Concern is mounting regarding the human health and environmental effects of bisphenol A (BPA), a high-production-volume chemical used in synthesis of plastics. We have reviewed the growing literature ...on effects of low doses of BPA, below 50
mg/(kg
day), in laboratory exposures with mammalian model organisms. Many, but not all, effects of BPA are similar to effects seen in response to the model estrogens diethylstilbestrol and ethinylestradiol. For most effects, the potency of BPA is approximately 10–1000-fold less than that of diethylstilbestrol or ethinylestradiol. Based on our review of the literature, a consensus was reached regarding our level of confidence that particular outcomes occur in response to low dose BPA exposure. We are confident that adult exposure to BPA affects the male reproductive tract, and that long lasting, organizational effects in response to developmental exposure to BPA occur in the brain, the male reproductive system, and metabolic processes. We consider it likely, but requiring further confirmation, that adult exposure to BPA affects the brain, the female reproductive system, and the immune system, and that developmental effects occur in the female reproductive system.
Atom interferometers covering macroscopic domains of space-time are a spectacular manifestation of the wave nature of matter. Because of their unique coherence properties, Bose-Einstein condensates ...are ideal sources for an atom interferometer in extended free fall. In this Letter we report on the realization of an asymmetric Mach-Zehnder interferometer operated with a Bose-Einstein condensate in microgravity. The resulting interference pattern is similar to the one in the far field of a double slit and shows a linear scaling with the time the wave packets expand. We employ delta-kick cooling in order to enhance the signal and extend our atom interferometer. Our experiments demonstrate the high potential of interferometers operated with quantum gases for probing the fundamental concepts of quantum mechanics and general relativity.
We present the first treatment of the refraction of physical electromagnetic waves in newly developed negative index media (NIM), also known as left-handed media (LHM). The NIM dispersion relation ...implies that group fronts refract positively even when phase fronts refract negatively. This difference results in rapidly dispersing, very inhomogeneous waves. In fact, causality and finite signal speed always prevent negative wave signal (not phase) refraction. Earlier interpretations of phase refraction as "negative light refraction" and "light focusing by plane slabs" are therefore incorrect, and published NIM experiments can be explained without invoking negative signal refraction.
Cell spheroids represent attractive building units for bone tissue engineering, because they provide a three-dimensional environment with intensive direct cell-cell contacts. Moreover, they allow for ...co-culture of both osteoblasts and vessel-forming cells, which may markedly increase their survival and vascularisation after transplantation. To test this hypothesis, we generated co-culture spheroids by aggregating different combinations of primary human osteoblasts (HOB), human dermal microvascular endothelial cells (HDMEC) and normal human dermal fibroblasts (NHDF) using the liquid overlay technique. Mono-culture spheroids consisting either of HOB or HDMEC served as controls. After in vitro characterisation, the different spheroids were transplanted into dorsal skinfold chambers of CD1 nu/nu mice to study in vivo their viability and vascularisation over a 2-week observation period by means of repetitive intravital fluorescence microscopy and immunohistochemistry. In vitro, co-culture spheroids containing HDMEC rapidly formed dense tubular vessel-like networks within 72 h and exhibited a significantly decreased rate of apoptotic cell death when compared to mono-culture HDMEC spheroids. After transplantation, these networks interconnected to the host microvasculature by external inosculation. Of interest, this process was most pronounced in HOB-HDMEC spheroids and could not further be improved by the addition of NHDF. Accordingly, HOB-HDMEC spheroids were larger when compared to the other spheroid types. These findings indicate that HOB-HDMEC spheroids exhibit excellent properties to preserve viability and to promote proliferation and vascularisation. Therefore, they may be used as functional vascularisation units in bone tissue engineering for the seeding of scaffolds or for the vitalisation of non-healing large bone defects.
We analyze the statistics of photons originating from amplified spontaneous emission generated by a quantum dot superluminescent diode. Experimentally detectable emission properties are taken into ...account by parametrizing the corresponding quantum state as a multimode phase-randomized Gaussian density operator. The validity of this model is proven in two subsequent experiments using fast two-photon-absorption detection observing second-order equal-time and second-order fully time-resolved intensity correlations on femtosecond timescales. In the first experiment, we study the photon statistics when the number of contributing longitudinal modes is systematically reduced by applying well-controlled optical feedback. In a second experiment, we add coherent light from a single-mode laser diode to quantum dot superluminescent diode broadband radiation. Tuning the power ratio, we realize tailored second-order correlations ranging from Gaussian to Poissonian statistics. Both experiments are very well matched by theory, thus giving first insights into the quantum properties of radiation from quantum dot superluminescent diodes.
We show that pair correlations may play an important role in the dynamical properties of a Bose-Einstein condensed gas composed of an atomic field resonantly coupled with a condensed field of ...molecular dimers. Specifically, pair correlations in this system can dramatically modify the coherent and incoherent transfers between the atomic and molecular fields.
This paper uses a shape-dependent form of Snoek's relation to show that the geometry of soft ferromagnetic objects can be chosen to maximize their linear susceptibilities at microwave frequencies. ...Composites made with such objects can fill a critical void in the frequency range (1 to 20 GHz) where thin films or spherical objects do not yield the maximum susceptibility allowed by Snoek's relation. The relatively small intrinsic anisotropies of soft ferromagnetic materials necessitate the use of shape anisotropy to maximize the susceptibility. Our results can be used to determine the optimum shape and the maximum theoretical susceptibility achievable at a given microwave frequency. The results show that a susceptibility enhancement by a factor of 10-100 can be obtained in the 1-20 GHz frequency range (0.3-7 GHz for low loss applications) by using oblate spheroids with aspect ratios between 10 and 1000. Keeping the thickness below the skin depth will require lateral dimensions /spl sim/1-1000 /spl mu/m. Fabrication and measurements of such objects are discussed in a companion paper.
We review the basic concepts of a non-equilibrium kinetic theory of a trapped bosonic gas. By extending the successful mean-field concept of the Gross–Pitaevskii equation with the effects of ...non-local, two particle quantum correlations, one obtains a renormalized binary interaction and allows for the dynamic establishment of non-classical many-particle quantum correlations. These concepts are illustrated by self-consistent numerical calculations of the first- and second-order ground state quantum correlations of a harmonically trapped, quasi one-dimensional bosonic gas. We do find a strong suppression of the density fluctuations or, in other words, an enhanced number squeezing with decreasing particle density.
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