Marco Polo: from Hangzhou to Quanzhou

When Marco Polo left China, he passed through Hangzhou (Quinsai) and then travelled approximately southwestwards into what is today Fujian province, to the cities of Fuzhou and Quanzhou (Zaiton). There are still a number of disagreements regarding his route, however, which are discussed here. Consideration is also given to Marco’s use of “Facfur” to designate the last Emperor of the Song dynasty, and more generally to the issue of the use of Persian language in Yuan China. It is suggested that there is no clear evidence that Marco Polo learned Persian. An error regarding consumption of pepper in China during the thirteenth century is corrected. More evidence of the importation of very substantial quantities of pepper into China during the Song and Yuan periods is adduced. Identifications of all the places which Marco mentions in this section of his book are suggested, with the support of evidence

Storax, Benzoin, and the Chinese Anxi xiang

The Chinese term Anxi xiang 安息香 is now usually applied to benzoin, an aromatic resin obtained from species of the genus Styrax native to Southeast Asia. However, it appears from Chinese records that this aromatic originally was imported into China from western Asia. What this early Anxi xiang was has never been ascertained. It is here suggested that, like benzoin, it was produced from a species of Styrax, and was the storax of the ancient Mediterranean region. A complication is that storax was obtained from more than one plant source. Another issue is that a different substance, known to the Chinese as suhe 蘇合, has often been identified with storax. The available evidence is assessed and probable solutions are proposed

Determination of the phase diagram of the electron doped superconductor Ba(Fe1−x_{1-x}Cox_x)2_2As2_2

Systematic measurements of the resistivity, heat capacity, susceptibility and Hall coefficient are presented for single crystal samples of the electron-doped superconductor Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$. These data delineate an $x-T$ phase diagram in which the single magnetic/structural phase transition that is observed for undoped BaFe$_2$As$_2$ at 134 K apparently splits into two distinct phase transitions, both of which are rapidly suppressed with increasing Co concentration. Superconductivity emerges for Co concentrations above $x \sim 0.025$, and appears to coexist with the broken symmetry state for an appreciable range of doping, up to $x \sim 0.06$. The optimal superconducting transition temperature appears to coincide with the Co concentration at which the magnetic/structural phase transitions are totally suppressed, at least within the resolution provided by the finite step size between crystals prepared with different doping levels. Superconductivity is observed for a further range of Co concentrations, before being completely suppressed for $x \sim 0.018$ and above. The form of this $x-T$ phase diagram is suggestive of an association between superconductivity and a quantum critical point arising from suppression of the magnetic and/or structural phase transitions

Smoke-free legislation and hospitalizations for childhood asthma

<b>BACKGROUND:</b> Previous studies have shown that after the adoption of comprehensive smoke-free legislation, there is a reduction in respiratory symptoms among workers in bars. However, it is not known whether respiratory disease is also reduced among people who do not have occupational exposure to environmental tobacco smoke. The aim of our study was to determine whether the ban on smoking in public places in Scotland, which was initiated in March 2006, influenced the rate of hospital admissions for childhood asthma.<br></br> <b>METHODS:</b> Routine hospital administrative data were used to identify all hospital admissions for asthma in Scotland from January 2000 through October 2009 among children younger than 15 years of age. A negative binomial regression model was fitted, with adjustment for age group, sex, quintile of socioeconomic status, urban or rural residence, month, and year. Tests for interactions were also performed. <br></br> <b>RESULTS:</b> Before the legislation was implemented, admissions for asthma were increasing at a mean rate of 5.2% per year (95% confidence interval [CI], 3.9 to 6.6). After implementation of the legislation, there was a mean reduction in the rate of admissions of 18.2% per year relative to the rate on March 26, 2006 (95% CI, 14.7 to 21.8; P<0.001). The reduction was apparent among both preschool and school-age children. There were no significant interactions between hospital admissions for asthma and age group, sex, urban or rural residence, region, or quintile of socioeconomic status. <b>CONCLUSIONS:</b> In Scotland, passage of smoke-free legislation in 2006 was associated with a subsequent reduction in the rate of respiratory disease in populations other than those with occupational exposure to environmental tobacco smoke. (Funded by NHS Health Scotland.

Jamming, two-fluid behaviour and 'self-filtration' in concentrated particulate suspensions

We study the flow of model experimental hard sphere colloidal suspensions at high volume fraction $\Phi$ driven through a constriction by a pressure gradient. Above a particle-size dependent limit $\Phi_0$, direct microscopic observations demonstrate jamming and unjamming--conversion of fluid to solid and vice versa--during flow. We show that such a jamming flow produces a reduction in colloid concentration $\Phi_{x}$ downstream of the constriction. We propose that this `self-filtration' effect is the consequence of a combination of jamming of the particulate part of the system and continuing flow of the liquid part, i.e. the solvent, through the pores of the jammed solid. Thus we link the concept of jamming in colloidal and granular media with a 'two-fluid'-like picture of the flow of concentrated suspensions. Results are also discussed in the light of Osborne Reynolds' original experiments on dilation in granular materials.Comment: 4 pages, 3 figure

Pinpointing Gap Minima in Ba(Fe0.94_{0.94}Co0.06)2_{0.06})_{2}As2_2 \textit{via} Band Structure Calculations and Electronic Raman Scattering

A detailed knowledge of the gap structure for the Fe-pnictide superconductors is still rather rudimentary, with several conflicting reports of either nodes, deep gap minima, or fully isotropic gaps on the Fermi surface sheets, both in the $k_{x}-k_{y}$ plane and along the c-axis. In this paper we present considerations for electronic Raman scattering which can help clarify the gap structure and topology using different light scattering geometries. Using density functional calculations for the Raman vertices, it is shown that the location of the gap minima may occur on loops stretching over a portion of the c-axis in Ba(Fe$_{0.94}$Co$_{0.06})_{2}$As$_2$.Comment: 4+ pages, three figure

Bulk Fermi surface coexistence with Dirac surface state in Bi2_2Se3_3: a comparison of photoemission and Shubnikov-de Haas measurements

Shubnikov de Haas (SdH) oscillations and Angle Resolved PhotoEmission Spectroscopy (ARPES) are used to probe the Fermi surface of single crystals of Bi2Se3. We find that SdH and ARPES probes quantitatively agree on measurements of the effective mass and bulk band dispersion. In high carrier density samples, the two probes also agree in the exact position of the Fermi level EF, but for lower carrier density samples discrepancies emerge in the position of EF. In particular, SdH reveals a bulk three-dimensional Fermi surface for samples with carrier densities as low as 10^17cm-3. We suggest a simple mechanism to explain these differences and discuss consequences for existing and future transport studies of topological insulators.Comment: 5 mages, 5 figure

Band and momentum dependent electron dynamics in superconducting Ba(Fe1−xCox)2As2{\rm Ba(Fe_{1-x}Co_{x})_2As_2} as seen via electronic Raman scattering

We present details of carrier properties in high quality ${\rm Ba(Fe_{1-x}Co_{x})_2As_2}$ single crystals obtained from electronic Raman scattering. The experiments indicate a strong band and momentum anisotropy of the electron dynamics above and below the superconducting transition highlighting the importance of complex band-dependent interactions. The presence of low energy spectral weight deep in the superconducting state suggests a gap with accidental nodes which may be lifted by doping and/or impurity scattering. When combined with other measurements, our observation of band and momentum dependent carrier dynamics indicate that the iron arsenides may have several competing superconducting ground states.Comment: 5 pages, 4 figure