Weak-Field Thermal Hall Conductivity in the Mixed State of d-Wave Superconductors

Thermal transport in the mixed state of a d-wave superconductor is considered within the weak-field regime. We express the thermal conductivity, $\kappa_{xx}$, and the thermal Hall conductivity, $\kappa_{xy}$, in terms of the cross section for quasiparticle scattering from a single vortex. Solving for the cross section (neglecting the Berry phase contribution and the anisotropy of the gap nodes), we obtain $\kappa_{xx}(H,T)$ and $\kappa_{xy}(H,T)$ in surprisingly good agreement with the qualitative features of the experimental results for YBa$_{2}$Cu$_{3}$O$_{6.99}$. In particular, we show that the simple, yet previously unexpected, weak-field behavior, $\kappa_{xy}(H,T) \sim T\sqrt{H}$, is that of thermally-excited nodal quasiparticles, scattering primarily from impurities, with a small skew component provided by vortex scattering.Comment: 5 pages, 2 figures; final version as published in Phys Rev Let

Bayesian cosmic density field inference from redshift space dark matter maps

We present a self-consistent Bayesian formalism to sample the primordial density fields compatible with a set of dark matter density tracers after cosmic evolution observed in redshift space. Previous works on density reconstruction did not self-consistently consider redshift space distortions or included an additional iterative distortion correction step. We present here the analytic solution of coherent flows within a Hamiltonian Monte Carlo posterior sampling of the primordial density field. We test our method within the Zel'dovich approximation, presenting also an analytic solution including tidal fields and spherical collapse on small scales using augmented Lagrangian perturbation theory. Our resulting reconstructed fields are isotropic and their power spectra are unbiased compared to the true one defined by our mock observations. Novel algorithmic implementations are introduced regarding the mass assignment kernels when defining the dark matter density field and optimization of the time step in the Hamiltonian equations of motions. Our algorithm, dubbed barcode, promises to be specially suited for analysis of the dark matter cosmic web down to scales of a few Megaparsecs. This large scale structure is implied by the observed spatial distribution of galaxy clusters --- such as obtained from X-ray, SZ or weak lensing surveys --- as well as that of the intergalactic medium sampled by the Lyman alpha forest or perhaps even by deep hydrogen intensity mapping. In these cases, virialized motions are negligible, and the tracers cannot be modeled as point-like objects. It could be used in all of these contexts as a baryon acoustic oscillation reconstruction algorithm.Comment: 34 pages, 25 figures, 1 table. Submitted to MNRAS. Accompanying code at https://github.com/egpbos/barcod

The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda I

Images have been obtained with the Hubble Space Telescope WFPC2 camera of Andromeda I, a dwarf spheroidal (dSph) galaxy that lies in the outer halo of M31. The resulting color-magnitude diagrams reveal for the first time the morphology of the horizontal branch in this system. We find that, in a similar fashion to many of the galactic dSph companions, the horizontal branch (HB) of And~I is predominantly red. Combined with the metal abundance of this dSph, this red HB morphology indicates that And I can be classified as a ``second parameter'' system in the outer halo of M31. This result then supports the hypothesis that the outer halo of M31 formed in the same extended chaotic manner as is postulated for the outer halo of the Galaxy.Comment: 26 pages using aas2pp4.sty, including 2 tables and 7 figures, to be published in AJ. Figure 1 is in gif form. To include in main ps file, use xv to create a ps file called Da_Costa.fig1.ps and uncomment appropriate lines in .tex fil

Analysis of apples

At request of Prof. J. L. Budd an investigation has been made into the composition of certain varieties of apples, of which some are well known throughout the State, others are being introduced by Prof. B. from his Russian. stock, and still others are undergoing trial on the College grounds. All the samples analyzed were grown, in this vicinity, and the few not from the College grounds were contributed by Mr. A. Graves of Ames. The chief value of apples and fruits in general, in man’s dietary, lies not in the nutrition which they furnish, for they are poor in nutritive elements, but rather in those constituents which gratify the senses of taste and smell, sharpen the appetite, promote digestion, and in other ways contribute to his health and pleasure. Such costituents are the vegetable acids and their salts, volatile oils and ethers (imparting flavor and odor), the “pectous substances” and gums (imparting viscosity and jelly-like consistence), sugars, including the glucoses (dextrose or grape sugar and levulose or fruit-sugar) together with sucrose or cane-sugar, and possibly other substances as yet but imperfectly known. Beside these, the water of fruits is an important constituent, imparting juiciness and serving to hold in solution the tasteful and healthful materials just named

The “Iowa station milk test. A new dairy test for determining the amount of butter fat in milk

During the spring of 1889, while engaged in analyzing the milk of the college herd, I was impressed anew with the very great need, long felt by farmers, dairymen and breeders, of a speedy, easily worked, inexpensive and reasonably accurate method for testing the quality of milk— a method capable of being executed by anyone at home, in the dairy or in the farmer’ s kitchen, and which would enable the milk producer or the breeder to determine, at trifling expense, the yield of butter fat (or milk fat) from the individual cows of his herd. That great differences often prevail among the cows of a herd, as regards the butter making quality of milk produced, is well known ; likewise that breed is not a guaranty of quality— the difference between two cows of the same breed being frequently as great as between the averages for different breeds, even for those of very unlike average quality. So it is regarding the actual, or possible, butter product for the year, of herd or animal— it depends upon individual peculiarities or tendencies, which vary widely within the same as well as among different breeds

Line of Chemical Work: Fodder

The chemical laboratories being the last rooms in the Station building to be completed, were not fully equipped and ready for work until the middle of the present month (August), hence the amount of work yet accomplished is but small; and, as it is only the beginning of a line of work to be continued through several months, report upon it will be reserved for a future bulletin

The composite sample at creameries. Size of samples; Chromate preservatives.

When, early in 1890, the writer first proposed the composite sample— or as it is now generally called, improperly, the “composite test” — as a means of rendering practicable the “value plan” at creameries, he was particular to emphasize, by repetition, the statement that to insure accuracy “the daily samples must be, for each patron, proportionate in amount to his daily deliveries” (Bulletin No. 9). Without this precantion it is evident that the composite may fail of being what it is intended, namely, a miniature of the entire delivery of the patron for the period. In the directions for carrying out the plan (same Bulletin) it was suggested that a convenient size for daily samples would be, in most cases, one-tenth as many cubic centimeters as the number of pounds in the delivery; and it was proposed to measure the samples in a graduated cylinder. This, the reader must bear in mind, was in the very infancy of the value system; we have now a much easier way of taking proportionate samples, which will be mentioned further on

Changes during cheese-ripening.

An investigation conducted by two sections of the station. The cheeses were made, ripened, sampled and weighed at monthly intervals, by the Agricultural Section; the samples were analyzed and all computations made by the Chemical Section