Design and Implementation of a Site for a One-Ångstrom TEM

1997 ◽  
Vol 3 (S2) ◽  
pp. 1177-1178
Author(s):  
John H. Turner ◽  
M.A. O'Keefe ◽  
M.A. O'Keefe
Keyword(s):  
Field Emission ◽  
Acoustic Noise ◽  
Mechanical Vibration ◽  
Region I ◽  
Critical Requirement ◽  
The One ◽  
A Site ◽  
Region Ii ◽  
Critical Direction ◽  
Suitable Environment

The National Center for Electron Microscopy has recently acquired a field-emission TEM to form thebasis of a project to achieve a resolution of one Ångstrom. To reach this resolution, both instrumental and environmental factors need to be considered. We have designed and constructed a new building to provide a suitable environment for this instrument, with emphasis on providing isolation from external influences detrimental to the achievement of ultra-high resolution. Such influences include mechanical vibration, temperature fluctuations, acoustic noise, and stray electromagnetic fields.The microscope chosen for the one-Ångstrom project is a Philips CM300 Ultra-Twin equipped with a field-emission gun. Pre-installation specifications provided by Philips for this 1.7Å-resolution TEM specify maximum-allowable values for vibration levels in three mutually-perpendicular directions. In the most critical direction (console left to right), vibration is required to remain below 0.8)μm/sec in the frequency range from 1Hz to 5Hz, although allowed to rise to 6μm/sec above 10Hz (Region I in fig. 1). Even when resolution is not a critical requirement, vibration must be minimized at 2.5Hz (Region II in fig.1).

scholarly journals The T788G Mutation in thecyp51CGene Confers Voriconazole Resistance in Aspergillus flavus Causing Aspergillosis

2012 ◽  
Vol 56 (5) ◽  
pp. 2598-2603 ◽  
Author(s):  
Wei Liu ◽  
Yi Sun ◽  
Wei Chen ◽  
Weixia Liu ◽  
Zhe Wan ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Resistant Strain ◽  
Antifungal Susceptibility ◽  
Gene Replacement ◽  
Content Type ◽  
Replacement Method ◽  
First Choice ◽  
The One ◽  
A Site ◽  
First Time

ABSTRACTWith voriconazole (VRC) being approved as the first choice in treating invasive aspergillosis (IA) and its increasing use in treatment, a VRC-resistant strain ofAspergillus flavus, the second leading cause of IA afterAspergillus fumigatus, has emerged. The VRC-resistant strain ofA. flavuswas isolated for the first time from the surgical lung specimen of an IA patient with no response to VRC therapy. In order to ascertain the mechanism of VRC resistance, the azole target enzyme genes in this strain ofA. flavuswere cloned and sequenced, and 4 mutations generating amino acid residue substitutions were found in thecyp51Cgene. To further determine the role of this mutated gene for VRC resistance inA. flavus, anAgrobacterium tumefaciens-mediated gene replacement approach was applied. Consequently, the mutatedcyp51Cgene from thisA. flavusstrain was proven to confer the VRC resistance. Finally, to discern the one out of the four mutations in thecyp51Cgene that is responsible for contributing to VRC resistance, a site-directed gene mutagenesis procedure combined with a gene replacement method was performed. As a result, the T788G missense mutation in thecyp51Cgene was identified as responsible for VRC resistance inA. flavus. These findings indicated that the detection of this mutation inA. flavuscould serve as an indicator for physicians to avoid the use of VRC during IA treatment. Further comprehensive surveillance for antifungal susceptibility, as well as intensive study on the mechanism of azole resistance inA. flavuscausing IA, would be required to fully understand this mechanism.

scholarly journals Testing Time and Frequency Fiber-Optic Link Transfer by Hardware Emulation of Acoustic-Band Optical Noise

2016 ◽  
Vol 23 (2) ◽  
pp. 309-316
Author(s):  
Marcin Lipiński ◽  
Przemysław Krehlik ◽  
Łukasz Śliwczyński ◽  
Łukasz Buczek ◽  
Jacek Kołodziej
Keyword(s):  
Fiber Optic ◽  
Data Transfer ◽  
Acoustic Noise ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
Propagation Delay ◽  
Optical Signal ◽  
Testing Time ◽  
Optical Noise ◽  
Signal Phase

Abstract The low-frequency optical-signal phase noise induced by mechanical vibration of the base occurs in field-deployed fibers. Typical telecommunication data transfer is insensitive to this type of noise but the phenomenon may influence links dedicated to precise Time and Frequency (T&F) fiber-optic transfer that exploit the idea of stabilization of phase or propagation delay of the link. To measure effectiveness of suppression of acoustic noise in such a link, a dedicated measurement setup is necessary. The setup should enable to introduce a low-frequency phase corruption to the optical signal in a controllable way. In the paper, a concept of a setup in which the mechanically induced acoustic-band optical signal phase corruption is described and its own features and measured parameters are presented. Next, the experimental measurement results of the T&F transfer TFTS-2 system’s immunity as a function of the fibre-optic length vs. the acoustic-band noise are presented. Then, the dependency of the system immunity on the location of a noise source along the link is also pointed out.

scholarly journals Identification and Removal of Non-acoustic Noise in Towed Array Sonar Using F-Κ Transform for Enhanced Torpedo Detection

2020 ◽  
Vol 14 ◽  
Keyword(s):  
Vibration Isolation ◽  
Acoustic Noise ◽  
Detection System ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
Acoustic Energy ◽  
Noise Sources ◽  
Towed Array ◽  
Spatio Temporal ◽  
Towed Arrays

Low frequency passive towed array sonar is an essential component in a torpedo detection system for surface ships. Compact towed arrays are used for torpedo detection and they will be towed at higher towing speeds compared to conventional towed array sonars used for surveillance. Presence of non-acoustic noise in towed array sensors at higher towing speeds degrades torpedo detection capability at lower frequencies. High wavenumber mechanical vibrations are induced in the array by vortex shedding associated with hydrodynamic flow over the array body and cable scope. These vibrations are known to couple into the hydrophone array as nonacoustic noise sources and can impair acoustic detection performance, particularly in the forward end fire direction. Lengthy mechanical vibration isolation modules can isolate vibration induced noise in towed arrays, but this is not recommended in a towed array which is towed at high speeds as it will increase the drag and system complexity. An algorithm for decomposing acoustic and non-acoustic components of signals received at sensor level using well known frequency-wavenumber transform (F-K transform) is presented here. Frequency-wavenumber diagrams can be used for differentiating between acoustic and non-acoustic signals. An area of V shape is identified within the F-K spectrum where acoustic energy is confined. Energy outside this V will highlight non-acoustic energy. Enhanced simultaneous spatio-temporal and spatio-amplitude detection is possible with this algorithm. Performance of this algorithm is validated through simulation and experimental data.

scholarly journals Re-Assembling Anti-Oppressive Practice (1): The Personal, the Political, the Professional

2021 ◽  
Vol 11 (10) ◽  
pp. 645
Author(s):  
Janet Batsleer
Keyword(s):  
Theory And Practice ◽  
Academic Disciplines ◽  
Memory Work ◽  
Work Spaces ◽  
Informal Educators ◽  
Paolo Freire ◽  
The One ◽  
The Uk ◽  
A Site ◽  
Uk Higher Education

This essay offers a broken narrative concerning the early history of anti-oppressive practice as an approach in the U.K. to youth and community work and the struggles over this in the context of UK higher education between the 1960′s and the early 2000’s. Educating informal educators as youth and community workers in the UK has been a site of contestation. Aspects of a genealogy of that struggle are presented in ways which link publicly available histories with personal memories and narratives, through the use of a personal archive developed through collective memory work. These are chosen to illuminate the links between theory and practice: on the one hand, the conceptual field which has framed the education of youth and community workers, whose sources lie in the academic disciplines of education and sociology, and, on the other hand, the social movements which have formed the practice of informal educators. Six have been chosen: (1) The long 1968: challenging approaches to authority; (2) the group as a source of learning; (3) The personal and political: experiential learning from discontent; (4) Paolo Freire and Critical Praxis; (5) A critical break in social education and the reality of youth work spaces as defensive spaces; (6) New managerialism: ethics vs. paper trails. The approach taken, of linking memory work with present struggles, is argued to be a generative form for current critical and enlivening practice.

scholarly journals Branding Stratford: Social Representation and the Re-making of Place

2013 ◽  
Author(s):  
Antonio Desiderio
Keyword(s):  
Critical Discourse Analysis ◽  
Urban Space ◽  
Urban Regeneration ◽  
Social Representation ◽  
London 2012 ◽  
Dialectical Process ◽  
The Media ◽  
The One ◽  
A Site ◽  
The Way

As part of the societal world, architecture and urban space do not have any ‘objective’ quality. They are representations. Their meaning is produced through the negotiation and interaction of individuals, groups and classes. Yet, such ‘subjective’ meanings do have a ‘material’ relevance, as they reflect a dialectical process between the functions, forms, ownership and practices of space. They reveal construal and construction: the way in which architectural spaces are represented on the one hand, and the way in which they are physically constructed and used on the other. Nowhere does this become more evident in our current society than in the arguments around urban renewal and regeneration. The Westfield Stratford City is a typical example. Part of the vast process of the urban regeneration of East London prompted by London 2012 Olympic Games, Westfield is a massive complex of luxury shops, restaurants, bars and five star hotels. It is seen by investors and local and national political authorities as capable of transforming Stratford into a site for shopping, tourism and leisure. It does this in numerous ways, one of which involves reconfiguring the image of the region through the press and media - through visual imagery and linguistic manipulations that promote a neoliberal agenda of gentrification that simultaneously devalue the existent societal structures and communities in the area. This paper offers a Critical Discourse Analysis of the manipulation of Stratford’s image by government, business and the media and suggests that the purely financially motivated misrepresentation it reveals, is typical of the urban regeneration ethos at work across the developed world today.

Plasmodium falciparum EBA-175 kDa protein peptides which bind to human red blood cells

Parasitology ◽  
2000 ◽  
Vol 120 (3) ◽  
pp. 225-235 ◽  
Author(s):  
L. E. RODRIGUEZ ◽  
M. URQUIZA ◽  
M. OCAMPO ◽  
J. SUAREZ ◽  
H. CURTIDOR ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Binding Activity ◽  
Ligand Interaction ◽  
Merozoite Invasion ◽  
Human Red Blood Cells ◽  
Affinity Constants ◽  
Region I ◽  
Binding Peptides ◽  
V Region ◽  
Region Ii

Solid experimental evidence indicates that EBA-175 is used as a ligand by the Plasmodium falciparum merozoite to bind to human RBC, via different binding processing fragments. Using synthetic peptides and specific receptor-ligand interaction methodology, we have identified 6 high-activity binding sequences from the EBA-175 CAMP strain; peptide 1758 (KSYGTPDNIDKNMSLIHKHN), located in the so-called region I for which no binding activity has been reported before, peptides 1779 (NIDRIYDKNLLMIKEHILAI) and 1783 (HRNKKNDKLYRDEWWKVIKK), located in region II, in a sub-region known as 5′ Cys F2, previously reported as being a binding region, and peptides 1814 (DRNSNTLHLKDYRNEENERH), 1815 (YTNQNINISQERDLQKHGFH) and 1818 (NNNFNNIPSRYNLYDKKLDL), in region III–V where antibodies inhibit merozoite invasion of erythrocytes. The affinity constants were between 60 and 180 nM and the critical amino acids involved in the binding were identified. The binding of these peptides to enzyme-treated RBC was analysed; binding of peptide 1814, located in the III–V region, was found to be sialic acid dependent. Some of these high binding peptides were able to inhibit in vitro merozoite invasion and to block the binding of recombinant RII-EBA to RBC. Several of these peptides are located in regions recognized by protective immune clusters of merozoites (ICMs) eluted antibodies.

Giant dielectric constant and high-temperature dielectric relaxation properties in La-doped SrTiO3 ceramics

2020 ◽  
pp. 2150046
Author(s):  
Tianyang Liu ◽  
Xiaofei Wang ◽  
Congcong Li ◽  
Bowen Shen ◽  
Mingyan Yao ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
High Temperature ◽  
Temperature Region ◽  
Relaxation Processes ◽  
Doping Amount ◽  
Solid State Method ◽  
Giant Dielectric ◽  
Region I ◽  
Giant Dielectric Constant ◽  
Region Ii

[Formula: see text] (SLTO) ceramics ([Formula: see text] = 0.05, 0.10, 0.15) were prepared with giant dielectric constant by the traditional solid-state method at 1350[Formula: see text]C. The temperature dependence of the dielectric constant was obtained at the temperature ranging from 29[Formula: see text]C to 500[Formula: see text]C and the frequency ranging from 2 kHz to 2 MHz. Two sets of relaxation peaks appear in the low temperature (region I) and the high temperature (region II), respectively. For region I, we conclude that the relaxation behavior is related to the oxygen vacancy migration. For region II, the two relaxation processes are caused by grain boundary for high frequency and Sr or Ti defects at grain interior for low frequency. With the doping amount reaching 0.15, the relaxation peaks disappear and become a common phase transition because of the aggravation of lattice distortion. These possible physical mechanisms of two sets of relaxation peaks are briefly discussed.

Ecologies of Oil and Trauma of the Future in Curse of the Black Gold

2019 ◽  
Vol 7 (1) ◽  
pp. 69-91
Author(s):  
Cajetan Iheka
Keyword(s):  
Niger Delta ◽  
Ecological Footprint ◽  
Fossil Fuel ◽  
Trauma Studies ◽  
Ecological Degradation ◽  
The Past ◽  
The Future ◽  
To Come ◽  
The One ◽  
A Site

Mineral extraction in Africa has exacerbated ecological degradation across the continent. This article focuses on the example of the Niger Delta scene of oil exploration depicted in Michael Watts and Ed Kashi’s multimedia project, Curse of the Black Gold: 50 Years of Oil in the Niger Delta. Analyzing the infringement on human and nonhuman bodies due to fossil fuel extraction, I read the Delta, inscribed in Watts and Kashi’s image-text, as an ecology of suffering and as a site of trauma. Although trauma studies tend to foreground the past and the present, I argue that Curse of the Black Gold invites serious consideration of trauma of the future, of-the-yet-to-come, in apprehending the problematic of suffering in the Delta. I conclude with a discussion of the ethics of representing postcolonial wounding, which on the one hand can create awareness of ecological degradation and generate affect, but which on the other hand, exploits the vulnerability of the depicted and leaves an ecological footprint.

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