4,839 research outputs found
Variable-focus liquid lens for miniature cameras
The meniscus between two immiscible liquids can be used as an optical lens. A change in curvature of this meniscus by electrowetting leads to a change in focal distance. It is demonstrated that two liquids in a tube form a self-centered lens with a high optical quality. The motion of the lens during a focusing action was studied by observation through the transparent tube wall. Finally, a miniature achromatic camera module was designed and constructed based on this adjustable lens, showing that it is excellently suited for use in portable application
Variable-focus liquid lens for miniature cameras
The meniscus between two immiscible liquids can be used as an optical lens. A change in curvature of this meniscus by electrowetting leads to a change in focal distance. It is demonstrated that two liquids in a tube form a self-centered lens with a high optical quality. The motion of the lens during a focusing action was studied by observation through the transparent tube wall. Finally, a miniature achromatic camera module was designed and constructed based on this adjustable lens, showing that it is excellently suited for use in portable application
Cellular maturation defects in Bruton's tyrosine kinase-deficient immature B cells are amplified by premature B cell receptor expression and reduced by receptor editing
In the mouse, Bruton's tyrosine kinase (Btk) is essential for efficient
developmental progression of CD43(+)CD2(-) large cycling into
CD43(-)CD2(+) small resting pre-B cells in the bone marrow and of
IgM(high) transitional type 2 B cells into IgM(low) mature B cells in the
spleen. In this study, we show that the impaired induction of cell surface
changes in Btk-deficient pre-B cells was still noticeable in kappa(+)
immature B cells, but was largely corrected in lambda(+) immature B cells.
As lambda gene rearrangements are programmed to follow kappa
rearrangements and lambda expression is associated with receptor editing,
we hypothesized that the transit time through the pre-B cell compartment
or receptor editing may affect the extent of the cellular maturation
defects in Btk-deficient B cells. To address this issue, we used 3-83 mu
delta transgenic mice, which prematurely express a complete B cell
receptor and therefore manifest accelerated B cell development. In
Btk-deficient 3-83 mu delta mice, the IgM(+) B cells in the bone marrow
exhibited a very immature phenotype (pre-BCR(+)CD43(+)CD2(-)) and were
arrested at the transitional type 1 B cell stage upon arrival in the
spleen. However, these cellular maturation defects were largely restored
when Btk-deficient 3-83 mu delta B cells were on a centrally deleting
background and therefore targeted for receptor editing. Providing an
extended time window for developing B cells by enforced expression of the
antiapoptotic gene Bcl-2 did not alter the Btk dependence of their
cellular maturation. We conclude that premature B cell receptor expression
amplifies the cellular maturation defects in Btk-deficient B cells, while
extensive receptor editing reduces these defects
Fermentation of animal components in strict carnivores: a comparative study with cheetah fecal inoculum
The natural diet of felids contains highly digestible animal tissues but also fractions resistant to small intestinal digestion, which enter the large intestine where they may be fermented by the resident microbial population. Little information exists on the microbial degradability of animal tissues in the large intestine of felids consuming a natural diet. This study aimed to rank animal substrates in their microbial degradability by means of an in vitro study using captive cheetahs fed a strict carnivorous diet as fecal donors. Fresh cheetah fecal samples were collected, pooled, and incubated with various raw animal substrates (chicken cartilage, collagen, glucosamine-chondroitin, glucosamine, rabbit bone, rabbit hair, and rabbit skin; 4 replicates per substrate) for cumulative gas production measurement in a batch culture technique. Negative (cellulose) and positive (casein and fructo-oligosaccharides; FOS) controls were incorporated in the study. Additionally, after 72 h of incubation, short-chain fatty acids (SCFA), including branched-chain fatty acids (BCFA), and ammonia concentrations were determined for each substrate. Glucosamine and glucosamine-chondroitin yielded the greatest OM cumulative gas volume (OMCV) among animal substrates (P < 0.05), whereas total SCFA production was greatest for collagen (P < 0.05). Collagen induced an acetate production comparable to FOS and a markedly high acetate-to-propionate ratio (8.41:1) compared to all other substrates (1.67:1 to 2.97:1)
Waste Management and Minimisation Strategies
Waste minimisation can potentially decrease the amount of waste to landfill by approximately 80%, using readily available means. This project examines ways in which a similar reduction could be achieved at the Australian Technology Park (ATP) and put the ATP at the forefront of waste reduction in NSW. The limitations of the current solid waste management system at the ATP include the lack of recycling services and the poor location of the communal waste facilities
Free surface cusp formation as a failure mechanism for hard disk drives with fluid dynamic bearings
Impaired precursor B cell differentiation in Bruton's tyrosine kinase-deficient mice
Bruton's tyrosine kinase (Btk) is a cytoplasmic signaling molecule that is
crucial for precursor (pre-B) cell differentiation in humans. In this
study, we show that during the transition of large cycling to small
resting pre-B cells in the mouse, Btk-deficient cells failed to
efficiently modulate the expression of CD43, surrogate L chain, CD2, and
CD25. In an analysis of the kinetics of pre-B cell differentiation in
vivo, Btk-deficient cells manifested a specific developmental delay within
the small pre-B cell compartment of about 3 h, when compared with
wild-type cells. Likewise, in in vitro bone marrow cultures, Btk-deficient
large cycling pre-B cells showed increased IL-7 mediated expansion and
reduced developmental progression into noncycling CD2(+)CD25(+) surrogate
L chain-negative small pre-B cells and subsequently into Ig-positive B
cells. Furthermore, the absence of Btk resulted in increased proliferative
responses to IL-7 in recombination-activating gene-1-deficient pro-B
cells. These findings identify a novel role for Btk in the regulation of
the differentiation stage-specific modulation of IL-7 responsiveness in
pro-B and pre-B cells. Moreover, our results show that Btk is critical for
an efficient transit through the small pre-B cell compartment, thereby
regulating cell surface phenotype changes during the developmental
progression of cytoplasmic mu H chain expressing pre-B cells into immature
IgM(+) B cells
The conduction pathway of potassium channels is water free under physiological conditions.
Ion conduction through potassium channels is a fundamental process of life. On the basis of crystallographic data, it was originally proposed that potassium ions and water molecules are transported through the selectivity filter in an alternating arrangement, suggesting a "water-mediated" knock-on mechanism. Later on, this view was challenged by results from molecular dynamics simulations that revealed a "direct" knock-on mechanism where ions are in direct contact. Using solid-state nuclear magnetic resonance techniques tailored to characterize the interaction between water molecules and the ion channel, we show here that the selectivity filter of a potassium channel is free of water under physiological conditions. Our results are fully consistent with the direct knock-on mechanism of ion conduction but contradict the previously proposed water-mediated knock-on mechanism
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