Search

The rotation around a fixed point of a heavy dynamically symmetric solid body with an arbitrary asymmetric cavity completely filled with an ideal in-compressible liquid is considered. The stability of a uniform rotation of a Lagrang' top with the ideal liquid in a resisting medium under condition of a given constant moment is investigated. The equation of the perturbed motion of the Lagrang' top with the ideal liquid is presented. It is proved the follow-ing: the asymptotic stability of uniform rotation for an ellipsoidal cavity will be only for a compressed ellipsoidal cavity. It has been observed that most practically important cases consider the main effect of the ideal liquid influence on the motion of a solid can be researched by means of considering only the fundamental tone of the liquid oscillation. Conditions of uniform rotation asymptotic stability in a resistive medium under the action of the Lagrange top' constant moment with an arbitrary axisymmetric cavity containing an ideal liquid are obtained. Stability conditions are derived with provisions for the main and additional tones of liquid oscillations. The heavy solid body with the fixed-point value is ex-posed to the action of a constant moment in the inertial coordinate system. Analytic and numerical investigations of the main and additional tones of liquid oscillations influence, over-turning, restoring, dissipative and constant moments on the conditions of the asymptotic stability of the uniform rotation of the Lagrange top with an ideal liquid are carried out. It is stated the following: cubic and square inequalities presented in the paper are conditions of asymptotic stability if the basic tone of liquid fluctuations will be mentioned. Stability region numerical studies have been carried out on the example of an ellipsoidal cavity. It is presented that increasing of the equatorial moment of inertia of the solid body de-creases its stability region as well as the increasing of the solid body inertia axial moment in-creases the last one.

In many works, there are studies of the asymptotic stability of rotation of a free Lagrange gyroscope in a resisting medium. This article generalizes this problem to the case of uniform rotations of two free Lagrange gyroscopes connected by an elastic restoring spherical hinge. The rotation of each gyroscope is maintained by a constant moment in an inertial coordinate system. The characteristic equation of the perturbed motion is presented in the form of an algebraic equation of the fourth degree with complex coefficients. Based on the innor approach, conditions of asymptotic stability are obtained in the form of a system of three inequalities. The left-hand side of these inequalities is represented, respectively, in the form of determinants of the third, fifth, and seventh orders. Up to first-order values of smallness, relative to the reciprocal of the stiffness coefficient, a study is made of the effect of the joint stiffness on stability conditions. From the conditions of positivity of the highest coefficients in three inequalities, it is shown that for a sufficiently large rigidity, the stability conditions are determined by only one inequality. Cases of degeneration of an elastic spherical joint into a spherical inelastic, cylindrical, and universal elastic joint (Hooke's joint) are considered. In the case of an inelastic spherical joint, the system of three inequalities is slightly simplified. The greatest simplification arises in the case of a cylindrical hinge. In this case, the characteristic equation is represented as a quadratic equation with complex coefficients. According to the innoric approach, the conditions of asymptotic stability are written in the form of a single inequality, the left side of which is presented in the form of third-order determinants. It is shown that this inequality coincides with the inequality obtained earlier for the case of a sufficiently large rigidity of the hinge. If the angular velocities of the proper rotations of the gyroscopes coincide, the inequality obtained for the cylindrical hinge coincides with the well-known inequality for one gyroscope. In the case of a universal elastic hinge (Hooke's hinge), the first inequality is represented as a square inequality with respect to the angular velocity of proper rotation.

This study proposed a novel image reconstruction technique using Bayesian estimation for Single-Photon Emission Computed Tomography (SPECT) in Boron Neutron Capture Therapy (BNCT) with limited view-angle projection data, and compered the performance with the existing method, ML-EM. BNCT requires real-time visualization of therapeutic effects, that is, output of reconstructed images to show local boron dose. Since BNCT-SPECT is a treatment, not a diagnosis, there are limits related to projection angle and measuring time. It should be noted that in BNCT-SPECT, unlike normal image reconstruction like Xray CT, the accuracy of each pixel value (dose) is more important than the structural similarity to the true image. This is because the most crucial estimate value is the patient's exposure dose in the normal cells. Therefore, we devised a method using Bayesian estimation as an image reconstruction method that could reproduce an individual pixel value accurately. As a result of numerical simulation, it was found that the proposed method is superior to the ML-EM method in terms of Mean Absolute Error (MAE). As the next step, we are planning to evaluate the performance of the proposed method using the measurement data acquired in the experiment.

We have simplified the previously received frequency equation of the natural axially symmetric oscillations of a heavy perfect incompressible liquid in a rigid cylindrical reservoir with elastic bases in the form of thin circular plates. The singularity in the frequency equation in the case of the coincidence of mass characteristics of the plates was removed. We have considered arbitrary methods of fixing the contours of the plates and different limiting cases: the degeneration of plates into membranes, absolutely rigid plates, the absence of upper plate (free surface on the liquid), and the case of zero gravity. It has been shown that the frequency spectrum of the coupled axially symmetric oscillations of elastic bases and the ideal liquid consists of two sets of frequencies, corresponding to oscillations of the upper and lower elastic bases, and additional oscillation frequency of a liquid column as a whole.

Hidroxyapatite yang dihasilkan berasal dari limbah tulang sapi dengan menggunakan metode sol-gel. Tujuan dari penelitian ini adalah untuk mendapatkan hidroxyapatite yang baik dengan variasi suhu (T = 400, 500, 600) 0 C dan waktu (t = 3, 4, 5, 6) jam didalam furnance melalui uji densitas dan karakterisasi. Konsentrasi HCl optimum pada sintesis prekursor CaCl 2 adalah 1 M dan volume H 3 PO 4 optimum pada sintesis hidroxyapatite adalah 25 mL. Densitas terbaik yang diproleh adalah 2,95 gr/mL dengan suhu 500 0 C dan waktu 6 jam. Hidroxyapatite terbaik dikarakterisasi dengan XRD dan FTIR. Hasil yang diperoleh pada XRD menunjukan kristalintas sampel yang tinggi dengan dibuktikan melalui peak yang tajam dan sempit. Sedangkan pada FTIR, bilangan gelombang 500 sampai 1500 cm -1 menunjukan adanya gugus PO 4 3- , pada bilangan gelombang 3500 sampai 3650 cm -1 menunjukan adanya gugus OH dan pada bilangan gelombang 3500 sampai 3650 cm -1 menunjukan adanya gugus CaO.

Variable-polarization synchrotron radiation is useful for measurements of circular dichroism (CD) in the vacuum ultraviolet (VUV) and soft X-ray regions. Since the polarization of the radiation is modified by beamline optics, it is therefore necessary to directly measure the polarization state of the light incident onto a sample in order to achieve quantitative measurements of the CD spectra. A reflection type polarimeter was designed and constructed to examine the polarization characteristics of the variable-polarization synchrotron radiation. The polarimeter consists of two quadruple reflectors which function as a phase shifter and a quasi-linear polarizer. The polarimeter is designed to be very compact. The compact size allows for easy and fast measurements of the complete set of Stokes parameters. The polarization states of the light output from the TERAS BL-5 beamline were measured using the new polarimeter in the vacuum ultraviolet range. The polarization states data of the light at the beamline were used for CD measurements, which yielded quantitative CD spectra in the VUV range.

Ferromagnetic semiconductor EuO and GdxEu1-xO (0.01

To measure spin-polarized core-level electron spectra, a spectrometer equipped with a highly efficient retarding-potential Mott spin polarimeter using undulator-based soft-x-ray beamlines has been set up. With a thin film of Au as a target this polarimeter has an efficiency estimated to be ∼2×10−4. The performance of this system for spin-polarized spectroscopy has been tested using core-level spin-polarized photoemission of magnetic and nonmagnetic thin films excited with linearly and circularly polarized light, respectively. Measurements using a new spin-resolved absorption technique are also discussed.

The group III (B, Al, Ga, In) nitride quaternary alloy systems are potentially useful for ultraviolet, blue, and green light-emitting devices, or high-temperature, high-power, and high-frequency electronic devices. There have been significant challenges to the epitaxial growth of these alloys and we have investigated the unstable mixing region in the phase field. The existence of an unstable mixing region is predicted based on a strictly regular solution model. The interaction parameter used in our model is analytically obtained by the valence force field model modified for wurtzite structures. From our calculations, among the group III nitride quaternary alloy systems, we find that InGaAlN system has the narrowest unstable mixing region, and that the BInAlN system has the widest unstable mixing region. The calculated interaction parameters which are the important to predict the unstable mixing region agree well with the best-fit line of experimental results for various alloy systems.

Vapor phase epitaxy (VPE) is a promising method to produce GaN substrates due to its high growth rate. In this paper, we first describe ZnO buffer layer deposition by pulsed laser deposition (PLD) on sapphire substrates for subsequent GaN VPE growth. Previously, ZnO buffer layers for GaN growth were RF-sputtered films with only poly or highly oriented crystal structure. PLD-grown ZnO buffer layers are single crystalline with streaky RHEED patterns and exhibit a sharp band-edge peak in photoluminescence. We examined the effect of ZnO buffer layer thickness on film quality of VPE-grown GaN layers on c-plane sapphire substrates. The VPE-grown GaN surfaces on ZnO buffer layers exhibit terrace-like flat surfaces, whereas three-dimensional growth with sharp rock-like structure occurs without the buffer layer. X-ray rocking curve (XRC) measurements showed that inserting the ZnO buffer reduced the GaN peak width by more than a factor of two, suggesting better crystalline quality. From the XRC measurement, buffer layers upto 50 nm thickness improve the GaN growth, while the optical properties measured by photoluminescence (PL) remain unchanged. With a 200 nm thick ZnO buffer layer, cracks occur in the subsequent GaN layer, resulting in a broader XRC peak width. In addition, the GaN film on a thick ZnO buffer shows strong peaks from donor–acceptor pair recombination and deep acceptor level from 2.6–3.2 eV in the PL spectra which are associated with Zn-doping of GaN. This implies that a thick ZnO buffer results in Zn diffusion from the buffer layer into the VPE-grown GaN film.

Zinc-blende type nanoscale MnAs dots were grown on a sulfur-passivated GaAs (0 0 1) surface by molecular beam epitaxy. We report on the dot density dependence of the X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) in the Mn 2p core-level region. The XAS spectrum of low-density MnAs dots showed “localized” behavior as in the case of (Ga,Mn)As, while the spectrum of high-density MnAs dots changed to metallic behavior. The magnetic-field dependence of the XMCD revealed ferromagnetic behavior in the case of high-density MnAs dots.

We have investigated the electronic structure of Zn1−xMxO (M: 3d transition metal) by x-ray absorption spectroscopy. Using configuration–interaction cluster-model analyses, electronic structure parameters have been deduced and their chemical trend is discussed. Results show that the p–d exchange constant Nβ is negative and large in cases of Mn, Fe, and Co, which is consistent with the enhancement of magnetic circular dichroism.

The polarization characteristics of a pn-junction Si photodiode and a Au-GaAsP Schottky photodiode which were revealed when the detectors were used obliquely to the incident radiation were investigated theoretically and experimentally in the spectral region from the vacuum ultraviolet to the visible. The experimental results in both cases were well explained by an optical model in the ultraviolet to the visible spectral range. It was found that the effect of beam divergence on the detector response could be negligible in the visible and resulted in a smaller response below about 90 nm for both the Si and the Au-GaAsP photodiode. The silicon photodiode showed complex spectral variation of polarization properties between 100 nm and 400 nm.

We have investigated the electronic and magnetic properties of a MnAs:GaAs granular film with MnAs clusters embedded in the GaAs matrix fabricated by high-temperature annealing of Ga1−xMnxAs using x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD). The XAS line shapes in the Mn 2p core level changed from a localized structure to an itinerant NiAs-type one. Magnetic-field dependence of the XMCD revealed no hysteresis curves at the fixed photon energy where the large XMCD signals were observed, suggesting the superparamagnetic behavior at 100 K.

A type of GaAs-based ferromagnetic semiconductor, (Ga, Cr)As, was successfully prepared by low-temperature molecular-beam epitaxy. The (Ga, Cr)As thin film shows a flat surface up to the Cr content x=0.18. However, when Cr content x exceeded 0.20, the roughness of the film became larger. The ferromagnetic ordering of the semiconductor sample with the Cr content of x=0.11 was observed. The electronic structures of (Ga, Cr)As were characterized by x-ray absorption spectroscopy (XAS). The XAS spectra show different line shapes in different Cr content.

Zinc-blende CrAs/GaAs multilayers were grown by molecular beam epitaxy. It was certified that each CrAs layer maintains an epitaxial relationship with the zinc-blende GaAs structure judging from the reflection high-energy electron diffraction observation. The film contains thicker zinc- blende CrAs layers in total than the CrAs thin film directly grown on the GaAs substrate which has the critical thickness of 3 nm. It was clarified that the optimum thicknesses of CrAs and GaAs to keep a good epitaxial relationship are 2 ML and 2 ML, respectively. The electronic structure of the multilayer is thought to be close to that of the (Ga, Cr)As thin film which has 50% of Cr content judging from x-ray absorption spectroscopy measurements.

of the medial femorotibial joint cartilage were assessed using a 3T MR system (Verio; Siemens). The whole and superficial (half of the whole cartilage) cartilage in the medial knee joint were assessed. The study was approved the Ethics Committee, and the nature of the study was explained to all participants, and written informed consent was obtained. Results: The peak knee adduction moment (external) and angle between the 20s (4.8 10z 1.9 10 z) and 40s (5.8 10z 1.7 10 z) during free gait was not significantly different (Fig. 2). Although the first peaks of knee flexionmoment in the 40s (5.7 10z 1.7 10 z) were significantly larger than the values in the 20s (3.2 10z 2.6 10 z) (Fig. 3, P < 0.05), the knee flexion angle between the 20s and 40s was not significantly different. T2 values of the femoral superficial cartilage in the 40s (34.0 1.8 msec) were significantly higher than the values in the 20s (32.2 1.4 msec) (P < 0.01). The first peak of the knee flexion moment and the T2 in the 40s were not significantly correlated (r 1⁄4 0.21). Conclusions: Knee flexion moments in the 20s were higher than the moment in the 40s during free gait. Kinematic and kinetic change of the knee joint during gait due to the ages might start on the sagittal plane. Although T2 mapping values at the medial superficial femoral cartilage in the 40s were higher than the values in the 20s, the knee flexion moment is not related to T2 mapping values of knee joint cartilage. We could not conclude that the increased knee flexion moment is the preceding knee kinetic change of the early knee OA from this crosssectional study.

En el presente trabajo se dan a conocer 11 nuevos registros de peces marinos para el Perú. Las colectas fueron efectuadas entre los años 1989 y 2007 en las localidades de Bocapan, Canoas de Punta Sal, Punta Sal (Tumbes); Los Órganos, Isla Foca (Piura); Islas Lobos de Afuera (Lambayeque); Bahía Samanco (Ancash); y Pucusana (Lima). Los nuevos registros para la ictiofauna marina del Perú son: Dasyatis longa, Urobatis halleri, Cephalopholis panamensis, Prognathodes carlhubbsi, Cirrhitus rivulatus, Stegastes beebei, Thalassoma lucasanum, Thalassoma grammaticum, Axoclinus lucillae, Elacatinus punticulatus y Coryphopterus urospilus. Las especies Cirrhitichthys oxycephalus, Lythrypnus dalli y Myripristis leiognathus, fueron anteriormente mencionadas para Perú pero sin existir registros documentados, con la presente publicación se certifica su presencia. Se discute sobre características biogeográficas y ampliación de distribución durante El Niño., In this paper I report on 11 new records of marine fishes from Peru. The collections were made between 1989 and 2007 in Bocapan, Canoas de Punta Sal, Punta Sal (Tumbes); Los Órganos, Isla Foca (Piura); Islas Lobos de Afuera (Lambayeque); Bahía Samanco (Ancash); y Pucusana (Lima). The new records for the marine fish fauna of Peru are: Dasyatis longa, Urobatis halleri, Cephalopholis panamensis, Prognathodes carlhubbsi, Cirrhitus rivulatus, Stegastes beebei, Thalassoma lucasanum, Thalassoma grammaticum, Axoclinus lucillae, Elacatinus punticulatus and Coryphopterus urospilus. Cirrhitichthys oxycephalus, Lythrypnus dalli and Myripristis leiognathus, previously have been referred to Peru but not documented there, this paper certify their presence.

Aims: Two different pathways of linoleic acid (LA) metabolism have opposite effects on the development of colonic cancer: a protumoral prostaglandin cascade metabolized by cyclooxygenase (COX)-2, and an antitumoral peroxisome proliferator-activated receptor (PPAR)-γ ligands metabolized by 15-lipooxygenase (LOX)-1. The aim was to examine the switching of the two LA metabolic pathways in colonic adenomas and carcinomas. Materials and methods: The expression of 15LOX-1 mRNA and COX-2 protein was examined in 54 adenomas, 21 pTis carcinoma-in-adenoma lesions and 36 pT3/p Stage II carcinomas of the colon by in-situ hybridization and immunohistochemistry, respectively. Results: 15LOX-1 expression was found in 89% (48 of 54) of adenomas, 43% (nine of 21) of adenomas and 10% (two of 21) of carcinomas in carcinoma-in-adenoma lesions, but not in pT3 carcinomas (P

Background: A high external knee adduction moment (KAM) during walking is known as one of the risk factors for progression of knee osteoarthritis (KOA). In the clinical practice, it is important to find a convenient method that can predict aKAMduringwalking in patientswithKOA.Wehave then hypothesized that kinematic behaviors of the pelvis and the trunk during single-leg standing could reflect the peak KAM during walking. Purpose: The purpose of the present study was to investigate the relationship between kinematic behaviors of the pelvis and the trunk during single-leg standing and the peak KAM during walking in the healthy subjects. Methods: Twenty-eight healthy subjects were recruited for this study (23.6± 4.0 years). These subjects performed the gait and the single-leg standing trials. In the single-leg standing trial, subjects stood on two force platforms. The subjects lifted one lower limb off the force plate ‘as fast as possible’ following a sonic cue, and held the posture. The onset of lift-off point (lift-off onset) was defined as the time when the vertical component of the ground reaction force becomes less than 10N. All data were recorded during the period from a ‘sonic cue’ until 1000ms following the lift-off onset. In the gait trial, subjectswalked at a self-selected speed. The data were collected with a six-camera motion analysis system and two force plates that were time synchronized and sampled at 200Hz and 1000Hz, respectively. Helen Hays marker set with additional markers placed on the spinous processes of C7 and S1 was used. The peak KAM during the walking and the single-leg standing were determined using the SIMM6.0.2 software. The maximum andminimum value of the lateral lean angle of the trunk and the lateral tilt angle of the pelvis during single-leg standing were calculated using the custom Matlab code. The trunk lean toward the swing limb side and the contralateral pelvis drop were denoted as a negative angle. Pearson correlation coefficients were used to determine a relationship between the KAM gait and the other variables during SLS. The level of significance was set at 0.05. Results: The peak KAM during single-leg standing was significantly correlated with that during walking (r= 0.40, p= 0.03). The peak KAM during walking was significantly correlated with the maximum value of the lateral lean angle (r=−0.45, p= 0.02) and lateral tilt angle of the pelvis (r=−0.40, p= 0.04) during single-leg standing. Conclusion(s): The present study showed that the lateral lean angle of the trunk and the lateral tilt angle of the pelvis during single-leg standing reflect the peakKAMduring walking. Implications:Findings of the present study indicate a possibility that kinematic behaviors during a single-leg standing task can predict a peak KAM during walking in the KOA patients.

We demonstrated low‐noise and high‐power GaAlAs laser diodes with small astigmatism. The low‐noise characteristics are realized by self‐sustained pulsation due to the saturable absorption of a single‐quantum‐well located close to the triple‐quantum‐well active layer. The high‐power and small‐astigmatism characteristics are achieved by using a real refractive index guided self‐aligned structure. The lasers showed a relative intensity noise less than −130 dB/Hz under 10% optical feedback in a very wide output‐power range (5–35 mW), a stable fundamental transverse mode up to 150 mW, and astigmatism less than 1 μm.

The objective of this study was to verify the effects of active (AR) and passive recovery (PR) after a judo match on blood lactate removal and on performance in an anaerobic intermittent task (4 bouts of upper body Wingate tests with 3-min interval between bouts; 4WT).The sample was constituted by 17 male judo players of different competitive levels: A) National (Brazil) and International medallists (n. 5). B) State (São Paulo) medallists (n. 7). C) City (São Paulo) medallists (n. 5). The subjects were submitted to: 1) a treadmill test for determination of V.O2peak and velocity at anaerobic threshold (VAT); 2) body composition; 3) a 5-min judo combat, 15-min of AR or PR followed by 4WT.The groups did not differ with respect to: body weight, V.O2peak, VAT, body fat percentage, blood lactate after combats. No difference was observed in performance between AR and PR, despite a lower blood lactate after combat (10 and 15 min) during AR compared to PR. Groups A and B performed better in the high-intensity intermittent exercise compared to athletes with lower competitive level (C).The ability to maintain power output during intermittent anaerobic exercises can discriminate properly judo players of different levels. Lactate removal was improved with AR when compared to PR but AR did not improve performance in a subsequent intermittent anaerobic exercise.

A GaAs MCM power amplifier has been developed for 1.9-GHz digital cordless telephones. Power-added efficiency of 40.2% and P/sub 1dB/ of 22.2 dBm have been obtained at drain supply voltage of 3.6 V. Adoption of the MCM structure and on-chip ferroelectric capacitors has successfully reduced the GaAs total chip area to be 1.1 mm/sup 2/. >

Extremely small GaAs PA has been implemented using the AlN multilayer MCM for 0.9 GHz digital cellular phones. The present PA exhibited the efficiency of 49% with drain supply voltage as low as 3.6 V. The PA was designed to provide the matching circuits with the maximum gain at the input and the minimum intermodulation distortion at the output. >

8 p. Describe a dos nuevas especies de peces no registradas para el Perú, determinando que se tratan de Microspathodon dorsalis (Famiia Pomacentridae) y Prionurus laticlavius (Familia Acanthridae), ambos del orden Perciformes. El registro de estas dos especies de aguas tropicales del norte del Perú, contribuye a la comprensión de la estructura comunitaria de los fondos rocosos costeros del litoral norte.

Informe IMARPE; n° 144, 1999, p. 61-70 Durante el crucero 9801 a bordo del BIC Humboldt, se realizaron, entre 12 y 24 de enero de 1998, 29 lances de pesca en el área comprendida entre el Estrecho de Bransfield e Isla Elefante, capturándose un total de 11.629 kg, correspondiendo 9.522 kg a krill y 2.107 kg a otros organismos. La fauna acompañante estuvo representada por 15 especies de peces, 4 celentéreos, 2 crustáceos y un tunicado. Es los aspectos biométricos de krill se encontraron tres grupos modales correspondiendo cada uno de estos a diversas zonas geográficas, distribuidos en modas de 34 mm, 38 mm y 42 mm siendo la moda promedio total de 36 mm. Los datos fueron obtenidos de un total de 12.822 ejemplares muestreados. Para la relación longitud-peso se encontró por regresión potencial la formula: peso = 0,003851 * long.3.38.

20 p. Describe como durante el evento de El Niño, algunas bahías del litoral peruano se convierten en importantes localidades de asentamiento de la fauna asociada a las aguas cálidas propias de las provincias biogeográficas Panameña y Oceánica. Según las observaciones realizadas, las bahías muy cerradas se transforman en localidades de refugio de esta fauna ocasional por presentar condiciones más estables que el resto del litoral. A su vez, brinda información sobre los cambios ocurridos en las comunidades teniendo en cuenta el asentamiento de nuevas especies en las bahías y la exclusión de otras, las cuales dan lugar a una sucesión ecológica que va cambiando las características poblacionales según avanzan las anomalías térmicas.

Publicación especial, 1997. 46 p. El crucero "Localización, Concentración y Distribución de los Langostinos Rojos de Profundidad", se desarrolló entre el 18 de julio y el 06 de agosto de 1996, utilizando una red de arrastre tipo Gran ton, modelo 400/130. Se exploró el área comprendida entre Puerto Pizarro y Huarmey a profundidades entre 254 y 1 021 m. A partir de la información obtenida en el rastreo acústico, realizado en el área citada y del conocimiento de la existencia de dos biocenosis en la zona arquibentónica, una al norte y la otra al sur del Banco de Máncora, se determinó realizar el estudio sistemático y bioecológico del recurso objetivo, en el área comprendida entre 03°24' a 04°05'S y 81"00' a 81"25'W. • En esta área de evaluación, la captura estuvo constituida por peces (86,92%), crustáceos (8,04 %), moluscos (2,78%), equinodermos (1,20%), onidarios (1 ,00%), poríferos (0,03%), anélidos (0,03%), briozoarios (0,00 1%) y sipuncúlidos (0,004 %). Se registraron 38 especies de crustáceos, de los cuales 7 constituyeron los denominados langostinos de profundidad: ifeterocarpus vicarius, Haliporoides" diomedeae, Nematocarcinus agassizii, Heterocarpus hostilis, Psathyrocaris fragilis, Plesionika trispinus y Pasiphaea magna. Los más importantes langostinos rojos de profundidad se presentaron desde los 08° 18.20' S hasta los 03"32.11' S, principalmente al sur del Banco de Máncora, a profundidades entre 382 y 1 021 m. La densidad media (t/mn2) del total de langostinos rojos de profundidad, para el área de evaluación estuvo comprendida entre 0,0017 y 0,420 t/mn 2• Se determinó una profundización de los langostinos rojos fuera de su área habitual, asociado a un desplaza­miento de la mínima de oxígeno hacia mayores profundidades. Esto determinó poca disponibilidad de los principales langostinos rojos de profundidad. Se destaca la mayor frecuencia de la "gamba" Haliporoides diomedeae entre 0,2 a 1,6 ml/l de oxígeno disuelto, con sus mayores densidades entre 0,8 a 1,6 ml/l. El "camarón naylon" Heterocarpus vicarius, mostró las mayores concentraciones a menores tenores de oxígeno (0, 17 a 0,25 ml/1). Se establecieron relaciones biométricas de las principales especies de langostinos rojos de profundidad.

p. 50 - 71 Evalúa el uso del chinchorro mecanizado y su relación con el deterioro del medio ambiente, teniendo en cuenta que su estilo de operación se asemeja a una red de arrastre de fondo que opera en zonas de mar abierto y/o en grandes ensenadas, cerca a la orilla de fondos someros, arenosos y planos; las cuales son zonas muy productivas por estar en áreas de intenso afloramiento que permiten el desarrollo de una gran variedad de invertebrados bentónicos (muy muy, machas. poliquetos, entre otros).

GaN films with good crystalline quality are grown on sapphire by atmospheric pressure vapor phase epitaxy using gallium tri-chloride (GaCl3) and ammonia (NH3). Epitaxial growth is carried out over temperature and V/III-ratio ranges of 800–1000°C and 100–1000, respectively. Typical growth rate obtained is in the range of 5–20 μm/hr. The films grown below 925°C typically show three dimensional (island) growth, while above that temperature, continuous films are obtained. Films grown at 975°C with a V/III ratio > 300 exhibit a smooth surface. XRD analysis shows that the films are single crystal with hexagonal polytype. Strong band-edge photoluminescence is observed with a FWHM of 60 meV at room temperature and 25 meV at 77K. The results indicate that this simple growth technique is effective for growing high quality bulk GaN, which can be used as a substrate for subsequent epitaxy. In order to further improve the surface morphology, a preliminary experiment on GaN growth on a thin GaN buffer layer prepared by gas source MBE is also presented.