3,167 research outputs found
IronâMediated Electrophilic Amination of Organozinc Halides using Organic Azides
A wide range of alkylâ, arylâ and heteroarylzinc halides were aminated with highly functionalized alkyl, aryl, and heterocyclic azides. The reaction proceeds smoothly at 50â°C within 1â
h in the presence of FeCl3 (0.5â
equiv) to furnish the corresponding secondary amines in good yields. This method was extended to peptidic azides and provided the arylated substrates with full retention of configuration. To demonstrate the utility of this reaction, we prepared two amine derivatives of pharmaceutical relevance using this ironâmediated electrophilic amination as the key step
The Brave study: promoting active breaks in secondary school from studentsâ point of view
Background: According to the WHO recommendations, children and adolescents should perform at least 60 minutes per day of moderate to vigorous physical activity (PA). Active Breaks (ABs) interventions, short physical activity breaks of 5-
15 minutes during school hours, have been examined in primary school children as a potential strategy to counteract a sedentary lifestyle, with minimal disruption to school learning activities. The aim of the BRAVE STUDY is to investigate the
feasibility of ABs in a secondary school setting from the studentsâ point of view.
Methods: In December 2020, 10 students (age 12-13, 6 females and 4
males) attending the second and third grade of secondary schools located in Bologna province (Italy) were involved in a focus group (FG). The FG was conducted online because of COVID-19 and the answers transcribed for a later analysis. Studentsâ opinions were probed on the role of PA in school
and possible facilitators/barriers to implementation of ABs in the school.
Results: Students reported they wanted to be more active as a consequence of time spent in class sitting at a desk. Students also reported that an organized activity like ABs conducted in the classroom setting provides an excellent opportunity to
improve social relations with classmates. Students also highlighted the possible psycho-physical well-being benefits arising from PA. Among the potentially negative aspects reported, students underlined the possible confusion that would be created in classroom and the time subtracted from academic
learning activities. Conclusions: The FG represents an ideal mean to obtain in-depth
information on how people feel about a pending program or a change in their routine. The current FG reinforces positive outcomes from exposure to a PA program that can be intertwined with their daily classroom activities. ABs programs
can help to reconcile the needs of students that arise during the day with the PA objectives recommended by the WHO.
Key messages:
ABs can be a zero-cost intervention strategy to achieve
WHO recommendations and would create conditions for a
greater psycho-physical benefits in classrooms.
A qualitative approach, such as FGs, provides a mean to
collect information not obtainable with quantitative methods,
that could be useful to co-design interventions for children and adolescents
A combined microRNA-based targeted therapeutic approach to eradicate glioblastoma stem-like cells
A minor population of glioblastoma stem-like cells (GSCs) has been implicated in the relapse and resistance of glioblastoma to therapeutic treatments. Based on knowledge of the involvement of multiple microRNAs in GSC propagation, we designed a combinational approach to target the GSC population with multiple miRNA-based therapeutics. As carriers for the targeted delivery we took advantage of two aptamers that bind to, and inhibit, the receptor tyrosine kinases, Axl and PDGFRÎČ. We showed that the aptamer conjugates are transported through an in vitro blood-brain barrier (BBB) model. Furthermore, combining miR-137 and antimiR-10b synergizes with the receptor inhibitory function of aptamer carriers and prevents GSC expansion. Results highlighted the potential of combining multifunctional RNA-based therapeutics for selective targeting of GSCs and offer a proof of principle strategy to potentially fulfill the still unmet need for effective and safe treatment of glioma
Orbifolding the Twistor String
The D-instanton expansion of the topological B-model on the supermanifold
CP(3|4) reproduces the perturbative expansion of N=4 Super Yang-Mills theory.
In this paper we consider orbifolds in the fermionic directions of CP(3|4).
This operation breaks the SU(4) R-symmetry group, reducing the amount of
supersymmetry of the gauge theory. As specific examples we take N=1 and N=2
orbifolds and obtain the corresponding superconformal quiver theories. We
discuss the D1 instanton expansion in this context and explicitly compute some
amplitudes.Comment: 24 pages, 8 figures; v2: minor correction
Phase II Study of Sorafenib in Patients With Advanced Hepatocellular Carcinoma
Purpose This phase II study of sorafenib, an oral multikinase inhibitor that targets Raf kinase and receptor tyrosine kinases, assessed efficacy, toxicity, pharmacokinetics, and biomarkers in advanced hepatocellular carcinoma (HCC) patients. Methods Patients with inoperable HCC, no prior systemic treatment, and ChildâPugh (CP) A or B, received continuous, oral sorafenib 400 mg bid in 4-week cycles. Tumor response was assessed every two cycles using modified WHO criteria. Sorafenib pharmacokinetics were measured in plasma samples. Biomarker analysis included phosphorylated extracellular signal regulated kinase (pERK) in pretreatment biopsies (immunohistochemistry) and blood-cell RNA expression patterns in selected patients. Results Of 137 patients treated (male, 71%; median age, 69 years), 72% had CP A, and 28% had CP B. On the basis of independent assessment, three (2.2%) patients achieved a partial response, eight (5.8%) had a minor response, and 46 (33.6%) had stable disease for at least 16 weeks. Investigator-assessed median time to progression (TTP) was 4.2 months, and median overall survival was 9.2 months. Grade 3/4 drug-related toxicities included fatigue (9.5%), diarrhea (8.0%), and handâfoot skin reaction (5.1%). There were no significant pharmacokinetic differences between CP A and B patients. Pretreatment tumor pERK levels correlated with TTP. A panel of 18 expressed genes was identified that distinguished "nonprogressors" from "progressors" with an estimated 100% accuracy. Conclusion Although single-agent sorafenib has modest efficacy in HCC, the manageable toxicity and mechanisms of action support a role for combination regimens with other anticancer agents
The evolution of the Compton thick fraction and the nature of obscuration for AGN in the Chandra Deep Field South
(Abridged) We present the results from the X-ray spectral analysis of high-z
AGN in the CDFS, making use of the new 4Ms data set and new X-ray spectral
models from Brightman & Nandra, which account for Compton scattering and the
geometry of the circumnuclear material. Our goals are to ascertain to what
extent the torus paradigm of local AGN is applicable at earlier epochs and to
evaluate the evolution of the Compton thick fraction (f_CT) with z, important
for XRB synthesis models and understanding the accretion history of the
universe. In addition to the torus models, we measure the fraction of scattered
nuclear light, f_scatt known to be dependant on covering factor of the
circumnuclear materal, and use this to aid in our understanding of its
geometry. We find that the covering factor of the circumnuclear material is
correlated with NH, and as such the most heavily obscured AGN are in fact also
the most geometrically buried. We come to these conclusions from the result
that f_scatt decreases as NH increases and from the prevalence of the torus
model with the smallest opening angle as best fit model in the fits to the most
obscured AGN. We find that a significant fraction of sources (~ 20%) in the
CDFS are likely to be buried in material with close to 4 pi coverage having
been best fit by the torus model with a 0\degree opening angle. Furthermore, we
find 41 CTAGN in the CDFS using the new torus models, 29 of which we report
here for the first time. We bin our sample by z in order to investigate the
evolution of f_CT. Once we have accounted for biases and incompleteness we find
a significant increase in the intrinsic f_CT, normalised to LX= 10^43.5 erg/s,
from \approx 20% in the local universe to \approx 40% at z=1-4.Comment: Accepted for publication in MNRA
Spectroscopy of new brown dwarf members of rho Ophiuchi and an updated initial mass function
To investigate the universality hypothesis of the initial mass function in
the substellar regime, the population of the rho Ophiuchi molecular cloud is
analysed by including a new sample of low-mass spectroscopically confirmed
members. To that end, we have conducted a large spectroscopic follow-up of
young substellar candidates uncovered in our previous photometric survey. The
spectral types and extinction were derived for a newly found population of
substellar objects, and its masses estimated by comparison to evolutionary
models. A thoroughly literature search was conducted to provide an up-to-date
census of the cluster, which was then used to derive the luminosity and mass
functions, as well as the ratio of brown dwarfs to stars in the cluster. These
results were then compared to other young clusters. It is shown that the study
of the substellar population of the rho Ophiuchi molecular cloud is hampered
only by the high extinction in the cluster ruling out an apparent paucity of
brown dwarfs. The discovery of 16 new members of rho Ophiuchi, 13 of them in
the substellar regime, reveals the low-mass end of its population and shows the
success of our photometric candidate selection with the WIRCam survey. The
study of the brown dwarf population of the cluster reveals a high disk fraction
of 76 (+5-8)%. Taking the characteristic peak mass of the derived mass function
and the ratio of brown dwarfs to stars into account, we conclude that the mass
function of rho Ophiuchi is similar to other nearby young clusters.Comment: Accepted to A&A (30 December 2011); v2 includes language editin
Dust tori in radio galaxies
We investigate the validity of the quasar - radio galaxy unification scenario
and detect dust tori within radio galaxies of various types. Using VISIR on the
VLT, we acquired sub-arcsecond (~0.40") resolution N-band images, at a
wavelength of 11.85 micron, of the nuclei of a sample of 27 radio galaxies of
four types in the redshift range z=0.006-0.156. The sample consists of 8
edge-darkened, low-power Fanaroff-Riley class I (FR-I) radio galaxies, 6
edge-brightened, class II (FR-II) radio galaxies displaying low-excitation
optical emission, 7 FR-IIs displaying high-excitation optical emission, and 6
FR-II broad emission line radio galaxies. Out of the sample of 27 objects, 10
nuclei are detected and several have constraining non-detections at
sensitivities of 7 mJy, the limiting flux a point source has when detected with
a signal-to-noise ratio of 10 in one hour of source integration. On the basis
of the core spectral energy distributions of this sample we find clear
indications that many FR-I and several low-excitation FR-II radio galaxies do
not contain warm dust tori. At least 57+-19 percent of the high-excitation
FR-IIs and almost all broad line radio galaxies display excess infrared
emission, which must be attributed to warm dust reradiating accretion activity.
The FR-I and low-excitation FR-II galaxies all possess low efficiencies,
calculated as the ratio of bolometric and Eddington luminosity log
(L_bol/L_Edd) < -3. This suggests that thick tori are absent at low accretion
rates and/or low efficiencies. We argue that the unification viewing angle
range 0-45 degrees of quasars should be increased to ~60 degrees, at least at
lower luminosities.Comment: 17 pages, 9 figures, published in Astronomy and Astrophysics. Version
2 matches published version
Aspergillus ustus Infections among Transplant Recipients
This is the first report of clustered Aspergillus ustus causing systemic disease in transplant patients
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