A Physical Apparatus for the Determination of the Circulation Time of the Blood in Dogs

A radical departure from previous apparatus for the determination of blood circulation time is described in detail. The ensemble consists of an ionization chamber (Geiger Counter), a high-voltage (to 2500 volts) power supply, a three-stage amplifying system, and an output circuit for recording the discharges which occur when radiations enter the chamber. A separate electrical circuit is utilized to measure the time interval between the injection of the radioactive material (radium C) in the jugular vein of the dog and its arrival in that part of the femoral artery lying in the adductor canal. The technique of separating radium C from radium emanation is described as is also that of shielding the ionization chamber from extraneous radiations. The record obtained during an experimental test is interpreted as to accuracy and physiological significance and the advantages and disadvantages of the method are outlined

The Circulation Time of the Blood in Dogs before and during the Digestion of Food

The circulation time of the blood in dogs was investigated by an ensemble of physical apparatus consisting of an ionization chamber, a high-voltage power supply, a three-stage amplifying system, and an output circuit for recording and timing discharges which occur in the ionization chamber when radiations such as gamma and beta rays enter

The Disruption of Potentials within a Raw Potato under Constant Applied Voltage

Uniformly shaped sections of raw potatoes were placed between parallel plane electrodes and subjected to a constant potential. The potential drops existing between one electrode and various points in the potatoes were measured. The equi-potential surfaces were found to be planes parallel to the surface of the terminal electrodes. The potentials of these planes were found to vary with time and previous passage of current. The relative size of the probing electrodes used influenced the shape of the potential distribution curves

Effect of Previous Training on Grades in Elementary Physics

A study has been made of the relationship between the grades received by students in an elementary course in Physics taken by Home Economics students at Iowa State College and the general high school average of the students. If the college course is taken during the student\u27s first quarter in college a comparison of the curves expressing this relationship for pupils who have had a high school physics course and for pupils who have had no previous physics course shows that there is a particular high school general average below which there is no advantage in having had a previous physics course. On the other hand, for those students whose high school general averages are above this particular average the curves indicate that the advantage of having had a high school course is more pronounced in proportion to the general ability of the student as shown by his general average grade in high school. If the college course in Physics is not taken until two quarters of other college work have been taken (generally including two quarters of chemistry) a comparison shows the same type of curves as for the group having had the college course in their first college quarter but the general high school average, below which no advantage of a previous course is evident, is considerably higher. The data also show no such differentiation in the curves expressing the relationship between the general college average for the previous two quarters and the physics grade in the subsequent quarter for the two groups of students; that is, those having had physics in high school and those not having had a previous course in physics

The Effects of Some Physical and Chemical Factors in the Circulation Time of the Blood in Dogs

After the determination of an average circulation time of the blood between the jugular vein and the femoral artery in a dog, the effect of such factors as exercise, fasting, high-temperature and low-temperature environments, ether and sodium amytal anesthesias; the intravenous injection of such drugs as histamine, nicotine, adrenalin, cobefrin, thyroxin, pituitrin, pitressin, and pitocin was studied

Biological Fluid Osmotic Pressure Determinations

An outgrowth of the method used by A. V. Hill to determine the next liberation accompanying the passage of a nerve impulse has resulted in the development of an apparatus by which the osmotic pressure of as small quantities of fluid as .5 cu. mm. may be determined to an accuracy of .1 per cent NaCl. The principle consists essentially in the differential cooling effect produced between the experimental sample and a standard solution when placed in a standard, constant temperature, constant humidity environment. A discussion of the necessary thermocouple loop construction, electrical difficulties, and optical system is included in the report

Factors Influencing the Electrical Resistance of the Potato

Extensive experimentation upon the electrical resistance of raw potatoes has given the following results: (1) the resistance of a uniformly shaped section varies inversely as its cross-sectional area; (2) the resistance is independent of the applied voltage; (3) the resistance of sections taken from a relatively homogeneous part of the tuber varies directly with the length; (4) the cortical layer lengthwise of the potato has the least resistance, the resistances of internal medullary area, the external medullary area, and the outer skin following in the order named. No investigation was made upon the resistance of the cortical layer transverse to the length of the tuber

Efficiency of Diffusing Bowls as a Function of the Lamp Wattage

It has been generally assumed that the efficiency of a diffusing bowl is independent of the intensity of the source of light providing the color is kept constant. As preliminary experiments indicated that this conclusion was not justified, a special photometer was constructed and measurements were made by eleven independent observers on different types of diffusing bowls and lamps. The results show (1) that the efficiency of a bowl is a function of the lamp wattage, the color of the lamp remaining the same; and (2) that the shape of the efficiency-wattage curve depends upon the color of the source

The VIRMOS deep imaging survey: I. overview and survey strategy

This paper presents the CFH12K-VIRMOS survey: a deep B, V, R and I imaging survey in four fields totalling more than 17 deg^2, conducted with the 30x40 arcmin^2 field CFH-12K camera. The survey is intended to be a multi-purpose survey used for a variety of science goals, including surveys of very high redshift galaxies and weak lensing studies. Four high galactic latitude fields, each 2x2 deg^2, have been selected along the celestial equator: 0226-04, 1003+01, 1400+05, and 2217+00. The 16 deg^2 of the "wide" survey are covered with exposure times of 2h, 1.5h, 1h, 1h, while the 1.3x1 deg^2 area of the "deep" survey at the center of the 0226-04 field is covered with exposure times of 7h, 4.5h, 3h, 3h, in B,V,R and I respectively. The data is pipeline processed at the Terapix facility at the Institut d'Astrophysique de Paris to produce large mosaic images. The catalogs produced contain the positions, shape, total and aperture magnitudes for the 2.175 million objects. The depth measured (3sigma in a 3 arc-second aperture) is I_{AB}=24.8 in the ``Wide'' areas, and I_{AB}=25.3 in the deep area. Careful quality control has been applied on the data as described in joint papers. These catalogs are used to select targets for the VIRMOS-VLT Deep Survey, a large spectroscopic survey of the distant universe (Le F\`evre et al., 2003). First results from the CFH12K-VIRMOS survey have been published on weak lensing (e.g. van Waerbeke & Mellier 2003). Catalogs and images are available through the VIRMOS database environment under Oracle ({\tt http://www.oamp.fr/virmos}). They will be open for general use on July 1st, 2003.Comment: 17 pages including 9 figures, submitted to A&

The VIRMOS deep imaging survey: III. ESO/WFI deep U-band imaging of the 0226-04 deep field

In this paper we describe the U-band imaging of the F02 deep field, one of the fields in the VIRMOS Deep Imaging Survey. The observations were done at the ESO/MPG 2.2m telescope at La Silla (Chile) using the 8k x 8k Wide-Field Imager (WFI). The field is centered at alpha(J2000)=02h 26m 00s and delta(J2000)=-04deg 30' 00", the total covered area is 0.9 deg**2 and the limiting magnitude (50% completeness) is U(AB) ~ 25.4 mag. Reduction steps, including astrometry, photometry and catalogue extraction, are first discussed. The achieved astrometric accuracy (RMS) is ~ 0.2" with reference to the I-band catalog and ~ 0.07" internally (estimated from overlapping sources in different exposures). The photometric accuracy including uncertainties from photometric calibration, is < 0.1 mag. Various tests are then performed as a quality assessment of the data. They include: (i) the color distribution of stars and galaxies in the field, done together with the BVRI data available from the VIMOS survey; (ii) the comparison with previous published results of U-band magnitude-number counts of galaxies.Comment: 10 pages, 13 figures, accepted for publication on Astronomy and Astrophysic