Matter-wave interferometry in a double well on an atom chip

Matter-wave interference experiments enable us to study matter at its most basic, quantum level and form the basis of high-precision sensors for applications such as inertial and gravitational field sensing. Success in both of these pursuits requires the development of atom-optical elements that can manipulate matter waves at the same time as preserving their coherence and phase. Here, we present an integrated interferometer based on a simple, coherent matter-wave beam splitter constructed on an atom chip. Through the use of radio-frequency-induced adiabatic double-well potentials, we demonstrate the splitting of Bose-Einstein condensates into two clouds separated by distances ranging from 3 to 80 microns, enabling access to both tunnelling and isolated regimes. Moreover, by analysing the interference patterns formed by combining two clouds of ultracold atoms originating from a single condensate, we measure the deterministic phase evolution throughout the splitting process. We show that we can control the relative phase between the two fully separated samples and that our beam splitter is phase-preserving

Non-equilibrium coherence dynamics in one-dimensional Bose gases

Low-dimensional systems are beautiful examples of many-body quantum physics. For one-dimensional systems the Luttinger liquid approach provides insight into universal properties. Much is known of the equilibrium state, both in the weakly and strongly interacting regime. However, it remains a challenge to probe the dynamics by which this equilibrium state is reached. Here we present a direct experimental study of the coherence dynamics in both isolated and coupled degenerate 1d Bose gases. Dynamic splitting is used to create two 1d systems in a phase coherent state. The time evolution of the coherence is revealed in local phase shifts of the subsequently observed interference patterns. Completely isolated 1d Bose gases are observed to exhibit a universal sub-exponential coherence decay in excellent agreement with recent predictions by Burkov et al. [Phys. Rev. Lett. 98, 200404 (2007)]. For two coupled 1d Bose gases the coherence factor is observed to approach a non-zero equilibrium value as predicted by a Bogoliubov approach. This coupled-system decay to finite coherence is the matter wave equivalent of phase locking two lasers by injection. The non-equilibrium dynamics of superfluids plays an important role in a wide range of physical systems, such as superconductors, quantum-Hall systems, superfluid Helium, and spin systems. Our experiments studying coherence dynamics show that 1d Bose gases are ideally suited for investigating this class of phenomena.Comment: to appear in natur

Tracking Invasion Histories in the Sea: Facing Complex Scenarios Using Multilocus Data

In recent years, new analytical tools have allowed researchers to extract historical information contained in molecular data, which has fundamentally transformed our understanding of processes ruling biological invasions. However, the use of these new analytical tools has been largely restricted to studies of terrestrial organisms despite the growing recognition that the sea contains ecosystems that are amongst the most heavily affected by biological invasions, and that marine invasion histories are often remarkably complex. Here, we studied the routes of invasion and colonisation histories of an invasive marine invertebrate Microcosmus squamiger (Ascidiacea) using microsatellite loci, mitochondrial DNA sequence data and 11 worldwide populations. Discriminant analysis of principal components, clustering methods and approximate Bayesian computation (ABC) methods showed that the most likely source of the introduced populations was a single admixture event that involved populations from two genetically differentiated ancestral regions - the western and eastern coasts of Australia. The ABC analyses revealed that colonisation of the introduced range of M. squamiger consisted of a series of non-independent introductions along the coastlines of Africa, North America and Europe. Furthermore, we inferred that the sequence of colonisation across continents was in line with historical taxonomic records - first the Mediterranean Sea and South Africa from an unsampled ancestral population, followed by sequential introductions in California and, more recently, the NE Atlantic Ocean. We revealed the most likely invasion history for world populations of M. squamiger, which is broadly characterized by the presence of multiple ancestral sources and non-independent introductions within the introduced range. The results presented here illustrate the complexity of marine invasion routes and identify a cause-effect relationship between human-mediated transport and the success of widespread marine non-indigenous species, which benefit from stepping-stone invasions and admixture processes involving different sources for the spread and expansion of their range

Body Mass Index can Similarly Predict the Presence of Multiple Cardiovascular Risk Factors in Middle-aged Japanese Subjects as Waist Circumference

ObjectiveAdiposity is closely associated with the clustering of metabolic risk factors such as high bloodpressure, dyslipidemia, and glucose intolerance. Waist circumference and body mass index (BMI) are the es-tablished markers of abdominal adiposity and general adiposity, respectively. However, it has not been exam-ined whether these two markers can detect the clustering of metabolic risk factors in Japanese subjects.Methods and ResultsWe studied 5,796 Japanese middle-aged subjects aged 40-60 years (4,344 males and1,452 females). Metabolic risk factors including highblood pressure, dyslipidemia, and glucose intolerancewere identified according to the diagnostic criteria for metabolic syndrome in Japan. The number of meta-bolic risk factors was significantly associated withthe BMI values in both male and female subjects. Theprevalence of subjects with multiple (two or more) metabolic risk factors was 29.4% and 7.6% in males andfemales, respectively. According to receiver operating characteristic (ROC) analysis, the area under curve val-ues of BMI and waist circumference did not differ in male (0.658 vs. 0.671, p=n.s.) and female (0.776 vs.0.790, p=n.s.) subjects, indicating that the waist circumference as well as the BMI could be useful in detect-ing the occurrence of multiple metabolic risk factors. The appropriate cut-off values of BMI to predict thepresence of multiple metabolic risk factors were 24.7 and 23.4 kg/m2in males and females, respectively. Thesensitivity and specificity using these cut-off values were 58 and 65% in males and 65 and 77% in females,respectively.ConclusionThe BMI values can similarly predict the presence of multiple metabolic risk factors just as thewaist circumference in Japanese middle-aged subjects

Colorectal Cancer Screening: What Do Women From Diverse Ethnic Groups Want?

BACKGROUND: Little is known about factors associated with willingness to undergo colorectal cancer (CRC) screening for personal or public health benefit among women from diverse race/ethnic groups. OBJECTIVE: To evaluate factors associated with willingness to undergo CRC screening for personal and public health benefit among women from diverse race/ethnic groups. METHODS: We interviewed women aged 50 to 80 from four racial/ethnic groups from primary care clinics in 2003–2005. We asked about demographics, CRC screening knowledge and history, perceived risk of colon cancer, and about the outcomes of intention to be screened for personal benefit and for public health benefit. RESULTS: Of the 492 women who completed the interview, 32 % were White, 16 % were African American, 21 % were Latina and 32 % were Asian. Up-to-date screening was reported by 77 % of women, with similar numbers obtaining fecal occult blood test (FOBT) within 2 years or colonoscopy within 10 years. The majority of women were “likely or very likely” to get FOBT or colonoscopy after learning the benefits and risks. Multivariate models showed that compared to Whites, fewer Asians would undergo colonoscopy (OR = 0.28; 95 % CI: 0.12, 0.63), while more Latinas would undergo colonoscopy (OR = 6.14; 95 % CI: 1.77, 21.34) and obtain regular CRC screening (OR = 4.47; 95 % CI: 1.66, 12.04). The majority would obtain CRC screening even if they would not personally benefit; those who perceived themselves to be at higher than average cancer risk were more likely to participate in CRC screening for public health benefit (OR = 2.32; 95 % CI: 1.32, 4.09). CONCLUSIONS: The majority of women are willing to undergo screening for personal benefit. Asians were less likely, and Latinas more likely, to accept colonoscopy. Most are also willing to undergo screening for public health benefit. Self-perceived risk of CRC was the most consistent predictor of willingness and intention to be screened for either personal or public health benefi

Individualizing Cancer Screening in Older Adults: A Narrative Review and Framework for Future Research

Older adults often have multiple chronic conditions that may decrease additional life expectancy. Research evaluating the benefits and harms of screening must include consideration of competing morbidities and patient heterogeneity (beyond age), potentially increased harms of screening, and patient preferences. Other areas in need of additional research include the lack of evidence for older adults on the harms of screening tests; the overdiagnosis of disease; the burden of disease labeling; the effects of inaccurate test results; the harms of disease treatment; and harms related to prioritization of healthcare (e.g., for a particular patient, lifestyle counseling may be more important than screening). Nontraditional outcomes, such as the effects on family caregivers, are also relevant. Studies comparing trajectories of quality-adjusted survival with and without screening to assess net benefit are typically lacking. There is little evidence on the preferences of older adults for deciding whether to be screened, the process of being screened, and the health states associated with being or not being screened. To enhance the quality and quantity of evidence, older adults need to be enrolled in screening trials and clinical studies. Measures of functional status and health-related quality of life (HRQL) need to be included in trials, registries, and cohort studies. This article addresses these challenges, and presents a framework for what research is needed to better inform screening decisions in older adults

A Preliminary Application of Social Cognitive Theory to Nonsuicidal Self-Injury

Researchers have established a relationship between exposure to nonsuicidal self-injury (NSSI), and increased probability of engaging in the behavior, but few have endeavored to explain the mechanisms underlying the relationship. We drew on Social Cognitive Theory to argue that core cognitions, including NSSI outcome expectancies and self-efficacy expectancies, moderate this relationship. We also explored whether knowledge about NSSI and attitudes toward the behavior played a role in this relationship. A sample of 389 university students (73.1 % female, M age = 20.90, SD = 2.36), completed online questionnaires assessing the constructs of interest. Our findings support the application of Social Cognitive Theory to better understanding NSSI, with clear links between expectancies, self-efficacy and NSSI. Further, these cognitions moderated a number of exposure-NSSI relationships. Implications of these findings for theory, research and intervention are discussed