The Linear Boltzmann Equation as the Low Density Limit of a Random Schrodinger Equation

We study the evolution of a quantum particle interacting with a random potential in the low density limit (Boltzmann-Grad). The phase space density of the quantum evolution defined through the Husimi function converges weakly to a linear Boltzmann equation with collision kernel given by the full quantum scattering cross section.Comment: 74 pages, 4 figures, (Final version -- typos corrected

La fuerza expresiva del deseo en Lan Yu de Stanley Kwan

El presente artículo analiza cómo la película Lan Yu, del director Stanley Kwan, retrata el surgimiento de la homosexualidad en la China contemporánea más allá de su legitimación en reconocidos términos identitarios occidentales: la afirmación de una población minoritaria existente pero poco reconocida; la defensa de la “perversión” sexual; la búsqueda por la libertad sexual, el reconocimiento legal y los derechos políticos; la justificación de un estilo de vida consumidor burgués, o incluso la expresión de un amor que universaliza y vincula a dos individuos abstractos. En contraste, en la película de Kwan la homosexualidad y su deseo expresivo marcan la aparición de un nuevo humanismo en la China (post)socialista bajo las sombras del capitalismo global y el desarrollo neoliberal. Así, al ayudar a situar a China en el lugar debido dentro de un mundo cosmopolita globalizado, los gays y las lesbianas actúan como precursores de una nueva modernidad. Desde esta perspectiva la homosexualidad funciona como una herramienta crítica para organizar y evaluar continuidades y rupturas históricas propias del pasado (semi)colonial chino, sus aspiraciones revolucionarias por una sociedad modernista, y sus actuales inversiones en el orden neoliberal del mundo capitalista.Stanley Kwan’s Lan Yu configures the emergence of homosexuality in contemporary China far beyond its validation in recognizably Western identitarian terms: the affirmation of an existing but misrecognized minority population; the defense of sexual “perversion”; the positing of sexual freedom, legal recognition, and political rights; the justification of a bourgeois consumer lifestyle, or even the expression of a universalizing and binding love bringing together two abstract individuals. Instead, in Kwan’s film, homosexuality and its expressive desire mark the emergence of a new humanism in (post)socialist China under the shadows of global capitalism and neoliberal development. Gays and lesbians, that is, are harbingers of a new modernity, helping to situate China in its proper place within a cosmopolitan globalized world. From this perspective, homosexuality functions as a critical tool for organizing and evaluating the historical continuities and ruptures among China’s (semi)colonial past, its revolutionary aspirations for a socialist modernity, and its present investments in a neoliberal capitalist world order.O presente artigo analisa a maneira como o filme Lan Yu, do diretor Stanley Kwan, retrata o surgimento da homossexualidade na China contemporânea além da sua legitimação em reconhecidos termos identitários ocidentais: a reafirmação de uma população minoritária existente, mas pouco reconhecida; a defesa da “perversão” sexual; a busca pela liberdade sexual, o reconhecimento legal e os direitos políticos; a justificativa por um estilo de vida consumidor burguês ou inclusive a expressão de um amor que universaliza e vincula dois indivíduos abstratos. Segundo o autor, contrário ao anterior, no filme de Kwan a homossexualidade e seu desejo expressivo marcam a aparição de um novo humanismo na China ‘pós-socialista’ sob as sombras do capitalismo global e do desenvolvimento neoliberal. Assim, ao ajudar a posicionar a China no lugar certo dentro de um mundo cosmopolita globalizado, os gays e as lésbica atuam como precursores de uma nova modernidade. A partir desta perspectiva, a homossexualidade opera como ferramenta crítica para organizar e avaliar continuidades e rupturas históricas próprias do passado semi-colonial chinês, suas aspirações revolucionárias por uma sociedade modernista e seus atuais investimentos na ordem neoliberal do mundo capitalista

Bringing Agriculture into the GATT: Designing Acceptable Agricultural Policies

Agricultural and Food Policy, International Relations/Trade,

Identification and assessment of markers of biotin status in healthy adults

Human biotin requirements are unknown and the identification of reliable markers of biotin status is necessary to fill this knowledge gap. Here, we used an outpatient feeding protocol to create states of biotin deficiency, sufficiency and supplementation in sixteen healthy men and women. A total of twenty possible markers of biotin status were assessed, including the abundance of biotinylated carboxylases in lymphocytes, the expression of genes from biotin metabolism and the urinary excretion of biotin and organic acids. Only the abundance of biotinylated 3-methylcrotonyl-CoA carboxylase (holo-MCC) and propionyl-CoA carboxylase (holo-PCC) allowed for distinguishing biotin-deficient and biotin-sufficient individuals. The urinary excretion of biotin reliably identified biotin-supplemented subjects, but did not distinguish between biotin-depleted and biotin-sufficient individuals. The urinary excretion of 3-hydroxyisovaleric acid detected some biotin-deficient subjects, but produced a meaningful number of false-negative results and did not distinguish between biotin-sufficient and biotin-supplemented individuals. None of the other organic acids that were tested were useful markers of biotin status. Likewise, the abundance of mRNA coding for biotin transporters, holocarboxylase synthetase and biotin-dependent carboxylases in lymphocytes were not different among the treatment groups. Generally, datasets were characterised by variations that exceeded those seen in studies in cell cultures. We conclude that holo-MCC and holo-PCC are the most reliable, single markers of biotin status tested in the present study

A Tandem Mass Spectrometry Sequence Database Search Method for Identification of O-Fucosylated Proteins by Mass Spectrometry.

Thrombospondin type 1 repeats (TSRs), small adhesive protein domains with a wide range of functions, are usually modified with O-linked fucose, which may be extended to O-fucose-β1,3-glucose. Collision-induced dissociation (CID) spectra of O-fucosylated peptides cannot be sequenced by standard tandem mass spectrometry (MS/MS) sequence database search engines because O-linked glycans are highly labile in the gas phase and are effectively absent from the CID peptide fragment spectra, resulting in a large mass error. Electron transfer dissociation (ETD) preserves O-linked glycans on peptide fragments, but only a subset of tryptic peptides with low m/ z can be reliably sequenced from ETD spectra compared to CID. Accordingly, studies to date that have used MS to identify O-fucosylated TSRs have required manual interpretation of CID mass spectra even when ETD was also employed. In order to facilitate high-throughput, automatic identification of O-fucosylated peptides from CID spectra, we re-engineered the MS/MS sequence database search engine Comet and the MS data analysis suite Trans-Proteomic Pipeline to enable automated sequencing of peptides exhibiting the neutral losses characteristic of labile O-linked glycans. We used our approach to reanalyze published proteomics data from Plasmodium parasites and identified multiple glycoforms of TSR-containing proteins

Dynamic control of neurochemical release with ultrasonically-sensitive nanoshell-tethered liposomes

The unique surface plasmon resonance of hollow gold nanoshells can be used to achieve drug release from liposomes upon laser stimulation, and adapted to mimic the intricate dynamics of neurotransmission ex vivo in brain preparations. However, to induce a physiological response in vivo requires the degree of temporal precision afforded by laser stimulation, but with a greater depth of penetration through tissue. Here we report that the attachment of hollow gold nanoshells to the surface of robust liposomes results in a construct that is highly sensitive to ultrasonic stimulation. The resulting construct can be remotely triggered by low intensity, therapeutic ultrasound. To our knowledge, this is the first example of nanoparticle-liposome system that can be activated by both laser and acoustic stimulation. The system is capable of encapsulating the neurochemical dopamine, and repeatedly releasing small amounts on-demand in a circulating environment, allowing for precise spatiotemporal control over the release profile

Spatial aberrations in high-order harmonic generation

We investigate the spatial characteristics of high-order harmonic radiation generated in argon, and observe cross-like patterns in the far field. An analytical model describing harmonics from an astigmatic driving beam reveals that these patterns result from the order and generation position dependent divergence of harmonics. Even small amounts of driving field astigmatism may result in cross-like patterns, coming from the superposition of individual harmonics with spatial profiles elongated in different directions. By correcting the aberrations using a deformable mirror, we show that fine-tuning the driving wavefront is essential for optimal spatial quality of the harmonics