Search results for "PICO"

Side-lobe suppression in electro-optic pulse generation

2007

A simple method is presented for rejecting undesirable tails and wings, around the main pulses of a periodic train, which is generated by electro-optical, sinusoidal phase modulation. It is shown that, by using a broadband optical carrier, the nonlinear chirp components generated by sinusoidal phase modulation can be filtered out. Thus, nearly apodised picosecond pulsation can be generated.

Acoustic dynamics of network-forming glasses at mesoscopic wavelengths

2013

The lack of long-range structural order in amorphous solids induces well known thermodynamic anomalies, which are the manifestation of distinct peculiarities in the vibrational spectrum. Although the impact of such anomalies vanishes in the long wavelength, elastic continuum limit, it dominates at length scales comparable to interatomic distances, implying an intermediate transition regime still poorly understood. Here we report a study of such mesoscopic domains by means of a broadband version of picosecond photo-acoustics, developed to coherently generate and detect hypersonic sound waves in the sub-THz region with unprecedented sampling efficiency. We identify a temperature-dependent fra…

Determinationes magistrales contra conclusiones Johannis Pici Mirandulani

1489

Entry of Human Parechovirus 1

2001

ABSTRACT Human parechovirus 1 (HPEV-1) is a prototype member of parechoviruses, a recently established picornavirus genus. Although there is preliminary evidence that HPEV-1 recognizes α V integrins as cellular receptors, our understanding of early events during HPEV-1 infection is still very limited. The aim of this study was to clarify the entry mechanisms of HPEV-1, including the attachment of the virus onto the host cell surface and subsequent internalization. In blocking experiments with monoclonal antibodies against different receptor candidates, antibodies against α V and β 3 integrin subunits, in particular in combination, appeared to be the most efficient ones in preventing the HPE…

Structural and functional analysis of integrin alpha2I domain interaction with echovirus 1.

2004

Integrins are cell surface receptors for several microbial pathogens including echovirus 1 (EV1), a picornavirus. Cryo-electron microscopy revealed that the functional domain (alpha(2)I) of human alpha(2)beta(1) integrin binds to a surface depression on the EV1 capsid. This three-dimensional structure of EV1 bound to alpha(2)I domain provides the first structural details of an integrin interacting with a picornavirus. The model indicates that alpha(2)beta(1) integrin cannot simultaneously bind both EV1 and the physiological ligand collagen. Compared with collagen binding to the alpha(2)I domain, the virus binds with a 10-fold higher affinity but in vitro uncoating of EV1 was not observed as…

Real-time Fluorescence Measurement of Enterovirus Uncoating

2019

Viruses need to open, i.e., uncoat, in order to release their genomes for efficient replication and translation. Especially for non-enveloped viruses, such as enteroviruses, the cues leading to uncoating are less well known. The status of the virus has previously been observed mainly by transmission electron microscopy using negative staining, cryo electron microscopy, X-ray crystallography or gradient separation (reviewed in Tuthill et al., 2010, Myllynen et al., 2016, Ruokolainen et al., 2019). However, monitoring of uncoating has been limited by the lack of methods detecting dynamic changes of the virions. Here, we present a real-time fluorescence based protocol, which detects the viral …

Globally defining the effects of mutations in a picornavirus capsid

2021

The capsids of non-enveloped viruses are highly multimeric and multifunctional protein assemblies that play key roles in viral biology and pathogenesis. Despite their importance, a comprehensive understanding of how mutations affect viral fitness across different structural and functional attributes of the capsid is lacking. To address this limitation, we globally define the effects of mutations across the capsid of a human picornavirus. Using this resource, we identify structural and sequence determinants that accurately predict mutational fitness effects, refine evolutionary analyses, and define the sequence specificity of key capsid-encoded motifs. Furthermore, capitalizing on the derive…

ICTV Virus Taxonomy Profile: Polycipiviridae

2019

Polycipiviridae is a family of picorna-like viruses with non-segmented, linear, positive-sense RNA genomes of approximately 10–12 kb. Unusually for viruses within the order Picornavirales, their genomes are polycistronic, with four (or more) consecutive 5′-proximal open reading frames (ORFs) encoding structural (and possibly other) proteins and a long 3′ ORF encoding the replication polyprotein. Members of species within the family have all been detected in ants or via arthropod transcriptomic datasets. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the Polycipiviridae, which is available at www.ictv.global/report/polycipiviridae.

Epicoccum un Polythrincium sēņu sporas Rīgas gaisā: 2013. un 2014. gada monitoringa rezultāti

2019

Bakalaura darba tēma ir: Epicoccum un Polythrincium sēņu sporas Rīgas gaisā: 2013. un 2014. gada monitoringa rezultāti. Par pētījuma pamatu tika izmantoti aerobioloģiskie un meteoroloģiskie dati 2013. un 2014. gadam. Bakalaura darba mērķis ir noskaidrot Epicoccum un Polythrincium sporu sezonalitāti un diennakts rādītājus Latvijā, un to ietekmējošos faktorus (diennakts gaisa vidējā temperatūra, gaisa relatīvais mitrums, diennakts nokrišņu summa, saules spīdēšanas ilgums utt.). Darba praktiskajā daļā, laboratorijā, tika veikta aerobioloģisko slaidu mikroskopiskā analīze, atpazīstot Epicoccum un Polythrincium sēņu sporas un nosakot to koncentrācijas gaisā. Pēc tam tika veikta sēņu sporu un met…

Dynamical properties of water in living cells

2018

With the aim of studying the effect of water dynamics on the properties of biological systems, in this paper, we present a quasi-elastic neutron scattering study on three different types of living cells, differing both in their morphological and tumor properties. The measured scattering signal, which essentially originates from hydrogen atoms present in the investigated systems, has been analyzed using a global fitting strategy using an optimized theoretical model that considers various classes of hydrogen atoms and allows disentangling diffusive and rotational motions. The approach has been carefully validated by checking the reliability of the calculation of parameters and their 99% confi…