Search

The effects of neutron irradiation on remanent magnetization in multidomain iron and kamacite (3wt% Ni) samples of varying initial coercivities were investigated in order to determine whether cosmic ray exposure significantly affects the natural remanent magnetization (NMR) of lunar samples and chondritic meteorites. Irradiation to 1017 fast neutrons/cm2 increased bulk coercive force (Hc) by an average of 15%. Annealing for 1 hour at 200-300°C returned Hc to its pre-irradiation value. The dominant effect of irradiation on remanent magnetization was to decrease the total intensity by 5-45%. AF demagnetization spectra of both isothermal and thermal remanence before and after irradiation indicate that neutron bombardment slightly increases the resistance to AF demagnetization. No similar increase in resistance to thermal demagnetization was indicated. The changes in Hc and AF demagnetization spectra are attributed to radiation induced point defects rather than to pinning of domain walls by vacancy clusters and dislocations. The NRM in chondritic meteorites and most lunar samples is too stable to be accounted for by exposure of isothermal remanence to cosmic rays. Thus the NRM must be some form of thermal or thermochemical remanence.

Comparison of two hyaluronidase preparations showed no difference to exist between them in their action on various tissue components. The enzyme can be stored in buffer for 3 weeks at 5°C without loss of potency. There was a good correlation between visual estimates of staining and microdensitometric measurements.

A system for zinc vapor generation and deposition onto a strip substrate at high rates is described. A resistance heated graphite crucible with a special design to suppress uncontrolled boiling is able to produce zinc vapor outputs as high as 150 lb/h for the 300 in.2 hearth area utilized. An efficient system for nozzling the zinc vapor onto the strip substrate from an enclosed hood allows this maximum vaporization rate to be condensed uniformly at a thickness of 0.6 mils across a 12-in. width at a line speed of 100 ft/min. Control of the vaporization rate is obtained through variation in the power input according to a heat flow model and also by means of a barometric liquid-zinc leg which is used to fill and empty the crucible and feed it continuously from outside the vacuum chamber. Other methods used to control the system are also discussed briefly as is the type of coating produced by deposition at these high rates.

(1966). Measuring Life-Science Concepts of Elementary-School Pupils. The Journal of Experimental Education: Vol. 35, No. 1, pp. 70-73.

Paleomagnetic examination of a 1-kg specimen of the Allende meteorite has revealed the existence of natural remanent magnetization of constant direction and moderate intensity (3.0 × 10 −4 emu/g). Cooling of the fusion crust in the Earth's magnetic field following atmospheric entry has remagnetized the outer 1 mm of the specimen. Comparison of AC demagnetization spectra of NRM with spectra of laboratory-produced remanence suggests that the natural remanence is thermal or thermochemical remanence formed during original accretion or post-accretion reheating of Allende. Paleointensity determinations on three samples show that the NRM was formed in a field of approximately 1.1 Oe. Thermomagnetic analysis indicates that the ferromagnetic minerals in Allende consist of 95 wt% taenite containing 67% Ni plus 5 wt% taenite with 36% Ni. These iron-nickel minerals amount to only 0.46 wt% of the whole rock.

Recent experimental data on synthetic titanomaghemites indicate that oxidation is accompanied by a decrease in magnetocrystalline anisotropy K1 as well as a decrease in the saturation magnetization σs. Theory of relaxation times predicts that the decrease of σs and K1 with oxidation will cause single-domain titanomagnetite grains with initially low blocking temperatures to become superparamagnetic as they are oxidized to titanomaghemite. For titanomagnetites (Fe3−x TixO4) of composition x = 0.4 and x = 0.5 the affected blocking temperature range is approximately 200° and 125°K below the Curie point, respectively. However, for x = 0.6 titanomagnetites the blocking temperature range affected is within 80°K of the Curie point and spans a temperature interval from 325° to as high as 380°K, depending on the degree of oxidation. The rapid quenching of oceanic pillow lavas (average composition x ≅ 0.6) produces efficient thermoremanence carriers but will also result in a significant grain size and blocking temperature distribution. Thus low-temperature oxidation of oceanic basalts could cause a significant portion of the originally stable carriers of natural remanence to become superparamagnetic. This mechanism could aid in explaining the large natural remanent magnetization intensity decrease of dredged basalts with distance from the mid-Atlantic ridge.

The authors of this report discuss the relative contributions of various rocks to the marine magnetic anomalies which are, of course, the crucial indicators of seafloor spreading.

A9145 is a new adenine-containing antifungal antibiotic. A9145 showed weak in vitro activity against Candida albicans in SABOURAUD'S medium, but was strongly inhibitory in a chemically defined medium. Viability counts of C. albicans following extended exposure to A9145 indicated a fungistatic action. Following a 100mg/kg dose, a peak of 64μg/mlof A9145 activity was detected in mouse blood. Administration of 10 mg/kg for 3 days extended the survival time of mice infected with C. albicans 128%; equivalent doses of amphotericin B extended survival time 112%. A total dose of 31.25 mg/kg administered over a 5-day period reduced by 400-fold the number of Candida recovered from kidney homogenates of infected mice. A combination of amphotericin B and A9145 caused a possible synergistic effect against C. albicans in vitro and an additive effect in vivo.

THE entire field of metastatic malignancy has for some time held the particular interest of the radiologist because of the admirable adaptability of the X-ray film to show the presence of metastases, and, when present, their extent. The term “silent metastasis” is familiar to all and by its very familiarity is suggestive of the frequency of occurrence of this clinical condition. While metastases to the abdominal organs, spine and long bones may be symptomless, nevertheless these are more frequently associated with ascites, nerve root pains, spontaneous fractures, etc., so that it seems reasonable to assert that the condition of silent metastases is more frequently found with secondary new-growths in the chest than in any other region. Not merely are the symptoms absent but quite often there are no physical signs either, especially when the nodules are deeply seated, hence at some distance from the surface of the chest. The treatment of metastatic tumors has not yet reached the stage of recognition and wid...

The paper deals with large slow-speed marine engines with a section on crankshaft stresses, including dynamic torque calculation; static bending moments owing to firing pressure, inertia, and misalignment; combined torque and bending stress; and experimental determination of stress concentration factors in the fillet radii. Other sections deal with top end bearing loading including cyclic variation, piston head stresses, deflection of bearing housings, prestressing of main bolts, frame stiffness, and stress in combustion chamber studs as a result of pressure and thermal loading.

Differences in the lattice parameters of hematite, ilmenite and magnetite are responsible for lattice mismatch across the boundaries of magnetite-ilmenite and hematite-ilmenite lamellae. Most of this mismatch is relieved by periodic edge dislocations, the remainder by constant strain of the lattice. The periodic stress field produced by the dislocations and the constant stress due to crystal strain are calculated for both types of lamellae. A model based on magnetostrictive control of magnetization can account for the coercivities of hematite lamellae in ilmenite. The model predicts that the coercive force of such a lamella should be inversely proportional to the square root of the lamella thickness, and calculated coercivities agree well with observed values. High coercivities associated with magnetite-ilmenite lamellae are probably due to single domain effects, since they cannot be accounted for by magnetostrictive control of any type.

is that on the proper policy as regards religious art in what used to be called 'the mission field', but which is now, in deference to political, psychological, and ecclesiastical changes, called 'the lands of the Younger Churches'. As Christianity, spreading from its established base in 'the West', takes root in countries which a century ago were almost solidly non-Christian, missionary planners have to ask: Are the new Churches there to go on, as they have begun, importing Western forms, which are true (more or less) to Christian purposes and doctrines, but which in their new lands are alien from the spirit of the surrounding cultures-cultures which are increasingly conscious of their own worth and resentful of denationalizings? Or are they to come to terms with those cultures, and thereby present the Christian Gospel with less offense, but risk its dilution with improper syncretisms, in which, for example, Christ might be presented as another Buddha? That is the usual way of setting out the problem of missionary art-a problem voluminously discussed, with great learning, intelligence, and sensitivity in the Roman Church in Europe, led in this respect, till his recent lamented death, by Cardinal Celso Costantini. Protestants (of whom I am one) may perhaps claim that our confessions have pioneered as much in practice; but we have discussed the problem much less, despite fine work by Professors Daniel Fleming of New York and Arno Lehmann of Halle.

THROUGH the years it has been emphasized1 , 2 that gout is a disease often overlooked by the physician although in the majority of cases the clinical picture is pathognomonic. Those whose interests lead them to see patients afflicted by bone and joint disease are not infrequently faced by a routine serum uric acid determination that returns a high level suggestive of gout whereas the clinical picture is not consistent with this diagnosis. It is our purpose in the presentation that follows to describe the experience at the Robert Breck Brigham Hospital with this problem in differential diagnosis. The approach has been . . .

A standard approach in programming an analog computer is to define a linear relationship between the independent problem variable and real time, i.e., computer time. This approach is not always necessary, as illustrated by the ex amples presented here. Quite often, an alternate approach utilizing a parametric technique is more convenient and makes it easier to obtain function values near singular points and points at which a function is indeterminate.

Differential cross-sections have been measured for π0 photoproduction over the energy range 0.8 GeV to 1.4 GeV and at angles between 50° and 90° c.m.

A start is being made in applying principles of advanced mathematics to problems of business competition. The author describes what he calls “business theorems,” derived in the same manner as the laws governing physical sciences. He believes that theorems will help management to go more directly to the heart of the problem … by indicating the feasibility of objectives and by isolating the really important considerations from irrelevant factors.

The glycosaminoglycan contents of samples from cat intervertebral discs were examined by using cetylpyridinium chloride salt elution techniques. The values obtained related to the region of the vertebral column from which they were derived, to the area of the disc, and to water content. In wet tissue there was a significant difference between regions of the vertebral column and between areas of the disc and findings agreed with previous histological reports. The greater part of the glycosaminoglycans present consisted of chondroitin sulphate and dermatan sulphate with smaller amounts of hyaluronic acid; little keratan sulphate was found. The maximum amounts of chondroitin sulphate and dermatan sulphate occurred in the 0.5m-magnesium chloride fractions usually, but moved towards higher molar concentrations in samples derived from some sites, particularly in the lumbar region. Mean values for the water content of the areas of the disc were: nucleus pulposus, 82.4%; inner anulus, 65.6%; outer anulus, 50.5%. The water content was directly related to the amounts of chondroitin sulphate and dermatan sulphate.

It is recognized that present-day techniques of intracardiacsurgery demand a satisfactory method of elective cardiac arrest. Potassium citrate, acetylcholineand hypoxic arrest have allbeen used with varying degrees of success.Each of these methods has its limitations and with each, difficulties in resuscitationare encountered. In general,because of the greater ease of resuscitation,hypoxic arrest seems preferableto potassium citrateor acetyicholine.Our previous studies’suggest that hypothermia offerssome degree of protection to myocardial metabolism by preserving sources of energy for myocardial contraction. It was demonstrated that when the dog’s heart was permanently arrested at normothermia with potassium citrate, myocardial glycogen values decreased by 78 per cent, ATP by 60 per cent and lactic acid increased by 500 per cent by the end of 90 minutes of arrest. When animals were placed on cardiopulmonary by-pass and arrest produced with potassium citrate or hypoxia for 30 minutes these changes were of the same order. When total body hypothermia was utilized with by-pass, however, with myocardial temperature reduced below 20CC., glycogen values were essentially unaltered and lactic acid increased to a less degree. Adenosine triphosphate and phosphocreatine values were less consistent, but some degree of protection by hypothermia was suggested. These results are similar to those recently presented by Gott.’ Cardiac resuscitation after arrest with potassium citrate or hypoxia has been shown to be poor after periods of 20 minutes. When hypothermia was utilized with arrest, resuscitation was accomplished in all cases with ease. Therefore, these biochemical studies correlated well with the observation that the heart behaves better functionally when hypothermia is used. Since the more complicated cardiac defects often necessitate cardiac arrest for prolonged periods of time, it seemed desirable to study further the protection afforded by hypothermia when used with cardiopulmonary by-pass and hypoxic arrest, and to establish the length of time over which this protective effect might be effective. Methods Mongrel dogs, weighing 12-15 kg., were placed on cardiopulmonary bypass with a Kay-Cross disc oxygenator and a DeBakey roller pump. Right thoracotomy was performed through the fourth intercostal space.

Mast cells of dog skin were examined by staining with Alcian Blue in magnesium chloride solutions and by a periodic acid-Schiff method. The results suggest that the usual fall in cell-count with age is largely due to increasing blockage of staining by protein-saccharide interaction. The degree of sulphation and molecular weight of the saccharide polymer appears to be reduced with age in animals with either normal or diseased skin, but in the diseased animals the protein-polysaccharide interaction did not occur. Significant differences between body regions occur, particularly in the anal region. It is considered unlikely that significant amounts of glycosaminoglycans other than heparin are present in dog mast cells.

Diode lasers with emission wavelengths as long as 28 μ have been fabricated using Pb1−xSnxTe with x up to 0.27. Properties of laser diodes at 77°K and 12°K have been measured for a number of compositions in the range 0.15 ≤ x ≤ 0.27. The vapor growth and annealing‐diffusion steps were performed in a special quartz ampoule which remained sealed throughout the process. Threshold current densities were dependent on diode surface conditions and could be reduced by at least 50% by etching.

An irradiation of 3 x 1017 neutrons per square centimeter in a reactor core produced an increase in the coercive force of iron and kamacite of 16 to 21 percent. The alternating-current demagnetization spectrum of saturation isothermal remanence was shifted toward higher coercive forces. Similar neutron fluences produced by cosmic-ray exposure may be capable of converting soft isothermal remanence in meteorites and lunar samples to remanence with a higher coercive force.