One-loop Evolution of a Rolling Tachyon

We study the time evolution of the one-loop diagram in Sen's rolling tachyon background. We find that at least in the long cylinder case they grow rapidly at late time, due to the exponential growth of the timelike oscillator terms in the boundary state. This can also be interpreted as the virtual open string pair creation in the decaying brane. This behavior indicates a breakdown of this rolling tachyon solution at some point during the evolution. We also discuss the closed string emission from this one-loop diagram, and the evolution of a one-loop diagram connecting a decaying brane to a stable brane, which is responsible for the physical open string creation on the stable brane.Comment: 21 pages, 2 figures; v2: references added, comments revised in various places; v3: footnotes 7&8 added, revised version to appear in PR

Winding Strings and Decay of D-Branes with Flux

We study the boundary state associated with the decay of an unstable D-brane with uniform electric field, 1>e>0 in the string units. Compactifying the D-brane along the direction of the electric field, we find that the decay process is dominated by production of closed strings with some winding numbers; closed strings produced are such that the winding mode carries precisely the fraction $e$ of the individual string energy. This supports the conjecture that the final state at tree level is composed of winding strings with heavy oscillations turned on. As a corollary, we argue that the closed strings disperse into spacetime at a much slower rate than the case without electric field.Comment: 14 pages, harvmac, minor changes, clarified gauge choice, version to appear in JHE

Are ‘advanced’ Japanese language programs sustainable? A look at Australia, New Zealand and Singapore

Economic, strategic and cultural connections to Japan have never been stronger and more students across the breadth of our education system, primary through to tertiary, continue to be interested in studying Japanese. But what, beyond Demon Slayer and Pokemon, motivates them and how can that knowledge help universities to build effective and engaging language programs? Japanese is one of the most popular Asian languages taught at tertiary institutions around the world. According to the Survey Report on Japanese-language Education Abroad 2018 (Japan Foundation, 2020), the number of learners outside Japan reached 3,851,774, the second highest on record, and the number of institutions and teachers was the highest since the Foundation’s 1979 survey. Despite the COVID-19 pandemic, enrolment in Japanese language subjects has remained relatively strong, even in 2021. Oceania (the majority from Australia and New Zealand) has the highest number of learners per 100,000 population globally. However, as the authors of this article, we have become increasingly concerned about the sustainability of advanced Japanese language programs in our region—specifically Australia, New Zealand and Singapore. Language education policies (at the governmental and institutional level) and diminishing investment into language education in the higher education sector have put many Japanese Studies/language programs under strain. Advanced-level subjects generally have lower enrolment numbers than beginner- and intermediate-level subjects, and so are most at risk of being merged, cut back or dropped altogether. According to the US Foreign Services Institute (FSI), Japanese is considered to be one of the ‘super-hard languages’ that require English native speakers three times as long as French or Italian to attain ‘professional working proficiency’. This means that without students’ long-term commitment (retention to advanced levels) and well supported, quality education, there can be no sustainable future for Japanese language programs producing highly advanced users of Japanese in those nations. Against this backdrop, we recently launched the Network for Teaching Advanced Japanese Project (上級日本語Network), supported by a Japan Foundation Sakura Mini Grant 2020. This project provides a platform to collect data through surveys and interviews to better understand the current state of advanced Japanese language programs at university level in Australia, New Zealand and Singapore, and advocate for communities of practice and ongoing support across the sector. This collaboration involves countries that are members of the Commonwealth. Not only are their universities’ medium of instruction English, but they also share similar program structures. The Network for Teaching Advanced Japanese Project approached colleagues from universities in Australia, New Zealand and Singapore in 2020, gathering data on Japanese language programs at 25 institutions in total (Australia 19, New Zealand four, Singapore two). In total, 76 participants responded to the survey and among those respondents, 38 teachers (34 from Australia, two from New Zeland and two from Singapore) participated in online interviews between December 2020 and January 2021. Our survey results show that the ‘advanced’ level was broadly defined by: the stage of progression at the institution, a proficiency level equivalent to external criteria such as the Japanese Language Proficiency Test or the Common European Framework of Reference for Languages; and the demonstration of specific skills through engagement with types of learning activities or resources (eg progression through language textbooks). What emerged from this is that there is a disparity in what is categorised as constituting the ‘advanced level’ within different institutional frameworks. Although this may seem merely a comparison with European languages these definitions have significant impact on institutional support for Japanese language. If institutions only support languages through to what we as teachers define as intermediate then it becomes harder for us to graduate advanced users of Japanese. We found that there are subjects with similar content and resources (for example the same textbook) that are called ‘advanced’ by some universities and ‘intermediate’ by others. It is common practice that in a three-year university degree program, students who start as beginners can progress to an ‘advanced’ level in their final year of study, but in many cases, realistically speaking, this ‘advanced’ level of study is nevertheless perceived as an ‘intermediate’ level of language acquisition by tertiary teachers of Japanese. The majority of students from the institutions we surveyed usually have three to four hours of class per week (five to six hours at most) during the semester or term. This gives them an average of around 100 class hours per year, and a total of around 300 over their three-year university degree program. It is clear this is insufficient when compared with 2,200 class hours deemed necessary to reach ‘professional working proficiency’ for Japanese in the aforementioned FSI estimate (for French and Spanish 600-700 and for German 900 class hours). It should be noted that ‘class hours’ here may assume that language learning does not occur beyond the classroom. Thus, the need to take account of the fact that tertiary students in Australia, New Zealand and Singapore increasingly engage in language learning outside the classroom, for example doing online tasks as part of a blended-learning curriculum, watching Japanese dramas or participating in in-country studies. Our project also found that there is a tendency for the teaching of Asian languages to be adapted to the framework used in the teaching of European languages. It is for example, common practice for universities to offer Levels 1 – 6 in each language with Levels 5 – 6 defined as ‘advanced’. This ignores the fact that students progress differently in different languages. The proficiency level reached by students in Japanese language programs at the official ‘advanced’ level may well be behind those in European language programs. All three countries involved in this project—Australia, New Zealand and Singapore—operate in an English-speaking context associated with the UK tradition of language education which may explain why European languages (which share the Roman alphabet based writing system with English) tend to be privileged in the institutional frameworks. There has been enthusiastic promotion of Asian language education (including Japanese) by the Australian and New Zealand governments since late 1990s, and the ongoing social commitment to multiculturalism. Australia, for example, has released several strategic plans such as the National Asian Language Studies in Australian Schools Strategy (NALSAS, 1995-2002) and recommendations on Asian language studies in the Australia in the Asian Century White Paper (2012). The New Zealand government implemented the Asian Language Learning in Schools (ALLiS) program in 2014, and have committed to a total of $10 million over five years, aiming to support schools by setting up new Asian language learning programs, or strengthening existing ones. In Singapore, mainly in response to industrial demand, the Ministry of Education established their Foreign Language Centre in 1978 to offer couses of French, German and Japanese for secondary school students (the Centre expanded to Ministry of Education Language Centre to offer language couses in wider age groups). Universities and polytechnics in Singapore also established Japanese language programs from the1980s. The development of Asian literacy can be better supported with a less Eurocentric and less English-monolingual mindset. A recent report (May 30, 2021) on the current state of school language programs and assessment in the Australian state of New South Wales suggests European languages such as French are advantaged over Japanese and Arabic, pointing to just such a bias. Further, the dominance of English in the global arena is creating a societal apathy for learning languages other than English. Despite acknowledgement that languages provide a key pathway to fostering ‘generalised national multilingualism, social harmony, and economic prosperity’ as noted by scholars Shannon Mason and John Hajek, representations of language education in the media can often exacerbate the precarious position of language education in Australia by presenting only superficial, narrow and negative editorial debate

Bosonic D-brane Effective Action in Linear Dilaton Background

In this paper we will study tachyon effective action for Dp-brane in bosonic string theory in the linear dilaton background. We obtain the tachyon effective Lagrangian from boundary state coeficient of Dp-brane in the linear dilaton background and compare it with tachyon effective Lagrangians that were proposed in previous papers.Comment: 16 pages, Typos correcte

Note on D-Brane Effective Action in the Linear Dilaton Background

In this short note we will study effective action for unstable D-brane in linear dilaton background. We will solve the equation of motion for large T and we will calculate the stress energy tensor. Then we compare our results with the calculations performed using exact conformal field theory description of the open string worldsheet theory.Comment: 12 page

The Final Fate of the Rolling Tachyon

We propose an alternative interpretation of the boundary state for the rolling tachyon, which may depict the time evolution of unstable D-branes in string theory. Splitting the string variable in the temporal direction into the classical part, which we may call "time" and the quantum one, we observe the time dependent behaviour of the boundary. Using the fermion representation of the rolling tachyon boundary state, we show that the boundary state correctly describes the time-dependent decay process of the unstable D-brane into a S-brane at the classical level.Comment: 9 pages, revte

On the origin of thermal string gas

We investigate decaying D-branes as the origin of the thermal string gas of string gas cosmology. We consider initial configurations of low-dimensional branes and argue that they can time evolve to thermal string gas. We find that there is a range in the weak string coupling and fast brane decay time regimes, where the initial configuration could drive the evolution of the dilaton to values, where exactly three spacelike directions grow large.Comment: 16 pages, 4 figures, v2: references adde

Patient acceptance of universal screening for hepatitis C virus infection

<p>Abstract</p> <p>Background</p> <p>In the United States, about 70% of 2.9-3.7 million people with hepatitis C (HCV) are unaware of their infection. Although universal screening might be a cost-effective way to identify infections, prevent morbidity, and reduce transmission, few efforts have been made to determine patient opinions about new approaches to screening.</p> <p>Methods</p> <p>We surveyed 200 patients in August 2010 at five outpatient clinics of a major public urban medical center in Seattle, WA, with an 85.8% response rate.</p> <p>Results</p> <p>The sample was 55.3% women, median 47 years of age, and 56.3% white and 32.7% African or African-American; 9.5% and 2.5% reported testing positive for HCV and HIV, respectively. The vast majority of patients supported universal screening for HCV. When presented with three options for screening, 48% preferred universal testing without being informed that they were being tested or provided with negative results, 37% preferred testing with the chance to "opt-out" of being tested and without being provided with negative results, and 15% preferred testing based on clinician judgment. Results were similar for HIV screening.</p> <p>Conclusions</p> <p>Patients support universal screening for HCV, even if that screening involves testing without prior consent or the routine provision of negative test results. Current screening guidelines and procedures should be reconsidered in light of patient priorities.</p

Continuous pellet fueling experiments on D-III

A centrifuge pellet injector developed at ORNL was used to continuously fuel beam-heated limiter discharges in D-III. This injector was capable of producing and maintaining a high density neutral beam-heated plasma without auxilary gas fueling. Viewgraphs from the presentation are included