺(CH3OH)n and Sr⁺(CH3OD)n, n = 1−4, in the wavelength range from 310 to 1500 nm. The parent ion clusters exhibit loss of hydrogen atoms by C−H bond cleavage in their ground electronic states, a channel that increases in magnitude with increasing cluster size. Electronic states of clusters based on excitation of metal-centered d, p ← s transitions are observed. The cluster spectra exhibit a size-dependent red shift that is consistent with increased metal−ligand repulsion with increasing size. The clusters decay by solvent evaporation, methyl radical loss to form the metal hydroxide cation, and loss of oxygen-bound hydrogen atoms to form the metal methoxide cation, SrOCH3⁺.

Increasing the net fixed-charge density in multilayer polyelectrolyte membranes using postdeposition reactions results in large enhancements of ion-transport selectivity. To control the fixed-charge density in poly(acrylic acid)/poly(allylamine hydrochloride) (PAA/PAH) films, we partially derivatized PAA using 2-nitrobenzyl bromide. The underivatized −COO^- groups still allow adsorption of PAA/PAH membranes on a permeable support, while postdeposition UV irradiation of these films cleaves the 2-nitrobenzyl esters to form fixed-charge sites. Diffusion dialysis experiments show that PAA/PAH membranes prepared with 23%, 50%, and 65% 2-nitrobenzyl esterified PAA exhibit Cl^-/SO4^2- selectivities of 100, 150, and 170, respectively (after photolysis). Underivatized PAA/PAH membranes show a selectivity of only 10. The order of magnitude increase in selectivity resulting from derivatization occurs with a minimal decrease in Cl^- flux. By modifying PAH with photolabile 2-nitrobenzyloxycarbonyl groups, we also introduced net, fixed positive charge into PAA/PAH films and improved cation (Na⁺/Mg²⁺) selectivity. Transport simulations suggest that both Donnan exclusion and selective diffusion contribute to selectivity.

The fluorene-based poly(iminoarylene)s with triarylamine unit were simply synthesized from palladium-catalyzed polycondensation of 2,7-dibromo-9,9-di-n-alkyllfluorene with primary amines such as aniline and p-toluidine. The polymers with high molecular weight were obtained and were thermally stable. The HOMO levels of the polymers (~−5.1 eV) were close to the work function of ITO. Organic light-emitting diodes (OLEDs) of the form ITO/polymer/TPD/Alq3/LiF/Al showed lower turn-on voltage (VT = 2.2 V), the enhanced efficiency, and the higher maximum luminance at the higher current density (PFA1:  12 370 cd/m² at 427 mA/cm²) than those of the device without polymer (VT = 3.6 V, 5790 cd/m² at 233 mA/cm²). It is expected that these polymers can be used as a buffer layer in OLEDs.

A series of copolymers, poly{9,9-bis(2‘-ethylhexyl)fluorene-2,7-diyl-co-2,5-bis(2-thienyl-1-cyanovinyl)-1-(2‘-ethylhexyloxy)-4-methoxybenzene-5‘ ‘,5‘ ‘‘-diyl} (PFTCVB), were synthesized from the monomers 2,7-dibromo-9,9-bis(2‘-ethylhexyl)fluorene and 2,5-bis(2-(5‘-bromothienyl)-1-cyanovinyl)-1-(2‘ ‘-ethylhexyloxy)-4-methoxybenzene (BTCVB) through the Ni(0)-mediated polymerization. The copolymers were characterized using FT-IR spectroscopy, UV−vis spectroscopy, TGA, photoluminescence (PL) and electroluminescence (EL) spectroscopy, elemental analysis, and molecular weight studies. The synthesized copolymers showed an absorption maximum at about 380 nm, and between 425 and 600 nm the absorption increased with increasing fraction of thiophene-containing monomer 4 (BTCVB). In PL, the emission maxima of the copolymers were red-shifted as the fraction of BTCVB increases, despite the copolymers showing little variation in UV−vis absorption characteristics. Light-emitting devices were fabricated in an ITO (indium−tin oxide)/PEDOT/polymer/LiF/Al configuration. The EL spectra showed similar emissions to the PL results, and the copolymer containing 15 mol % of BTCVB showed bright-red emission.

The effects of dietary conjugated linoleic acid (CLA) on fatty acid composition, lipid oxidation, and pork quality were investigated. Pigs (n = 20) were fed a diet containing 0, 1, 2.5, or 5% CLA for 4 wk and slaughtered at 105 kg. The longissimus thoracis et lumborum muscle was collected at 24 h postmortem. Pork loin chops (3 cm thick) were packaged aerobically and stored at 4 degrees C for 7 d. Samples were analyzed for ultimate pH, intramuscular fat content, fatty acid composition, thiobarbituric acid-reactive substances, color (L*, a*, b*), and water-holding capacity. Dietary CLA reduced the concentration of linoleic acid and increased CLA concentration in intramuscular fat of pork loin (P < 0.05). The concentration of CLA in muscle was increased with dietary CLA level and did not change during storage. Thiobarbituric acid-reactive substance value of control was higher than that of the CLA-fed groups (P < 0.05). Intramuscular fat content was increased by dietary CLA, and less purge loss was observed with samples from CLA-fed pigs (P < 0.05). Dietary CLA improved the color stability of pork loin during cold storage. After 7 d, lightness (L*) and yellowness (b*) of the 5% CLA-fed group were significantly lower than those of control (P < 0.05). The results indicated that the water-holding capacity of pork loin was increased with increased intramuscular fat content apparently caused by dietary CLA. Also, the data indicated that color stability of pork was improved with inhibition of lipid oxidation and changing of fatty acid composition by dietary CLA.

The role of the region of the principal somatic sensory nucleus of the human thalamus (ventral caudal – Vc) in signaling painful sensations is unclear. We have now studied the response of cells (n = 57) in this region to both thermal and mechanical stimuli graded into the painful range during surgeries (n = 24) for treatment of movement disorders. Fifteen cells had a graded response to mechanical stimuli extending into the painful range and, thus, were classified in the wide dynamic range (WDR) category. The mean stimulus‐response function of cells in the WDR class, normalized to baseline, showed a fourfold mean increase in firing rate above baseline across the mechanical series of stimuli. Seven of these cells responded to heat stimuli (WDR‐H) and two responded to cold stimuli (WDR‐C). Twenty‐five cells were in a class (multiple receptive – MR) that showed a response to both brush and compressive stimuli, although the responses were not graded into the painful range. Three of these cells (MR‐H) had a response to heat stimuli and five cells responded to cold stimuli (MR‐C). Nine cells responded to brushing without a response to the compressive stimuli (low threshold – LT). Cells responsive to painful mechanical and thermal stimuli were located throughout the thalamic region where cells responded to nonpainful cutaneous stimulation. These results show that cells in the region of the human thalamic principal somatic sensory nucleus respond to mechanical and thermal stimuli extending into the painful range. J. Comp. Neurol. 410:541–555, 1999. © 1999 Wiley‐Liss, Inc.

We have prepared a series of cross-linkable oligo- and poly(dialkylfluorene)s by nickel(0)-mediated polymerization of 2,7-dibromo-9,9-dialkylfluorene (alkyl = n-hexyl) and 4-bromostyrene. The resulting fully soluble and processable, styryl-functionalized oligomers and polymers can be cross-linked via the vinyl end-groups by curing at 175−200 °C, consistent with the autopolymerization mechanism of styrene. These relatively mild conditions render the materials insoluble and enable multilayering of polymers in organic light emitting devices. At the same time, the electrical and/or optical properties of the cross-linked polymers are preserved and no deleterious species or undesirable byproducts are produced. Furthermore, the cross-linking allows control of the supramolecular ordering of the planarized rigid rod-type fluorene segments in the polymer backbone that leads to suppression of troublesome excimer/aggregate in the photo- and electrolumenescence.

Poly(9,9-dialkylfluorene-2,7-diyl) derivatives end-capped with 2-fluorenyl, 9,9-di-n-hexyl-2-fluorenyl, and 9-fluorenone-2-yl substituents have been synthesized through Ni(0)-mediated polymerization. Absorption and emission spectra of these polymers were measured after annealing at elevated temperatures in air as a function of annealing time. The fluorescence stability of the polymers end-capped using 2-bromo-9,9-di-n-hexylfluorene was much better than for the polymers end-capped with 2-bromofluorene. The exceptional sensitivity of the luminescence of the polymers end-capped with 2-fluorenyl substituents to thermal annealing in air is rationalized by a combination of π-stacking and chemical oxidation of the end groups to fluorenones. The latter was demonstrated by the IR spectra of annealed films and comparison of the results with the absorption, emission, and IR spectra of the polymers deliberately end-capped using 2-bromo-9-fluorenone. This study is directed toward the investigation of color stability of planarized π-systems for light emitting diodes (LEDs).

Leader peptidase (Lep) is a central component of the secretory machinery of Escherichia coli, where it serves to remove signal peptides from secretory proteins. It spans the inner membrane twice with a large C‐terminal domain protruding into the periplasmic space. To investigate the importance of the different structural domains for the catalytic activity, we have studied the effects of a large panel of Lep mutants on the processing of signal peptides, both in vivo and in vitro. Our data suggest that the first transmembrane and cytoplasmic regions are not directly involved in catalysis, but that the second transmembrane region and the region immediately following it may be in contact with the signal peptide and/or located spatially close to the active site of Lep.

Twenty-nine intestinal spirochetes isolated from Australian aboriginal children and six strains from Italian adults (HRM1, -2, -4, -5, -7, and -14) were genetically examined at 15 enzyme loci by using multilocus enzyme electrophoresis. Results were compared with those previously obtained for 188 porcine intestinal spirochetes. DNA from human strain HRM7 and porcine strain Serpulina hyodysenteriae P18A were also radioactively labeled and hybridized with DNA from 12 other human and porcine intestinal spirochetes. Both the multilocus enzyme electrophoresis and hybridization techniques demonstrated that the human spirochetes were not S. hyodysenteriae. They belonged to another distinct genetic group of spirochetes that included P43/6/78, the bacterium recovered from the first recorded case of porcine intestinal spirochetosis. Bacteria in this distinct group also differed from Serpulina spp. in possessing only four, five, or occasionally six axial filaments, being slightly thinner, and having more pointed ends. These findings add further weight to the possibility that human intestinal spirochetes may act as enteric pathogens.

Leader peptidase of Escherichia coli spans the plasma membrane twice with its amino terminus on the periplasmic surface of the membrane and its large carboxyl-terminal domain protruding into the periplasm. To monitor the transfer of the amino terminus of leader peptidase to the periplasm, we have constructed a fusion protein between the 18-residue amino-terminal periplasmic domain of Pf3 bacteriophage coat protein and the beginning of leader peptidase. We find that neither the SecA or SecY proteins nor a transmembrane electrochemical potential is required for insertion of the amino terminus, while the transfer of the carboxyl-terminal domain of leader peptidase has these requirements. The first 35 residues of leader peptidase, which include the first hydrophobic domain and the carboxyl-terminal positively charged cluster, are sufficient to insert the amino terminus. When positively charged residues are introduced before the first transmembrane segment, translocation of the amino terminus is abolished. These studies in protein membrane topogenesis, showing that there are different requirements for amino and carboxyl termini insertion, indicate that multiple mechanisms exist even within the same protein.

Leader peptidase (Lep) is a central component of the secretory machinery of Escherichia coli, where it serves to remove signal peptides from secretory proteins. It spans the inner membrane twice with a large C‐terminal domain protruding into the periplasmic space. To investigate the importance of the different structural domains for the catalytic activity, we have studied the effects of a large panel of Lep mutants on the processing of signal peptides, both in vivo and in vitro. Our data suggest that the first transmembrane and cytoplasmic regions are not directly involved in catalysis, but that the second transmembrane region and the region immediately following it may be in contact with the signal peptide and/or located spatially close to the active site of Lep.

High-relfection (HR)-coated facet effects on the spectral characteristics of a three-section distributed Bragg reflector (DBR) tunable laser are investigated theoretically, in which the output power emits to the DBR section. It is found that the output power to the DBR sectionPDBR compared to the cleaved facet output powerP0 is nearly constant to some degree with increasing tuning current. Owing to the high-Q resonator, the HR-coated DBR laser showed a decrease in spectral linewidth. However, there is still linewidth broadening of the HR-coated DBR laser even though the rate of increase is smaller than that of the cleaved-facet DBR laser. In the case of output power emission to the DBR section, it is thought that the HR-coated effect can overcome the decrease in output power under frequency tuning, which is one of the most important drawbacks of DBR laser performance.

The energy transfer in a blend of electroluminescent conjugated polymers, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and conjugated−nonconjugated multiblock copolymers (CNMBC), was investigated. Energy transfer from CNMBC to MEH-PPV leads to the enhanced emission of MEH-PPV. Fluorescence decays also support this energy-transfer process, which is faster than radiative and nonradiative decays. PL and EL quantum efficiencies of the blended polymer were enhanced as the relative content of CNMBC was increased, and surprisingly, 500 times improved EL efficiency was observed for some blend ratios. These results provide further insight into the photophysics of conjugated polymers and the improvement of the electroluminescence quantum efficiency using the blended polymer systems.

The generation of a large number of tangled dislocations and subgrain boundaries by dislocation pileups in the stir cast AI-6'2 wt-%Si alloy was observed by a transmission electron microscopy (TEM) study. Misorientations between grains were measured by selected area diffraction (SAD) and convergent beam electron diffraction (CBED) patterns. The density and entanglement of dislocations increased with higher solid fraction (or shear stress) and higher shear rate as a result of increased plastic strain. Longer isothermal stirring time gave rise to higher dislocation density and smaller subgrain size. The meltoff of high angle boundaries, which was suggested by Vogel-Doherty-Cantor's grain boundary melting model, is supported by the observation of subgrain boundaries owing to dislocation pileups during semisolid stirring.

AbstractPPV was sensitized by ethyl viologen which is well known as a good electron acceptor, to achieve efficient ionization of the excitons created by photoexcitation of PPV. PPV/ethyl-viologen composites were successfully prepared from PPV-precursor and ethyl-viologen because both compounds could be soluble in polar solvents such as methanol, water etc. We observed dramatic decrease of photoluminescence efficiency in the PPV/ethyl-viologen composite film as compared with PPV film. This is attributed to photoinduced electron transfer in PPV/ethyl-viologen composites and the efficient ionization of the excitons was occurred in this composite film. Time-resolved photoluminescence of composite films was also studied to obtain the information of this photoinduced electron transfer dynamics.

Five lacY mutants with amber stop codons at known positions were each placed into 12 different suppressor strains. The 60 amino acid substitutions obtained in this manner were tested for growth on lactose-minimal medium plates and for transport of lactose, melibiose, and thiomethylgalactoside. Most of the amino acid substitutions in the regions of the putative loops (between transmembrane alpha helices) resulted in a reasonable growth rate on lactose with moderate-to-good transport activity. In one strain (glycine substituted for Trp-10), abnormal sugar recognition was found. The substitution of proline for Trp-33 (in the region of the first alpha helix) showed no activity, while four additional substitutions (lysine, leucine, cysteine, and glutamic acid) showed low activity. Altered sugar specificity was observed when Trp-33 was replaced by serine, glutamine, tyrosine, alanine, histidine, or phenylalanine. It is concluded that Trp-33 may be involved directly or indirectly in sugar recognition.

Sample-path-based stochastic gradient estimators for performance measures of queueing systems rely on the assumption that a probability distribution of the random vector of interest (e.g., a service or interarrival time sequence) is given. In this paper, we address the issue of dealing with unknown probability distributions and investigate the robustness of such estimators with respect to possibly erroneous distribution choices. We show that infinitesimal perturbation analysis (IPA) can be robust in this sense and, in some cases, provides distribution-independent estimates. Comparisons with other gradient estimators are provided, including experimental results. We also show that finite perturbation analysis (FPA), though only providing gradient approximations, possesses some attractive robustness properties with respect to unknown distribution parameters. An application of FPA estimation is included for a queueing system performance optimization problem involving customers with real-time constraints.

A new method for assaying ubiquitin C-terminal hydrolases was developed using a 125I-labeled ubiquitin-alpha NH-MHISPPEPESEEEEEHYC was substrate. Since the peptide portion was almost exclusively radiolabeled, the enzymes could be assayed directly by simple measurement of the radioactivity released into acid-soluble products. Using this assay protocol, we identified at least 10 ubiquitin C-terminal hydrolase activities from the extract of chick skeletal muscle, which were tentatively named UCHs 1 through 10. Of these, UCH-6 was purified to apparent homogeneity. Purified UCH-6 behaved as a dimer of 27-kDa subunits. The apparent molecular masses of the other partially purified UCHs ranged from 35 to 810 kDa as determined under a non-denaturing condition. Muscle UCHs, except UCH-1, were activated dramatically by poly-L-Lys but with an unknown mechanism. All of the UCHs were sensitive to inhibition by sulfhydryl-blocking agents such as iodoacetamide. In addition, all of the UCHs were capable of releasing free ubiquitin from a ubiquitin-alpha NH-carboxyl extension protein of 80 amino acids and from ubiquitin-alpha NH-dihydrofolate reductase. Five of the enzymes, UCHs 1 through 5, were also capable of generating free ubiquitin from poly-His-tagged diubiquitin. In addition, UCH-1 and UCH-7 could remove ubiquitin that had been ligated covalently by an isopeptide linkage to a ubiquitin (RGA)-alpha NH-peptide, the peptide portion of which consists of the 20 amino acids of the calmodulin binding domain of myosin light chain kinase. These results suggest that the 10 UCH activities isolated from chick skeletal muscle appear to be distinct from each other at least in their chromatographic behavior, size, and substrate specificity.