1,132 research outputs found
Alien Registration- Godbout, Gerard A. (Biddeford, York County)
https://digitalmaine.com/alien_docs/4185/thumbnail.jp
Toward the total synthesis of spirastrellolide A. Part 3: Intelligence gathering and preparation of a ring-expanded analogue
Different methods for the formation of the C.25–C.26 bond of spirastrellolide A (1) are evaluated that might qualify for the end game of the projected total synthesis, with emphasis on metathetic ways to forge the macrocyclic frame
Testing nonlocality over 12.4 km of underground fiber with universal time-bin qubit analyzers
We experimentally demonstrate that the nonlocal nature of time-bin entangled
photonic qubits persists when one or two qubits of the pair are converted to
polarization qubits. This is possible by implementing a novel Universal
Time-Bin Qubit Analyzer (UTBA), which, for the first time, allows analyzing
time-bin qubits in any basis. We reveal the nonlocal nature of the emitted
light by violating the Clauser-Horne-Shimony-Holt inequality with measurement
bases exploring all the dimensions of the Bloch sphere. Moreover, we conducted
experiments where one qubit is transmitted over a 12.4 km underground fiber
link and demonstrate the suitability of our scheme for use in a real-world
setting. The resulting entanglement can also be interpreted as hybrid
entanglement between different types of degrees of freedom of two physical
systems, which could prove useful in large scale, heterogeneous quantum
networks. This work opens new possibilities for testing nonlocality and for
implementing new quantum communication protocols with time-bin entanglement.Comment: 6 pages, 5 figure
Fast and simple characterization of a photon pair source
We present an exact model of the detection statistics of a probabilistic
source of photon pairs from which a fast, simple and precise method to measure
the source's brightness and photon channel transmissions is demonstrated. We
measure such properties for a source based on spontaneous parametric
downconversion in a periodically poled LiNbO crystal producing pairs at 810
and 1550 nm wavelengths. We further validate the model by comparing the
predicted and measured values for the of a heralded single photon
source over a wide range of the brightness. Our model is of particular use for
monitoring and tuning the brightness on demand as required for various quantum
communication applications. We comment on its applicability to sources
involving spectral and/or spatial filtering.Comment: 10 pages, 5 figures. Published versio
Toward the Total Synthesis of Spirastrellolide A. Part 1: Strategic Considerations and Preparation of the Southern Domain
North and South: The unique biological activity of the natural product spirastrellolide A renders it an attractive lead for anticancer agents. The southern hemisphere (C1–C25) and the northern hemisphere (including the chlorinated [5,6,6]-bis-spiroacetal entity and the lateral C42–C47 chain) are prepared by concise and efficient routes. Consequently, the entire carbon framework of this potent phosphatase inhibitor, which contains 21 chiral centers, is prepared in an optically active form, and an important step toward structure determination by total synthesis is achieved
Toward the Total Synthesis of Spirastrellolide A. Part 2: Conquest of the Northern Hemisphere
North and South: The unique biological activity of the natural product spirastrellolide A renders it an attractive lead for anticancer agents. The southern hemisphere (C1–C25) and the northern hemisphere (including the chlorinated [5,6,6]-bis-spiroacetal entity and the lateral C42–C47 chain) are prepared by concise and efficient routes. Consequently, the entire carbon framework of this potent phosphatase inhibitor, which contains 21 chiral centers, is prepared in an optically active form, and an important step toward structure determination by total synthesis is achieved
Ultra-Narrow Faraday Rotation Filter at the Rb D1 Line
We present a theoretical and experimental study of the ultra-narrow bandwidth
Faraday anomalous dispersion optical filter (FADOF) operating at the rubidium
D1 line (795 nm). This atomic line gives better performance than other lines
for the main FADOF figures of merit, e.g. simultaneously 71% transmission, 445
MHz bandwidth and 1.2 GHz equivalent noise bandwidth.Comment: 3 pages, 2 figures. Manuscript same as v1. FADOF calculator
(ancillary file) now allows for extension to the D2 lin
Fair Loss-Tolerant Quantum Coin Flipping
Coin flipping is a cryptographic primitive in which two spatially separated
players, who in principle do not trust each other, wish to establish a common
random bit. If we limit ourselves to classical communication, this task
requires either assumptions on the computational power of the players or it
requires them to send messages to each other with sufficient simultaneity to
force their complete independence. Without such assumptions, all classical
protocols are so that one dishonest player has complete control over the
outcome. If we use quantum communication, on the other hand, protocols have
been introduced that limit the maximal bias that dishonest players can produce.
However, those protocols would be very difficult to implement in practice
because they are susceptible to realistic losses on the quantum channel between
the players or in their quantum memory and measurement apparatus. In this
paper, we introduce a novel quantum protocol and we prove that it is completely
impervious to loss. The protocol is fair in the sense that either player has
the same probability of success in cheating attempts at biasing the outcome of
the coin flip. We also give explicit and optimal cheating strategies for both
players.Comment: 12 pages, 1 figure; various minor typos corrected in version
Post-traumatic stress disorder in sexually abused children: secure attachment as a protective factor
The aim of the present study was to examine the hypothesis that attachment and CSA interacted such that school aged CSA survivors with insecure attachment to parents would be at an elevated risk of developing PTSD and trauma symptoms. Participants (n = 111, ages 7-12) comprised two groups, child CSA survivors (n = 43) and a matched comparison group of children (n = 68) recruited from the community. Children completed the Child Attachment Interview as well as the Trauma Symptom Checklist for Children (TSCC). There was a significant interaction between sexual abuse history and attachment security, such that sexually abused children with insecure attachment representations had significantly more PTSD and trauma symptoms than sexually abused children with secure attachment to parents. The findings show that using a dual lens of attachment and CSA can facilitate identification children most at risk have important implications for understanding risk and resilience processes
The Impact of Superior Labral Anterior to Posterior Lesions on Functional Status in Shoulder Instability: A Multicenter Cohort Study
BACKGROUND: Type IV superior labral anterior to posterior (SLAP) lesions, which are superior labral detachments associated with Bankart tears, are reported to occur in up to 25% of recurrent shoulder instability patients. However, the clinical implications of this finding are debatable.
PURPOSE: To determine whether there are any functional differences between anterior instability patients with and without type IV SLAP lesions at the time of presentation and at short-term follow-up after surgical intervention.
STUDY DESIGN: Cohort study; Level of evidence, 2.
METHODS: A prospective, multicenter database was established to follow the clinical evolution of patients with shoulder instability. Patients were diagnosed as having a type IV SLAP lesion at the time of arthroscopic Bankart surgery (SLAP+). These patients were compared with a group of patients who simply had a Bankart lesion (SLAP-). The 2 groups had their functional outcomes (Western Ontario Shoulder Instability Index [WOSI]; Disability of the Arm, Shoulder, and Hand [QuickDASH]; and Walch-Duplay) compared prior to surgery and 1 year postoperatively.
RESULTS: A total of 103 subjects were included in the study; of these, 56 (43 men, 13 women) completed 1-year follow-up. Twenty-three subjects had a type IV SLAP tear, and most had this repaired along with their Bankart lesion. At baseline, SLAP+ subjects had inferior QuickDASH scores compared with SLAP- subjects (37.8 vs 29.0) as well as poorer pain subscores on both the WOSI and QuickDASH. At 1-year follow-up, however, there were no significant differences in any of the outcome measures.
CONCLUSION: A type IV SLAP lesion can be expected in 22% of patients with recurrent shoulder instability. This finding implies that at baseline, the patient will have slightly worse functional scores related to pain. However, following surgical management of the labral pathology, these patients will have equivalent functional outcomes at short-term follow-up.
CLINICAL RELEVANCE: With surgical management of the superior and anteroinferior labrum, patients with type IV SLAP lesions will do as well as those with only Bankart tears. Thus, the presence of SLAP lesions should not alter the decision to provide surgical management and should not change the prognosis for a specific patient
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