1,083 research outputs found
Tuning and Switching a Plasmonic Quantum Dot Sandwich in a Nematic Line Defect
We study the quantum-mechanical effects arising in a single semiconductor
core/shell quantum dot controllably sandwiched between two plasmonic nanorods.
Control over the position and the sandwich confinement structure is achieved by
the use of a linear-trap, liquid-crystal line defect and laser tweezers that
push the sandwich together. This arrangement allows for the study of exciton
plasmon interactions in a single structure, unaltered by ensemble effects or
the complexity of dielectric interfaces. We demonstrate the effect of plasmonic
confinement on the photon-antibunching behavior of the quantum dot and its
luminescence lifetime. The quantum dot behaves as a single emitter when
nanorods are far away from the quantum dot but shows possible multiexciton
emission and a significantly decreased lifetime when tightly confined in a
plasmonic sandwich. These findings demonstrate that liquid crystal defects,
combined with laser tweezers, enable a versatile platform to study plasmonic
coupling phenomena in a nanoscale laboratory, where all elements can be
arranged almost at will.Comment: Supporting information at the en
LOTOSphere:software development with LOTOS
LOTOS (Language Of Temporal Ordering Specification) became an international standard in 1989, although application of preliminary versions of the language to communication services and protocols of the ISO/OSI family dates back to 1984. This history of the use of LOTOS made it apparent that more advantages than the pure production of standard reference documents were to be expected from the use of such formal description techniques. LOTOSphere: Software Development with LOTOS describes in depth a five year project that moved LOTOS out of the ISO tower into software engineering practice. LOTOS became a vehicle for efficient, yet formally based industrial software specification, design, verification, implementation and testing. LOTOSphere: Software Development with LOTOS is divided into six parts. The first introduces the reader to LOTOS and the project LOTOSphere. The five remaining each treat an important part of the software development life cycle using LOTOS. This is the first book to give a comprehensive treatment of the use of these formal description techniques in a software engineering environment. It will thus be a valuable reference for researchers and software developers and can also be used as a text for an advanced course on the subject
A critical reappraisal of paleomagnetic evidence for Philippine Sea Plate rotation
SHAvdL and DJJvH were funded by NWO Vici grant 865.17.001 to DJJvH. DPG is funded by a âRamĂłn y Cajalâ Fellowship (RYC2019-028244-I) and the grant KiTSuNE (PID2021-128801NA-I00) both funded by â MCIN/AEI/ESF Investing in your futureâ. We thank Fagan Matthys and CJ Paulino for their help in the field.The kinematic history of the Philippine Sea Plate (PSP) is crucial for interpreting its geological record related to subduction initiation processes and the paleogeography of the junction between the Paleo-Pacific and Tethyan oceanic realms. However, reconstructing PSP's kinematic history is difficult because the plate has been surrounded by subduction zones for most of its history. In absence of marine magnetic anomalies to constrain PSP's motion relative to its neighboring plates, paleomagnetic data may be used as quantitative constraints on its motion. Previous paleomagnetic studies interpreted easterly deflected declinations to infer clockwise rotations of up to 90° since the Eocene. However, rotations inferred from these datasets may also reflect local block rotations related to plate margin deformation. We here re-evaluate to what extent paleomagnetic data from the PSP unequivocally demonstrate plate motion rather than local rotation. To this end, we provide new data from Guam, in the Mariana forearc, and reassess published paleomagnetic data. Our new data from Guam come from two localities in the Eocene, two in the Oligocene, and two in the Miocene. Our compilation assesses data quality against recently defined criteria. Our new results demonstrate that in Guam, declination differences of up to 35° exist in rocks of Eocene age, indicating local rotations. Our compilation identifies both clockwise and counterclockwise rotations from the plate margins, with little confidence which of these would reflect plate-wide rotation. We compiled paleolatitude data from igneous rocks, which we correct for microplate rotation constrained by intra-PSP marine magnetic anomalies and show a northward drift of the PSP of âŒ15° since the Eocene, but without a paleomagnetic necessity for major vertical axis rotation. Hence, with the currently available data, rotations of the PSP may be permitted, but are not required. Plate motion is currently better reconstructed from geological constraints contained in circum-PSP orogenic belts.Nederlandse Organisatie voor Wetenschappelijk Onderzoek
865.17.001âRamĂłn y Cajalâ Fellowship RYC2019-028244-IKiTSuNE (PID2021-128801NA-I00)MCIN/AEI/ESF Investing in your futur
Formal description techniques for distributed computing systems:the challenges for the 1990's
Initially FDTs where developed within IS0 and CCITT for specification, at a high-level of abstraction, of distributed systems. Research is now being performed on the use of FDTs to support the complete implementation trajectory. In this paper we discuss a number of such research activities that are conducted within the framework of the Lotosphere project(*). The paper discusses aspects of design methodology, correctness preserving transformation, the reflection of design criteria, the role of pre-defined specification and implementation constructs, and formal approaches to conformance testing. Furthermore some insight is given in the development of a comprehensive toolset that supports these aspects of design methodology. The paper concludes with some experience obtained from the application of these methods and tools to some realistic pilot implementations: an ISDN and MHS application and a Transaction Processing application
Multiple effects govern endogenous retrovirus survival patterns in human gene introns
BACKGROUND: Endogenous retroviruses (ERVs) and solitary long terminal repeats (LTRs) have a significant antisense bias when located in gene introns, suggesting strong negative selective pressure on such elements oriented in the same transcriptional direction as the enclosing gene. It has been assumed that this bias reflects the presence of strong transcriptional regulatory signals within LTRs but little work has been done to investigate this phenomenon further. RESULTS: In the analysis reported here, we found significant differences between individual human ERV families in their prevalence within genes and degree of antisense bias and show that, regardless of orientation, ERVs of most families are less likely to be found in introns than in intergenic regions. Examination of density profiles of ERVs across transcriptional units and the transcription signals present in the consensus ERVs suggests the importance of splice acceptor sites, in conjunction with splice donor and polyadenylation signals, as the major targets for selection against most families of ERVs/LTRs. Furthermore, analysis of annotated human mRNA splicing events involving ERV sequence revealed that the relatively young human ERVs (HERVs), HERV9 and HERV-K (HML-2), are involved in no human mRNA splicing events at all when oriented antisense to gene transcription, while elements in the sense direction in transcribed regions show considerable bias for use of strong splice sites. CONCLUSION: Our observations suggest suppression of splicing among young intronic ERVs oriented antisense to gene transcription, which may account for their reduced mutagenicity and higher fixation rate in gene introns
Multiple effects govern endogenous retrovirus survival patterns in human gene introns
BACKGROUND: Endogenous retroviruses (ERVs) and solitary long terminal repeats (LTRs) have a significant antisense bias when located in gene introns, suggesting strong negative selective pressure on such elements oriented in the same transcriptional direction as the enclosing gene. It has been assumed that this bias reflects the presence of strong transcriptional regulatory signals within LTRs but little work has been done to investigate this phenomenon further. RESULTS: In the analysis reported here, we found significant differences between individual human ERV families in their prevalence within genes and degree of antisense bias and show that, regardless of orientation, ERVs of most families are less likely to be found in introns than in intergenic regions. Examination of density profiles of ERVs across transcriptional units and the transcription signals present in the consensus ERVs suggests the importance of splice acceptor sites, in conjunction with splice donor and polyadenylation signals, as the major targets for selection against most families of ERVs/LTRs. Furthermore, analysis of annotated human mRNA splicing events involving ERV sequence revealed that the relatively young human ERVs (HERVs), HERV9 and HERV-K (HML-2), are involved in no human mRNA splicing events at all when oriented antisense to gene transcription, while elements in the sense direction in transcribed regions show considerable bias for use of strong splice sites. CONCLUSION: Our observations suggest suppression of splicing among young intronic ERVs oriented antisense to gene transcription, which may account for their reduced mutagenicity and higher fixation rate in gene introns
The Physics of Protoplanetesimal Dust Agglomerates. Vi. Erosion of Large Aggregates as a Source of Micrometer-Sized Particles
Observed protoplanetary disks consist of a large amount of micrometer-sized
particles. Dullemond and Dominik (2005) pointed out for the first time the
difficulty in explaining the strong mid-IR excess of classical T-Tauri stars
without any dust-retention mechanisms. Because high relative velocities in
between micrometer-sized and macroscopic particles exist in protoplanetary
disks, we present experimental results on the erosion of macroscopic
agglomerates consisting of micrometer-sized spherical particles via the impact
of micrometer-sized particles. We find that after an initial phase, in which an
impacting particle erodes up to 10 particles of an agglomerate, the impacting
particles compress the agglomerate's surface, which partly passivates the
agglomerates against erosion. Due to this effect the erosion halts within our
error bars for impact velocities up to ~30 m/s. For larger velocities, the
erosion is reduced by an order of magnitude. This outcome is explained and
confirmed by a numerical model. In a next step we build an analytical disk
model and implement the experimentally found erosive effect. The model shows
that erosion is a strong source of micrometer-sized particles in a
protoplanetary disk. Finally we use the stationary solution of this model to
explain the amount of micrometer-sized particles in observational infrared data
of Furlan et al. (2006)
Arkeologisk undersÞkelse av steinalderlokalitet. MÄganeset 4 : ID 264210, gnr. 3, bnr. 19 i Gjesdal kommune : Prosjekt: Arkeologi pÄ nye veier.
Oppdragsgiver: Nye Veier ASArkeologisk museum, Universitetet i Stavanger gjennomfĂžrte en arkeologisk undersĂžkelse av MĂ„ganeset 4, et aktivitetsomrĂ„de fra steinalder (Askeladden id 264210), i tidsrommet 6.7 â 10.8.2020. Bakgrunnen var planlegging av ny E39 pĂ„ strekning mellom RĂžyskĂ„r i Agder og Ă
lgÄrd i Rogaland i regi av Nye Veier AS. Lokaliteten lÄ pÄ MÄganeset gnr. 3 bnr. 19 i Gjesdal kommune, og var etter registreringen antatt Ä ha bruksfaser fra tidlig- til mellomneolitikum. Lokaliteten ble avdekket for hÄnd. Totalt ble det gravd 83 kvm i kvadranter pÄ 50 x 50 cm, i inntil fem nivÄer av 10 cm til Ä fÄ en oversikt over den horisontale og vertikale funndistribusjonen. Det ble ikke pÄvist spor etter forhistoriske strukturer som ildsteder, kokegroper eller stolpehull.
Det ble gjort 5254 funn pÄ lokaliteten under utgravingen. Funnmaterialet er nesten utelukkende av littisk karakter, og flint er det dominerende rÄstoffet. Det var ogsÄ mindre innslag av bergkrystall, bergart og pimpstein. Funnmaterialet framstÄr som enfaset og kan dateres typologisk til fÞrste halvdel av yngre steinalder (neolitikum). Av diagnostiske funn var det tre A1-spisser. I tillegg ble det samlet inn fire kullprÞver og to brente hasselnÞttskall. Tre radiologiske dateringer viser til aktivitet i tidlig- og mellomneolitikum, ca. 3700-2400 cal. BC. Dette samsvarer godt med funnmaterialet og gir derfor en god indikasjon pÄ hvilke perioder lokaliteten var i bruk. Lokaliteten er tolket som en boplass for ett eller flere kortvarige opphold. Funnmateriale og plassering i landskapet antyder aktivitet knyttet til jakt og/eller fiske
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