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Articles 10291 - 10320 of 10327
Full-Text Articles in Entire DC Network
A Simple Method For The Construction Of Empirical Confidence Limits For Economic Forecasts, William (Bill) H. Williams, M. L. Goodman
A Simple Method For The Construction Of Empirical Confidence Limits For Economic Forecasts, William (Bill) H. Williams, M. L. Goodman
Publications and Research
A simple method for the construction of empirical confidence intervals for time series forecasts is described. The procedure is to go through the series making a forecast from each point in time. The comparison of these forecasts with the known actual observations will yield an empirical distribution of forecasting errors. This distribution can then be used to set confidence intervals for subsequent forecasts. The technique appears to be particularly useful when the mechanism generating the series cannot be fully identified from the available data or when limits based on more standard considerations are difficult to obtain.
Analysis And Prediction Of Telephone Demand In Local Geographic Areas, Douglas M. Dunn, William (Bill) H. Williams, W. Allen Spivey
Analysis And Prediction Of Telephone Demand In Local Geographic Areas, Douglas M. Dunn, William (Bill) H. Williams, W. Allen Spivey
Publications and Research
An approach to forecasting the demand or local area telephone service is presented in this paper. The specific problem discussed is the fore casting of main stations in three Michigan metropolitan areas. Several different statistical models are used. The first class of models introduced uses adaptive exponential smoothing and is based solely on the past history of the time series involved. Although appropriate data at the local area level are very difficult to obtain, two exogenous time series related to household formations are used to construct more elaborate models for one of the areas. The various models are evaluated by …
Effect Of Calcium, Temperature, And Polarizing Currents Upon Alternating Current Excitation Of Space-Clamped Squid Axons, Rita Guttman, Lon Hachmeister
Effect Of Calcium, Temperature, And Polarizing Currents Upon Alternating Current Excitation Of Space-Clamped Squid Axons, Rita Guttman, Lon Hachmeister
Publications and Research
Alternating current threshold excitation of space-clamped squid giant axons was measured as a function of frequency, external calcium concentration, temperature (from 10° to 35°C), and hyper- and depolarizing steps. In normal axons there is usually an optimum frequency at about 120 Hz, at which the threshold is a minimum. The threshold rises at both lower and higher frequencies to give a resonance curve. Low calcium causes an increase in optimum frequency, a decrease in current threshold, and an increase in sharpness of tuning in both real axons and axons computed according to the Hodgkin-Huxley formulation; high calcium causes opposite effects. …
A Statistical Grouping Of Corporations By Their Financial Characteristics., William (Bill) H. Williams, Michael L. Goodman
A Statistical Grouping Of Corporations By Their Financial Characteristics., William (Bill) H. Williams, Michael L. Goodman
Publications and Research
It appears to a widely held view that corporations with similar operational characteristics ought to have similar financial characteristics. For example, one might expect that the financial characteristics of two drug companies would be similar. This seems entirely reasonable. Unfortunately however, there does not appear to be any quantitative analysis of this point in the literature. Furthermore, discussions with our financial colleagues lead to the conclusion that, if such financial differentiation of corporations were possible, it is by no means obvious what the variables of differentiation would be. Consequently, such an analysis was undertaken and is described in this paper. …
Systematic Biases In Panel Surveys Due To Differential Nonresponse., William (Bill) H. Williams, Colin L. Mallows Phd
Systematic Biases In Panel Surveys Due To Differential Nonresponse., William (Bill) H. Williams, Colin L. Mallows Phd
Publications and Research
Panel surveys involve repeated observations on the same sample units of the population. In some of these studies, systematic biases have appeared. It is shown that these systematic biases can also be he result of the characteristics of the response probabilities.
Williams, W. H. "The Systematic Bias Effects Of Incomplete Responses In Roatation Samples., William (Bill) H. Williams Ph.D
Williams, W. H. "The Systematic Bias Effects Of Incomplete Responses In Roatation Samples., William (Bill) H. Williams Ph.D
Publications and Research
No abstract provided.
Oscillation And Repetitive Firing In Squid Axons, Rita Guttman, Robert Barnhill
Oscillation And Repetitive Firing In Squid Axons, Rita Guttman, Robert Barnhill
Publications and Research
Space-clamped squid axons treated with low calcium and computed Hodgkin-Huxley (HH) axons were stimulated by steps of superthreshold current from 101 to 400% of the rheobasic value over a temperature range of 5–27°C. The natural frequency of sustained repetitive firing of real and computed axons depended weakly upon stimulus intensity and strongly upon temperature, with a Q10 of 2.7 (experimental) and 2.6 (computed). For real axons, but not the computed axon, the intervals between the first two spikes were shorter than between subsequent spikes. Constant spike frequencies from 75 Hz at low intensities and temperatures to 330 Hz at high …
The Systematic Bias Effects Of Incomplete Responses In Rotation Samples, William (Bill) H. Williams
The Systematic Bias Effects Of Incomplete Responses In Rotation Samples, William (Bill) H. Williams
Publications and Research
Rotation samples are frequently used in continuing surveys in order to obtain estimates of changes in a characteristic over time as well as separate estimates of the characteristic at specific points in time. Rotation designs involve the retention of some sampling units and the replacement of others. It has been observed in some studies that there are systematic changes in the estimate of a characteristic, depending on the frequency of appearance of a rotation group in the sample. It is shown in this paper that these systematic changes must occur provided (1) the probability of a selected unit actually appearing …
Encountering The Male Establishment: Sex-Status Limits On Women's Careers In The Professions, Cynthia Fuchs Epstein
Encountering The Male Establishment: Sex-Status Limits On Women's Careers In The Professions, Cynthia Fuchs Epstein
Publications and Research
Despite impressive extensions in the scope of women's social and political rights, there have been few extensions of sex-linked boundaries in the prestigious, male-dominated professions. This paper identifies the processes and structure of the professions in the United States which act to limit women's participation and achievement within them. Because their sex status is defined within the culture of professions as inappropriate, women find that the institutionalized channels of recruitment and advancement, such as the protégé system, are not available to them. Various modes of behavior on the part of women and their colleagues are described which are consequences of …
The Effect Of Cortisone On The Volume And Total Protein Content Of Mouse Liver Nuclei, Leonard Amaral, Louis G. Moriber, Marion Himes
The Effect Of Cortisone On The Volume And Total Protein Content Of Mouse Liver Nuclei, Leonard Amaral, Louis G. Moriber, Marion Himes
Publications and Research
No abstract provided.
Planning And Design Workbook For Community Participation, Bernard P. Spring, Carmi Bee, Lance Jay Brown, Gordon Gebert, Charles Zucker
Planning And Design Workbook For Community Participation, Bernard P. Spring, Carmi Bee, Lance Jay Brown, Gordon Gebert, Charles Zucker
Publications and Research
The Planning and Design Workbook for Community Participation is an in depth manual for the design of communities and multiple dwelling unit housing in the urban context. It was originally written to help nonprofessionals participate in the design of their communities and housing and has since become a valuable tool for practicing design professionals. It has for parts. PART I: Planning and Design Aids includes Using the Workbook, Selecting a Site, Economics, Glossary, References. PART II: Community Design Guidelines includes a list of sample issues (questions), alternative answers (policies), and results (consequences) of the choices made when designing a community; …
Analysis Of Time Usage In Bell System Business Offices, William (Bill) H. Williams, Hwei Chen
Analysis Of Time Usage In Bell System Business Offices, William (Bill) H. Williams, Hwei Chen
Publications and Research
No abstract provided.
Temperature Dependence Of Accommodation And Excitation In Space-Clamped Axons, Rita Guttman
Temperature Dependence Of Accommodation And Excitation In Space-Clamped Axons, Rita Guttman
Publications and Research
Accommodation and excitation in space-clamped squid axons were studied with the double sucrose gap technique, using linear current ramps, short (50 µsec) square wave pulses, and rheobasic square wave pulses as stimuli. The temperature was varied from 5° to 35°C. Experimental results showed a Q10 for accommodation which was 44% higher than that for excitation. Yet calculations on the basis of the Hodgkin-Huxley equations predict equal Q10's for excitation and accommodation. Although the Hodgkin-Huxley equations are spectacularly successful for so many nerve phenomena, the differences between calculations of accommodation and these experiments, which were designed to test the equations, show …
Effect Of Low Sodium, Tetrodotoxin, And Temperature Variation Upon Excitation, Rita Guttman
Effect Of Low Sodium, Tetrodotoxin, And Temperature Variation Upon Excitation, Rita Guttman
Publications and Research
The lowering of external sodium raised both the constant quantity threshold, Qo, and the rheobase, Io, in both real space-clamped squid axons and the theoretical axon as computed on the basis of the standard Hodgkin-Huxley equations. In both real and theoretical axons the minimum intensity for excitability for short pulses, which occurs at about 15°C, was still present when low sodium replaced seawater. Low sodium did not affect the temperature dependence of the strength-duration relationship in the range, 5° to 25°C. The excitability of tetrodotoxin-treated real axons was found to be more temperature-dependent than that of normal real axons. Also …
An Analysis Of Heterochromatin In Maize Root Tips, Marion Himes
An Analysis Of Heterochromatin In Maize Root Tips, Marion Himes
Publications and Research
The B chromosomes of maize are condensed in appearance during interphase and are relatively inert genetically; therefore they fulfill the definition of heterochromatin. This heterochromatin was studied in root meristem cells by radioautography following administration of tritiated thymidine and cytidine, and was found to behave in a characteristic way, i.e. it showed asynchronous DNA synthesis and very low, if any, RNA synthesis. A cytochemical comparison of normal maize nuclei with nuclei from isogenic maize stock containing approximately 15–20 B-chromosomes in addition to the normal complement has revealed the following: (a) the DNA and histone contents are greater in nuclei with …
Dna-Protein Binding In Interphase Chromosomes, Marion Himes
Dna-Protein Binding In Interphase Chromosomes, Marion Himes
Publications and Research
The metachromatic dye, azure B, was analyzed by microspectrophotometry when bound to DNA fibers and DNA in nuclei with condensed and dispersed chromatin. The interaction of DNA and protein was inferred from the amount of metachromasy (increased β/α-peak) of azure B that resulted after specific removal of various protein fractions. Dye bound to DNA-histone fibers and frog liver nuclei fixed by freeze-methanol substitution shows orthochromatic, blue-green staining under specific staining conditions, while metachromasy (blue or purple color) results from staining DNA fibers without histone or tissue nuclei after protein removal. The dispersed chromatin of hepatocytes was compared to the condensed …
Temperature Characteristics Of Excitation In Space-Clamped Squid Axons, Rita Guttman
Temperature Characteristics Of Excitation In Space-Clamped Squid Axons, Rita Guttman
Publications and Research
Temperature characteristics of excitability in the squid giant axon were measured for the space-clamped axon with the double sucrose gap technique. Threshold strength-duration curves were obtained for square wave current pulses from 10 µsec to 10 msec and at temperatures from 5°C to 35°C. The threshold change of potential, at which an action potential separated from a subthreshold response, averaged 17 mv at 20°C with a Q10 of 1.15. The average threshold current density at rheobase was 12 µa/cm2 at 20°C with a Q10 of 2.35 compared to 2.3 obtained previously. At short times the threshold charge was 1.5·10-8 coul/cm2. …
Dna-Dependent Rna Synthesis In Chloroplasts Of Euglena Gracilis, Vinod C. Shah, Harvard Lyman
Dna-Dependent Rna Synthesis In Chloroplasts Of Euglena Gracilis, Vinod C. Shah, Harvard Lyman
Publications and Research
No abstract provided.
A Linear Model Approach To Time And Cost Analysis, William (Bill) H. Williams
A Linear Model Approach To Time And Cost Analysis, William (Bill) H. Williams
Publications and Research
Systems analyses frequently require estimates of the average time that it takes to perform repetitive tasks. These time estimates may be easy to obtain; for example, if one man is performing a single operation, then a simple division of his total working time by the frequency of the task repetition, gives an estimate of the average performance time. However, in many instances, work consolidation requires that individuals be called upon to perform several different operations. For example, crews may be sent into the field to carry out a number of different tasks, for which the relative rate of occurrence may …
An Analysis Of Time And Cost Studies By Frequency Counts, William (Bill) H. Williams
An Analysis Of Time And Cost Studies By Frequency Counts, William (Bill) H. Williams
Publications and Research
This work was originally published in Industrial Management.
Sample Selection And The Choice Of Estimator In Two-Way Stratified Populations, William (Bill) H. Williams
Sample Selection And The Choice Of Estimator In Two-Way Stratified Populations, William (Bill) H. Williams
Publications and Research
No abstract provided.
Role Of The Gamete Membranes In Fertilization In Saccoglossus Kowalevskii (Enteropneusta): I. The Acrosomal Region And Its Changes In Early Stages Of Fertilization, Arthur L. Colwin, Laura Hunter Colwin
Role Of The Gamete Membranes In Fertilization In Saccoglossus Kowalevskii (Enteropneusta): I. The Acrosomal Region And Its Changes In Early Stages Of Fertilization, Arthur L. Colwin, Laura Hunter Colwin
Publications and Research
Previous electron microscope studies of sperm-egg association in the annelid Hydroides revealed novel aspects with respect to the acrosomal region. To determine whether these aspects were unique, a comparable study was made of a species belonging to a widely separated phylum, Hemichordata. Osmium tetroxide-fixed polyspermic material of the enteropneust, Saccoglossus, was used. The acrosomal region includes the membrane-bounded acrosome, with its large acrosomal granule and shallow adnuclear invagination, and the periacrosomal material which surrounds the acrosome except at the apex; here, the acrosomal membrane lies very close to the enclosing sperm plasma membrane. After reaching the egg envelope, the spermatozoon …
Role Of The Gamete Membranes In Fertilization In Saccoglossus Kowalevskii (Enteropneusta): Ii. Zygote Formation By Gamete Membrane Fusion, Laura Hunter Colwin, Arthur L. Colwin
Role Of The Gamete Membranes In Fertilization In Saccoglossus Kowalevskii (Enteropneusta): Ii. Zygote Formation By Gamete Membrane Fusion, Laura Hunter Colwin, Arthur L. Colwin
Publications and Research
An earlier paper showed that in Saccoglossus the acrosomal tubule makes contact with the egg plasma membrane. The present paper includes evidence that the sperm and egg plasma membranes fuse to establish the single continuous zygote membrane which, consequently, is a mosaic. Contrary to the general hypothesis of Tyler, pinocytosis or phagocytosis plays no role in zygote formation. Contact between the gametes is actually between two newly exposed surfaces: in the spermatozoon, the surface was formerly the interior of the acrosomal vesicle; in the egg, it was membrane previously covered by the egg envelopes. The concept that all the events …
Effect Of Temperature On The Potential And Current Thresholds Of Axon Membrane, Rita Guttman
Effect Of Temperature On The Potential And Current Thresholds Of Axon Membrane, Rita Guttman
Publications and Research
The effect of temperature on the potential and current thresholds of the squid giant axon membrane was measured with gross external electrodes. A central segment of the axon, 0.8 mm long and in sea water, was isolated by flowing low conductance, isoosmotic sucrose solution on each side; both ends were depolarized in isoosmotic KCl. Measured biphasic square wave currents at five cycles per second were applied between one end of the nerve and the membrane of the central segment. The membrane potential was recorded between the central sea water and the other depolarized end. The recorded potentials are developed only …
The Variance Of An Estimator With Post-Stratified Weighting.Pdf, William (Bill) H. Williams
The Variance Of An Estimator With Post-Stratified Weighting.Pdf, William (Bill) H. Williams
Publications and Research
A straight forward procedure for the estimation of the variance of a post-stratified estimator.
On Two Methods Of Unbiased Estimation With Auxiliary Variates, William (Bill) H. Williams
On Two Methods Of Unbiased Estimation With Auxiliary Variates, William (Bill) H. Williams
Publications and Research
No abstract provided.
Fine Structure Of The Spermatozoon Of Hydroides Hexagonus (Annelida), With Special Reference To The Acrosomal Region, Arthur L. Colwin, Laura Hunter Colwin
Fine Structure Of The Spermatozoon Of Hydroides Hexagonus (Annelida), With Special Reference To The Acrosomal Region, Arthur L. Colwin, Laura Hunter Colwin
Publications and Research
This paper describes in some detail the structure of the acrosomal region of the spermatozoon of Hydroides as a basis for subsequent papers which will deal with the structural changes which this region undergoes during fertilization. The material was osmium-fixed and mild centrifugation was used to aggregate the spermatozoa from collection to final embedding. The studies concern also the acrosomal regions of frozen-thawed sperm prepared by a method which previously had yielded extracts with egg membrane lytic activity. The plasma membrane closely envelops four readily recognizable regions of the spermatozoon: acrosomal, nuclear, mitochondrial, and flagellar. The acrosome consists of an …
Changes In The Spermatozoon During Fertilization In Hydroides Hexagonus (Annelida): Ii. Incorporation With The Egg, Arthur L. Colwin, Laura Hunter Colwin
Changes In The Spermatozoon During Fertilization In Hydroides Hexagonus (Annelida): Ii. Incorporation With The Egg, Arthur L. Colwin, Laura Hunter Colwin
Publications and Research
This, the last of a series of three papers, deals with the final events which lead to the incorporation of the spermatozoon with the egg. The material used consisted of moderately polyspermic eggs of Hydroides hexagonus, osmium-fixed at various times up to five minutes after insemination. The first direct contact of sperm head with egg proper is by means of the acrosomal tubules. These deeply indent the egg plasma membrane, and consequently at the apex of the sperm head the surfaces of the two gametes become interdigitated. But at first the sperm and egg plasma membranes maintain their identity and …
Changes In The Spermatozoon During Fertilization In Hydroides Hexagonus (Annelida): I. Passage Of The Acrosomal Region Through The Vitelline Membrane, Laura Hunter Colwin, Arthur L. Colwin
Changes In The Spermatozoon During Fertilization In Hydroides Hexagonus (Annelida): I. Passage Of The Acrosomal Region Through The Vitelline Membrane, Laura Hunter Colwin, Arthur L. Colwin
Publications and Research
In the previous paper the structure of the acrosomal region of the spermatozoon was described. The present paper describes the changes which this region undergoes during passage through the vitelline membrane. The material used consisted of moderately polyspermic eggs of Hydroides hexagonus, osmium-fixed usually 9 seconds after insemination. There are essentially four major changes in the acrosome during passage of the sperm head through the vitelline membrane. First, the acrosome breaks open apically by a kind of dehiscence which results in the formation of a well defined orifice. Around the lips of the orifice the edges of the plasma and …
On The Order Of A Bias, William (Bill) H. Williams
On The Order Of A Bias, William (Bill) H. Williams
Publications and Research
No abstract provided.