Showing papers by "State University of New York System published in 1971"

Paradox of Enrichment: Destabilization of Exploitation Ecosystems in Ecological Time

Abstract: Six reasonable models of trophic exploitation in a two-species ecosystem whose exploiters compete only by depleting each other's resource supply are presented. In each case, increasing the supply of limiting nutrients or energy tends to destroy the steady state. Thus man must be very careful in attempting to enrich an ecosystem in order to increase its food yield. There is a real chance that such activity may result in decimation of the food species that are wanted in greater abundance.

Tumor Detection by Nuclear Magnetic Resonance

Abstract: Spin echo nuclear magnetic resonance measurements may be used as a method for discriminating between malignant tumors and normal tissue. Measurements of spin-lattice (T 1 ) and spin-spin (T 2 ) magnetic relaxation times were made in six normal tissues in the rat (muscle, kidney, stomach, intestine, brain, and liver) and in two malignant solid tumors, Walker sarcoma and Novikoff hepatoma. Relaxation times for the two malignant tumors were distinctly outside the range of values for the normal tissues studied, an indication that the malignant tissues were characterized by an increase in the motional freedom of tissue water molecules. The possibility of using magnetic relaxation methods for rapid discrimination between benign and malignant surgical specimens has also been considered. Spin-lattice relaxation times for two benign fibroadenomas were distinct from those for both malignant tissues and were the same as those of muscle.

Statistical Mechanics of the X Y Model. II. Spin-Correlation Functions

Abstract: The spin-correlation functions of the one-dimensional $XY$ model are studied in the presence of a constant magnetic field. We find that the asymptotic behavior of these correlation functions depends strongly on the various parameters of the Hamiltonian.

Boundary Energy of a Bose Gas in One Dimension

Abstract: By the superposition of Bethe's wave functions, using the Lieb's solution for the system of identical bosons interacting in one dimension via a $\ensuremath{\delta}$-function potential, we construct the wave function of the corresponding system enclosed in a box by imposing the boundary condition that the wave function must vanish at the two ends of an interval. Coupled equations for the energy levels are derived, and approximately solved in the thermodynamic limit in order to calculate the boundary energy of this Bose gas in its ground state. The method of superposition is also applied to the analogous problem of the Heisenberg-Ising chain (not the ring).

Thermodynamics of the Heisenberg-Ising Ring for Δ >~ 1

Abstract: The thermodynamics of the Heisenberg-Ising ring is reduced to the solution of a system of recurrent nonlinear integral equations.

Projections and termination of the corticospinal tract in rodents.

Abstract: An examination of the precise mode of termination of the corticospinal system in the spinal cord of rodents has been conducted by use of light and electron microscope methods This study confirms the position of the normal corticospinal tract in rodents in the ventralmost portion of the dorsal column white matter Three to four days following unilateral sensorimotor cortex ablation, Nauta-Gygax and Fink-Heimer silver methods reveal a dorsomedial projection of degenerating debris into the dorsal horn from the contralateral corticospinal tract Although the silver methods do not show degeneration at survival times earlier than two days, the electron microscope shows degenerating axons and synaptic knobs as early as 24 hours following cortical lesion The degenerating synaptic knobs are found only in the dorsal regions of the dorsal horn subjacent to the substantia gelatinosa They usually make synaptic contact with several small to medium sized dendrites These terminals do not appear to participate in axosomatic or axoaxonal synapses No degeneration is seen in the ipsilateral corticospinal tract, the lateral white columns, or the ventral horn of the spinal cord

Cholinergic receptor molecules and cholinesterase molecules at mouse skeletal muscle junctions.

Abstract: Studies of the binding of labelled α-bungarotoxin to mouse skeletal muscle endplates have allowed the quantification of acetylcholine receptor sites at the post-synaptic membrane.

Vibrational Spectra of Hydrothermally Prepared Hydroxyapatites

Abstract: Apatites can be used as bioceramic materials for tooth and bone implants. Infrared (4000 to 400 cm−1) and laser-Raman spectra were obtained for hydrothermally prepared hydroxyapatites with the general formula X10(PO4)6(OH)2 where X= Ca2+ Sr2+, Ba2+, or Pb2+ Fundamental vibrational modes were identified and empirical band assignments made. Analysis of the vibrational spectra led to the reassignment of the v2 mode to a higher wave-number, lower-intensity band (e.g. ∼470 cm−1 for Ca hydroxyapatite). Effects of solid-state interaction were noted in the vibrational spectra and interpreted by factor-group analysis. An “effective” factor group C6h, which neglects the locations of the OH− ions, best describes the vibrational spectra of the hydroxyapatites.

An intense clinicopathologic study of 305 teratomas of the ovary

Abstract: A 20-year retrospective review of 305 consecutive ovarian teratomas diagnosed in the surgical pathology department of the Kings County Hospital is presented All but 10 cases represented the benign cystic variety of this tumor One case of benign solid ovarian teratoma and 9 cases of malignant ovarian teratomas were also encountered The laterality, age incidence, size, and gross and microscopic description of these tumors are discussed in considerable detail, as is the distribution of structures found within the benign cystic variety Brief mention also is made regarding the incidence of struma ovarii, pregnancy, torsion, intraperitoneal rupture, and coincidental lesions found in association with ovarian teratomas

Statistical Mechanics of the XY Model. IV. Time-Dependent Spin-Correlation Functions

Abstract: We compute the correlation functions $〈{S}_{0}^{x}(t){S}_{R}^{x}(0)〉$ and $〈{S}_{0}^{y}(t){S}_{R}^{y}(0)〉$ at $T=0$ for the one-dimensional $\mathrm{XY}$ model in the presence of a magnetic field.

Meningococcal Carriage in a Population of “Normal” Families

Abstract: "Meningococcal meningitis follows a pattern that is indicative of neither the immunization of population groups or areas during years of prevalence, as in the immunizing infections of childhood, nor of any overall restriction of epidemic areas by persistence of chronic carriage, as in typhoid," concluded Ay cock and Mueller in 1950 [1]. Little more has been learned since then to explain the extraordinary epidemiology of meningococcal disease. The anticipation of additional epidemics and the emergence of sulfonamide-resistant strains lend some urgency to the elucidation of phenomena such as the approximate 10-year periodicity of epidemics, the infrequent but regular occurrence of cases in interepidemic years, the ratio of carriers to cases, the dynamic inter-

Estimation of the Probability that Y<X

Abstract: The problem of estimating θ = Pr[Y < X] has been considered in the literature in both distribution-free and parametric frameworks. In this article, using a Bayesian approach, we consider the estimation of θ from two approaches. The first, analogous to the classical procedure, is concerned with the problem of parametric estimation. The second, peculiar to the Bayesian approach, is directed to the query, “For two future observations, × and Y, what is the probability (given only the available sample data) that Y is less than X” This probability, termed the predictive probability, is not an estimate but is, in fact, a probability. These two views are related in that this predictive probability is the mean of the posterior distribution of θ. In the following sections, these Bayesian procedures are applied to the case of independent exponentially distributed random variables and to various cases of the normal distribution. The Bayesian estimates thus obtained are compared, whenever possible, with their...

New Calcium Phosphate Ceramic Material for Bone and Tooth Implants

Abstract: Synthetic hydroxyapatite was fabricated into a white translucent polycrystalline ceramic that displays the hardness of natural apatite. The mineral composition of this product after sintering was chiefly dehydrated hydroxyapatite. In addition, a portion of the apatite was converted into α-whitlockite. Because of the similarities among the mineral compositions of bone and teeth and this ceramic, it offers prospects for implant prosthetic devices.

Recuperation from Illness: Flavor Enhancement for Rats

Abstract: Rats were given a distinctive fluid (milk or grape) during recuperation from an injection of a noxious drug (apomorphine). Single-bottle tests conducted after treatment indicated elevated consumption of the fluid conditionally paired with recuperation. This positive "medicinal" effect is to some degree independent of initial preference, of novelty effects, and of aversive reactions to other substances paired with the onset of illness.

Modifications in the response to alcohol following the establishment of physical dependence.

Abstract: An alcohol withdrawal syndrome characterized by the successive appearance of hyperactivity and tremors, muscle spasticity and, in some animals, generalized convulsions was induced in rats. It was obtained by the administration to rats whose weight had been previously reduced, of a liquid diet containing 45% of alcohol for a period of 3 weeks. The establishment of a state of physical dependence increased the incidence of withdrawal symptoms in a subsequent period of alcoholization. The administration of the 45% alcohol liquid diet during a 4-day period did not induce any noticeable withdrawal symptomatology in animals not previously exposed to alcohol. On the other hand, when previously alcoholdependent animals were subjected to the same procedure, 50% of them demonstrated a severe withdrawal symptomatology.

Fabric of Kaolinite and Illite Floccules

Abstract: A scanning and high voltage electron microscope study of the fabric of laboratory sedimented moist uncompressed kaolinite and illite floccules reveals an abundance of face-face flake orientation in the porous clay network. Clays were flocculated in the laboratory in both distilled water and slightly saline (1 g/l. NaCl) water using various clay concentrations. Floccules taken from the moist clay mass were prepared for study by freeze-drying and impregnation with polyethylene glycol. There is little difference in the fabric of kaolinite flocculated in distilled or slightly saline water. The fabric is dominated by a 3-dimensional network of twisted chains of face-face oriented flakes having the appearance of a stair-stepped cardhouse. Illite floccules in distilled water also consist of abundant face-face oriented overlapping flakes. However, in salt water there is a more even mixture of fabrics—edge-to-face flocculation of individual platelets and also stepped clusters of face-to-face oriented flakes, the latter being more abundant. It is suggested that under the experimental conditions the double layer of each clay particle is compressed resulting in an increase in the importance of van der Waals forces of attraction. As a result flakes approach each other and rotate into a parallel or subparallel position. The resultant dominant fabric is that of a stepped cluster of overlapping flakes.

Malabsorption and Cerebral Dysfunction: A Multivariate and Comparative Study of Autistic Children.

Abstract: Gastrointestinal disorders observed in autistic children prompted a series of related investigations of biological abnormalities. TCDC electrophysiologic recordings, histamine wheal response tests, eosinophile counts, blood cortisol determinations, and behavioral observations involving 15 autistic children were conducted to study several interrelationships, particularly malabsorption and cerebral dysfunction. Control subjects included siblings, other normal children, and normal, schizophrenic and nonschizophrenic adults. Observed differences tended to support approaches that distinguish autism from the large majority of “the schizophrenias.” Characteristic “DC bursts” were found in autistic children, suggesting a maturational failure of a brain control system. Abnormal response of their TCDC system to gliadin and cortisol postulated an underlying cerebral defect affected by stress, diet, or other chemical change. Conclusions imply a fundamental neurobiological dysfunction in “childhood autism,” its possible correlation with malabsorption, and mutual compatibility of various other approaches to etiology.

New Regge Phenomenology of Inclusive Reactions

Abstract: Inclusive reactions are studied in terms of familiar techniques of Regge phenomenology. Distributions are predicted to approach limiting behavior as $A+B{s}^{\frac{\ensuremath{-}1}{2}}$. The constraints of duality and factorization lead to many interesting relations between different single-particle spectra, all of which can be tested at energies below 20 GeV.

Age, Sex, and the Versatility of Delinquent Involvements

Abstract: An analysis of the self-reported delinquent involvements of 763 male and female adolescents revealed that although the males generally had engaged in the 24 activities with a greater frequency than the females, the patterns of involvement were quite similar for both sexes. An intercorrelational analysis of the activities indicated that participation in the activities was more a generalized than a specialized phenomenon; the behaviors showed a tendency to be more generalized among the females than among the males; generalization-specialization was not found to be related to age.

Mescaline and lysergic acid diethylamide (LSD) as discriminative stimuli.

Abstract: The observation that a particular drug state may acquire the properties of a discriminative stimulus is explicable on the basis of drug-induced interoceptive cues. The present investigation sought to determine (a) whether the hallucinogens mescaline and LSD could serve as discriminative stimuli when either drug is paired with saline and (b) whether discriminative responding would occur when the paired stimuli are produced by equivalent doses of LSD and mescaline. In a standard two-lever operant test chamber, rats received a reinforcer (sweetened milk) for correct responses according to a variable interval schedule. All sessions were preceded by one of two treatments; following treatment A, only responses on lever A were reinforced and, in a similar fashion, lever B was correct following treatment B. No responses were reinforced during the first five minutes of a daily thirty-minute session. It was found that mescaline and LSD can serve as discriminative stimuli when either drug is paired with saline and that the degree of discrimination varies with drug dose. When equivalent doses of the two drugs were given to the same animal, no discriminated responding was observed. The latter finding suggests that mescaline and LSD produce qualitatively similar interoceptive cues in the rat.

Bewegliche Molekülgerüste – Pseudorotation und Turnstile-Rotation pentakoordinierter Phosphorverbindungen und verwandte Vorgänge†

Abstract: Molekule konnen sich unter Erhaltung von Bindungen und Koordinationszahlen durch regulare Prozesse umordnen – oder aber durch irregulare Prozesse unter Spaltung und erneuter Knupfung von Bindungen sowie Durchlaufen von Zustanden mit veranderten Koordinationszahlen. Beide Arten von Prozessen an Molekulen mit n-platzigem Molekulgerust konnen mittels Permutationsoperatoren aus der symmetrischen Gruppe Sn beschrieben werden. Diese Operatoren werden in einfacher Weise aus den Deskriptoren der Molekule erhalten; die denkbaren Reaktionsmechanismen entsprechen Klassen konjugierter Permutationen. Regulare Prozesse – z. B. Umordnungsvorgange bei. Phosphoran-Derivaten mit monozentrischem Gerust oder konformationelle Umwandlungen bei Athan-Derivaten mit dizentrischem Gerust – beruhen auf der Beweglichkeit des Molekulgerustes. Flexible Molekulgeruste konnen durch eine Anzahl starrer Gerustmodelle reprasentiert werden, die durch Verformung von Bindungswinkeln und/oder Drehungen um Bindungsachsen ineinander uberfuhrbar sind. Fur das mechanistische Verstandnis regularer Prozesse ist es notwendig, die Symmetrien der starren Gerustmodelle und die gegebenen Ligandenaquivalenzen sowie auch Gerustflexibilitaten und deren Beeinflussung durch den Ligandensatz durch Permutationsgruppen, Untergruppen von Sn, wiederzugeben. Solches Vorgehen beruht auf Polyas, von DeBruijn und Ruch erweiterter Konzeption der Aufspaltung einer permutationellen Molekulsymmetrie in Gerustsymmetrie und Symmetrie des Ligandensatzes in Kombination mit der von Longuet-Higgins fur flexible, symmetrische Molekule – wie Ammoniakeingefuhrten totalen Molekulsymmetrie, woraus man die von uns definierte dynamische Gerustsymmetrie ableiten kann. Die regularen Prozesse pentakoordinierter Phosphorverbindungen werden auf der Grundlage dieser Vorstellungen in einer auch fur mathematisch wenig vorgebildete Chemiker verstandlichen Weise diskutiert, und es ergibt sich unter Berucksichtigung der quantenmechanischen Eigenschaften des P-Bindungssystems, insbesondere der Beteiligung der d-Orbitale, das neben dem bisher fur die Deutung der beobachteten Phanomene ausschlieslich herangezogenen BPR-Mechanismus[2] auch einfache und multiple TR-Prozesse[2] in Betracht zu ziehen sind. Es gibt Beobachtungen, die sowohl durch BPR- als auch durch TR-Prozesse interpretierbar sind, und es gibt Vorgange, die als regulare Prozesse nur auf der Grundlage des TR-Mechanismus zu verstehen sind, aber man kennt noch keine regularen Umordnungen, welche sich allein durch BPR-Prozesse und nicht durch TR-Prozesse deuten lassen.

Afferent volleys in limb nerves influencing impulse discharges in cerebellar cortex II. In purkyně cells

Abstract: Impulses discharged by Purkyně cells provide the only output from the cerebellar cortex Usually the Purkyně cells can be identified with certainty because they alone respond by the brief bursting discharge generated by climbing fiber (CF) impulses, as well as by the ubiquitous simple spikes The discharges from single Purkyně cells in the anterior lobe have been studied in lightly anesthetized and in decerebrate unanesthetized cats All of our 275 identified cells had an average background discharge frequency in the range of 5/sec to 100/sec The discharge was increased and/or depressed by afferent volleys from a number of limb nerves In addition there was usually a slow rate of CF-evoked spike bursts at 05–2/sec, and many afferent inputs also evoked CF responses