18 research outputs found
A physically motivated analytical expression for the temperature dependence of the zero-field splitting of the nitrogen-vacancy center in diamond
The temperature dependence of the zero-field splitting (ZFS) between the
and levels of the nitrogen-vacancy (NV)
center's electronic ground-state spin triplet can be used as a robust nanoscale
thermometer in a broad range of environments. However, despite numerous
measurements of this dependence in different temperature ranges, to our
knowledge no analytical expression has been put forward that captures the
scaling of the ZFS of the NV center across all relevant temperatures. Here we
present a simple, analytical, and physically motivated expression for the
temperature dependence of the NV center's ZFS that matches all experimental
observations, in which the ZFS shifts in proportion to the occupation numbers
of two representative phonon modes. In contrast to prior models our expression
does not diverge outside the regions of fitting. We show that our model
quantitatively matches experimental measurements of the ZFS from 15 to 500 K in
single NV centers in ultra-pure bulk diamond, and we compare our model and
measurements to prior models and experimental data.Comment: Main text: 7 pages, 4 figures, 1 table, 44 references. Supplemental
Material: 12 pages, 5 figures, 2 tables, 23 reference
Super-resolution Airy disk microscopy of individual color centers in diamond
Super-resolution imaging techniques enable nanoscale microscopy in fields
such as physics, biology, and chemistry. However, many super-resolution
techniques require specialized optical components, such as a helical-phase
mask. We present a novel technique, Super-resolution Airy disk Microscopy (SAM)
that can be used in a standard confocal microscope without any specialized
optics. We demonstrate this technique, in combination with ground state
depletion, to image and control nitrogen-vacancy (NV) centers in bulk diamond
below the diffraction limit. A greater than 14-fold improvement in resolution
compared to the diffraction limit is achieved, corresponding to a spatial
resolution of 16.9(8) nm for a 1.3 NA microscope with 589 nm light. We make use
of our enhanced spatial resolution to control the spins states of individual NV
centers separated from each other by less than the diffraction limit, including
pairs sharing the same orientation that are indistinguishable with a
conventional electron spin resonance measurement.Comment: Main text: 6 pages, 4 figures, 31 references. Supplement: 14 pages,
10 figures, 15 references. Version 2 contains updated figures and modified
text to improve clarity and readabilit
Instruction manual usage: A comparison of younger people, older people and people with cognitive disabilities
This paper was presented at the DESRIST 2010 conference in Swizerland, 4-5 June 2010. Copyright ยฉ 2010, Springer Berlin/Heidelberg. The final version of this article can be viewed at the link below.When people are faced with new products for the first time or require assistance using features, the instruction manual is a key information source and therefore the design of instruction manuals is as important as the design of the product itself. There are often situations where the design embedded in the product is not sufficient to express its usage to the user. In addition, users differ significantly from each other in terms of their needs, expectations and capabilities. The main question is โare instruction manuals accessible enough and do they consider a variety of user groups?โ This paper investigates the differences between three user groups (i.e. younger people, older people and people with cognitive disabilities) regarding their approach to understanding of instruction manuals. An experimental study was carried out testing thirty volunteer participants from the aforementioned user groups, using two digital products from two different market segments and their instruction manuals.The Turkish Board of Higher Educatio
Mitotane inhibits sterol-O-acyl transferase 1 triggering lipid-mediated endoplasmic reticulum stress and apoptosis in adrenocortical carcinoma cells
Adrenocortical carcinoma (ACC) is a rare malignancy that harbors a dismal prognosis in advanced stages. Mitotane is approved as an orphan drug for treatment of ACC and counteracts tumor growth and steroid hormone production. Despite serious adverse effects, mitotane has been clinically used for decades. Elucidation of its unknown molecular mechanism of action seems essential to develop better ACC therapies. Here, we set out to identify the molecular target of mitotane and altered downstream mechanisms by combining expression genomics and mass spectrometry technology in the NCI-H295 ACC model cell line. Pathway analyses of expression genomics data demonstrated activation of endoplasmic reticulum (ER) stress and profound alteration of lipid-related genes caused by mitotane treatment. ER stress marker CHOP was strongly induced and the two upstream ER stress signalling events XBP1-mRNA splicing and eukaryotic initiation factor 2 A (eIF2ฮฑ) phosphorylation were activated by mitotane in NCI-H295 cells but to a much lesser extent in four nonsteroidogenic cell lines. Lipid mass spectrometry revealed mitotane-induced increase of free cholesterol, oxysterols, and fatty acids specifically in NCI-H295 cells as cause of ER stress. We demonstrate that mitotane is an inhibitor of sterol-O-acyl-transferase 1 (SOAT1) leading to accumulation of these toxic lipids. In ACC tissue samples we show variable SOAT1 expression correlating with the response to mitotane treatment. In conclusion, mitotane confers adrenal-specific cytotoxicity and down-regulates steroidogenesis by inhibition of SOAT1 leading to lipid-induced ER stress. Targeting of cancer-specific lipid metabolism opens new avenues for treatment of ACC and potentially other types of cancer.</jats:p