In defence of amateurism:on not professionalizing ethnic and racial studies

This piece suggests that the field of ethnic and racial studies is too diverse in theoretical and methodological approach and subject of study to constitute its own discipline. Instead, ethnic and racial studies remains a loosely defined space of interdisciplinary exchange. There is a sense of community among researchers in this field, but teaching continues to be organized to meet the imperatives of different home disciplines. This article argues that in these times of increasing bureaucracy, standardization and managerial intrusion into academic life, there is a positive benefit in retaining a relatively open space of inquiry where we can consider the construction of contemporary social boundaries.

Freezing process optimisation of pharmaceutical formulations for freeze drying

The body of work presented in this thesis are in three main parts: [1] the effect of ultrasound on freezing events of ionic systems, [2] the importance of formulation osmolality in freeze drying, and [3] a novel system for increasing primary freeze drying rate. Chapter 4 briefly presents the work on method optimisation, which is still very much in its infancy. Aspects of freezing such as nucleation and ice crystal growth are strongly related with ice crystal morphology; however, the ice nucleation process typically occurs in a random, non-deterministic and spontaneous manner. In view of this, ultrasound, an emerging application in pharmaceutical sciences, has been applied to aid in the acceleration of nucleation and shorten the freezing process. The research presented in this thesis aimed to study the effect of sonication on nucleation events in ionic solutions, and more importantly how sonication impacts on the freezing process. This work confirmed that nucleation does occur in a random manner. It also showed that ultrasonication aids acceleration of the ice nucleation process and increases the freezing rate of a solution. Cryopreservation of animal sperm is an important aspect of breeding in animal science especially for endangered species. In order for sperm cryopreservation to be successful, cryoprotectants as well as semen extenders are used. One of the factors allowing semen preservation media to be optimum is the osmolality of the semen extenders used. Although preservation of animal sperm has no relation with freeze drying of pharmaceuticals, it was used in this thesis to make a case for considering the osmolality of a formulation (prepared for freeze drying) as a factor for conferring protein protection against the stresses of freeze drying. The osmolalities of some common solutes (mostly sugars) used in freeze drying were determined (molal concentration from 0.1m to 1.2m). Preliminary investigation on the osmolality and osmotic coefficients of common solutes were carried out. It was observed that the osmotic coefficient trend for the sugars analysed could be grouped based on the types of sugar they are. The trends observed show the need for further studies to be carried out with osmolality and to determine how it may be of importance to protein or API protection during freeze drying processes. Primary drying is usually the longest part of the freeze drying process, and primary drying times lasting days or even weeks are not uncommon; however, longer primary drying times lead to longer freeze drying cycles, and consequently increased production costs. Much work has been done previously by others using different processes (such as annealing) in order to improve primary drying times; however, these do not come without drawbacks. A novel system involving the formation of a frozen vial system which results in the creation of a void between the formulation and the inside wall of a vial has been devised to increase the primary freeze drying rate of formulations without product damage. Although the work is not nearly complete, it has been shown that it is possible to improve and increase the primary drying rate of formulations without making any modifications to existing formulations, changing storage vials, or increasing the surface area of freeze dryer shelves.

Secret key exchange in ultra-long lasers by radio-frequency spectrum coding

We propose a new approach to the generation of an alphabet for secret key exchange relying on small variations in the cavity length of an ultra-long fiber laser. This new concept is supported by experimental results showing how the radio-frequency spectrum of the laser can be exploited as a carrier to exchange information. The test bench for our proof of principle is a 50 km-long fiber laser linking two users, Alice and Bob, where each user can randomly add an extra 1 km-long segment of fiber. The choice of laser length is driven by two independent random binary values, which makes such length become itself a random variable. The security of key exchange is ensured whenever the two independent random choices lead to the same laser length and, hence, to the same free spectral range.

Short-horizon excess returns and exchange rate and interest rate effects

stocks. We examine the effects of foreign exchange (FX) and interest rate changes on the excess returns of U.S. stocks, for short-horizons of 1-40 days. Our new evidence shows a tendency for the volatility of both excess returns and FX rate changes to be negatively related with FX rate and interest rate effects. Both the number of firms with significant FX rate and interest rate effects and the magnitude of their exposures increase with the length of the return horizon. Our finding seems inconsistent with the view that firms hedge effectively at short-return horizons.

Synergistic synthesis of quasi-monocrystal CdS nanoboxes with high-energy facets

Hollow nanostructures with a highly oriented lattice structure and active facets are promising for catalytic applications, while their preparation via traditional approaches contains multiple steps and is time and energy consuming. Here, we demonstrate a new one-step strategy involving two complementary reactions which promote each other; it is capable of producing unique hollow nanoparticles. Specifically, we apply synergic cooperation of cation exchange and chemical etching to attack PbS nanosized cubes (NCs) and produce CdS quasi-monocrystal nanoboxes (QMNBs) which possess the smallest dimensions reported so far, a metastable zinc-blende phase, a large specific surface area, and particularly high-energy {100} facets directly visualized by aberration-corrected scanning transmission electron microscopy. These properties in combination allow the nanoboxes to acquire exceptional photocatalytic activities. As an extension of the approach, we use the same strategy to prepare Co9S8 and Cu7.2S4 single-crystal hollow nanooctahedrons (SCHNOs) successfully. Hence, the synergic reaction synthesis strategy exhibits great potential in engineering unique nanostructures with superior properties.

Resonance properties of domain boundaries in quasi-two dimensional antiferromagnets

The so-called "internal modes" localized near the domain boundaries in quasi-two dimensional antiferromagnets are investigated. The possible localized states are classified and their frequency dependences on the system discreteness parameter λ=J/β, which describes the ratio of the magnitudes of the exchange interplane interaction and the magnetic anisotropy, are found. A sudden change in the spectrum of the local internal modes is observed at a critical value of this parameter, λ=λb=3/4, where the domain wall shifts from a collinear to a canted shape. When λ<λb there are one symmetric and two antisymmetric local modes, and when λ>λb the modes are two symmetric, one antisymmetric, and one shear. For discreteness parameters close to the critical value, the frequencies of some of the local modes lie deep inside the gap for the linear AFM magnon spectrum and can be observed experimentally. © 2010 American Institute of Physics.