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Laser cavity-solitons can appear in systems comprised of a nonlinear microcavity nested within an amplifying fiber loop. These states are robust and self-emergent and constitute an attractive class of solitons that are highly suitable for microcomb generation. Here, we present a detailed study of the free-running stability properties of the carrier frequency and repetition rate of single solitons, which are the most suitable states for developing robust ultrafast and high repetition rate comb sources. We achieve free-running fractional stability on both optical carrier and repetition rate (i.e., 48.9 GHz) frequencies on the order of [Formula: see text] for a 1 s gate time. The repetition rate results compare well with the performance of state-of-the-art (externally driven) microcomb sources, and the carrier frequency stability is in the range of performance typical of modern free-running fiber lasers. Finally, we show that these quantities can be controlled by modulating the laser pump current and the cavity length, providing a path for active locking and long-term stabilization.

Objectives: The purpose of this study was to evaluate the effect of prevetebral space involvement on treatment outcomes in patients with nasopharyngeal carcinoma (NPC) who were treated with radiotherapy/concurrent chemoradiotherpy or concurrent chemoradiotherpy with adjuvant chemotherapy. Design: A retrospective review of case notes from the Kaohsiung Veterans General Hospital archives was performed. Setting: A medical centre in Taiwan. Participants: There were 145 newly diagnosed cases of NPC. Thirty-nine patients were excluded because of the presence of distant metastasis at the time of presentation, loss of follow-up and incomplete image information. Main outcome measures: Pearson’s chi-square tests were used to analyse correlation between tumour invasion and prevetebral space involvement during univariate analysis and logistic regression was applied during multivariate analysis. Kaplan–Meier survival curves were constructed. Multivariate analysis was performed to examine the impact of various prognostic factors. Pearson’s chi-square and Fisher’s exact test were also used to evaluate the correlation between failure patterns and treatment modality. Results: A total of 106 patients with newly diagnosed NPC were enrolled in this study. Forty-three patients (41%) in this series were found to have prevertebral space involvement. Patients with prevertebral space involvement conferred a poor overall survival rate and metastasis-free survival rate compared with those without prevertebral space invasion (P = 0.04 and 0.02 respectively). Multivariate analysis showed that prevertebral space invasion was associated with an increased risk for distant metastasis [hazard ratio (HR) 14, 95% confidence interval (CI) 1.0–17.4; P = 0.03)] and overall survival (HR 7, 95% CI 1.1–135; P = 0.04). In patients with prevertebral space involvement, their metastasis-free survival rate, with and without adjuvant chemotherapy, was 100% and 72.7% (P = 0.047). This phenomenon was not observed in NPC patients without prevertebral space invasion. Conclusions: The present data revealed that prevertebral space involvement has a close relationship with survival rates and recurrence rates of patients with NPC. Nasopharyngeal carcinoma patients with prevertebral space involvement have more recurrence and poorer survival rates and should be the group to benefit from concurrent chemoradiotherapy followed by adjuvant chemotherapy. Inclusion of prevertebral space involvement may be needed to predict prognosis of NPC and help us to identify the high-risk group.

Previous simulation studies dealing with surface runoff use mathematical models based on a single soil infiltration relationship to estimate the influence of irrigation application depths and rates on surface runoff depths. Soil infiltration is influenced by such parameters as soil type, tillage practices, and soil water content. Surface runoff data from a field study with a continuous-move irrigation lateral indicate that Green and Ampt soil infiltration parameter values may also be influenced by sprinkler technologies. Soil infiltration parameter values derived from a sprinkler test with a low application rate may produce results that overestimate runoff values for sprinklers with higher application rates. Likewise, parameter values derived from a sprinkler with a high application rate can produce results that underestimate surface runoff for sprinkler technologies with lower application rates.

We examined 24p3 expression in the mouse uterus at various stages of the natural estrous cycle and during the preimplantation period. The level of 24p3 mRNA appeared intensively in proestrus and estrus, then declined sharply from metestrus to diestrus. Consistent with this observation, 24p3 protein was abundant in proestrus, decreased from estrus to metestrus and declined to a very low level in diestrus. The uterine 24p3 expression closely overlapped with the estradiol (E2) surge in proestrus and estrus but it was suppressed when progesterone (P4) rose to a high level during the reproductive cycle. Neither the protein nor its message was detected in the uteri of immature mice or ovariectomized adult animals. While an injection of P4 to these animals was unable to initiate uterine 24p3 expression, administration of estrogenic steroids to these animals markedly stimulated the gene expression. Treatment of these animals with E2 together with P4, on the other hand, did not stimulate the gene expression. In pregnant animals (day 1 (D1)=day of vaginal plug), 24p3 mRNA remained at a high level on D1 and D2 but dropped to an almost undetectable level on D3 and D4. This was accompanied by a decrease in 24p3 protein from D1 to D2 and a decline in the protein to undetectable levels from D3 to D4. The staining patterns of both the immunohistochemical localization of 24p3 protein and in situ hybridization for the detection of 24p3 mRNA in the uterine sections showed that 24p3 expression took place mainly in the luminal and glandular epithelial cells of the endometrium. This together with our previous observation that 24p3 protein is found in uterine luminal fluid indicates that the protein is secreted primarily from these cells to their respective luminal surfaces during proestrus and estrus.

The wetting front concept of Green and Ampt (1911) is extended to develop an infiltration model for a soil profile with a non-uniform initial soil water condition. This model can be applied to describe the water infiltration process in wetlands or areas under drainage where a water table is present. Two types of model applications are considered. The first type is when the initial soil water distribution is known. The infiltration model is used to estimate the infiltration rate for a soil profile with a shallow or deep water table level. The second type is when the initial soil water distribution is unknown and only the initial water table level is given. Under such a condition, the equilibrium condition (the water energy in the vadose zone is a constant) is used to provide an approximation for the initial soil water distribution. Such an approximation is adequate in a shallow water table environment (water table depth < 3 m) and represents a limitation in the application of the developed model.

Water table level is an important feature in subterranean hydrology and is relatively easy to observe. Groundwater recharge is a cause of water table rise and the carrier of contaminants to groundwater. However, groundwater recharge is an elusive quantity because accurate field measurements are difficult to obtain. A study of the relationship between groundwater recharge and water table rise is advantageous because it will allow the evaluation of groundwater recharge based on field-measured water table rise.

We introduce an innovative geometry for OPOs in a CMOS-compatible microring resonator that is robust against the effect of thermal fluctuations. It exploits lasing of the pump inherently positioned within the resonances of the microcavity.

Recent studies on soil water movement emphasize the description of soil macropore flow. In this article, an infiltration model is developed which separates water flow in large soil pores from flow in small pores. The soil water retention curve is considered to represent a bundle of capillary tubes. The matric potential of the retention curve is used to determine capillary tube hydraulic conductivity based on Hagen-Poiseuille equation. Infiltration capacity curves under a surface ponded condition are derived. The model predicts a spatially varied wetting front. An example to illustrate the application of capillary-tube infiltration model to determine the spatially wetting front of Yolo light clay is presented.

Low‐pressure irrigation systems are developed to reduce energy requirement and cost. A consequence of low pressure is a reduced sprinkler wetting coverage. Small wetting coverages cause high water application rates and surface runoff potential. Trail tubes are perforated polyethylene hoses designed to replace sprinklers and reduce surface runoff potential in low‐pressure irrigation conditions. Long tube length can be used to create large wetting coverage to reduce surface runoff potential. Previous design of trail tubes emphasized on variable hole‐spacing tubes. Such a design produced minimum tube length and material cost. Constant hole‐spacing tubes will be longer than variable hole‐spacing tubes but have manufacturing and installation advantages. In practice, such advantages can more than offset the additional material cost due to longer tubes. Therefore, the study of constant hole‐spacing design is needed to provide an alternative selection of trail tubes. In this paper, the hydraulics of constant hole...

Trail-tubes are lengths of perforated tubing designed to replace individual sprinklers on moving lateral irrigation machines. Water is applied such that the application rate matches the soil infiltration rate (no surface runoff), a reduced line pressure can be used (low energy), and evaporation and wind drift losses are minimized (maximum application efficiency). Trail-tube hydraulic theories were verified in laboratory studies. Field studies were conducted on corn and soybean plots with three trailtube spacings (1.5, 3.0, and 4.5 m) (4.9, 9.8, and 14.7 ft) and a 40 kPa (6 psi) spray sprinkler. The 4.5-m (14.7-ft) treatment was unsatisfactory because of poor application uniformity and excess surface runoff. Representative coefficients of uniformity for the 1.5-m (4.9-ft), 3.0-m (9.8-ft), and sprinkler treatments were 80, 65, and 96%, respectively. Surface runoff for the 1.5-m (4.9-ft) and 3.0-m (9.8-ft) treatments was about one half of the sprinkler runoff value. Crop yields were not affected by the water application treatments.

Gardening for Ants and Termites Among the social insects, ants and termites are the most diverse and ecologically dominant. Termites are known to engage in a mutualism with nitrogen-fixing bacteria, and Pinto-Tomás et al. (p. 1120 ) have identified similar relationships occurring among leaf-cutter ants, which maintain specialized nitrogen-fixing bacteria in their fungus gardens. Together, these mutualisms are a major source of nitrogen in terrestrial ecosystems. How is the evolutionary stability of such mutualistic cooperation maintained? Aanen et al. (p. 1103 ) show that the Termitomyces fungus cultured by termites remains highly related because mycelia of the same clone fuse together and grow more efficiently to out-compete rare clones.

To test the hypothesis that firefighter exposures may increase cancer risk, mortality rates were calculated for 3,066 San Francisco Fire Department firefighters employed between 1940 and 1970. Vital status was ascertained through 1982, and observed and expected rates, rate ratios (RR), and 95% confidence intervals (CI) were computed using United States death rates for comparison. The total number deceased (1,186) was less than expected and there were fewer cancer deaths than expected. However, there were significant excess numbers of deaths from esophageal cancer (12 observed, 6 expected), cirrhosis and other liver diseases (59 observed, 26 expected), and accidental falls (21 observed, 11 expected). There were 24 line-of-duty deaths, which were primarily due to vehicular injury, falls, and asphyxiation. Heart disease and respiratory disease deaths occurred significantly less often than expected. It was concluded that the increased risks of death from esophageal cancer and cirrhosis and other liver diseases may have been due to firefighter exposures, alcohol consumption, or interaction between alcohol and exposures. Because this was an older cohort and firefighter exposures have changed due to the increasing use of synthetic materials, it is recommended that the effects of modern-day exposures be further studied.

To evaluate the usefulness of dynamic Gd-enhanced MR imaging in distinguishing recurrent inverted papilloma (IP) from postoperative changes. Ten patients with 13 surgical proved lesions were examined. T1-weighted (pre- and postcontrast), proton-density, and T2-weighted spin-echo images were evaluated. A total of nine dynamic FSE (fast spin-echo) images were obtained at 0, 5, 30, 60, 90, 120, 150, 180, and 300 seconds after bolus Gd-DTPA injection. Signal-time curves were obtained from dynamic scan. Reading of the T2-weighted images yielded a sensitivity of 75%, a specificity of 80%, and an accuracy of 77%. The contrast T1-weighted studies yielded a sensitivity of 63%, a specificity of 60%, and an accuracy of 67%. With a relative signal increase (RSI) of 2.0 or higher, a 60-second imaging time provided the sensitivity of 87% for the detection of recurrence and a specificity of 80%. There were significant differences in the RSI at 30, 60, 90, 120, 150, and 180 seconds (P < 0.01) between recurrent tumor and postoperative changes. Dynamic MR imaging can increase the diagnostic accuracy in the local recurrence of IP, and help differentiate recurrence and postoperative changes.

The relationship between initial water content and Green-Ampt parameters was established explicitly using the Brooks-Corey representation of the soil-water retention curve. Such a relationship enhanced the versatility of Green-Ampt infiltration model. The parametric values measured at a given initial water content can be adjusted to obtain the parametric values at other initial water content conditions.

We studied the effect of a mouse seminal vesicle autoantigen (SVA) on BSA-stimulated functions of mouse sperm. Uncapacitated, capacitated, and acrosome-reacted stages of sperm were morphologically scored, and the cellular zinc content was examined cytologically in a modified Tyrode solution at 37 degrees C for 80 min. More than 85% of control cells remained uncapacitated. Addition of 0.3% SVA to the cell incubation did not affect the cell status. Approximately 65% of cells were capacitated in the incubation medium containing 0.3% BSA. Only 30% of the cells became capacitated after incubation with 0.3% BSA and 0.3% SVA together. The decapacitation effect by 0.3% SVA could be subdued by more than 3% BSA in the cell incubation. Whereas BSA did, SVA did not cause removal of Zn(2+) from sperm, but SVA could suppress the BSA effect. The tyrosine phosphorylated proteins in sperm were detected after incubation in a modified HEPES medium containing 0.3% BSA and/or 0.3% SVA at 37 degrees C for 90 min. Whereas BSA enhanced greatly, SVA did not cause phosphorylation of proteins in the range of M:(r) 40 000-120 000. The BSA-stimulated protein tyrosine phosphorylation could be suppressed by SVA in the cell incubation.

The cDNA sequence for 24p3 protein in ICR mouse epididymal tissue was determined by PCR using primers designed according to the cDNA sequence derived from 24p3 protein in mouse uterine tissue. In the present study, 24p3 protein was immunolocalized in the epithelial cells and lumen of mouse epididymis. Both immunoblot analysis for protein and northern blot analysis for mRNA level showed a declining gradient of 24p3 expression from the caput to caudal region of the epididymis. The 24p3 protein was undetectable in the testis. These findings suggest that the 24p3 protein is a caput-initiated secretory protein in the mouse epididymis. A postnatal study revealed that 24p3 gene expression occurred in mice at the age of 14 days, before the completion of epididymal differentiation. This expression remained at a constant level until epididymal differentiation was completed. We also found that the secreted 24p3 protein interacted predominantly with the acrosome of caudal spermatozoa. Our findings suggest that the epididymal 24p3 protein is a caput-initiated and sperm-associated gene product and may be important in the reproductive system.

BACKGROUND AND PURPOSE: Dynamic gadolinium-enhanced MR imaging has been used successfully to identify post-treatment recurrence or postoperative changes in rectal and cervical carcinoma. Our purpose was to evaluate the usefulness of dynamic gadolinium-enhanced MR imaging for distinguishing recurrent inverted papilloma (IP) from postoperative changes. METHODS: Fifteen patients with 20 pathologically proved lesions (recurrent IP, 12; fibrosis or granulation tissue, eight) were enrolled in the study. Three observers, blinded to pathologic results, independently evaluated conventional MR images, including T1-weighted (unenhanced and postcontrast), proton-density–weighted, and T2-weighted spin-echo images. Results then were determined by consensus. Dynamic images were obtained using fast spin-echo sequences at 5, 30, 60, 90, 120, 150, 180, and 300 seconds after the injection of gadolinium-diethylenetriamine penta-acetic acid. Time-signal intensity curves of suspected lesions were analyzed by a pharmacokinetic model. The calculated amplitude and tissue distribution time were used to characterize tissue, and their values were displayed as a color-coded overlay. RESULTS: T2-weighted images yielded a sensitivity of 67%, a specificity of 75%, and an accuracy of 70% in the diagnosis of recurrent IP. Contrast-enhanced T1-weighted images yielded a sensitivity of 75%, a specificity of 50%, and an accuracy of 65%. Pharmacokinetic analysis showed that recurrent IP had faster (distribution time, 41 versus 88 seconds) and higher (amplitude, 2.4 versus 1.2 arbitrary units) enhancement than did fibrosis or granulation tissue. A cut-off of 65 seconds for distribution time and 1.6 units for amplitude yielded a sensitivity of 100% and a specificity of 100% for diagnosing recurrent IP. CONCLUSION: Dynamic MR imaging can differentiate accurately recurrent IP from postoperative changes and seems to be a valuable diagnostic tool.

Seminal vesicle autoantigen (SVA) is a 19 kDa glycoprotein purified from mouse seminal vesicle secretion. It was quantified to be 0.9% (w/v) in the seminal vesicle fluid. We examined its distribution in the accessory sexual gland, characterized its binding sites on the sperm surface and assessed its effect on sperm motility. It was immunolocalized on the epithelium of the primary and secondary folds in the tissue. Mouse spermatozoa collected from caudal epididymis were devoid of SVA. A cytochemical study illustrated the presence of SVA-binding region on the entire cells. The cytochemical staining intensity for the binding of SVA to spermatozoa remained even when the cells were pretreated with protease digestion, acid or heat at 100 degrees C for 10 min. Moreover, the SVA-sperm binding could be inhibited by the dispersed sperm lipid. The specificity of interaction between (125)I-SVA and phospholipids was studied by TLC overlay techniques. The radiolabelled protein showed strong binding to purified phosphatidylcholine and phosphatidylserine and weak binding to purified sphingomyelin, lysophosphatidylcholine and phosphatidylethanolamine, but did not interact with phosphatidic acid, lysophosphatidic acid or phosphatidylinositol. Among the lipids extracted from spermatozoa, SVA showed strong binding to phosphatidylcholine and weak binding to sphingomyelin and neutral lipids. The assay for SVA-sperm binding with (125)I-SVA determined the IC(50) as being (3.89+/-0.65)x10(-5) M(-1), which is compatible with an apparent dissociation constant of (9.10+/-0.02)x10(-5) M(-1) estimated by fitting the data of phosphatidylcholine-perturbed SVA fluorescence to a modified Scatchard plot. SVA showed an ability to suppress sperm motility. The average path velocity, straight-line velocity and curvilinear velocity of sperm were not detectable by computer-assisted sperm assay after incubation of the cells in the presence of 0.3% SVA at 37 degrees C for more than 40 min.

Three cases of carcinosarcoma of the salivary gland, two in the submandibular gland, and one in the parotid, were investigated with CT and exhibited a variety of findings. The density of the tumors was lower than that of normal submandibular tissue. A calcification was found in one case. One case showed extensive lymphadenopathy. The parotid lesion had low central density with an enhancing margin.

The characteristics, such as the propagation constant and the propagation loss, of an isolated ARROW have been studied and are well understood[1,2]

Since the introduction of the antiresonant reflecting optical waveguides (ARROW),1 extensive research has been devoted to the investigation of this novel way of guiding optical power.2,3 Aside from the ease of fabrication and low loss, the ARROWS provide strong confinement of optical power in the core region, so that one can stack the ARROW together to form waveguide arrays.2 The core dimension and refractive index of the ARROW can also be made similar to that of the optical fiber to obtain very good coupling efficiency at the fiber and integrated optical component interface. Low loss propagation only occurs when the interference layer is at its optimum thickness for antiresonance, consequently, the propagating characteristics in the ARROW are very sensitive to changes in polarization and wavelength and they can be readily implemented in a number of integrated components, such as sensors and polarization splitters. Because the propagation characteristic in the ARROW depends so strongly on the layer thickness of the interference layer, slight deviations in its dimensions or properties from the optimum design, for example, waveguide bends, may drastically affect the propagation characteristics in the waveguides. This behavior can be exploited and used in sensors. The purpose of the paper is to analyze the propagation characteristics at the ARROW bends.

Modeling and simulation are important to the optimum design and precise prediction of the possible performance of optical guided-wave devices. One of the commonly used numerical methods for the simulation of wave propagation in optical waveguides is the beam propagation method (BPM)1,2 and its variations.3,4 Since all these methods assume Fresnel approximation, the reflection of the waves due to the inhomogeneous perturbations along the waveguiding axis has been neglected. The reflection, however, may not be negligible at abrupt junctions and certainly become dominant in structures such as distributed feedback reflectors. A finite-difference time-domain technique (FDTD) that solves the Maxwell′s equations directly has been recently introduced and in principle can be applied to the structures that both the reflection and the polarization effects become important.5 Since most practical optical waveguides are weakly-guiding, the scalar analysis is often sufficient. Therefore, as an alternative approach, we propose to apply FDTD technique to the scalar analysis.

The ability to make in miniature basic optical components is one of the most important factors in the development of intergrated optics circuit. Recently, fabrication of extremely compact components, such as beam splitters1 and zero-gap directional couplers,2 have been realized. These devices require interaction lengths of only a fraction of a millimeter to perform their required functions. The miniature beam splitter1 consists of two perpendicular AlGaAs/GaAs ridge waveguides, with a groove at the intersection. The groove was milled with a microfocused ion beam, and it was reported that the beam-splitting ratio could be adjusted by varying the groove depth. This device could be used as a power splitter or coupler or in the DFB laser circuit. The simple geometry permits easy integration, and a network of such structures may find application in optical computing. In this paper the beam-splitting characteristics of two perpendicular waveguides containing a 45° gap at the intersection, as shown in Fig. 1, are simulated by the FDTD method.3 Simulated results of the splitting ratio as functions of wavelength, gap width, and index change in the gap are presented.

The kinetics of hydrolysis of a series of 10 new hippurate esters (C6H5CONHCH2CO2CRR1CO2H (I)) by bovine pancreatic carboxypeptidase A have been investigated at pH 7.5, 25 °C, and ionic strength 0.5. Pronounced substrate inhibition was displayed by I: R = H, R1 = C6H5(CH2)2, 3-indolylmethyl, 4-HOC6H4CH2, and 4-FC6H4 whereas pronounced substrate activation was observed for I: R = H, R1 = 4-CH3C6H4, 4-C2H5C6H4, 4-C6H5C6H4, 1-naphthyl, 2-naphthyl, and R = R1 = C2H5. In all cases substrate activation and substrate inhibition were shown to be consistent with ES2 complex formation similar to that previously observed for other hippurate esters. Kinetic parameters were evaluated for each ester and it is noted that ail 13 hippurate esters now known to display substrate inhibition have kcat/Km > 106 M−1 min−1, whereas kcat/km 6 M−1 min−1 for all 9 hippurate esters known to display substrate activation. The enzymic specificity for the R1 unit of I suggests binding of R1 in a 'bent' hydrophobic pocket having a restricted entrance.

1. 1. The reactivities of pepsins, isolated from three different sources (porcine, bovine, and Penicillium jathiuelum ), toward ester and peptide substrates were compared. 2. 2. Porcine pepsin showed the highest activity followed by penicillopepsin with bovine pepsin being the least active. 3. 3. The esterase activity of penicillopepsin was greater than that of porcine pepsin with bovine pepsin again showing the least activity. 4. 4. The CD spectra indicate that porcine and bovine pepsin have similar conformations, even though bovine pepsin shows less ellipticity at 220 nm. 5. 5. Penicillopepsin showed a completely opposite sign in the near-u.v. region of the CD spectrum. 6. 6. The far-u.v. region of the CD spectrum of penicillopepsin strongly suggests a β-sheet structure. 7. 7. Previously reported X-ray crystallographic data suggest that porcine pepsin has a compact three-dimensional structure, while the structures of bovine and penicillopepsins are partially unfolded.

The rates of hydrolysis of a series of 21 N-acylglycine esters (YCONHCH2CO2CH(CH2CH3)CO2H ( 2 ) by bovine pancreatic carboxypeptidase A (peptidyl- l -amino-acid hydrolase, EC 3.4.12.2) have been studied over the substrate concentration range 10−4–10−1 M at pH 7.5, 25°C, ionic strength 0.5. All substrates display substrate inhibition except Y = CH3, CH3CH2 and (CH3)3C for which normal Michaelis-Menten kinetics are observed. In all cases substrate inhibition is consistent with the formation of an ES2 complex and parameters for the second-degree rate equation v/E = (k2appS + k3appS2/KSSapp)/(KSapp + S + S2/KSSapp) have been evaluated. For a series of eight aliphatic groups varying in size between Y = CH3 and Y = cyclo-C6H11 the following linear correlations were observed: -log KSapp = 0.82π + 1.32 and log k2app/KSapp = 0.71π + 5.81 (π is Hansch's hydrophobicity parameter). Aryl and aralkyl Y moieties deviate from these correlation lines. KSSapp also depends on the hydrophobicity of Y but no quantitative correlation is obvious. Thus the Y unit of 2 is involved in a hydrophobic interaction with the enzyme when 2 binds at both the catalytically productive and inhibitory sites. Parameters for the enzymic hydrolysis of the esters YCONHCH2CO2CH(CH2CH(CH3)2)CO2H ( 3 ) (Y = C6H5(CH2)n (n = 0, 1, 2)) are also presented. Pronounced non-productive 1:1 enzyme · substrate complex formation is observed for each of 2 : Y = C6H5(CH2)n (n = 2,3) and 3 : Y = C6H5(CH2)2. Hippurate anion is shown to be an uncompetitive inhibitor (Ki = 12 mM) for the hydrolysis of 2 : Y = (CH3)3C. Data are now available which can only be interpreted in terms of at least three enzymic sites being available for hydrophobic interactions with ester substrate molecules.

Analytical solutions have been obtained for a type of variable-lift modulation applicable to a lifting body entering the atmosphere from superorbital and orbital speeds. The variablelift modulation analyzed here results in nonoscillatory trajectories and achieves a smooth transition into a nominal glide phase such as constant flight path angle, constant altitude, constant dynamic pressure, or any other glide desired. Simple closed-form formulas were derived which permit quick estimation of 1) the peak deceleration and the altitude where it occurs, and 2) the required lift modulation necessary for any set of prescribed transition conditions. These approximate formulas show the explicit dependence of trajectory quantities in terms of re-entry conditions, vehicle aerodynamic characteristics, and parameters defining the lift modulation. It can be shown that the analytical solutions obtained in this report include the constant lift-drag solutions obtained by Lees, Hartwig, and Cohen in the orbital case and by Ting and Wang in the superorbital case. Furthermore, in the case of variable lift, this report deals with a continuous lift modulation program instead of a stepwise change of lift-drag considered by Lees, Hartwig, and Cohen.

The probability of spacecraft returning from circular or elliptical orbits to multiple sites is examined as a function of spacecraft cross-range capabilities and waiting time allowed in orbit. The analysis involves the determination of ascending nodes from which the spacecraft with a given cross-range capability could land at a specified site. The loci of these nodes form coverage belts along the equator. A procedure for determining the magnitude and locations of these belts is presented. The series of ascending belts generated by the waiting of spacecraft in orbit and the availability of multiple sites overlap in some of their coverages. A discrete set of regions of accessibility along the equator is thus created and, in turn, determines the probability of return. The concept of coverage belts and regions of accessibility is useful for missions in which the ascending node and the in-track position of the spacecraft are random at the time of recall. Sample results of return probability are presented. (Author)

Because of limitations of weather, sea state, and visibility, planning efforts for the emergency return by abort or escape from orbit to contingency recovery sites must consider factors of local time constraints and redundant access. The first factor provides a means of evaluating the impact of a daylight return requirement; the second permits appraising safer emergency recovery plans when unacceptable weather or sea state conditions exist at the initially selected recovery site. The return probability of spacecraft including these factors involves the determination of coverage belts along the equator that are generated by the loci of ascending nodes of orbits from which the recovery circle can be reached within the local time constraints and with the specified degree of redundancy in access. In general, the coverage belts collectively form a complicated and juxtaposed set. By using the linear Borel set concept, a logic is developed for properly counting and summing these belts to arrive at a general formulation for determining the return probability. Sample results show that the local time constraints have a significant effect upon the return probability. The seasonal variation of available daylight hours can also have pronounced influence on the return probability and the required waiting time for an assured emergency return if the recovery sites are in the same hemisphere. On the other hand, redundant access of the second degree, while having a lower return probability than single access, does not greatly increase the required waiting time for an assured emergency return of a spacecraft. (Author)

The problem of landing site coverage of orbiting vehicles with maneuvering capability is analyzed in this report. The first part deals with the determination of the latitude coverage of a landing site per orbital period for the re-entry vehicle with a given maneuver capability defined by a rectangulaaped landing footprint. The second part relates the required latitude coverage to guarantee that within a specific waiting time in orbit the vehicle would attain a position from which it could be deboosted from orbit and subsequently land at a preselected location. Extensive numerical results are ob tained and presented in convenient graphical form.

The study of waveguide-crossings is important in the design of integrated optic (IO) components and in the integration of IO circuits. Authors of [2] have employed the beam propagating method (BPM) in the analysis of "Δn" and "2Δn” type passive crossings at small angles (θ n. The BPM neglects reflection and simulates wave propagation in a forward sense, thus it cannot analyze structures with large geometry and material discontinuities or in situation when reflections add up coherently.

The kinetics of the hydrolysis of five esters of N-hippurylglycine (C6H5CONHCH2CONHCH2CO2CRR1CO2H (2 approximately) and seven esters of N-pivaloylglycine ((CH3)3CCONHCH2CRR1CO2H (3 approximately)) by bovine pancreatic carboxypeptidase A (Peptidyl-L-amino-acidhydrolase, EC 3.4.12.2) have been studied at pH 7.5, 25 degrees C and ionic strength 0.5. All N-hippurylglycine esters (2: R=H, R1=H, C2H5, 4-ClC6H4, C6H5CH2) display Michaelis-Menten kinetics up to at least 0.1 M substrate. The N-pivaloylglycine esters display either Michaelis-Menten kinetics (3 approximately: R=H, R1=H, C2H5 C6H5), substrate activation (3 approximately: R=H, R1=4-ClC6H4; R=R1=CH3) or substrate inhibition (3 approximately: R=H, R1=(CH3)2CHCH2, C6H5CH2). Kinetic parameters have been evaluated for each ester and compared with those for the corresponding hippuric acid esters (1 approximately). The enzymic specificity is shown to be identical for the alcohol moieties of the esters 1 approximately, 2 approximately and 3 approximately and unrelated to the occurrence of substrate activation or inhibition phenomena. These latter phenomena are shown to be characteristic of the enzymic hydrolysis of N-acyl amino acid esters but unimportant for N-acyl dipeptide ester substrates.

The pH dependence (pH 4.5-10.5) of the hydrolysis of seven hippuric acid esters (C6H5CONHCH2C-O2CR1R2CO2H: 1a: R1 = R2 = H; 1b: R1 = R2 = CH3; 1c: R1 = H, R2 = p-ClC6H4; 1d: R1 = H, R2 = C2H5; 1e: R1 = H, R2 = (CH3)2CHCH2; 1f: R1 = H, R2 = C6H5; 1g: R1 = H, R2 = C6H5CH2) by bovine carboxypeptidase A has been investigated, and the pH dependence of the substrate activation of 1a-c and the substrate inhibition of 1d-g have been compared. For all seven esters the catalytically productive binding of the first substrate molecule depends on enzymatic pKa values of 6.0 and 9.1. For 1d, 1e, and 1g the rate of hydrolysis (k2app) of this complex is pH independent, whereas for 1f k2app depends on a pKa of 5.9. The rate of hydrolysis (k3app) of the 1:2 enzyme-substrate complex (ES2) is pH independent for 1d-g, but for 1a-c k3app depends on the following pKa values: 1a, 6.1 and 9.1; 1b, 5.4; 1c, 6.6. The pH dependences of k2app for 1f and k3app for 1c are rationalized by the presence of catalytically nonproductive species. Equivalent ES2 species are believed to be productive for 1c-g; however, the productive ES2 species for 1b must be quite different.

Xanthomonas oryzae was shown to contain a constitutive alkaline phosphatase (EC 3.1.3.1.). The enzyme was detectable in intact cells and releasable by osmotic shock or spheroplast formation indicating its periplasmic location in the cell. Sonication released about 85% of the total enzyme, and the releasable amount was increased to 97% when lysozyme was added to the sonicated cells prior to centrifugation. These changes suggest an association of the enzyme with peptidoglycan; the enzyme is not released unless the polymer is digested to small units. Adapted usual method of spheroplast formation released 85%, while modified osmotic shock procedure released about 75% of the enzyme. These procedures released decreased amounts of the enzyme following cell growth reflecting that some changes were taking place toward a tighter association between the enzyme and the cell envelope during aging of the culture. During osmotic shock, the major portion of the released enzyme distributed in supernatant of the first stage (S1) hypertonic solution. The enzyme was inhibited by EDTA, whereas the inhibition was partially removed by dialysis and completely reversed by addition of MgCl2. Data obtained also indicated that X. oryzae seems to have relatively high content of periplasmic protein.

beta-Bungarotoxin, which consists of two polypeptide chains (A- and B-chain), in the venom of Formosan banded krait is stable in 7.5 M urea but can be denatured in 6.0 M guanidine hydrochloride. Its conformation remains virtually the same in solvents of lower polarity than water such as a mixture of 1,2-ethanediol-water (4:1 by volume). The circular dichroism spectrum in water shows a double minima at 222 and 209 nm, which is characteristic of the helical structure. The ellipticities at these two wavelengths indicate that the helical content of this toxin is not high. Comparing how guanidine hydrochloride effects the helix-coil transition of the toxin with that of phospholipase A2's which are structurally homologous to A-chain implicates that the two polypeptide chains should be coexisted and interacted with each other in order to maintain the active conformation of beta-bungarotoxin. Removal of eight amino acid residues from the N-terminus of the A-chain by action of CNBr on beta-bungarotoxin does not disrupt the polypeptide folding but abolishes the neurotoxicity.