284 research outputs found
Occupancy and abundance of a West African mangabey species (\u3ci\u3eCercocebus atys\u3c/i\u3e Audebert, 1797) in forest patch habitat
Sooty mangabeys are Old World primates from the Upper Guinea Rainforests of West Africa. They suffer from habitat degradation due to deforestation and hunting for the bush-meat trade. Tiwai Island and adjacent small islands are a small protected area surrounded by the Moa River that is known for its high diversity of primate species. We evaluated the occupancy and abundance of sooty mangabeys on Tiwai Island and the surrounding islands using camera traps during 2008–2011. Over two seasons, we obtained a naïve occupancy rate of 0.77 for Tiwai Island but only 0.19 for surrounding smaller islands. We used Abundance-Induced Heterogeneity Model and Royle Repeated Count Model to estimate the abundance of 326 ± 92 (SE) and 530 ± 102 (SE) individuals of sooty mangabeys respectively. Based on these occurrences, sooty mangabeys usually appeared in riparian, mature and young secondary forests. Activity patterns of sooty mangabeys based on circadian patterns of detections confirmed that they were diurnal with several activity peaks during the daylight hours. The results of this study suggest that a viable population of sooty mangabeys still inhabits Tiwai Island and its vicinity, but that their core population is primarily limited to the Tiwai Island reserve. Thus, there is a need to protect the island and its adjacent habitats to ensure the conservation of sooty mangabeys in particular and other primate species in general
In Situ Identification of Secondary Structures in Unpurified <i>Bombyx mori</i> Silk Fibrils Using Polarized Two-Dimensional Infrared Spectroscopy
[Image: see text] The mechanical properties of biomaterials are dictated by the interactions and conformations of their building blocks, typically proteins. Although the macroscopic behavior of biomaterials is widely studied, our understanding of the underlying molecular properties is generally limited. Among the noninvasive and label-free methods to investigate molecular structures, infrared spectroscopy is one of the most commonly used tools because the absorption bands of amide groups strongly depend on protein secondary structure. However, spectral congestion usually complicates the analysis of the amide spectrum. Here, we apply polarized two-dimensional (2D) infrared spectroscopy (IR) to directly identify the protein secondary structures in native silk films cast from Bombyx mori silk feedstock. Without any additional peak fitting, we find that the initial effect of hydration is an increase of the random coil content at the expense of the helical content, while the β-sheet content is unchanged and only increases at a later stage. This paper demonstrates that 2D-IR can be a valuable tool for characterizing biomaterials
Dynamic photo-cross-linking of native silk enables macroscale patterning at a microscale resolution
Light-based structuring methods have shown reconstituted silk to be a versatile and appropriate material for a range of optical and biomaterial-based applications. However, without an understanding of how an unmodified, native, silk responds to photoprocessing, the full potential of this material cannot be realized. Here, we show that the use of native silk enables the production of compound patterns with improved resolution and image quality when quantitatively compared to standard reconstituted silk, which we link directly to the influence of molecular weight. Further insights into the mechanism behind silk structure development are provided through mechanical (rheological) and structural (FTIR) measurements and results show that processing can tune properties over several orders of magnitude, enabling potential replication of several soft tissue types. Finally, broadening our application perspective, this combination of mask-less lithography and native silk resulted in the fabrication of transparent optical elements for data storage and labeling
Unconventional PDV applications: detecting plasma and radiation
Author Institution: Sandia National LaboratoriesSlides presented at the 2018 Photonic Doppler Velocimetry (PDV) Users Workshop, Drury Plaza Hotel, Santa Fe, New Mexico, May 16-18, 2018
The NStED Exoplanet Transit Survey Service
The NASA Star and Exoplanet Database (NStED) is a general purpose stellar
archive with the aim of providing support for NASA's planet finding and
characterization goals, stellar astrophysics, and the planning of NASA and
other space missions. There are two principal components of NStED: a database
of (currently) 140,000 nearby stars and exoplanet-hosting stars, and an archive
dedicated to high-precision photometric surveys for transiting exoplanets. We
present a summary of the latter component: the NStED Exoplanet Transit Survey
Service (NStED-ETSS), along with its content, functionality, tools, and user
interface. NStED-ETSS currently serves data from the TrES Survey of the Kepler
Field as well as dedicated photometric surveys of four stellar clusters.
NStED-ETSS aims to serve both the surveys and the broader astronomical
community by archiving these data and making them available in a homogeneous
format. Examples of usability of ETSS include investigation of any
time-variable phenomena in data sets not studied by the original survey team,
application of different techniques or algorithms for planet transit
detections, combination of data from different surveys for given objects,
statistical studies, etc. NStED-ETSS can be accessed at
\tt{http://nsted.ipac.caltech.edu}Comment: To appear in the Proceedings of the 253rd IAU Symposium: "Transiting
Planets", May 2008, Cambridge, MA. 4 pages, 2 figure
Differential scanning calorimetry of native silk feedstock
Native silk proteins, extracted directly from the silk gland prior to spinning, offer access to a naturally hydrated protein that has undergone little to no processing. Combined with differential scanning calorimetry (DSC), it is possible to probe the thermal stability and hydration status of silk and thus investigate its denaturation and solidification, echoing that of the natural spinning process. It is found that native silk is stable between -10 °C and 55 °C, and both the high-temperature enthalpy of denaturation (measured via modulated temperature DSC) and a newly reported low-temperature ice-melting transition may serve as useful quality indicators in the future for artificial silks. Finally, compared to albumin, silk's denaturation enthalpy is much lower than expected, which is interpreted within a recently proposed entropic desolvation framework which can serve to unveil the low-energy aquamelt processing pathway
Progesterone receptor expression contributes to gemcitabine resistance at higher ECM stiffness in breast cancer cell lines
Chemoresistance poses a great barrier to breast cancer treatment and is thought to correlate with increased matrix stiffness. We developed two-dimensional (2D) polyacrylamide (PAA) and three-dimensional (3D) alginate in vitro models of tissue stiffness that mimic the stiffness of normal breast and breast cancer. We then used these to compare cell viability in response to chemotherapeutic treatment. In both 2D and 3D we observed that breast cancer cell growth and size was increased at a higher stiffness corresponding to tumours compared to normal tissue. When chemotherapeutic response was measured, a specific differential response in cell viability was observed for gemcitabine in 2 of the 7 breast cancer cell lines investigated. MCF7 and T-47D cell lines showed gemcitabine resistance at 4 kPa compared to 500 Pa. These cell lines share a common phenotype of progesterone receptor (PGR) expression and, indeed, pre-treatment with the selective progesterone receptor modulator (SPRM) mifepristone abolished resistance to gemcitabine at high stiffness. Our data reveals that combined treatment with SPRMs may therefore help in reducing resistance to gemcitabine in stiffer breast tumours which are PGR positive
Broadband multidimensional spectroscopy Identifies the amide II vibrations in silkworm films
We used two-dimensional infrared spectroscopy to disentangle the broad infrared band in the amide II vibrational regions of Bombyx mori native silk films, identifying the single amide II modes and correlating them to specific secondary structure. Amide I and amide II modes have a strong vibrational coupling, which manifests as cross-peaks in 2D infrared spectra with frequencies determined by both the amide I and amide II frequencies of the same secondary structure. By cross referencing with well-known amide I assignments, we determined that the amide II (N-H) absorbs at around 1552 and at 1530 cm–1 for helical and β-sheet structures, respectively. We also observed a peak at 1517 cm−1 that could not be easily assigned to an amide II mode, and instead we tentatively assigned it to a Tyrosine sidechain. These results stand in contrast with previous findings from linear infrared spectroscopy, highlighting the ability of multidimensional spectroscopy for untangling convoluted spectra, and suggesting the need for caution when assigning silk amide II spectra
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