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Measurements of the electrical conductivity of a 137 \ifmmode\times\else\texttimes\fi{} 137-site simple-square screen mesh versus concentration of removed sites are reported. The new critical exponent is reported to be $t=1.38\ifmmode\pm\else\textpm\fi{}0.12$ within an estimated critical region $\ensuremath{\Delta}x\ensuremath{\sim}0.1$ about a critical percolation concentration ${x}_{c}=0.413\ifmmode\pm\else\textpm\fi{}0.005$. A new effective medium theory, which includes overlap effects of adjacent removed sites, is derived, which gives $\frac{\ensuremath{\sigma}(x)}{\ensuremath{\sigma}(0)}=1\ensuremath{-}\ensuremath{\pi}x+\frac{\ensuremath{\pi}{x}^{2}}{2}$, in agreement with the experiment, except within the critical region.

Excitation energies and nuclear lifetimes of states in $^{42}\mathrm{Ar}$ have been measured by employing the reaction $^{40}\mathrm{Ar}(t,p)^{42}\mathrm{Ar}$ at a triton bombarding energy of 2.8 MeV. Protons were detected by an annular silicon surface barrier counter at an average angle of 174\ifmmode^\circ\else\textdegree\fi{}, and coincident $\ensuremath{\gamma}$ rays were detected by a 20-cm$^{3}\mathrm{Ge}$(Li) counter positioned at angles of 30 and 120\ifmmode^\circ\else\textdegree\fi{}. The extraction of nuclear lifetimes by the Doppler-shift-attenuation technique was made possible by the use of a solid argon target operated at 15 K. Experimental results for excitation energies (keV) and lifetimes (psec) are: 1208.2\ifmmode\pm\else\textpm\fi{}0.3, ${3.8}_{\ensuremath{-}0.8}^{+1.0}$; 2486.7\ifmmode\pm\else\textpm\fi{}0.6, 0.40\ifmmode\pm\else\textpm\fi{}0.16; 2512.5\ifmmode\pm\else\textpm\fi{}0.5, ${4.0}_{\ensuremath{-}1.2}^{+3.1}$; 3014.6\ifmmode\pm\else\textpm\fi{}0.6, 0.12; 3096.4\ifmmode\pm\else\textpm\fi{}0.6, g5; 3557.8\ifmmode\pm\else\textpm\fi{}0.6, 0.09; 4006.1\ifmmode\pm\else\textpm\fi{}0.6, 3.3\ifmmode\pm\else\textpm\fi{}0.8; 4127.4\ifmmode\pm\else\textpm\fi{}0.7, 1.4\ifmmode\pm\else\textpm\fi{}0.3; 4287.0\ifmmode\pm\else\textpm\fi{}0.7, 0.05; 4633.7\ifmmode\pm\else\textpm\fi{}0.7, 0.05. The experimental results are in good agreement with the shell-model calculations of Gloeckner, Lawson, and Serduke.[NUCLEAR REACTIONS $^{40}\mathrm{Ar}(t,p)$, ${E}_{t}=2.8$ MeV; measured $\ensuremath{\sigma}({E}_{p},{E}_{\ensuremath{\gamma}},{\ensuremath{\theta}}_{\ensuremath{\gamma}})$. $^{42}\mathrm{Ar}$ deduced ${E}_{x}$, ${I}_{\ensuremath{\gamma}}$, ${\ensuremath{\tau}}_{m}$. Solid Ar target; Doppler shift attenuation.]

A triple-coincidence, five-parameter technique was employed to search for two-photon emission in the decay of the $^{16}\mathrm{O}$(6.05-MeV) state. Data were event-recorded and analyzed in parallel with events associated with decay of the $^{16}\mathrm{O}$(6.13-MeV) and the $^{16}\mathrm{O}$(7.12-MeV) states. Our measured branching ratio is $\frac{{N}_{\ensuremath{\gamma}\ensuremath{\gamma}}}{{N}_{\ensuremath{\pi}}}=(2.5\ifmmode\pm\else\textpm\fi{}1.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$.

The rate of phloem translocation in willow stems was found to be little reduced on cooling considerable lengths of the transport pathway. Even when 65 cm lengths of stem were cooled from about 23 to 0 °C the reduction in rate was judged to be less than 20 per cent. It is argued that the velocity of translocation is well maintained in cooled stems and that there is no good case for supposing that the concentration of the translocate had altered. The rate of radial transfer of materials from the phloem to the xylem did show a decrease in cooled zones. The implications of the results on current theories of phloem transport are discussed.

Two types of radiation monitor are described, which are of use in reducing the exposure of personnel in contact with radioactive substances. A pocket monitor for nurses working on radium wards is described which gives an audible indication when the dose-rate exceeds 30 mr per hour. A description is also given of a radiation level indicator which sounds an alarm when the radiation level at the apparatus exceeds a preset value.

A radiation detector in the form of a shielded p-n junction is described. The junction with the appropriate shielding is quality independent over the range 0?8 to 14 mm cu H.V.T. to better than 10%, and, with the instrumentation described, the output voltage is proportional to the incident dose rate (to within 5%) over the range 0?3 to 750 r/min. Also described are the temperature and polar responses, as well as measurement of radiation damage from 60Co ?-rays. A comparison is made between the p-n junction detector and a cadmium sulphide probe. The development of probes of smaller physical dimensions and to measure lower dose-rates, is discussed.

The fine structure of the body-wall in Ascaris lumbricoides was investigated by electron-microscopical techniques. The body-wall is composed of a cuticle, epidermis, and a single layer of muscle cells. The cuticle contains several layers: a superficial membrane, a cortex, the ‘fibrillar layer’, a matrix or homogeneous layer, 3 fibre layers, and a basal lamella. The cortex is divided into a homogeneous, external cortical layer, and a fibrous, internal cortical layer. The ‘fibrillar layer’ is a series of canals which extend from the inner part of the matrix layer to the cortex. The canals have distinct walls but no contents were demonstrated. No fibres or lamellae could, be detected in the matrix layer. The strands of the fibre layers and the basal lamella are formed from fine fibrils, less than 10 mµ in diameter. There is an inner system of canals that links the epidermis with the basal lamella and the fibre layers. The epidermis has a network of fibres, some of which attach the muscle cells to the cuticle. The muscle cell contains myofilaments of 2 types, an array of large filaments about 30 mµ. in diameter, each surrounded by a number of smaller filaments about 5 to 7 mµ in diameter. Glycogen occurs in the epidermis and muscle and is identified as granules; there tends to be a clumping together of granules to form deposits about 100 mµ in diameter. External to the sarcolemma lies a connective tissue sheath which contains collagen, probably in the form of fibrillar and particulate material. The cuticles of young adult Ascaris have a basic structure similar to that of the fully grown worms. During the growth of the adult worm the cuticle increases in volume, and this increase involves all the layers of the cuticle. The homogeneous or matrix layer increases in thickness more rapidly than the fibre layers, and both of these layers grow faster than the cortex. Ribonucleic acid is more abundant in the epidermis of young adults than in the fully grown worms and this is correlated with the development of endoplasmic reticulum and ribosomes. It is suggested that the extensive canal system in the cuticle transports materials to all layers of the cuticle.

In the literature on the prevention of diabetes one finds attention drawn to the fact that heredity, race, and obesity are among the important factors that influence the development of this disease. If one could choose a mate with no diabetic taint in the family and not develop obesity the incidence of diabetes could be appreciably reduced. Strome and Blaine (1) point out that mortality rates from diabetes are higher in the United States than in any other major civilized country and that these are increasing every year. In 1933 the author (2) suggested that if one could diagnose diabetes before it became clinically apparent and could treat the disturbance successfully a considerable step forward in reducing the incidence and mortality of this disease would be achieved. The author has previously reported (3) that approximately 15 per cent of patients of college age having glycosuria on one examination would have some degree of disturbance of carbohydrate metabolism as judged by routine glucose tolerance tests.

A simple, inexpensive turbidity system is described which enables growth of a bacterial culture to be recorded automatically over long periods. The system responds linearly to changes in bacterial concentration over a hundredfold range, up to fully grown cultures; this provides an adequate range for most purposes. The system is versatile and can be expanded to a multi-channel system for simultaneously recording growth in different conditions by using individual tubes and recording the output on a multi-channel potentiometer recorder or a digital voltmeter with print out.

THE TERM menopause, strictly interpreted, means the cessation of menstruation. As used clinically it is made to include many phenomena commonly seen in women around the menopausal age. That age varies greatly in different women. In a few, menstruation stops before forty; in a few it may continue until well on to fifty-five. The average age is between forty-six and forty-eight. In a small minority of women the stoppage is abrupt. They menstruate regularly and normally up to a certain month and thereafter have no further uterine bleeding of any kind. In the great majority the menstrual periods gradually diminish in amount (in a few there may be an increased flow), they skip a month, then have a period, may be regular for a month or two, then skip one or two or three months, bleed again, and so on until there is a final cessation. During all this time they may be having so-called menopausal symptoms. Some women have these symptoms even when still menstruating regularly.

The body-wall of adult Euchromadora vulgaris is composed of the 3 layers common to all nematodes, the cuticle, epidermis, and muscle cells. The cuticle is composed of 4 layers, a thin membrane resolvable only by the electron microscope, and 3 layers which can be observed in the light microscope. Histochemical tests show that the cuticle is predominantly protein and contains collagen. Of the 3 main layers of the cuticle, the outermost is about 0.4µ, thick and it is penetrated at regular intervals by grooves which divide the cuticle into annuli. This layer has several features in common with the external cortical layer of the cuticle in Ascaris lumbricoides; it is hardened by disulphide bonds and possibly quinone tanning, and is resistant to collagenase. The middle layer is about 1 to 1.5µ thick and is formed from a series of overlapping plates. The rod-like bodies of de Man are located in this layer and are hollow. Internally, the cuticle is bounded by a basal lamella about 0.2µ thick. The epidermis is thickened to form 4 chords and is composed of a large number of cells, which contain filamentous mitochondria with many cristae, granules of glycogen, and, in the pharyngeal region, pigment spots. The fibrillar zone of the muscle cell contains myofilaments of two types, large filaments 20 to 25 mµ in diameter, which are surrounded by smaller filaments 5 to 7 mµ in diameter. There are filamentous mitochondria, glycogen and a nucleus in the protoplasmic bulb. Covering the muscle cell is a thin membrane, the sarcolemma, which is infolded at regular intervals between groups of myofilaments. The sarcolemma is fused with the basal cuticular layer at both ends of each muscle cell.

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Binaural masked thresholds were measured for periodic 100‐μsec rectangular pulses of period T. Signal parameters were pulse rate (10, 50, 100, 250, and 1000 pps), interaural phase difference (0 and π rad), and interaural time difference (0–5 msec). Spectral content of the signal was controlled by addition or subtraction of phase‐locked harmonic components and by high‐pass and low pass filtering (cutoff frequencies 300, 600, 1200, and 2400 cps). Broad‐band, interaurally in‐phase, masking noise at 60 dB sensation level was used throughout. The signals were transduced by headphones, and the masked thresholds were determined by a modified Bekesy technique. The difference between the threshold for a given test condition and threshold for the signal in‐phase condition is defined as the masking‐level difference (MLD), or the binaural release from masking. For all pulse rates, maximum release from masking obtains for an interaural time of 1.5 msec or T/2, whichever is smaller. The greatest binaural unmasking occurs for a pulse rate of 250 pps and is less at higher and lower rates. For all tonal cases (pulse rates of 250 pps and higher) the release from masking is found to relate primarily to the fundamental component. Elimination of the fundamental substantially reduces the MLD. At the lowest pulse rate, high pass filtering of the signal also reduces the MLD to a small value. The largest MLD's are found for signal conditions that give rise to basilar‐membrane motion near the 300‐cps place and that lead to interaural time differences of about 1.5 msec in the neural activity originating from these places. The same interaural disparity at higher‐frequency places produces substantially smaller MLD's. The MLD therefore appears specific to membrane place as well as to interaural time difference.

Results from a computational model for middle ear and basilar‐membrane operation suggest several binaural phenomena. The effects are sought experimentally in tests on the binaural lateralization of pulses. The interaural times for producing centered images are measured as functions of pulse polarity and noise masking. To a large extent. the interaural disparities appear explicable in terms of the mechanical response of the basilar membrane together with simple hypotheses about the mechanical‐to‐neural transduction in the inner ear. The time disparity can be manipulated by symmetrically masking with high‐pass or low pass noise. By this means, the coherent neural information is elicited from a restricted place on the membrane and reflects the mechanical properties of that place. Similarly, asymmetrical masking (for example, high pass in one ear and low pass in the other) yields interaural times that reflect the transit times to specific membrane places. Calculations from the mathematical model for the middle ear and basilar membrane are used to interpret the psychoacoustic behavior in terms of physiological response. The results are discussed in the context of related findings, and an effort is made to assess the relative influence of mechanical and neural factors.

The instability of the accelerated interface between a liquid (methanol or carbon tetrachloride) and air has been investigated experimentally for approximate sinusoidal disturbances of wave-number range from well below to well above the cut-off. The growth rates are measured and compared with theoretical results. A third-order theory shows the phenomena of overstability which is found in the experimental results. Some measurements of later stages of growth agree moderately well with the available theory and disclose some additional phenomena of bubble competition, Helmholtz instability with transition to turbulence, and jet instability with production of drops.

Purified preparations of hemolytic and lipolytic antigens were shown to be cytotoxic for tissue cultures of mouse peritoneal macrophage monolayers. The percent reduction in viability was proportional to the concentration of antigen used although, for a brief period, the hemolytic antigen stimulated the growth of cultured macrophages. Hemolytic and lipolytic antigens were synthesized by an hemolysin-producing strain (7973), but were deficient or totally lacking in nonhemolysin-producing strains (9037-7, 4219). The inoculation of strain 7973 onto macrophage monolayers at a bacterium to macrophage ratio of 10:1 resulted in a complete loss of viable phagocytic cells. The decrease in viable phagocytic cells was accompanied by an increase in viable listeria. Pronounced cytopathic activity with proliferation of listeria was also observed when 200 U of lipolytic antigen were added to macrophage monolayers that had been infected with the smooth type nonhemolysin-producing strain (4219) on the previous day. On the other hand, a high percentage of macrophages survived when exposed to nonhemolysin-producing strains only. In this case, listeria were not recovered by routine culture methods. The data presented do not establish that phagocytic cell destruction with accompanying microbial proliferation is the direct result of hemolysin elaboration; however, they suggest that there is need for further exploration of the role of the hemolysin in listeriosis.

Rats were hypophysectomized, and 2 hr later one adrenal was excised. An intravenous infusion was then carried out for 1 hr followed by the removal of the remaining adrenal. Assay of the 2 adrenals revealed that infusion of 30 mg dibutyryl cyclic AMP resulted in a decrease in ascorbic acid concentration of 20±2% (mean±SEM, 17 rats), while 5 U of ACTH produced a decrease of 28±3% (11 rats). Saline controls exhibited an increase of 6±3%. During 1-hr incubations of rat adrenals, 10 mM cyclic AMP produced a 13±3% decrease in ascorbic acid levels, a result similar to that produced by ACTH. These results suggest that cyclic AMP mediates the ascorbic acid depleting effect of ACTH. Cycloheximide in quantities sufficient to block adrenal protein synthesis and the stimulation of steroidogenesis also impaired the ascorbic acid depleting effects of ACTH and cyclic AMP in vivo and in vitro. An NADPH generating system produced a significant increase in corticosterone production, but failed to bring about ascorbic acid r...

Differential cross sections for protons scattered from ${\mathrm{B}}^{10}$ were measured and, combined with published differential cross sections and polarizations for protons elastically scattered from ${\mathrm{Li}}^{6}$, ${\mathrm{Li}}^{7}$, ${\mathrm{Be}}^{9}$, ${\mathrm{B}}^{10}$, ${\mathrm{B}}^{11}$, ${\mathrm{C}}^{12}$, ${\mathrm{C}}^{13}$, ${\mathrm{N}}^{14}$, and ${\mathrm{O}}^{16}$ at bombarding energies between 10 and 50 MeV, are analyzed in terms of the optical model. An investigation of the systematic effects observed in applying the optical model to light nuclei reveals two peculiarities. First, an examination of the effects of a nonlocal potential indicates that the radius parameter of the real central potential is energy-dependent. Second, the Thomas form usually used for the spin-orbit potential is shown to lose its surface-peaked character in the case of light nuclei; but a proposed slight modification avoids this defect. The set of parameters found to give a good description of the data over a range of incident nucleon energy and target mass was shown to be similar to the sets of parameters found to describe the nucleon scattering from heavy nuclei. Using the prescriptions for the parameters of the present study but reversing the signs of the $\frac{(N\ensuremath{-}Z)}{A}$ terms leads to fits of comparable quality to the differential cross sections for 14-MeV neutrons scattered from ${\mathrm{Li}}^{7}$, ${\mathrm{Be}}^{9}$, ${\mathrm{B}}^{11}$, and ${\mathrm{N}}^{14}$.

In November 1780 a meeting was called at which the formation of the society was proposed, and from which we may date its existence. A royal charter was obtained in 1782, whereby the reigning monarch is declared to be the patron of the Society. The first meeting at the house was held in April 1781. A history of the house and its depiction on early maps is presented.

In all vertebrates, as the embryo develops at one pole of the egg, it sinks inwards till it becomes completely enclosed in a hood or sac filled with fluid, the amnion. When the sac or true amnion has completely closed over the embryo, it becomes separated from the outer layer, which remains in contact with the covering of the egg as the false or chorionic amnion.

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SUMMARY Changes in blood glucose levels in children during surgery have been found not to follow the pattern reported in adults, no relationship being found between the ‘stress-fulness' of the operation and the rate of rise of blood glucose concentration. In 10 per cent of the children studied the blood glucose level immediately after induction was within the hypoglycaemic range.

A thermocouple is described for the detection of beat by beat temperature changes in the ascending aorta following the injection of cold saline into the left ventricle. Standard manufacturing techniques have been used and the thermocouple can be produced cheaply. The good baseline stability, the frequency response and the linearity of this instrument give it considerable advantages and it can be positioned in the ascending aorta with the minimun of discomfort to the patient. An estimation of the left ventricular end-diastolic volume has been made in 30 patients and no important difficulties were encountered in the use of the thermocouple.

To date there have been two reports (1, 2) in the literature of the clinical use of ethinyl estradiol benzoate as replacement therapy. This brief report is to summarize our experiences over a period of twenty-three months in the use of ethinyl estradiol1 for treatment of the menopause. There were 18 women, all of whom had typical menopausal complaints including hot flashes. No patients were included in this study who did not experience flashes because it was felt that the disappearance of these would more clearly indicate subjective improvement. The average age was 48 years (range 36–63 years). Two 24-hour urine specimens were collected and assayed for estrogens and 17-ketosteroids. If the results of the assays did not check, additional aliquots were assayed until constant results were obtained. The urines were hydrolyzed, and extracted by the method of Hershberg and Wolfe (3); fractionated by the method of Gallagher et al (4).

An instrument for recording the displacement of the cardiac apex relative to the rib cage has been constructed using a commercially available displacement transducer and operational amplifier. A simple E.C.G. unit for timing purposes is also described. Recordings using this instrument are comparable with the apexcardiogram obtained from a more expensive apparatus.

Three K-Ar dates have been obtained on rocks associated with copper mineralization in Peru. A maximum age of 58.7

When patients with urinary infection drink large volumes of water and empty the bladder at frequent regular intervals, the concentration of bacteria in the voided samples commonly falls rapidly at first and then remains almost constant. The present theoretical analysis leads to the conclusion that the rapid initial fall in concentration is a function of diuresis and that the subsequent constant output originates from bacteria bound to multiplication sites on the uroepithelium from which their progeny are shed into the urine.

The organisation of an electronics department required to support the work of a large teaching hospital is described. The research and development programme involves the interaction of graduates from many disciplines since problems can emerge from any of the specialities, for example general surgery, obstetrics and gynaecology, clinical neurophysiology. Examples from the research and development programme of the department are described in order to illustrate the range of medical electronic techniques needed to provide adequate support for the clinical research programmes which have received support from the Joint Research Board of the Hospital and Medical College.

This paper deals with the fluorescent antibody (FA) method for identifying six commonly occuring and two rare groups of streptococci by using commercially prepared (Difco) conjugates. We have shown that group-specific FA produced frequent cross-reactions with heterologous groups of organisms. These reactions varied with different strains of the same serogroup. Nonetheless, there was distinct overall patterns in the intensity and appearance of the homologous and heterologous reactions. When monitored by the precipitin test with Rantz and Randall extracts, these patterns led to the correct identification of 90 to 100% of specimens of serogroup A, B, C, and G streptococci. Many members of groups D and F also showed distinctive reaction patterns. However, there was a significant number of strains of both groups D and F that either failed to strain or stained poorly with the homologous conjugate. As a result, the identification of these serogroups by FA was less reliable.

A rectangular waveguide commutating-hybrid array channelling filter and a centre-excited band branching unit have been combined to form a frequency division multiplexing (f.d.m.) network in the 32-50GHz frequency region. These units terminate the circular waveguide in a millimetric trunk communication system. The 32-90GHz frequency range is divided into transmit-receive sub-bands by the band branching unit which also transduces the TE01° mode in circular waveguide into the TE10 ? mode of rectangular waveguide. A commutating-hybrid array, constructed from rectangular waveguide, further divides each 32-40GHz and 41-49GHz sub-bands into sixteen individual channels spaced 0.5GHz apart. For these sub-bands the average insertion losses measured for the complete f.d.m. network, i.e. between the circular waveguide input to the channel output, are 2.0 and 2.88dB. This paper summarizes the operating principles and measured electrical characteristics. A statistical analysis of results is presented together with an outline of the mechanical construction employed.