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We investigate the effect of ellipticity ratio of the polarized radiation field on optoelectronic properties of a two-dimensional (2D) semi-Dirac (SD) system. The optical conductivity is calculated within the energy balance equation approach derived from the semiclassical Boltzmann equation. We find that there exists the anisotropic optical absorption induced via both the intra- and interband electronic transition channels in the perpendicular $xx$ and $yy$ directions. Furthermore, we examine the effects of the ellipticity ratio, the temperature, the carrier density, and the band-gap parameter on the optical conductivity of the 2D SD system placed in transverse and vertical directions, respectively. It is shown that the ellipticity ratio, temperature, carrier density, and band-gap parameter can play the important roles in tuning the strength, peak position, and shape of the optical conductivity spectrum. The results obtained from this study indicate that the 2D SD system can be a promising anisotropic and tunable optical and optoelectronic material for applications in innovative 2D optical and optoelectronic devices, which are active in the infrared and terahertz bandwidths., Comment: 9 pages, 8 figures

Caroli's disease is a rare congenital disease characterized by non-obstructive dilatation of the intrahepatic bile ducts, with a prevalence of one in a million in the general population[1]. Most of it is considered to be an autosomal recessive genetic disease, but in many cases, the typical genetic family history cannot be traced back. There are two forms of Caroli's disease: simple type (commonly called Caroli disease) and Caroli syndrome (characterized by congenital liver fibrosis and/or polycystic kidney disease). PKHD1 gene is considered to be the causative gene of Caroli's disease, congenital liver fibrosis and/or polycystic kidney disease [2]. Here, we introduce a case of Caroli's disease confirmed by pathology, atypical symptoms and images in our hospital.Caroli病是一种以非阻塞性肝内胆管扩张为特征的罕见先天性疾病。大多认为是常染色体隐性遗传病，但许多病例无法追寻典型的遗传家族史。Caroli病包括两种类型，简单型（称为Caroli病）和以先天性肝纤维化和/或多囊肾病为特征的Caroli综合征。认为PKHD1基因是Caroli病、Caroli综合征的致病基因。.

Risk assessment is a necessary technical means to protect human health and environmental safety. Traditional risk assessment based on toxicity data obtained from animal experiments was difficult to meet the need for risk assessment for a large number of chemicals due to the low throughput, long cycle, high cost and uncertainty of extrapolation to human exposure dose. The proposed risk assessment frameworks, the model of action (MOA) and the adverse outcome pathway (AOP), pointed the way for us to develop new and efficient evaluation methods. In this review, the basic concepts and contents of MOA and AOP, as well as the relationship between them, were introduced. Taking acrylamide (AA) as an example, this review briefly described the application of MOA/AOP framework in chemical risk assessment, so as to provide theoretical guidance for better application of MOA/AOP framework in chemical risk assessment.风险评估方法是保障人类健康和环境安全的必要技术手段。基于动物实验获取毒性数据的传统风险评估，由于动物实验通量低、周期长、成本高和高剂量外推至人类暴露剂量的不确定性等问题，难以满足大量化学品亟需开展风险评估的需求。毒作用模式（MOA）和有害结局路径（AOP）风险评估框架的提出为我们开发新型、高效的评价方法指明了方向。本综述介绍了MOA和AOP的基本概念、内容以及两者之间的关系，并以丙烯酰胺（AA）为例，简述MOA/AOP框架在化学物风险评估中的具体应用，以期为更好运用MOA/AOP框架进行化学物风险评估提供理论指导。.

Micropapillary bladder cancer (MPBC) is a very rare and aggressive variant of urothelial carcinoma (UC). The aim of this study was to investigate the clinico-pathological characteristics, treatment, and prognosis of MPBC to improve the understanding of this invasive disease. We reviewed the records of 6 patients with MPBC who were evaluated and treated at our hospital between 2009 and 2015, and additionally reviewed 38 cases reported in the literature. In 44 cases, 36 cases (81.8%) were male and 8 cases (18.2%) were female, with a male:female ratio of 4.5:1; the median age of the patients was 68 years (range 45–91 years). A majority (81.8%) of patients with cT1 above or with lymph node and distant metastasis (cT2N0 in 18.2%, cT3-4N0 in 13.6%, cTanyN+ in 43.2%, and cTanyM+ in 6.8%). There was a high grade in 70.5% of patients. Lymphovascular invasion (LVI) was present in 61.4% of patients, and LVI in cT2 was more common than in cT1 (71.4 vs 22.2%). 52.3% of patients were treated with radical cystectomy (RC). After a mean follow-up of 16.2 months, 77.3% of patients developed distant metastases, and 47.7% of patients died of the disease. The mean overall survival (OS) was 28.9 months and the median OS was 20 months, and the amount of micropapillary (MPP) is correlated inversely with prognosis. Micropapillary bladder cancer is a rare variant of UC associated with a poor prognosis, which often presents at an advanced stage with LVI and distant metastases. The optimal treatment strategy is early RC combined with chemotherapy.

The feasibility of thermal pressure ventilation technology for ventilation and cooling of extra long construction tunnel with high altitude and high ground temperature was discussed. A physical model was built with a proportional factor of 1:1 based on the design documents of Zilashan tunnel in China. The CFD model considering buoyancy effects was used to evaluated the influence of the initial rock temperature, the insulation performance of the left tunnel and the outdoor air temperature on the effect of thermal pressure ventilation. Results show that the effect of thermal pressure ventilation increases by 12.2%, and the effect of cooling enhances by 3.7% when the left tunnel has no insulation. Compared with the initial rock temperature, the outdoor air temperature has a greater influence on thermal pressure ventilation. When the initial rock temperature is below 54 °C, outdoor air temperature is below 17.5 °C and the left tunnel has no insulation, thermal pressure ventilation technology is feasible for ventilation and cooling of Zilashan tunnel with a shaft of 450 m height. The thermal pressure ventilation technology provides a reference for other construction tunnel projects as a design of ventilation and cooling.

SummaryOne-year-old bulblets of Lycoris aurea were obtained by propagation of cuttings. Different concentrations of N-(2-chloro-4-pyridyl)-N1-phenylurea (CPPU; 0, 1.0, 2.0, 5.0, 7.5, or 10.0 mg l 1) were sprayed on all the leaves on each plant at the green-leaf stage. Morphological indices including bulblet fresh weights (FW) and diameters, carbohydrate concentrations, the activities of enzymes related to starch metabolism, and the concentrations of endogenous hormones were determined in bulblets during dormancy. Bivariate correlation analysis was used to analyse the relationships of all parameters. The results showed that spray treatment with an appropriate concentration of CPPU was beneficial for the enlargement of L. aurea bulblets. The optimum concentration was 1.0 mg l 1. Bivariate correlation analysis showed that bulblet FW and diameter had a significant (P ≤ 0.05) positive correlation with starch concentration. The concentration of zeatin riboside (ZR) showed a significant (P ≤ 0.01) positive corre...

To investigate the optimal anticoagulation methods and monitoring strategy for Chinese patients undergoing heart valve replacement, which is potentially quite different from western populations.In this multicenter prospective cohort study, the anticoagulation and monitoring strategy data was acquired from 25 773 in-hospital patients in 35 medical centers and 20 519 patients in outpatient clinic in 11 medical centers from January 1st, 2011 to December 31th, 2015.As for in-hospital patients, mean age of study population was (48.6±11.2) years old; main etiology of valve pathology was rheumatic (87.5%) origin among study cohort; 94.8% of study population received mechanical valve implantation; international normalized ratio (INR) monitoring (in all the study centers) and low-intensity anticoagulation strategy (31 hospitals chose target INR range of 1.5-2.5, and actual values of INR among 89.2% of 100 069 in-hospital monitoring samples were 1.5-2.5), with mean actual INR values of 1.84±0.53, and warfarin dosage of (2.82±0.93) mg/d were widely adopted among the study centers; strategies of in-hospital warfarin administration were similar in all the study centers; complication rates of low-intensity anticoagulation strategy were low in severe hemorrhage (0.02%), thrombosis (0.05%), and thromboembolism (0.05%) events, without anticoagulation-related death.As for 18 974 outpatient clinic patients, the follow-up rate was 92.47%, with a total of 30 012 patient-years (Pty). Anticoagulation-related morbidity and mortality rates were 0.67% and 0.15% Pty; major hemorrhage morbidity and mortality rates were 0.25% and 0.13% Pty; thromboembolism morbidity and mortality rates were 0.45% and 0.03% Pty.The mean dosage of warfarin daily dosage was (2.85±1.23) mg/d and INR value was 1.82±0.57.No significant regional difference in the intensity of anticoagulation therapy was noted during the study.INR can be used as a normalized indicator for intensity of anticoagulation therapy in China.The optimal anticoagulation intensity with INR range from 1.5 to 2.5 is safe and effective for Chinese patients with heart valve replacement, and there is no significant regional difference in the intensity of anticoagulation therapy.

It has been demonstrated that anesthetics exposure may lead to neurocognitive impairment in developing brain of animal models. However, for the limitation that the animal models cannot fully mimic the dose and duration in clinical settings especially for dental general anesthesia, the clinical significance of anesthetics exposure on developing central nervous system remains undetermined. Therefore, we conducted the current study in order to observe the fluctuation of intelligence quotient (IQ) after the administration of dental general anesthesia comparing to that before surgery. We conducted the current study in order to observe the fluctuation of intelligence quotient (IQ) after the administration of dental general anesthesia compared with that before surgery.Thirty two patients, ASA I, who were exposed to dental general anesthesia in Department of Pediatric Dentistry Peking University School and Hospital of Stomatology, aged 4 to 6.5 years, were enrolled in this prospective study. Patients with severe learning difficulties or communication disorders were excluded. Written and informed consent was obtained from each patients' family which was fully explained of the purpose and method of study. Their intelligence quotients were evaluated with the Chinese Wechsler young children scale of intelligence (Urban version) before and 2 weeks after dental anesthesia. They were treated by experienced pediatric dentists and the sevoflurane, propofol and nitrous oxide were used for general anesthesia by anesthetist. Articaine hydrochloride and epinephrine tartrate injections were used for their pulp treatment or extraction. The examiners and scorers for IQ had technical training in the test administration. All the patients were tested by the same examiner and with standardized guide language. Each subtest was scored according to the tool review. Verbal IQ and performance IQ consisted of relevant 5 subtests and full scale IQ. Statistical analyses were performed by SPSS 18.0. All the scores of subtests and 3 types of IQ were expressed as mean±standard deviation. Paired two-tailed t test was applied and P0.05 was accepted as statistically significant.The results of intelligent assessment from 28 subjects were collected. The anesthetic time was (163.4±32.6) min and the number of treated teeth was 12.1±2.3, mean age (4.60±0.41) years; age range=4.04 to 5.44 years. Among the patients, there were 13 girls and 15 boys. There was no significant difference in gender distribution. The postoperative full IQ (128.46±10.85) was higher than that before surgery (124.64±11.46, P= 0.017). We found that the elevation of performance IQ, to a large extent, contributed to this change in full IQ (P= 0.007). Correspondingly, there was no statistical difference in the verbal IQ, which was 119.68±11.74 to 120.21±15.61 (P=0.854).Dental general anesthesia has no negative effect on the intelligence of preschool children, who were treated under general anesthesia by sevoflurane, propofol and nitrous oxide for 2 to 4 hours. The full IQ and performance IQ were slightly enhanced after treatment which can be explained by the memory effect.

AKT pathway has a critical role in mediating signaling transductions for cell proliferation, differentiation and survival. Previous studies have shown that AKT activation is achieved through a series of phosphorylation steps: first, AKT is phosphorylated at Thr-450 by JNK kinases to prime its activation; then, phosphoinositide-dependent kinase 1 phosphorylates AKT at Thr-308 to expose the Ser-473 residue; and finally, AKT is phosphorylated at Ser-473 by several kinases (PKD2 and others) to achieve its full activation. For its inactivation, the PH-domain containing phosphatases dephosphorylate AKT at Ser-473, and protein serine/threonine phosphatase-2A (PP-2A) dephosphorylates it at Thr-308. However, it remains unknown regarding which phosphatase dephosphorylates AKT at Thr-450 during its inactivation. In this study, we present both in vitro and in vivo evidence to show that protein serine/threonine phosphatase-1 (PP-1) is a major phosphatase that directly dephosphorylates AKT to modulate its activation. First, purified PP-1 directly dephosphorylates AKT in vitro. Second, immunoprecipitation and immunocolocalization showed that PP-1 interacts with AKT. Third, stable knock down of PP-1alpha or PP-1beta but not PP-1gamma, PP-2Aalpha or PP-2Abeta by shRNA leads to enhanced phosphorylation of AKT at Thr-450. Finally, overexpression of PP-1alpha or PP-1beta but not PP-1gamma, PP-2Aalpha or PP-2Abeta results in attenuated phosphorylation of AKT at Thr-450. Moreover, our results also show that dephosphorylation of AKT by PP-1 significantly modulates its functions in regulating the expression of downstream genes, promoting cell survival and modulating differentiation. These results show that PP-1 acts as a major phosphatase to dephosphorylate AKT at Thr-450 and thus modulate its functions.

Most of the Flight Payload hardware for the Gravity Probe B Relativity Mission is currently being manufactured. The design, fabrication, and integration of this hardware has already been subjected to an extensive program of full scale prototyping and testing in order to provide maximum assurance that the payload will meet all requirements. Full scale prototyping is considered to be a crucial aspect of the payload development because of the complexity of the payload, the stringency of its requirements, and the necessity for integration of a warm cryostat probe into a dewar maintained at liquid helium temperature. This latter requirement is derived from the fact that the dewar contains a superconducting ultralow magnetic field shield which provides an ambient magnetic field environment for the probe of

Gravity Probe B is an experiment to measure the geodetic and frame-dragging precessions, relative to the “fixed” “stars”, of a gyroscope placed in a 650 km altitude polar orbit about the earth. For Einstein's general relativity, the precessions are calculated to be 6.6 arcsec/yr for the geodetic precession and 0.042 arcsec/yr for the frame-dragging precession. The goal of the experiment is to measure these precessions to better than 0.01% and 1%, respectively. This paper gives an overview of the experiment and a discussion of the flight hardware development and its status. This paper also includes an estimate of the geodetic and frame-dragging errors expected for the experiment.

The most demanding goal of the Gravity Probe B Relativity Mission (GP-B) is the measurement of the parametrized post-Newtonian parameter γ to one part in 105. This goal requires a total experimental accuracy of ≤ 0.044 marcsec/yr. Analysis of and results from 100,000 hours of gyroscope operation on the ground show that the residual Newtonian drift will be < 0.17 marcsec/yr for a supported gyroscope in 10−9 m/s2, and < 0.020 marcsec/yr for an unsupported gyroscope in a fully inertial orbit. The expected error due to gyroscope drift is thus consistent with the measurement goal. The main gyroscope disturbance caused by cosmic radiation is charging of the rotor. A force modulation technique allows measurement of the charge of the gyroscope rotor to about 5 pC, while bipolar charge control to 10 pC is achieved using electrons generated by UV photoemission.

The NASA/Stanford Relativity Mission Gravity Probe B (GP-B) experiment will provide two extremely precise tests of General Relativity based on observations of electrically suspended gyroscopes in a satellite in a 650 km circular polar orbit around the Earth. The project is now nearing completion. Final assembly of the instrument will take place later this year and launch is scheduled for October 2000. GP-B will provide a very accurate measurement of the frame-dragging effect, with its subtle connections to gravitomagnetism and Mach's principle. In addition to measuring frame dragging to 0.3%, it will measure the geodetic effect to approximately 1 part in 105. GP-B is a controlled physics experiment where error terms such as the Newtonian drifts of gyroscopes are reduced to negligible values, and where the apparatus is under the experimenters' control.

The Gravity Probe B relativity mission experiment is designed to measure the frame dragging and geodetic relativistic precessions in a 650 km polar orbit. We describe some of the advanced experimental techniques used to achieve the required gyroscope accuracy of between 0.05 and . The subjects discussed are: (i) the development of high-precision gyroscopes with drift rates of less than , (ii) a low-temperature bake-out procedure resulting in a helium pressure of less than at 2.5 K, (iii) a read-out system using DC SQUID magnetometers with a noise figure of at 5 mHz and (iv) AC and DC magnetic shielding techniques which produce an AC attenuation factor in excess of and a residual DC field of less than .

We report an NMR study of solid H[sub 2] formed by the recombination of doubly polarized atomic hydrogen at a temperature of [similar to]0.3 K. The molecules are formed in a highly excited ortho state with [ital M][sub [ital I]]=[minus]1, thermalize through collisions with the [sup 4]He-coated walls of the containment chamber, and form a solid. The solid is essentially pure ortho H[sub 2] in the fcc phase, as expected. However, the nuclear polarization is close to zero, in contrast to the value of [minus]1 if there was no relaxation, and +0.034 if the spin temperature was in equilibrium with the surface of the cell. Possible mechanisms for depolarization are discussed, though no plausible explanation for the loss has yet been found.

The London-moment readout has been observed in flight quality gyroscopes and it has been demonstrated that it is possible to reduce magnetic field trapped in these gyroscopes to levels as low as 1.5*10/sup -11/ T. A preliminary analysis shows that the horizontal component of the London-moment signal is 60% of the total expected London-moment signal and is proportional to the gyro spin speed. Experiments were carried out in a unique ground test facility which was designed to provide the conditions necessary to observe the London moment of the spinning gyroscope. >

This paper presents the results of dynamical testing of an electrostatically levitated, spherical gyroscope that has a superconducting coating. These results are used to verify and to assess the characteristics and the performance of these gyroscopes in preparation for the Stanford Relativity Experiment (also known as Gravity Probe B) space mission intended for 1996. During this mission the angular drift of the spin axis of a spinning gyroscope will be measured during a period of one full year or more in orbit. This measured drift rate will be compared with the theoretical drift rate as predicted by the general theory of relativity. Research presented here shows that it is possible to measure the time history of the spin vector of a spherical gyroscope with respect to two mutually perpendicular pickup loops in a Helmholtz configuration using the dipole component of the magnetic trapped flux inside the gyroscope. With the use of the time history of the gyroscope spin axis, it is possible to estimate the gyroscope characteristics, in particular its mass unbalance. The measurements recorded during this research are unique in a sense that it is the first time a superconducting sensor in conjunction with trapped magnetic flux was used to determine the orientation of the spin vector of a nearly perfect spherical gyroscope.

To study the relationship between herpes viral infection and viral encephalitis.The cerebral spinal fluid(CSF) and sera of the patients with viral encephalitis were detected for herpes virus-specific IgG and IgM with indirect fluorescent antibody assay (IFA).One hundred and thirty-three (14.4%) cases of 921 patients with viral encephalitis were diagnosed as herpes simplex viral encephalitis, of which the maximum morbidity is under the age of 10, 9(0.98%) cases as cytomegaloviral encephalitis and 12 (1.3%) cases as varicella-zoster viral encephalitis.Herpes simplex viruses are the common causative agents of viral encephalitis in Changsha area, and IFA is valuable for the diagnosis of herpes viral encephalitis.

We have demonstrated that the molecular hydrogen obtained from atomic recombination at 300 mK has nonstatistic ortho–para ratio. The ortho para conversion is less than 3% in the vibrational relaxation phase. We suggest that it is possible to carry out detailed comparison between calculations and measurements at conditions similar to our experiments.

The low temperature transport properties of Ce75−xAl25+x (x = 0, 10, and 15 at. %) metallic glasses were investigated. Magnetic field and composition tuned magnetoresistances changing from negative to positive values were observed at low temperature. It was suggested that these peculiar phenomena were caused by the tunable competition between the Kondo effect and the Ruderman-Kittel-Kasuya-Yoshida interaction in Ce-Al metallic glass with the variation in Ce content and magnetic field. Further magnetization and Ce-2p3d resonant inelastic x-ray scattering spectroscopy measurements supported this scenario. These Ce-Al metallic glasses could provide an interesting model system for the investigation of 4f electron behaviors in complex condensed matter with tunable transport properties.

We report on the measurement of the London moment produced in a rotating spherical shell superconductor. In the process of qualifying gyroscopes for the Gravity Probe B Relativity Mission we investigated the question of how a magnetic moment develops in rotating superconductors. We have been able to perform experiments which show that the dipole moment appears independent of the initial rotational state of the superconductor.

We report measurements of flux distributions on superconducting spherical shells in an ambient magnetic field of 0.2±0.1 μG. The aim of these experiments is to minimize the number of flux lines trapped in the superconducting shells, an important requirement for the Gravity Probe B gyroscopes.

We have conducted an NMR study of the hydrogen recombination process in the temperature range 0.2K – 0.6K. Starting with a gas of doubly polarized atomic hydrogen we produce molecular ortho hydrogen. The nuclear spin polarization is quickly lost after the recombination process. The time constant for the de-polarization is less than 0.1 s, and the initial nuclear spin temperature of the solid is larger than 4K.

The Gravity-Probe-B relativity gyroscope experiment (GP-B) will measure the geodetic and frame-dragging precession rates of gyroscopes in a 650 km high polar orbit about the earth. The goal is to measure these two effects, which are predicted by Einstein's General Theory of Relativity, to 0.01 percent (geodetic) and 1 percent (frame-dragging). This paper presents the development progress for full-size prototype flight hardware including the gyroscopes, gyro readout and magnetic shielding system, and an integrated ground test instrument.

The correlation between the retinotopic organization of receptive fields in the striate-peristriate border region and the distribution pattern of the visual callosal projections was investigated in hamsters with corpus callosum transected 2 days before recording. The results, showed that in all the animals studied, the V1/V2 border defined by reversal of receptive fields at the vertical meridian was located in the dense central portion of the visual callosal projection which terminated in cortical regions bordering areas 17 and 18a. These results indicate that there is a close relationship between the striate-peristriate border determined by anatomical and physiological methods. In addition, these data strengthen the suggestion that the pattern of visual callosal projections is a useful and reliable reference system for delineating boundaries of different visual areas in the golden hamster.

The retinotopic map for the contralateral eye is similar to that found in the pigmented rats and in other rodents. Cells which had ipsilateral responses were recorded in a fairly large area in the rostral portion of the tectum. Their receptive fields lay from about 40 degrees in the contralateral hemifield to about 40 degrees in the ipsilateral hemifield. The ipsilateral response of a binocular cell is similar in almost every respect to its counterpart in the opposite eye except being very weak and that the receptive field is usually smaller. Most binocular cells are distributed in the Stratum griseum superficiale (SGS) and the Stratum opticum (SO). Less binocular cells recorded in the Stratum griseum intermediale (SGI) have more scattered distribution both in the size and in the position of the receptive field.

We have studied relaxation and recombination processes in compressed, doubly polarized atomic hydrogen at temperatures from 0.13 to 0.60 K and magnetic fields from 3 to 9 T. The gas and surface dipole three-body recombination rate constants at a field of 7.6 T are measured to be, respectively, ${L}_{g}$=8.9(8)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}39}$ ${\mathrm{cm}}^{6}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$ and ${L}_{s}$=1.2(4)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}24}$ ${\mathrm{cm}}^{4}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$. They decrease slowly with field and ${L}_{s}$ exhibits no significant angular dependence. The three-body recombination rate due to hyperfine mixing has also been measured. Electronic and nuclear relaxation rates have been measured; the b-c electronic relaxation rate constant in the gas is ${G}^{\mathrm{bc}}$=1.03(7)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}15}$ ${\mathrm{cm}}^{3}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$exp(-${E}_{\mathrm{bc}}$/${k}_{B}$T). The temperature and field dependence of the nuclear relaxation rate in the gas are observed to be in excellent agreement with recent theoretical calculations. Three-body surface recombination-rate measurements using $^{3}\mathrm{\ensuremath{-}}^{4}$He surfaces indicate that as little as one monolayer of $^{3}\mathrm{He}$ on the liquid $^{4}\mathrm{He}$ surface appreciably decreases the adsorption energy of atomic hydrogen. Densities achieved include 4.5\ifmmode\times\else\texttimes\fi{}${10}^{18}$ atoms${\mathrm{?}}^{\mathrm{\ensuremath{-}}3}$ at 0.55 K (pure $^{4}\mathrm{He}$ walls), and 1.4\ifmmode\times\else\texttimes\fi{}${10}^{18}$ atoms${\mathrm{?}}^{\mathrm{\ensuremath{-}}3}$ at 0.19 K (8 at. ? sup 3---He).

Laboratory tests of the spherical electrostatically levitated cryogenically cooled coated gyroscope being developed for the Gravity Probe B (GP-B) spacecraft (Bardas et al., 1986) are reported. Spin speed and the dc components of the trapped magnetic field are measured with three orthogonal pickup loops attached to SQUID detectors as the levitated gyro is brought up to speed by an He gas jet. Data on the spin-vector time history, mass unbalance, higher rotor-shape harmonics, and spin-vector position are presented in extensive graphs and characterized in detail, and a mathematical model of the electrostatic suspension torques is derived. Prototype gyro 86-4 is found to have mass unbalance within the range required for the GP-B mission (to detect the geodetic and motional effects predicted by general relativity theory).

We have used NMR to observe the two-dimensional gas of atomic hydrogen adsorbed on a fritted glass "sponge" covered with superfluid $^{4}\mathrm{He}$. Measurements were made at a magnetic field of 7 T and at temperatures down to 0.080 K for a $^{4}\mathrm{He}$ surface and to 0.060 K for a $^{3}\mathrm{He}$-$^{4}\mathrm{He}$ substrate. The temperature dependence of the resonant frequency agrees with Anderson's multiple-residency model. On the $^{4}\mathrm{He}$ surface the adsorbed hydrogen is first detected at 0.095 K and has a frequency shift of -21.64(40) kHz with respect to the bulk adsorption line, corresponding to a zero-field wall shift of -43.0(8) kHz.

Electrophysiological mapping techniques were used to determine the representation of the central field of vision in the superior colliculus of the albino rat. The retinotopic map for the contralateral eye is similar to that found in other mammals. There is an unexpected extensive binocular segment subserving the central 40 degrees of the ipsilateral hemifield as well as the central 40 degrees of the contralateral hemifield in the rostrolateral portion of the tectum.

Studies using electrophysiological and HRP-labeling techniques showed that the lateral border of physiologically determined primary visual cortex coincides with the cytoarchiectonically defined area 17/18a border. The dense callosal projections are distributed in a zone, about 1.5 mm wide, along this border, which lies in the callosal zone, about 1/4-1/3 of the zone width from its lateral limit. There are two representations of the vertical meridian of the visual field, one in the proper of area 17, about 1/3 of the zone width from its medial limit, the other in area 18a, at about the lateral zone limit.

The functions of interhemispheric axons linking the borders between cortical areas 17 and 18 on the two sides of the brain were investigated by two techniques. A well-matched sample of neurones was recorded in the 17/18 border region before and after an extensive lesion was made in the corresponding part of the other hemisphere. The proportion of binocularly driven cells fell from 96% to 67%, confirming the results of Dreher & Cottee (1975). Orientation-and direction-selectivity, as well as the responsiveness of the population of neurones, seemed unaltered. The reduction in binocularity was much less convincing for cells in the body of area 17, even very close to the callosal-recipient zone. Reversible cooling of the 17/18 border had no effect on the few cells recorded outside the callosal zone in the other hemisphere nor on eighteen of the thirty-five cells recorded in the callosal zone. However, in ten cells the receptive field disappeared completely in one eye; in five cells there was a general reduction in responsiveness; two cells lost a portion of the receptive field, on the ipsilateral side, in both eyes. The receptive fields that were apparently transmitted via the corpus callosum lay around the vertical meridian of the visual field and were not restricted to the visual hemifield ipsilateral to the receiving hemisphere: their distribution overlapped that provided by the direct geniculo-cortical input. The principal function of the callosal projection between the 17/18 borders may be to contribute to binocular convergence on cortical cells and perhaps to play a part in stereoscopic vision.

The structure of retina of the Lipotes Vexillifer has been studied quantitatively under light microscope. The results obtained are as follows. (i) The thickness of the retina is 268 micrometer. The lamination of retina can be clearly distinguished. It consists of 10 layers. The thicknesses of the layers from pigment epithelium to internal limiting membrane are 12 micrometer, 44 micrometer, 2 micrometer, 48 micrometer, 20 micrometer, 36 micrometer, 68 micrometer, 32 micrometer, 8 micrometer and 2 micrometer respectively. (ii) The number of cells in the outer nuclear layer is larger than that in the inner nuclear layer. Two types of cell can be distinguished in this layer. The number of receptors and ganglion cells is in a ratio of 12 to 1. These results show that the retina type of the Lipotes corresponds to that of nocturnal animals. (iii) The diameters of ganglion cells range 1.5-37 micrometer with two peaks at 6 micrometer and 35 micrometer. This means that the ganglion cells fall into two groups according to size, and this has been proved by the observation on morphology of ganglion cells in the whole-mount preparation and sections of the retina. The percentages of large cells and small cells are 3% and 97% respectively. The proportion of small cells to large cells does not change greatly in different parts of the retina. (iv) No fovea and visual streak have been found in the retina.