Observations on the life history and identity of intraspecific groups of the anchoveta, Cetengraulis mysticetus, in Montijo Bay and Chiriquí Province, Panama

ENGLISH: Howard and Landa (1958) and Barrett and Howard (1961) have studied the life history of the anchoveta in most of the areas where this species occurs in important quantities. The Gulf of Panama was the only area of Panama included in these studies, as this was the only one from which sufficient samples were available. Berdegue (1958) compared certain meristic and morphometric characters of anchovetas from Montijo Bay and nine other areas of the eastern tropical Pacific Ocean. He found statistically significant differences, and concluded that the fish of the different areas belonged to separate "populations." Fish from Chiriquí province were not included in his study. Since the, completion of the above-mentioned studies, a number of collections of anchovetas from Montijo Bay and Chiriquí province have been obtained. In the present report use is made of this material to determine the salient facts regarding the life history of the anchoveta from these areas and to supplement the available knowledge of the identity of the intraspecific groups. Acknowledgment is extended to Dr. Milner B. Schaefer, formerly Director of Investigations, Inter-American Tropical Tuna Commission (now Director, Institute of Marble Resources, University of California), Mr. Clifford L. Peterson, Assistant Director of Investigations, and Mr. Edward F. Klima (now with the U. S. Bureau of Commercial Fisheries) for advice and assistance rendered to the project. The shrimp-boat samples were collected by Captains Robert Barrett, Stephen Barrett, and Chester McLean. SPANISH: Howard y Landa (1958) y Barrett y Howard (1961) han estudiado la historia natural de la anchoveta en la mayoría de las áreas en donde esta especie aparece en cantidades importantes. El Golfo de Panamá es la única area de Panamá incluida en estos estudios, ya que es la única de la cual hubo suficientes muestras disponibles. Berdegué (1958) camparó ciertos caracteres merístieos y morfométricos de la anehoveta del Golfo de Montijo y otras nueve áreas del Océano Pacífico Oriental Tropical. Encontró diferencias estadísticamente significativas e hizo la conclusión de que los peces de las diferentes áreas pertenecían a "poblaciones" separadas. Los peces de la Provincia de Chiriquí no fueron incluidos en su estudio. Desde la terminación de los estudios antes meneionados se obtuvieron varias recolecciones de anchovetas del Golfo de Montijo y de la Provincia de Chiriquí. En el presente informe se usó este material para determinar los hechos sobresalientes referentes a la historia natural de la anchoveta de estas áreas y suplir el conocimiento disponible de la identidadde los grupos intraespecíficos. Se hace extensivo un reconocimiento al Dr. Milner B. Schaefer, antiguo director de investigaciones de la Comisión Interamericana del Atún Tropical (ahora director del Institute of Marine Resources, University of California), al Sr. Clifford L. Peterson, asistente del director de investigaciones, y al Sr. Edward F. Klima (ahora can el U. S. Bureau of Commercial Fisheries) por su consejo y ayuda prestados en este proyecto. Las muestras de los barcos camaroneros fueron reeolectadas por los capitanes Robert Barrett, Stephen Barrett y Chester McLean

Micro Insert: A Prototype Full-Ring PET Device for Improving the Image Resolution of a Small-Animal PET Scanner

A full-ring PET insert device should be able to enhance the image resolution of existing small-animal PET scanners. Methods: The device consists of 18 high-resolution PET detectors in a cylindric enclosure. Each detector contains a cerium-doped lutetium oxyorthosilicate array (12 x 12 crystals, 0.72 x 1.51 x 3.75 mm each) coupled to a position-sensitive photomultiplier tube via an optical fiber bundle made of 8 x 16 square multiclad fibers. Signals from the insert detectors are connected to the scanner through the electronics of the disabled first ring of detectors, which permits coincidence detection between the 2 systems. Energy resolution of a detector was measured using a Ge-68 point source, and a calibrated 68Ge point source stepped across the axial field of view (FOV) provided the sensitivity profile of the system. A Na-22 point source imaged at different offsets from the center characterized the in-plane resolution of the insert system. Imaging was then performed with a Derenzo phantom filled with 19.5 MBq of F-18-fluoride and imaged for 2 h; a 24.3-g mouse injected with 129.5 MBq of F-18-fluoride and imaged in 5 bed positions at 3.5 h after injection; and a 22.8-g mouse injected with 14.3 MBq of F-18-FDG and imaged for 2 h with electrocardiogram gating. Results: The energy resolution of a typical detector module at 511 keV is 19.0% +/- 3.1 %. The peak sensitivity of the system is approximately 2.67%. The image resolution of the system ranges from 1.0- to 1.8-mm full width at half maximum near the center of the FOV, depending on the type of coincidence events used for image reconstruction. Derenzo phantom and mouse bone images showed significant improvement in transaxial image resolution using the insert device. Mouse heart images demonstrated the gated imaging capability of the device. Conclusion: We have built a prototype full-ring insert device for a small-animal PET scanner to provide higher-resolution PET images within a reduced imaging FOV. Development of additional correction techniques are needed to achieve quantitative imaging with such an insert.

The role of secretory leucoprotease inhibitor in the resolution of inflammatory responses

Chronic lung disease is one of the most common causes of death and disability worldwide. This group of diseases is characterized by a protease burden, an infective process and a dominant pro-inflammatory profile. While SLPI (secretory leucoprotease inhibitor) was initially identified as a serine protease inhibitor, it has since been shown that SLPI possesses other properties distinct from those associated with its antiprotease capabilities that play an important role in protecting the host from infection and injury. In the course of this review, we will highlight the findings from a range of studies that illustrate the multiple functions of SLPI and its role in the resolution of the immune response.

Analysis of the esophagogastric junction using the 3D high resolution manometry

Contexte & Objectifs : La manométrie perfusée conventionnelle et la manométrie haute résolution (HRM) ont permis le développement d’une variété de paramètres pour mieux comprendre la motilité de l'œsophage et quantifier les caractéristiques de la jonction œsophago-gastrique (JOG). Cependant, l'anatomie de la JOG est complexe et les enregistrements de manométrie détectent à la fois la pression des structures intrinsèques et des structures extrinsèques à l'œsophage. Ces différents composants ont des rôles distincts au niveau de la JOG. Les pressions dominantes ainsi détectées au niveau de la JOG sont attribuables au sphincter œsophagien inférieur (SOI) et aux piliers du diaphragme (CD), mais aucune des technologies manométriques actuelles n’est capable de distinguer ces différents composants de la JOG. Lorsqu’on analyse les caractéristiques de la JOG au repos, celle ci se comporte avant tout comme une barrière antireflux. Les paramètres manométriques les plus couramment utilisés dans ce but sont la longueur de la JOG et le point d’inversion respiratoire (RIP), défini comme le lieu où le pic de la courbe de pression inspiratoire change de positif (dans l’abdomen) à négatif (dans le thorax), lors de la classique manœuvre de « pull-through ». Cependant, l'importance de ces mesures reste marginale comme en témoigne une récente prise de position de l’American Gastroenterology Association Institute (AGAI) (1) qui concluait que « le rôle actuel de la manométrie dans le reflux gastro-œsophagien (RGO) est d'exclure les troubles moteurs comme cause des symptômes présentés par la patient ». Lors de la déglutition, la mesure objective de la relaxation de la JOG est la pression de relaxation intégrée (IRP), qui permet de faire la distinction entre une relaxation normale et une relaxation anormale de la JOG. Toutefois, puisque la HRM utilise des pressions moyennes à chaque niveau de capteurs, certaines études de manométrie laissent suggérer qu’il existe une zone de haute pression persistante au niveau de la JOG même si un transit est mis en évidence en vidéofluoroscopie. Récemment, la manométrie haute résolution « 3D » (3D-HRM) a été développée (Given Imaging, Duluth, GA) avec le potentiel de simplifier l'évaluation de la morphologie et de la physiologie de la JOG. Le segment « 3D » de ce cathéter de HRM permet l'enregistrement de la pression à la fois de façon axiale et radiale tout en maintenant une position fixe de la sonde, et évitant ainsi la manœuvre de « pull-through ». Par conséquent, la 3D-HRM devrait permettre la mesure de paramètres importants de la JOG tels que sa longueur et le RIP. Les données extraites de l'enregistrement fait par 3D-HRM permettraient également de différencier les signaux de pression attribuables au SOI des éléments qui l’entourent. De plus, l’enregistrement des pressions de façon radiaire permettrait d’enregistrer la pression minimale de chaque niveau de capteurs et devrait corriger cette zone de haute pression parfois persistante lors la déglutition. Ainsi, les objectifs de ce travail étaient: 1) de décrire la morphologie de la JOG au repos en tant que barrière antireflux, en comparant les mesures effectuées avec la 3D-HRM en temps réel, par rapport à celle simulées lors d’une manœuvre de « pull-through » et de déterminer quelles sont les signatures des pressions attribuables au SOI et au diaphragme; 2) d’évaluer la relaxation de la JOG pendant la déglutition en testant l'hypothèse selon laquelle la 3D-HRM permet le développement d’un nouveau paradigme (appelé « 3D eSleeve ») pour le calcul de l’IRP, fondé sur l’utilisation de la pression radiale minimale à chaque niveau de capteur de pression le long de la JOG. Ce nouveau paradigme sera comparé à une étude de transit en vidéofluoroscopie pour évaluer le gradient de pression à travers la JOG. Méthodes : Nous avons utilisé un cathéter 3D-HRM, qui incorpore un segment dit « 3D » de 9 cm au sein d’un cathéter HRM par ailleurs standard. Le segment 3D est composé de 12 niveaux (espacés de 7.5mm) de 8 capteurs de pression disposés radialement, soit un total de 96 capteurs. Neuf volontaires ont été étudiés au repos, où des enregistrements ont été effectués en temps réel et pendant une manœuvre de « pull-through » du segment 3D (mobilisation successive du cathéter de 5 mm, pour que le segment 3D se déplace le long de la JOG). Les mesures de la longueur du SOI et la détermination du RIP ont été réalisées. La longueur de la JOG a été mesurée lors du « pull-through » en utilisant 4 capteurs du segment 3D dispersés radialement et les marges de la JOG ont été définies par une augmentation de la pression de 2 mmHg par rapport à la pression gastrique ou de l’œsophage. Pour le calcul en temps réel, les limites distale et proximale de la JOG ont été définies par une augmentation de pression circonférentielle de 2 mmHg par rapport à la pression de l'estomac. Le RIP a été déterminée, A) dans le mode de tracé conventionnel avec la méthode du « pull-through » [le RIP est la valeur moyenne de 4 mesures] et B) en position fixe, dans le mode de représentation topographique de la pression de l’œsophage, en utilisant l’outil logiciel pour déterminer le point d'inversion de la pression (PIP). Pour l'étude de la relaxation de la JOG lors de la déglutition, 25 volontaires ont été étudiés et ont subi 3 études de manométrie (10 déglutitions de 5ml d’eau) en position couchée avec un cathéter HRM standard et un cathéter 3D-HRM. Avec la 3D-HRM, l’analyse a été effectuée une fois avec le segment 3D et une fois avec une partie non 3D du cathéter (capteurs standard de HRM). Ainsi, pour chaque individu, l'IRP a été calculée de quatre façons: 1) avec la méthode conventionnelle en utilisant le cathéter HRM standard, 2) avec la méthode conventionnelle en utilisant le segment standard du cathéter 3D-HRM, 3) avec la méthode conventionnelle en utilisant le segment « 3D » du cathéter 3D-HRM, et 4) avec le nouveau paradigme (3D eSleeve) qui recueille la pression minimale de chaque niveau de capteurs (segment 3D). Quatorze autres sujets ont subi une vidéofluoroscopie simultanée à l’étude de manométrie avec le cathéter 3D-HRM. Les données de pression ont été exportés vers MATLAB ™ et quatre pressions ont été mesurées simultanément : 1) la pression du corps de l’œsophage, 2cm au-dessus de la JOG, 2) la pression intragastrique, 3) la pression radiale moyenne de la JOG (pression du eSleeve) et 4) la pression de la JOG en utilisant la pression minimale de chaque niveau de capteurs (pression du 3D eSleeve). Ces données ont permis de déterminer le temps permissif d'écoulement du bolus (FPT), caractérisé par la période au cours de laquelle un gradient de pression existe à travers la JOG (pression œsophagienne > pression de relaxation de la JOG > pression gastrique). La présence ou l'absence du bolus en vidéofluoroscopie et le FPT ont été codés avec des valeurs dichotomiques pour chaque période de 0,1 s. Nous avons alors calculé la sensibilité et la spécificité correspondant à la valeur du FPT pour la pression du eSleeve et pour la pression du 3D eSleeve, avec la vidéofluoroscopie pour référence. Résultats : Les enregistrements avec la 3D-HRM laissent suggérer que la longueur du sphincter évaluée avec la méthode du « pull-through » était grandement exagéré en incorporant dans la mesure du SOI les signaux de pression extrinsèques à l’œsophage, asymétriques et attribuables aux piliers du diaphragme et aux structures vasculaires. L’enregistrement en temps réel a permis de constater que les principaux constituants de la pression de la JOG au repos étaient attribuables au diaphragme. L’IRP calculé avec le nouveau paradigme 3D eSleeve était significativement inférieur à tous les autres calculs d'IRP avec une limite supérieure de la normale de 12 mmHg contre 17 mmHg pour l’IRP calculé avec la HRM standard. La sensibilité (0,78) et la spécificité (0,88) du 3D eSleeve étaient meilleurs que le eSleeve standard (0,55 et 0,85 respectivement) pour prédire le FPT par rapport à la vidéofluoroscopie. Discussion et conclusion : Nos observations suggèrent que la 3D-HRM permet l'enregistrement en temps réel des attributs de la JOG, facilitant l'analyse des constituants responsables de sa fonction au repos en tant que barrière antireflux. La résolution spatiale axiale et radiale du segment « 3D » pourrait permettre de poursuivre cette étude pour quantifier les signaux de pression de la JOG attribuable au SOI et aux structures extrinsèques (diaphragme et artéfacts vasculaires). Ces attributs du cathéter 3D-HRM suggèrent qu'il s'agit d'un nouvel outil prometteur pour l'étude de la physiopathologie du RGO. Au cours de la déglutition, nous avons évalué la faisabilité d’améliorer la mesure de l’IRP en utilisant ce nouveau cathéter de manométrie 3D avec un nouveau paradigme (3D eSleeve) basé sur l’utilisation de la pression radiale minimale à chaque niveau de capteurs de pression. Nos résultats suggèrent que cette approche est plus précise que celle de la manométrie haute résolution standard. La 3D-HRM devrait certainement améliorer la précision des mesures de relaxation de la JOG et cela devrait avoir un impact sur la recherche pour modéliser la JOG au cours de la déglutition et dans le RGO.

The resolution sensitivity of the South Asian monsoon and Indo-Pacific in a global 0.35◦ AGCM

The South Asian monsoon is one of the most significant manifestations of the seasonal cycle. It directly impacts nearly one third of the world’s population and also has substantial global influence. Using 27-year integrations of a high-resolution atmospheric general circulation model (Met Office Unified Model), we study changes in South Asian monsoon precipitation and circulation when horizontal resolution is increased from approximately 200 to 40 km at the equator (N96 to N512, 1.9 to 0.35◦). The high resolution, integration length and ensemble size of the dataset make this the most extensive dataset used to evaluate the resolution sensitivity of the South Asian monsoon to date. We find a consistent pattern of JJAS precipitation and circulation changes as resolution increases, which include a slight increase in precipitation over peninsular India, changes in Indian and Indochinese orographic rain bands, increasing wind speeds in the Somali Jet, increasing precipitation over the Maritime Continent islands and decreasing precipitation over the northern Maritime Continent seas. To diagnose which resolution related processes cause these changes we compare them to published sensitivity experiments that change regional orography and coastlines. Our analysis indicates that improved resolution of the East African Highlands results in the improved representation of the Somali Jet and further suggests that improved resolution of orography over Indochina and the Maritime Continent results in more precipitation over the Maritime Continent islands at the expense of reduced precipitation further north. We also evaluate the resolution sensitivity of monsoon depressions and lows, which contribute more precipitation over northeast India at higher resolution. We conclude that while increasing resolution at these scales does not solve the many monsoon biases that exist in GCMs, it has a number of small, beneficial impacts.

DRUG METABOLISM IN LIVER TUMORS: PURIFICATION AND CHARACTERIZATION OF NADPH-CYTOCHROME-P450 REDUCTASE AND THE RESOLUTION OF MULTIPLE FORMS OF CYTOCHROME P-450

The hydroxylation of N- and O-methyl drugs and a polycyclic hydrocarbon has been demonstrated in microsomes prepared from two transplantable Morris hepatomas (i.e., 7288C. t.c. and 5123 t.c.(H). The hydroxylation rates of the drug benzphetamine and the polycyclic hydrocarbon benzo {(alpha)} pyrene by tumor microsomes were inducible 2 to 3-fold and 2-fold, respectively by pretreatment of rats with phenobarbital/hydrocortisone. Hepatoma 5123t.c.(h) microsomal hydroxylation activities were more inducible after these pretreatments than hepatoma 7288C.t.c. Two chemotherapeutic drugs (cyclophosphamide and isophosphamide) were shown to be mutagenic after activation by the tumor hemogenate with the TA100 strain of Salmonella typhimurium bacteria. NADPH-cytochrome P-450 was purified from phenobarbital/hydrocortisone treated rat hepatoma 5123t.c.(H) microsomes 353-fold with a specific activity 63.6 nmol of cytochrome c reduced per min per mg of protein. The purified enzyme, has an apparent molecular weight of 79,500 daltons, and contained an equal molar ratio of FMN and FAD, with a total flavin content of 16.4 nmol per mg of protein. The purified enzyme also catalyzed electron transfer to artificial electron acceptors with the K(,m) values of the hepatoma reductase similar to those of purified liver reductase. The K(,m) value of the hepatoma reductase (13 uM) for NADPH was similar to that of purified liver reductase (5.0 uM). In addition the purified hepatoma reductase was immunochemically similar to the liver reductase.^ Hepatoma cytochrome P-450, the hemeprotein component of the hepatoma microsomes of rats pretreated with phenobarbital/hydrocortisone. The resolution of the six forms was achieved by the DE-53 ion-exchange chromatography, and further purified by hydroxyapatite. The six different fractions that contained P-450 activity, had specific contents from 0.47 to 1.75 nmol of cytochrome P-450 per mg of protein, and indicated a 2 to 9-fold purification as compared to the original microsomes. In addition, difference spectra, molecular weights and immunological results suggest there are at least six different forms of cytochrome P-450 in hepatoma 5123 t.c.(H). ^

Phase identity of the maize leaf is determined after leaf initiation

The vegetative development of the maize shoot can be divided into juvenile and adult phases based on the types of leaves produced at different times in shoot development. Models for the regulation of phase change make explicit predictions about when the identity of these types of leaves is determined. To test these models, we examined the timing of leaf type determination in maize. Clones induced in transition leaf primordia demonstrated that the juvenile and adult regions of these leaves do not become clonally distinct until after the primordium is 700 μm in length, implying that these cell fates were undetermined at this stage of leaf development. Adult shoot apices were cultured in vitro to induce rejuvenation. We found that leaf primordia as large as 3 mm in length can be at least partially rejuvenated by this treatment, and the location of rejuvenated tissue is correlated with the maturation pattern of the leaf. The amount and distribution of juvenile tissue in rejuvenated leaves suggests that rejuvenation occurs nearly simultaneously in all leaf primordia. In vitro culture rejuvenated existing leaf primordia and the P0 primordium, but did not change the identity of subsequent primordia or the total number of leaves produced by the shoot. This result suggests that leaf identity can be regulated independently of the identity of the shoot apical meristem, and it implies that vegetative phase change is not initiated by a change in the identity of the shoot apical meristem.

Interactions between tRNA identity nucleotides and their recognition sites in glutaminyl-tRNA synthetase determine the cognate amino acid affinity of the enzyme.

Sequence-specific interactions between aminoacyl-tRNA synthetases and their cognate tRNAs both ensure accurate RNA recognition and prevent the binding of noncognate substrates. Here we show for Escherichia coli glutaminyl-tRNA synthetase (GlnRS; EC 6.1.1.18) that the accuracy of tRNA recognition also determines the efficiency of cognate amino acid recognition. Steady-state kinetics revealed that interactions between tRNA identity nucleotides and their recognition sites in the enzyme modulate the amino acid affinity of GlnRS. Perturbation of any of the protein-RNA interactions through mutation of either component led to considerable changes in glutamine affinity with the most marked effects seen at the discriminator base, the 10:25 base pair, and the anticodon. Reexamination of the identity set of tRNA(Gln) in the light of these results indicates that its constituents can be differentiated based upon biochemical function and their contribution to the apparent Gibbs' free energy of tRNA binding. Interactions with the acceptor stem act as strong determinants of tRNA specificity, with the discriminator base positioning the 3' end. The 10:25 base pair and U35 are apparently the major binding sites to GlnRS, with G36 contributing both to binding and recognition. Furthermore, we show that E. coli tryptophanyl-tRNA synthetase also displays tRNA-dependent changes in tryptophan affinity when charging a noncognate tRNA. The ability of tRNA to optimize amino acid recognition reveals a novel mechanism for maintaining translational fidelity and also provides a strong basis for the coevolution of tRNAs and their cognate synthetases.

Magnetic resonance microscopy of the equine hoof wall: a study of resolution and potential

Reasons for performing study: Obtaining magnetic resonance images of the inner hoof wall tissue at the microscopic level would enable early accurate diagnosis of laminitis and therefore more effective therapy. Objectives: To optimise magnetic resonance imaging (MRI) parameters in order to obtain the highest possible resolution of the structures beneath the equine hoof wall. Methods: Magnetic resonance microscopy (MRM) was performed in front feet from 6 cadaver horses using T-2-weighted fast spin echo (FSE-T-2), and T-1-weighted gradient echo (GRE-T-1) sequences. Results: In T-2 weighted FSE images most of the stratum medium showed no signal, however the coronary, terminal and sole papillae were visible. The stratum lamellatum was clearly visible and primary epidermal lamellae could be differentiated from dermal lamellae. Conclusion: Most structures beneath the hoof wall were differentiated. Conventional scanners for diagnostic MRI in horses are low or high field. However this study used ultra-high field scanners currently not available for clinical use. Signal-to-noise ratio (SIN) increases as a function of field strength. An increase of spatial resolution of the image results in a decreased SIN. SIN can also be improved with better coils and the resolution of high field MRI scanners will increase as technology develops and surface array coils become more readily available. Potential relevance: Although MR images with microscopic resolution were obtained ex vivo, this study demonstrates the potential for detection of lamellar pathology as it occurs. Early recognition of the development of laminitis to instigate effective therapy at an earlier stage and may improve the outcome for laminitic horses. Clinical MR is now readily available at 3 T, while 4 T, 7 T and 9 T systems are being used for human whole body applications.

Matrix-assisted diffusion-ordered spectroscopy:application of surfactant solutions to the resolution of isomer spectra

The component spectra of a mixture of isomers with nearly identical diffusion coefficients cannot normally be distinguished in a standard diffusion-ordered spectroscopy (DOSY) experiment but can often be easily resolved using matrix-assisted DOSY, in which diffusion behaviour is manipulated by the addition of a co-solute such as a surfactant. Relatively little is currently known about the conditions required for such a separation, for example, how the choice between normal and reverse micelles affects separation or how the isomer structures themselves affect the resolution. The aim of this study was to explore the application of sodium dodecyl sulfate (SDS) normal micelles in aqueous solution and sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) aggregates in chloroform, at a range of concentrations, to the diffusion resolution of some simple model sets of isomers such as monomethoxyphenols and short chain alcohols. It is shown that SDS micelles offer better resolution where these isomers differ in the position of a hydroxyl group, whereas AOT aggregates are more effective for isomers differing in the position of a methyl group. For both the normal SDS micelles and the less well-defined AOT aggregates, differences in the resolution of the isomers can in part be rationalised in terms of differing degrees of hydrophobicity, amphiphilicity and steric effects. Copyright © 2012 John Wiley & Sons, Ltd.

Defining the Resolution of a Network for Transportation Analyses: a New Method to Improve Transportation Planning Decisions

Travel demand models are important tools used in the analysis of transportation plans, projects, and policies. The modeling results are useful for transportation planners making transportation decisions and for policy makers developing transportation policies. Defining the level of detail (i.e., the number of roads) of the transport network in consistency with the travel demand model’s zone system is crucial to the accuracy of modeling results. However, travel demand modelers have not had tools to determine how much detail is needed in a transport network for a travel demand model. This dissertation seeks to fill this knowledge gap by (1) providing methodology to define an appropriate level of detail for a transport network in a given travel demand model; (2) implementing this methodology in a travel demand model in the Baltimore area; and (3) identifying how this methodology improves the modeling accuracy. All analyses identify the spatial resolution of the transport network has great impacts on the modeling results. For example, when compared to the observed traffic data, a very detailed network underestimates traffic congestion in the Baltimore area, while a network developed by this dissertation provides a more accurate modeling result of the traffic conditions. Through the evaluation of the impacts a new transportation project has on both networks, the differences in their analysis results point out the importance of having an appropriate level of network detail for making improved planning decisions. The results corroborate a suggested guideline concerning the development of a transport network in consistency with the travel demand model’s zone system. To conclude this dissertation, limitations are identified in data sources and methodology, based on which a plan of future studies is laid out.

Infrared and Raman spectroscopic characterization of the borate mineral hydroboracite CaMg[B3O4(OH)3]2⋅3H2O : implications for the molecular structure

We have studied the mineral hydroboracite CaMg[B3O4(OH)3]2∙3H2O using electron microscopy and vibrational spectroscopy. Both tetrahedral and trigonal boron units are observed. The nominal resolution of the Raman spectrometer is of the order of 2 cm-1 and as such is sufficient enough to identify separate bands for the stretching bands of the two boron isotopes. The Raman band at 1039 cm-1 is assigned to BO stretching vibration. Raman bands at 1144, 1157, 1229, 1318 cm-1 are attributed to the BOH in-plane bending modes. Raman bands at 825 and 925 cm-1 are attributed to the antisymmetric stretching modes of tetrahedral boron. The sharp Raman peak at 925 cm-1 is from the 11-B component such a mode, then it should have a smaller 10-B satellite near (1.03)x(925) = 952 cm-1, and indeed a small peak at 955 is observed. Four sharp Raman bands observed at 3371, 3507, 3563 and 3632 cm-1 are attributed to the stretching vibrations of hydroxyl units. The broad Raman bands at 3076, 3138, 3255, 3384 and 3551 cm-1 are assigned to water stretching vibrations. Infrared bands at 3367, 3505, 3559 and 3631 cm-1are assigned to the stretching vibration of the hydroxyl units. Broad infrared bands at 3072 and 3254 cm-1 are assigned to water stretching vibrations. Infrared bands at 1318, 1349, 1371, 1383 cm-1 are assigned to the antisymmetric stretching vibrations of trigonal boron

A vibrational spectroscopic study of the borate mineral ezcurrite Na4B10O17·7H2O – Implications for the molecular structure

We have studied the boron containing mineral ezcurrite Na4B10O17·7H2O using electron microscopy and vibrational spectroscopy. Both tetrahedral and trigonal boron units are observed. The nominal resolution of the Raman spectrometer is of the order of 2 cm−1 and as such is sufficient enough to identify separate bands for the stretching bands of the two boron isotopes. The Raman band at 1037 cm−1 is assigned to BO stretching vibration. Raman bands at 1129, 1163, 1193 cm−1 are attributed to BO stretching vibration of the tetrahedral units. The Raman band at 947 cm−1 is attributed to the antisymmetric stretching modes of tetrahedral boron. The sharp Raman peak at 1037 cm−1 is from the 11-B component such a mode, then it should have a smaller 10-B satellite near (1.03) × (1037) = 1048 cm−1, and indeed a small peak at 1048 is observed. The broad Raman bands at 3186, 3329, 3431, 3509, 3547 and 3576 cm−1 are assigned to water stretching vibrations. Broad infrared bands at 3170, 3322, 3419, 3450, 3493, 3542, 3577 and 3597 cm−1 are also assigned to water stretching vibrations. Infrared bands at 1330, 1352, 1389, 1407, 1421 and 1457 cm−1 are assigned to the antisymmetric stretching vibrations of trigonal boron. The observation of so many bands suggests that there is considerable variation in the structure of ezcurrite. Infrared bands at 1634, 1646 and 1681 cm−1 are assigned to water bending modes. The number of water bending modes is in harmony with the number of water stretching vibrations.

Structural characterization of the borate mineral inyoite – CaB3O3(OH)5⋅4(H2O)

We have studied the mineral Ca(H4B3O7)(OH)⋅4(H2O) or CaB3O3(OH)5⋅4(H2O) using electron microscopy and vibrational spectroscopy. The mineral has been characterized by a range of techniques including X-ray diffraction, thermal analysis, electron microscopy with EDX and vibrational spectroscopy. Electron microscopy shows a pure phase and the chemical analysis shows the presence of calcium only. The nominal resolution of the Raman spectrometer is of the order of 2 cm−1 and as such is sufficient enough to identify separate bands for the stretching bands of the two boron isotopes. Raman and infrared bands are assigned to the stretching and bending modes of trigonal and tetrahedral boron and the stretching modes of the hydroxyl and water units. By using a combination of techniques we have characterized the borate mineral inyoite.

The molecular structure of the borate mineral szaibelyite MgBO2(OH): A vibrational spectroscopic study

We have studied the borate mineral szaibelyite MgBO2(OH) using electron microscopy and vibrational spectroscopy. EDS spectra show a phase composed of Mg with minor amounts of Fe. Both tetrahedral and trigonal boron units are observed. The nominal resolution of the Raman spectrometer is of the order of 2 cm−1 and as such is sufficient enough to identify separate bands for the stretching bands of the two boron isotopes. The Raman band at 1099 cm−1 with a shoulder band at 1093 cm−1 is assigned to BO stretching vibration. Raman bands at 1144, 1157, 1229, 1318 cm−1 are attributed to the BOH in-plane bending modes. Raman bands at 836 and 988 cm−1 are attributed to the antisymmetric stretching modes of tetrahedral boron. The infrared bands at 3559 and 3547 cm−1 are assigned to hydroxyl stretching vibrations. Broad infrared bands at 3269 and 3398 cm−1 are assigned to water stretching vibrations. Infrared bands at 1306, 1352, 1391, 1437 cm−1 are assigned to the antisymmetric stretching vibrations of trigonal boron. Vibrational spectroscopy enables aspects of the molecular structure of the borate mineral szaibelyite to be assessed.