Comment on ``Stripes and the t-J Model''

This is a comment being submitted to Physical Review Letters on a recent letter by Hellberg and Manousakis on stripes in the t-J model.Comment: One reference correcte

Political communications in the USSR: letters to party, state and press

The letters sent by Soviet citizens to party and state bodies and to the press have been relatively little studied in the West, although the Soviet authorities themselves have been devoting increasing attention to this ‘link with the masses’ since at least the late 1960s. An examination of the extent and nature of such communications shows that their total number has increased significantly since the 1950s, and that more constructive and general proposals have been increasing at the expense of particular individual grievances, although this change is less apparent at the local level. Critics are sometimes victimized and frequently ignored, but the evidence suggests that a considerable groundswell of opinion as reflected in letters can have some influence upon public policy and that particular cases of maladministration or abuse of position can be relatively readily corrected in this way

The Effects of a Rapidly-Fluctuating Random Environment on Systems of Interacting Species

Some models of interacting species in a random environment are analyzed. Approximate solutions of the stochastic differential or delay-differential equations describing the systems are obtained, on the assumption that the random environment is fluctuating rapidly

Looking Back at Five Eras: The Mott Foundation's First 75 Years

Summarizes five distinct eras in the foundation's first 75 years, and takes a look forward to continuing the practice of building long-term relationships and partnering with community groups in order to enable philanthropy at the local level

Spin Gaps in a Frustrated Heisenberg model for CaV4_4O9_9

I report results of a density matrix renormalization group (DMRG) study of a model for the two dimensional spin-gapped system CaV$_4$O$_9$. This study represents the first time that DMRG has been used to study a two dimensional system on large lattices, in this case as large as $24\times 11$, allowing extrapolation to the thermodynamic limit. I present a substantial improvement to the DMRG algorithms which makes these calculations feasible.Comment: 10 pages, with 4 Postscript figure

Checkerboard patterns in the t-J model

Using the density matrix renormalization group, we study the possibility of real space checkerboard patterns arising as the ground states of the t-J model. We find that checkerboards with a commensurate (pi,pi) background are not low energy states and can only be stabilized with large external potentials. However, we find that striped states with charge density waves along the stripes can form approximate checkerboard patterns. These states can be stabilized with a very weak external field aligning and pinning the CDWs on different stripes.Comment: 4 pages, 5 figure

Unique case of inverted papilloma of septum with nasopharyngeal carcinoma:Is it a metachronous tumour?

Inverted papilloma is a rare and benign tumour. It affects the nasal cavity and paranasal sinuses, has a high rate of recurrence and is associated with malignant transformation. Only few cases of a poorly differentiated carcinoma arising from inverted papilloma have been reported, none of which in the nasopharynx. We report a case of a 37-year-old female, who presented originally in 2012 with inverted papilloma of the nasal septum which was surgically resected. Nasopharyngeal biopsy from 2014 was reported as carcinoma in situ and treated with local endoscopic resection. Three years later she presented with a solitary lesion of the right Eustachian tube opening, confirmed as invasive poorly differentiated carcinoma. Imaging revealed T4 N2b M0 malignancy with skull base and prevertebral space invasion, likely extension into right temporal lobe and malignant adenopathy. Although rare, malignant transformation of inverted papilloma in unusual places should be considered during workup and monitoring of patients

Russia and its neighbours: East or West?

As ‘Europe’ becomes more diverse, the countries that were formerly part of the USSR face new choices. One of the most fundamental is whether they identify with the economic and military institutions of the ‘West’, such as NATO and the European Union, or with the Commonwealth of Independent States and other forms of association with the Slavic ‘East’. We examine these choices in each of three societies—Belarus, Russia and Ukraine—on the basis of national surveys conducted between 2000 and 2008. Across the three, ‘Eastern’ orientations have more popular support than ‘Western’ ones, but Ukrainian opinion is more sharply polarised than opinion in the other two countries. There is more support for a ‘Slavic choice’ in Russia than in either of the other two countries, and particularly large numbers there who regret the demise of the USSR; but opinion on such matters is moderate rather than fundamentalist and does not necessarily exclude a closer relationship with the European Union and NATO