402 research outputs found
Technologically sensed social exposure related to slow-wave sleep in healthy adults
No full textObjective:
The aim of this study is to understand the relationship between automatically captured social exposure and detailed sleep parameters of healthy young adults.
Methods:
This study was conducted in a real-world setting in a graduate-student housing community at a US university. Social exposure was measured using Bluetooth proximity sensing technology in mobile devices. Sleep was monitored in a naturalistic setting using a headband sleep monitoring device over a period of 2 weeks. The analysis included a total of 11 subjects (6 males and 5 females) aged 24–35 (149 subject nights).
Results:
Slow-wave sleep showed a significant positive correlation (Spearman’s rho = 0.51, p < 0.0001) with social exposure, whereas light non-REM (N1 + N2) sleep and wake time were found to be negatively correlated (rho = −0.25, p < 0.01; rho = −0.21, p < 0.01, respectively). The correlation of median slow-wave sleep with median social exposure per subject showed a strong positive significance (rho = 0.88, p < 0.001). On average, within subjects, following day’s social exposure was higher when (slow-wave NREM + REM) percentage was high (Wilcoxon sign-ranked test, p < 0.05).
Conclusions:
Subjects with higher social exposure spent more time in slow-wave sleep. Following day’s social exposure was found to be positively affected by previous night’s (slow-wave NREM + REM) percentage. This suggests that sleep affects following day’s social exposure and not vice versa. Capturing an individual’s dynamic social behavior and sleep from their natural environment can provide novel insights into these relationships.MIT Media Lab ConsortiumMIT and Masdar Institute Cooperative Program (MIT/Masdar Collaborative Research Grant)Masdar Institute of Science and Technology (Masdar Institute Fellowship
[İnas Sanayi-i Nefise Mektebi]
No full textTaha Toros Arşivi, Dosya No: 33-İnas Sanayi Nefise Mektebiİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033
[İnas Sanayi-i Nefise Mektebi]
No full textTaha Toros Arşivi, Dosya No: 33-İnas Sanayi Nefise Mektebiİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033
Ultrafast and reversible electrochemical lithiation of InAs nanowires observed by in-situ transmission electron microscopy
No full textThe electrochemical lithiation/delithiation processes of InAs nanowires (NWs) are studied by in-situ transmission electron microscopy. Our results indicate that InAs NWs have a fast lithiation speed of 275 nm/s and a high lithium ion (Li-ion) diffusion coefficient of 2.49 x 10(-8) cm(2)/s at room temperature. Upon lithiation, the Li-ion insertion firstly results in severe lattice distortions of InAs NWs, and the formation of Li3As and LixIn through the conversion and alloying processes take place on further lithiation. A small volume expansion of 157% is observed in full lithiation and is attributed to the naturally formed surface oxide layer. During the delithiation process, volume contraction and the dealloying of LixIn take place. Induced by the alloying and dealloying of LixIn, the dark and bright strips along the basal plane of InAs NWs appear and disappear alternately during the lithiation-delithiation cycling. Our results provide important insights into the lithiation/delithiation mechanism of III-V group nanomaterials and are envisaged to be helpful for designing lithium ion battery anode materials with fast lithiation speed, small volume expansion and reversible lithiation/delithiation processes. (C) 2015 Elsevier Ltd. All rights reserved.MOST of the China [2012CB932702, 2012CB932701]; NSF of China [11374022, 61371001, 11304003, 61321001]; Foundation for the Author of National Excellent Doctoral Dissertation of China [201241]; Specialized Research Fund for the Doctoral Program of Higher Education of China [20130001110030]SCI(E)[email protected]; [email protected]; [email protected]
Crystal phase- and orientation-dependent electrical transport properties of InAs nanowires
No full textWe
report a systematic study on the correlation of the electrical
transport properties with the crystal phase and orientation of single-crystal
InAs nanowires (NWs) grown by molecular-beam epitaxy. A new method
is developed to allow the same InAs NW to be used for both the electrical
measurements and transmission electron microscopy characterization.
We find both the crystal phase, wurtzite (WZ) or zinc-blende (ZB),
and the orientation of the InAs NWs remarkably affect the electronic
properties of the field-effect transistors based on these NWs, such
as the threshold voltage (VT), ON–OFF
ratio, subthreshold swing (SS) and effective barrier
height at the off-state (ΦOFF). The SS increases while VT, ON–OFF ratio,
and ΦOFF decrease one by one in the sequence of WZ
⟨0001⟩, ZB ⟨131⟩, ZB ⟨332⟩,
ZB ⟨121⟩, and ZB ⟨011⟩. The WZ InAs NWs
have obvious smaller field-effect mobility, conductivities, and electron
concentration at VBG = 0 V than the ZB
InAs NWs, while these parameters are not sensitive to the orientation
of the ZB InAs NWs. We also find the diameter ranging from 12 to 33
nm shows much less effect than the crystal phase and orientation on
the electrical transport properties of the InAs NWs. The good ohmic
contact between InAs NWs and metal remains regardless of the variation
of the crystal phase and orientation through temperature-dependent
measurements. Our work deepens the understanding of the structure-dependent
electrical transport properties of InAs NWs and provides a potential
way to tailor the device properties by controlling the crystal phase
and orientation of the NWs
[İnas Sanayi-i Nefise Mektebi hakkında notlar]
No full textTaha Toros Arşivi, Dosya No: 33-İnas Sanayi Nefise Mektebiİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033
Negative photoconductivity of InAs nanowire
No full textNegative photoconductivity is observed in InAs nanowires (NWs) without a surface defective layer. The negative photoconductivity is strongly dependent on the wavelength and intensity of the light, and is also sensitive to the environmental atmosphere. Two kinds of mechanisms are discerned to work together. One is related to gas adsorption, which is photodesorption of water molecules and photo-assisted chemisorption of O-2 molecules. The other one can be attributed to the photogating effect introduced by the native oxide layer outside the NWs.MOST [2012CB932702, 2012CB932701]; NSF of China [11374022, 61321001, 11528407]SCI(E)[email protected]
Schottky barrier heights at the interfaces between pure-phase InAs nanowires and metal contacts
No full textUnderstanding of the Schottky barriers formed at metal contact-InAs nanowire interfaces is of great importance for the development of high-performance InAs nanowire nanoelectronic and quantum devices. Here, we report a systematical study of InAs nanowire field-effect transistors (FETs) and the Schottky barrier heights formed at the contact-nanowire interfaces. The InAs nanowires employed are grown by molecular beam epitaxy and are high material quality single crystals, and the devices are made by directly contacting the nanowires with a series of metals of different work functions. The fabricated InAs nanowire FET devices are characterized by electrical measurements at different temperatures and the Schottky barrier heights are extracted from the measured temperature and gate-voltage dependences of the channel current. We show that although the work functions of the contact metals are widely spread, the Schottky barrier heights are determined to be distributed over 35-55 meV, showing a weak but not negligible dependence on the metals. The deduced Fermi level in the InAs nanowire channels is found to be in the band gap and very close to the conduction band. The physical origin of the results is discussed in terms of Fermi level pinning by the surface states of the InAs nanowires and a shift in pinned Fermi level induced by the metal-related interface states. (C) 2016 AIP Publishing LLC.National Basic Research Program of China [2012CB932700, 2012CB932703]; National Natural Science Foundation of China [91221202, 91421303, 11274021, 61321001]; Specialized Research Fund for the Doctoral Program of Higher Education of China [20120001120127]; Swedish Research Council (VR)SCI(E)[email protected]; [email protected]
Spin injection through an Fe/InAs interface
No full textThe spin dependence of the interface resistance between ferromagnetic Fe and InAs is calculated from first principles for specular and disordered (001) interfaces. Because of the symmetry mismatch in the minority-spin channel, the specular interface acts as an efficient spin filter with a transmitted current polarization between 98% and 89%. The resistance of a specular interface in the diffusive regime is comparable to the resistance of a few microns of bulk InAs. Symmetry breaking arising from interface disorder reduces the spin asymmetry substantially, and we conclude that efficient spin injection from Fe into InAs can only be realized using high-quality epitaxial interfaces
[İnas Sanayi-i Nefise Mektebi'nin ilk öğrencilerine ait toplu fotoğraf]
No full textTaha Toros Arşivi, Dosya No: 33-İnas Sanayi Nefise Mektebiİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033
- …
