1,234 research outputs found
Rotational spectrum of cisâcis HOONO
The pure rotational spectrum of cis-cis peroxynitrous acid, HOONO, has been observed. Over 220 transitions, sampling states up to J(')=67 and K-a(')=31, have been fitted with an rms uncertainty of 48.4 kHz. The experimentally determined rotational constants agree well with ab initio values for the cis-cis conformer, a five-membered ring formed by intramolecular hydrogen bonding. The small, positive inertial defect Delta=0.075667(60) amu A(2) and lack of any observable torsional splittings in the spectrum indicate that cis-cis HOONO exists in a well-defined planar structure at room temperature
Rotational spectroscopy and dipole moment of cis-cis HOONO and DOONO
The rotational spectrum of cis-cis HOONO has been studied over a broad range of frequencies, 13â840 GHz, using pulsed beam Fourier-transform microwave spectroscopy and room-temperature flow cell submillimeter spectroscopy. The rotational spectrum of the deuterated isotopomer, cis-cis DOONO, has been studied over a subset of this range, 84â640 GHz. Improved spectroscopic constants have been determined for HOONO, and the DOONO spectrum is analyzed for the first time. Weak-field Stark effect measurements in the region of 84â110 GHz have been employed to determine the molecular dipole moments of cis-cis HOONO [”a=0.542(8) D,”b=0.918(15) D,”=1.07(2) D] and DOONO [”a=0.517(9) D,”b=0.930(15) D,”=1.06(2) D]. The quadrupole coupling tensor in the principal inertial axis system for the 14N nucleus has been determined to be chiaa=1.4907(25) MHz,chibb=â4.5990(59) MHz,chiab=3.17(147) MHz, and chicc=3.1082(59) MHz. Coordinates of the H atom in the center-of-mass frame have been determined with use of the Kraitchman equations, |aH|=0.516 Ă
and |bH|=1.171 Ă
. The inertial defects of HOONO and DOONO are consistent with a planar equilibrium structure with significant out-of-plane H atom torsional motion. Comparisons of the present results are made to ab initio calculations
HI studies of the Sculptor group galaxies. VIII. The background galaxies: NGC 24 and NGC 45
In order to complete our HI survey of galaxies in the Sculptor group area,
VLA observations of NGC 24 and NGC 45 are presented. These two galaxies of
similar magnitude M_B ~ -17.4 lie in the background of the Sculptor group and
are low surface brightness galaxies, especially NGC 45. The HI distribution and
kinematics are regular for NGC 24 while NGC 45 exhibits a kinematical twist of
its major axis. A tilted-ring model shows that the position angle of the major
axis changes by ~25 degrees. A best-fit model of their mass distribution gives
mass-to-light ratios for the stellar disk of 2.5 and 5.2 for NGC 24 and NGC 45
respectively. These values are higher than the ones expected from stellar
population synthesis models. Despite the large dark matter contribution, the
galaxy mass is still dominated by the stellar component in their very inner
regions. These high mass-to-light ratios are typical of what is seen in low
surface brightness galaxies and may indicate that, in those galaxies, disks are
far from the maximum disk case. The halo parameters derived from the best-fit
models are thus lower limits.Comment: 23 pages, 10 figures, accepted for publication in The Astronomical
Journa
Dermal fibroblasts from patients with Parkinsonâs disease have normal GCase activity and autophagy compared to patients with PD and GBA mutations
Background: Recently, the development of Parkinsonâs disease (PD) has been linked to a number of genetic risk factors, of which the most common is glucocerebrosidase (GBA) mutations.
Methods: We investigated PD and Gaucher Disease (GD) patient derived skin fibroblasts using biochemistry assays.
Results: PD patient derived skin fibroblasts have normal glucocerebrosidase (GCase) activity, whilst patients with PD and GBA mutations have a selective deficit in GCase enzyme activity and impaired autophagic flux.
Conclusions: This data suggests that only PD patients with a GBA mutation have altered GCase activity and autophagy, which may explain their more rapid clinical progression.We are grateful to an NIHR award of a Biomedical Research Centre to Addenbrookes Hospital and the University of Cambridge. We are also grateful to the Rosetrees Trust, the WT-MRC Stem Cell Institute and the Canadian Institutes of Health Research (CIHR) fellowship (358492) for the funding for this work
Gender specific factors contributing to cognitive resilience in APOE É4 positive older adults in a population-based sample
Although APOE É4 has been identified as the strongest genetic risk factor for Alzheimerâs Disease, there are some APOE É4 carriers who do not go on to develop Alzheimerâs disease or cognitive impairment. This study aims to investigate factors contributing to this âresilienceâ separately by gender. Data were drawn from APOE É4 positive participants who were aged 60 + at baseline in the Personality and Total Health Through Life (PATH) Study (N = 341, Women = 46.3%). Participants were categorised into âresilientâ and ânon-resilientâ groups using Latent Class Analysis based on their cognitive impairment status and cognitive trajectory across 12Â years. Logistic regression was used to identify the risk and protective factors that contributed to resilience stratified by gender. For APOE É4 carriers who have not had a stroke, predictors of resilience were increased frequency of mild physical activity and being employed at baseline for men, and increased number of mental activities engaged in at baseline for women. The results provide insights into a novel way of classifying resilience among APOE É4 carriers and risk and protective factors contributing to resilience separately for men and women
Laboratory Characterization and Astrophysical Detection of Vibrationally Excited States of Vinyl Cyanide in Orion-KL
New laboratory data of CHCHCN (vinyl cyanide) in its ground and
vibrationally excited states at the microwave to THz domain allow searching for
these excited state transitions in the Orion-KL line survey.
Frequency-modulated spectrometers combined into a single broadband 50-1900 GHz
spectrum provided measurements of CHCHCN covering a spectral range of
18-1893 GHz, whose assignments was confirmed by Stark modulation spectra in the
18-40 GHz region and by ab-initio anharmonic force field calculations. For
analyzing the emission lines of CHCHCN species detected in Orion-KL we used
the excitation and radiative transfer code (MADEX) at LTE conditions. The
rotational transitions of the ground state of this molecule emerge from four
cloud components of hot core nature which trace the physical and chemical
conditions of high mass star forming regions in the Orion-KL Nebula. The total
column density of CHCHCN in the ground state is (3.00.9)x10
cm. We report on the first interstellar detection of transitions in the
v10=1/(v11=1,v15=1) dyad in space, and in the v11=2 and v11=3 states in
Orion-KL. The lowest energy vibrationally excited states of vinyl cyanide such
as v11=1 (at 328.5 K), v15=1 (at 478.6 K), v11=2 (at 657.8 K), the
v10=1/(v11=1,v15=1) dyad (at 806.4/809.9 K), and v11=3 (at 987.9 K) are
populated under warm and dense conditions, so they probe the hottest parts of
the Orion-KL source. Column density and rotational and vibrational temperatures
for CHCHCN in their ground and excited states, as well as for the
isotopologues, have been constrained by means of a sample of more than 1000
lines in this survey. Moreover, we present the detection of methyl isocyanide
(CHNC) for the first time in Orion-KL and a tentative detection of vinyl
isocyanide (CHCHNC) and give column density ratios between the cyanide and
isocyanide isomers.Comment: 46 pages, 22 figures, 14 tables, 9 online table
Structure-Enabled Discovery of a Stapled Peptide Inhibitor to Target the Oncogenic Transcriptional Repressor TLE1.
TLE1 is an oncogenic transcriptional co-repressor that exerts its repressive effects through binding of transcription factors. Inhibition of this protein-protein interaction represents a putative cancer target, but no small-molecule inhibitors have been published for this challenging interface. Herein, the structure-enabled design and synthesis of a constrained peptide inhibitor of TLE1 is reported. The design features the introduction of a four-carbon-atom linker into the peptide epitope found in many TLE1 binding partners. A concise synthetic route to a proof-of-concept peptide, cycFWRPW, has been developed. Biophysical testing by isothermal titration calorimetry and thermal shift assays showed that, although the constrained peptide bound potently, it had an approximately five-fold higher Kd than that of the unconstrained peptide. The co-crystal structure suggested that the reduced affinity was likely to be due to a small shift of one side chain, relative to the otherwise well-conserved conformation of the acyclic peptide. This work describes a constrained peptide inhibitor that may serve as the basis for improved inhibitors
A Manifesto for project management research
Project management research has evolved over the past five decades and is now a mature disciplinary field investigating phenomena of interest to academics, practitioners and policymakers. Studies of projects and project management practices are theoretically rich and scientifically rigorous. They are practically relevant and impactful when addressing the pursuit of operational, tactical and strategic advancements in the world of organisations. We want to broaden the conversation between project management scholars and other scholars from cognate disciplines, particularly business and management, in a true scholarship of integration and cross-fertilisation. This Manifesto invites the latter scholars to join efforts providing a foundation for further creative, theoretical and empirical contributions, including but not limited to tackling grand challenges such as climate change, pandemics, and global poverty. To this end, we identify five theses: Projects are often âagents of changeâ and hence fundamental to driving the innovation and change required to tackle grand challenges. Much project management research leverages and challenges theories across disciplines, including business, organisation and management studies, contributing to developing new theories, including those specific to projects and temporary organisations. âProjectsâ are useful units of analysis, project management research is ideal for scientific cross-fertilisation and project management scholars welcome academics from other communities to engage in fruitful conversations. As in many other fields of knowledge, the project management research community embraces diversity, welcoming researchers of different genders and various scientific and social backgrounds. Historically rooted in âproblem-solvingâ and normative studies, project management research has become open to interpretative and emancipatory research, providing opportunities for other business, management and organisational scholars to advance their knowledge communities
Approximate probabilistic verification of hybrid systems
Hybrid systems whose mode dynamics are governed by non-linear ordinary
differential equations (ODEs) are often a natural model for biological
processes. However such models are difficult to analyze. To address this, we
develop a probabilistic analysis method by approximating the mode transitions
as stochastic events. We assume that the probability of making a mode
transition is proportional to the measure of the set of pairs of time points
and value states at which the mode transition is enabled. To ensure a sound
mathematical basis, we impose a natural continuity property on the non-linear
ODEs. We also assume that the states of the system are observed at discrete
time points but that the mode transitions may take place at any time between
two successive discrete time points. This leads to a discrete time Markov chain
as a probabilistic approximation of the hybrid system. We then show that for
BLTL (bounded linear time temporal logic) specifications the hybrid system
meets a specification iff its Markov chain approximation meets the same
specification with probability . Based on this, we formulate a sequential
hypothesis testing procedure for verifying -approximately- that the Markov
chain meets a BLTL specification with high probability. Our case studies on
cardiac cell dynamics and the circadian rhythm indicate that our scheme can be
applied in a number of realistic settings
- âŠ