Air-core photonic band-gap fibers: the impact of surface modes

We study the dispersion and leakage properties for the recently reported low-loss photonic band-gap fiber by Smith et al. [Nature 424, 657 (2003)]. We find that surface modes have a significant impact on both the dispersion and leakage properties of the fundamental mode. Our dispersion results are in qualitative agreement with the dispersion profile reported recently by Ouzounov et al. [Science 301, 1702 (2003)] though our results suggest that the observed long-wavelength anomalous dispersion is due to an avoided crossing (with surface modes) rather than band-bending caused by the photonic band-gap boundary of the cladding.Comment: 7 pages including 4 figures. Accepted for Optics Expres

Size-dependent nonlocal effects in plasmonic semiconductor particles

Localized surface plasmons (LSP) in semiconductor particles are expected to exhibit spatial nonlocal response effects as the geometry enters the nanometer scale. To investigate these nonlocal effects, we apply the hydrodynamic model to nanospheres of two different semiconductor materials: intrinsic InSb and $n$-doped GaAs. Our results show that the semiconductors indeed display nonlocal effects, and that these effects are even more pronounced than in metals. In a $150\mathrm{\,nm}$ InSb particle at $300\mathrm{\,K}$, the LSP frequency is blueshifted 35%, which is orders of magnitude larger than the blueshift in a metal particle of the same size. This property, together with their tunability, makes semiconductors a promising platform for experiments in nonlocal effects.Comment: 7 pages, 3 figures, 1 table, corrected typos in text and figure

Factors which influence the yield and consistency of ice cream

The pasteurization, aging and homogenization of the cream used, the temperature of the circulating brine and the amount of the mix in the freezer all have an influence upon the yield and texture of ice cream. In some instances that influence is marked and has much to do with successful results in ice cream manufacture. Just what influence these various factors exert was determined in a series of tests made by the author at the Iowa Agricultural Experiment station. The results of these tests are presented in this bulletin for the information of ice cream manufacturers. The bulletin also presents a comparison of the results obtained in figuring the daily ice cream yield by weight and by volume as well as the influence of holding ice cream on uniformity in fat content. There is also a discussion of some of the cost items in ice cream manufacture, such as salt and ice

Influence of acidity on flavor and keeping quality of butter.

An increased demand during recent years for sweet cream butter emphasizes the question as to its flavor and keeping qualities as compared with ripened cream butter, and the desirability of manufacturing still more of the sweet cream product. Merchants who are primarily interested in fancy butter are possibly to some extent responsible for creating this increased demand for sweet cream butter, altho it has been recognized for some years that this product has better keeping qualities than butter churned from sour cream and is therefore better suited for cold storing. Both factors are evidently responsible for the changes brought about in the type of butter manufactured in many plants

Creamery bookkeeping

The cause of many creamery failures can largely be attributed to mismanagement and lack of business records. It is not safe for any creamery manager to try to meet present keen competition without an accurate set of records of his own business. There are still a few creamery men who are not keeping any records of the business transactions of their creamery outside of the milk sheets, receipted bills, and the stubs of their check books. The amount of labor required to keep a complete set of books is not large. If it seems impossible to begin a complete system at once, we would advise making a start at least. The proper way to start is to make a record of purchase and sales and at the end of each month follow this up with a complete inventory report. From the information thus recorded can be determined the profits or losses for the month. After making a start, it will be only a matter of time until the need of more complete records will be felt. Losses which formerly occurred, and which in one year’s time may amount to an astonishing sum, will be brought under better control as the system of bookkeeping is improved

Mode-Field Radius of Photonic Crystal Fibers Expressed by the V-parameter

We numerically calculate the equivalent mode-field radius of the fundamental mode in a photonic crystal fiber (PCF) and show that this is a function of the V-parameter only and not the relative hole size. This dependency is similar to what is found for graded-index standard fibers and we furthermore show that the relation for the PCF can be excellently approximated with the same general mathematical expression. This is to our knowledge the first semi-analytical description of the mode-field radius of a PCF.Comment: Accepted for Opt. Let

Improved large-mode area endlessly single-mode photonic crystal fibers

We numerically study the possibilities for improved large-mode area endlessly single mode photonic crystal fibers for use in high-power delivery applications. By carefully choosing the optimal hole diameter we find that a triangular core formed by three missing neighboring air holes considerably improves the mode area and loss properties compared to the case with a core formed by one missing air hole. In a realized fiber we demonstrate an enhancement of the mode area by ~30 % without a corresponding increase in the attenuation.Comment: 3 pages including 3 eps-figures. Accepted for Optics Letter

Price Volatility and Banking in Green Certificate Markets

There is concern that prices in a market for Green Certificates (GCs) primarily based on volatile wind power will fluctuate excessively, leading to corresponding volatility of electricity prices. Applying a rational expectations simulation model of competitive storage and speculation of GCs the paper shows that the introduction of banking of GCs may reduce price volatility considerably and lead to increased social surplus. Banking lowers average prices and is therefore not necessarily to the benefit of “green producers”. Proposed price bounds on GC-prices will reduce the importance of banking and even of the GC system itself.electricity; environment; commodity speculation; green certificates; marketable permits; uncertainty

Price Volatility and Banking in Green Certificate Markets

There is concern that prices in a market for Green Certificates (GCs) primarily based on volatile wind power will fluctuate excessively, leading to corresponding volatility of electricity prices. Applying a rational expectations simulation model of competitive storage and speculation of GCs the paper shows that the introduction of banking of GCs may reduce price volatility considerably and lead to increased social surplus. Banking lowers average prices and is therefore not necessarily to the benefit of “green producers”. Proposed price bounds on GC -prices will reduce the importance of banking and even of the GC system itself.Electricity; Green Certificates; Uncertainty; Commodity Speculation