Pure down-conversion photons through sub-coherence length domain engineering

Photonic quantum technology relies on efficient sources of coherent single photons, the ideal carriers of quantum information. Heralded single photons from parametric down-conversion can approximate on-demand single photons to a desired degree, with high spectral purities achieved through group-velocity matching and tailored crystal nonlinearities. Here we propose crystal nonlinearity engineering techniques with sub-coherence-length domains. We first introduce a combination of two existing methods: a deterministic approach with coherence-length domains and probabilistic domain-width annealing. We then show how the same deterministic domain-flip approach can be implemented with sub-coherence length domains. Both of these complementary techniques create highly pure photons, outperforming previous methods, in particular for short nonlinear crystals matched to femtosecond lasers.Comment: 12 pages, 4 figures. Minor update to Fig.

Limits to sustained energy intake. XXIII. Does heat dissipation capacity limit the energy budget of lactating bank voles?

Acknowledgements We are grateful to our technicians and several students for their help during this study and for animal care. We thank Catherine Hambly and Peter Thompson for technical assistance for the isotope analysis for the DLW measurements. We thank Ulf Bauchinger for stimulating discussion and his comments, and two anonymous referees for comments on the manuscript. Funding This project was supported by grants from the Polish Ministry of Science and Higher Education [0595/B/P01/2011/40 to E.T.S. and 8167/B/P01/2011/40 to P.K.], and Jagiellonian University [DS/WBINOZ/INOS/757 to P.K.].Peer reviewedPublisher PD

Teleportation using squeezed single photons

We present an analysis of squeezed single photon states as a resource for teleportation of coherent state qubits and propose proof-of-principle experiments for the demonstration of coherent state teleportation and entanglement swapping. We include an analysis of the squeezed vacuum as a simpler approximation to small-amplitude cat states. We also investigate the effects of imperfect sources and inefficient detection on the proposed experiments.Comment: 9 pages, 12 figures. Submitted to Phys. Rev.

Time ordering in spontaneous parametric down-conversion

We consider the multi‐mode parametric down‐conversion Hamiltonian that governs the evolution of the fields inside a nonlinear crystal. If the Hamiltonian does not commute with itself at all times—as is the case for the multimode down‐conversion Hamiltonian—then the expansion of the evolution operator must take the form of the time‐ordered Dyson series, as opposed to the simplified Taylor series. By expanding the evolution operator to third order, the conditions under which the Taylor series is a valid approximation are revealed. In addition, some new and interesting behaviour is predicted

Th17 responses are not altered by natural exposure to seasonal allergens in pollen-sensitive patients

Background: Allergic rhinitis affects 10–30 % of the global population and this number is likely to increase in the forthcoming years. Moreover, it commonly co-exists with allergic asthma as a chronic allergic respiratory syndrome. While the involvement of Th2 cells in allergy is well understood, alterations of pro-inflammatory Th17 responses remain poorly characterized. The aim of our study was to determine whether natural seasonal allergen exposure causes changes in T cell subset characteristics in patients with allergic rhinitis and asthma. Methods: Sixteen patients with allergic rhinitis/atopic asthma (9M, 7F; age 31.8 ± 12.1) and 16 healthy controls were recruited into the study (9M, 7F; age 31.2 ± 5.3). Blood samples were collected from the patients 1–3 months before pollen season (visit 1), within 7 days of the appearance of pollen/initiation of allergic symptoms (visit 2) and 2 weeks after visit 2 following the introduction of symptomatic treatment with antihistamines (visit 3). Flow cytometry was used to assess major T cell subsets (naïve, central memory, effector memory and CD45RA+ effector) and key T cell cytokine production (IFNγ, IL-17A, TNF and IL-4) using intracellular staining. Data were analyzed using repeated measures ANOVA and paired t test. Results: As expected, an increase in the percentage of IL‐4+ CD4+ cells was observed during natural pollen exposure in patients with allergic respiratory syndrome. No significant changes were observed in the production of other cytokines, including Th17 cells, which tended to be lower than in the control population but unchanged during pollen exposure. Introduction of antihistamine treatment led to only moderate changes in cytokine production from CD4 and CD8 T cells. Selective changes in CD8+ T cells were observed during natural pollen exposure including a decrease in transient cells (with features of CD45RA+ and CD45RO+ cells) and a decrease in the percentage of central memory cells in the peripheral circulation. Within the CD4 cell group the total percentage of CD45RA positive CD4 cells was increased during pollen exposure. Conclusions: Th1 and Th17 responses are not altered during pollen season but allergen exposure affects T cell activation and memory cell status in patients with allergic respiratory syndrome

Ancient DNA reveals the chronology of walrus ivory trade from Norse Greenland.

The importance of the Atlantic walrus ivory trade for the colonization, peak, and collapse of the medieval Norse colonies on Greenland has been extensively debated. Nevertheless, no studies have directly traced medieval European ivory back to distinct Arctic populations of walrus. Analysing the entire mitogenomes of 37 archaeological specimens from Europe, Svalbard, and Greenland, we here discover that Atlantic walrus comprises two monophyletic mitochondrial (MT) clades, which diverged between 23 400 and 251 120 years ago. Our improved genomic resolution allows us to reinterpret the geographical distribution of partial MT data from 306 modern and nineteenth-century specimens, finding that one of these clades was exclusively accessible to Greenlanders. With this discovery, we ascertain the biological origin of 23 archaeological specimens from Europe (most dated between 900 and 1400 CE). These results reveal a significant shift in trade from an early, predominantly eastern source towards a near exclusive representation of Greenland ivory. Our study provides empirical evidence for how this remote Arctic resource was progressively integrated into a medieval pan-European trade network, contributing to both the resilience and vulnerability of Norse Greenland society.This work was supported by the Nansenfondet, the Research Council of Norway projects 262777 and 230821, and the Leverhulme Trust project ‘Northern Journeys’ MRF-2013-065

Kesesuaian Komposisi Gizi dan Klaim Kandungan Gizi pada Produk Mp-asi Bubuk Instan dan Biskuit

Complementary food for breastfeeding period is known as one of the nutrition source for children aged 6 – 24 months old. However, nutritional content of complementary good has not been confirmed with International and national standard, yet, nutrition problems in Indonesia. This research on processed complementary food, aimed to confirmnutritional content with standard and identify the most frequently-appeared nutritional claims. There were nine samples of processed complementary food in a format of instant powder and five samples in a format of biscuit representing mereks and categories were in scope of this research. Conformity of nutritional content obtained from information on the label, were compared with International standard (Codex Alimentarius- CAC/GL 8-1991) and Indonesian National Standard (SNI 2005). According to this research, 88 percent of nutritional compositions in instant powder were conformed to Codex Alimentarius standard, however only 31 percent in biscuit were conformed to this International standard. On the comparison with Indonesian National Standard, 94 percent of nutritional content in instant powder were conformed to the standard and 86 percent of nutritional compositions in biscuit were also conformed to standard. The most frequently-apperead nutritional claims in the processed complementary food in scope were iron, calcium, protein, dietary fibre, and vitamin A. Three from five nutrients were closely relevant with current nutrition problem in Indonesia namely aenemia, protein/chronic energy deficiency, and vitamin A deficiency