481 research outputs found
Using quantum state protection via dissipation in a quantum-dot molecule to solve the Deutsch problem
The wide set of control parameters and reduced size scale make semiconductor
quantum dots attractive candidates to implement solid-state quantum
computation. Considering an asymmetric double quantum dot coupled by tunneling,
we combine the action of a laser field and the spontaneous emission of the
excitonic state to protect an arbitrary superposition state of the indirect
exciton and ground state. As a by-product we show how to use the protected
state to solve the Deutsch problem.Comment: 8 pages, 1 figure, 2 table
Schizanthus grahamii and Schizanthus hookeri. Is there any relationship between their anthocyanin compositions and their different pollination syndromes?
[EN] Three different pollination syndromes (bee, hummingbird and moth-pollination syndromes) have been described for the different species of the genus Schizanthus Ruiz & Pav. (Solanaceae). Two closely related species from a phylogenetic point of view, Schizanthus grahamii and Schizanthus hookeri, show hummingbird and bee-pollination syndromes, respectively. One of the traits used to assign these pollination syndromes is the colour of the petals, which is red in S. grahamii and bluish-pink in S. hookeri. The objective of this work was to establish the differences in the anthocyanin composition of these two Schizanthus species that contribute to the different pollination syndrome. Identification of the pigments was carried out from the chromatographic and spectral data supplied by the HPLC-DAD-MSn analyses of the samples. Alkaline and acid hydrolyses were also performed in the extracts and in some isolated compounds in order to confirm the identities. First difference between these two species was found in the total anthocyanin content, which was about 13-fold higher in S. grahamii than in S. hookeri. Furthermore, the major peak was also different in both cases, thus explaining quantitative and qualitative colour differences between species. Delphinidin 3-O-rutinoside represented ca. 72% of the total area in S. grahamii and petanin (Petunidin 3-O-p-coumaroylrutinoside-5-O-glucoside) accounted for almost 62% of the total area in S. hookeri. The presence of the p-coumaroylrutinosyl moiety in the petanin makes the intramolecular copigmentation possible, thus conferring the bluish-pink hue to the petals of S. hookeri. Delphinidin 3-O-rutinoside is in turn responsible for the red colour exhibited by the petals of S. grahamii and along with other floral traits, responsible for the attraction of hummingbirds to the plant. Pigments structurally related to petanin, which have been often detected in other genus of Solanaceae, were detected in both species and in similar contents, supporting results from previous studies that pointed to a bee-pollinated common ancestor for both species that further specialised acquiring traits attractive to hummingbirds and among them, red colour of the petals which is mainly supplied by delphinidin 3-O-rutinoside
Fault interpretation in seismic reflection data: an experiment analyzing the impact of conceptual model anchoring and vertical exaggeration
[EN]This paper presents an analysis on the limitations and advantages that some types of seismic data display present on the interpretation of the dataset
Spindle cell carcinoma: Two instances mistaken for vocal polyps
Spindle cell carcinoma is a variant of squamous carcinoma, with
behavior that is apparently more aggressive than that of squamous
carcinoma and that can produce distant lymphatic metastasis.
It was first described by Virchow in 1864 [1], but the origin of the
tumor is still not clear. The tumor is biphasic, with an epidermal
component and a sarcomatous component involving spindle cells;
transition zones between these components can be found [2–5]. In part
due to this peculiar and complex nature, the tumor has accumulated
various names since it was first described: sarcomatoid tumor, carci-
nosarcoma, pleomorphic carcinoma, collision tumor, etc. [2,5,6]
QSO 2237+0305 VR light curves from Gravitational Lenses International Time Project optical monitoring
We present VR observations of QSO 2237+0305 conducted by the GLITP
collaboration from 1999 October 1 to 2000 February 3. The observations were
made with the 2.56 m Nordic Optical Telescope at Roque de los Muchachos
Observatory, La Palma (Spain). The PSF fitting method and an adapted version of
the ISIS subtraction method have been used to derive the VR light curves of the
four components (A-D) of the quasar. The mean errors range in the intervals
0.01-0.04 mag (PSF fitting) and 0.01-0.02 mag (ISIS subtraction), with the
faintest component (D) having the largest uncertainties. We address the
relatively good agreement between the A-D light curves derived using different
filters, photometric techniques, and telescopes. The new VR light curves of
component A extend the time coverage of a high magnification microlensing peak,
which was discovered by the OGLE team.Comment: 15 pages, 3 figures, ApJ accepted (Feb 19
New cranial characters in the tribe Hydropsini (Serpentes: Dipsadidae: Xenodontinae)
We here describe the skull in four species of the three genera of the tribe Hydropsini (Serpentes: Dipsadidae: Xenodontinae): Helicops infrataeniatus, H. leopardinus, Hydrops caesurus and Pseudoeryx plicatilis. We compare them with several genera of Dipsadidae. We found that the unpaired foramen on the parabasisphenoid with anterior position is the only skull feature shared by all Hydropsini genera. This feature also occurs in semi-aquatic (Erythrolamphrus semiaureus) and fully-aquatic (Farancia abacura) dipsadids. All species of Hydrops with available skull descriptions and Pseudoeryx plicatilis share four features: (1) The anterior border of the angular is higher than the posterior border of the splenial, (2) the vomerine processes of the premaxilla are long, (3) the ascending process of the premaxilla overlaps the horizontal lamina of the nasals, and (4) an anterior projection of the prefrontal is present. All species of Helicops with available skull descriptions and Pseudoeryx plicatilis share three features: (1) A vertical lamina of the nasal with a notch, (2) a single foramen rotundum, and (3) the presence of a ventral projection of the transverse crista of the basioccipital. Finally, we found small, paired parietal foramina in most of the dipsadids studied here, which are filled with a Sudan-Black-positive tissue of possible nervous origin
Robust Light Driven Enzymatic Oxyfunctionalization via Immobilization of Unspecific Peroxygenase
Unspecific peroxygenases have attracted interest in synthetic chemistry, especially for the oxidative activation of C−H bonds, as they only require hydrogen peroxide (H2O2) instead of a cofactor. Due to their instability in even small amounts of H2O2, different strategies like enzyme immobilization or in situ H2O2 production have been developed to improve the stability of these enzymes. While most strategies have been studied separately, a combination of photocatalysis with immobilized enzymes was only recently reported. To show the advantages and limiting factors of immobilized enzyme in a photobiocatalytic reaction, a comparison is made between free and immobilized enzymes. Adjustment of critical parameters such as (i) enzyme and substrate concentration, (ii) illumination wavelength and (iii) light intensity results in significantly increased enzyme stabilities of the immobilized variant. Moreover, under optimized conditions a turnover number of 334,500 was reached
Lacrimal Diversion Devices (Sinopsys Lacrimal Stent): Sharing our Experience with Patients with Chronic Rhinosinusitis without Polyposis
Introduction: Chronic rhinosinusitis (CRS) is a highly prevalent pathology in our society. Due to the prevalence of this condition and to the persisting symptoms despite an appropriate medical treatment, surgical techniques are often required. Lately, minimal invasive techniques have been described, such as lacrimal diversion devices (LDDs). This technique offers a fast and convenient choice for delivery of sinus irrigation and topical medication.
Objective: We aimed to describe our experience with LDDs and evaluate the safety and effectiveness of the procedure in patients with moderate to severe CRS without nasal polyposis (CRSsNP) and persistent symptomatology despite medical therapy.
Methods: A total of 7 patients underwent bilateral lacrimal stents placement in the operating room. A retrospective observational study was conducted. The Sino-Nasal Outcome Test-20 (SNOT-20) survey was performed and the score obtained was compared before and 1 month after the procedure.
Results: The LDDs were used for an average of 80 days. During the follow-up, only three patients had a mild complication with the device (granuloma in the punctum, obstruction, and early extrusion). The mean baseline SNOT-20 score dropped significantly (p ¼ 0.015) from 25.85 to 11.57 (mean: - 14.29) 1 month after the procedure.
Conclusion: According to our experience and results, the use of LDD is a novel, feasible, and less invasive technique to treat refractory CRS. It reduces the risk of mucosal stripping, provides short-term outcomes, and the surgical procedure does not require advanced training in endoscopic sinus surgery. Moreover, it can be performed in-office under local anesthesia or sedation
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