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Articles 2371 - 2400 of 3436

Full-Text Articles in Physical Sciences and Mathematics

Genetic Analysis Of The Role Of Smpb In Establishing The Reading Frame On Tmrna, Talina Christensen Watts Jul 2008

Genetic Analysis Of The Role Of Smpb In Establishing The Reading Frame On Tmrna, Talina Christensen Watts

Theses and Dissertations

Ribosomes translate the genetic information encoded by mRNA into proteins. Defective mRNAs can cause stalling of translating ribosomes. The molecule tmRNA (transfer-messenger RNA) rescues stalled ribosomes in eubacteria. Together with its protein partner SmpB, tmRNA mimics a tRNA by entering the ribosomal A site and linking an alanine residue to the growing polypeptide chain. The ribosome then abandons the defective mRNA template and resumes translation on tmRNA, adding ten more amino acids to the nascent polypeptide. As a result of tmRNA action, stalled ribosomes are released and recycled, the defective mRNA is destroyed, and the aborted protein product is tagged …

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An Ultrahigh Stability, Low-Noise Laser Current Driver With Digital Control, Christopher J. Erickson, Marshall Van Zijll, Greg Doermann, Dallin S. Durfee Jul 2008

An Ultrahigh Stability, Low-Noise Laser Current Driver With Digital Control, Christopher J. Erickson, Marshall Van Zijll, Greg Doermann, Dallin S. Durfee

Faculty Publications

We present a low-noise, high modulation-bandwidth design for a laser current driver with excellent long-term stability. The driver improves upon the commonly used Hall–Libbrecht design. The current driver can be operated remotely by way of a microprocessing unit, which controls the current set point digitally. This allows precise repeatability and improved accuracy and stability. It also allows the driver to be placed near the laser for reduced noise and for lower phase lag when using the modulation input. We present the theory of operation for our driver in detail, and give a thorough characterization of its stability, noise, set-point accuracy …

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Using Live Sequence Chart Specifications For Formal Verification, Rahul Kumar Jul 2008

Using Live Sequence Chart Specifications For Formal Verification, Rahul Kumar

Theses and Dissertations

Formal methods play an important part in the development as well as testing stages of software and hardware systems. A significant and often overlooked part of the process is the development of specifications and correctness requirements for the system under test. Traditionally, English has been used as the specification language, which has resulted in verbose and difficult to use specification documents that are usually abandoned during product development. This research focuses on investigating the use of Live Sequence Charts (LSCs), a graphical and intuitive language directly suited for expressing communication behaviors of a system as the specification language for a …

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Complete Tropical Bezout's Theorem And Intersection Theory In The Tropical Projective Plane, Gretchen Rimmasch Jul 2008

Complete Tropical Bezout's Theorem And Intersection Theory In The Tropical Projective Plane, Gretchen Rimmasch

Theses and Dissertations

In this dissertation we prove a version of the tropical Bezout's theorem which is applicable to all tropical projective plane curves. There is a version of tropical Bezout's theorem presented in other works which applies in special cases, but we provide a proof of the theorem for all tropical projective plane curves. We provide several different definitions of intersection multiplicity and show that they all agree. Finally, we will use a tropical resultant to determine the intersection multiplicity of points of intersection at infinite distance. Using these new definitions of intersection multiplicity we prove the complete tropical Bezout's theorem.

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Ion Permeation Through Membrane Channels: Molecular Dynamics Simulations Studies, Morad Mustafa Jul 2008

Ion Permeation Through Membrane Channels: Molecular Dynamics Simulations Studies, Morad Mustafa

Theses and Dissertations

Molecular dynamics simulation was used to study ion permeation through different membrane proteins embedded in a lipid bilayer (DMPC) with different saline solutions. The potential of mean force (PMF) for ion transport was obtained by umbrella sampling simulations. A revised MacKerell force field for tryptophan residues was studied using gramicidin A (gA) channel as a test model. The revised force field contribution to the Na+ PMF was consonant with the prediction from the experimental results, but in stark contrast to the prediction of the CHARMM force field, version 22, for the tryptophan side-chain. A new grid-based correction map algorithm by …

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Early Dynamics Of Ultracold Neutral Plasmas, Adam W. Denning Jul 2008

Early Dynamics Of Ultracold Neutral Plasmas, Adam W. Denning

Theses and Dissertations

We report new studies on the early-time dynamics of ultracold neutral plasmas. We use fluorescence spectroscopy to probe plasma dynamics on the nanosecond time scale. We determine the rms ion velocity during the initial plasma period. The initial ion acceleration is found as the time derivative of the ion velocity. We compare to a theoretical model. The experimental results agree with the model at low plasma densities. However, the ion acceleration is a factor of ten lower than the model at higher densities. The cause of this discrepancy is currently unknown.

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Adapting Adtrees For Improved Performance On Large Datasets With High Arity Features, Robert D. Van Dam Jul 2008

Adapting Adtrees For Improved Performance On Large Datasets With High Arity Features, Robert D. Van Dam

Theses and Dissertations

The ADtree, a data structure useful for caching sufficient statistics, has been successfully adapted to grow lazily when memory is limited and to update sequentially with an incrementally updated dataset. However, even these modified forms of the ADtree still exhibit inefficiencies in terms of both space usage and query time, particularly on datasets with very high dimensionality and with high arity features. We propose five modifications to the ADtree, each of which can be used to improve size and query time under specific types of datasets and features. These modifications also provide an increased ability to precisely control how an …

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Rational Schur Rings Over Abelian Groups, Brent L. Kerby Jul 2008

Rational Schur Rings Over Abelian Groups, Brent L. Kerby

Theses and Dissertations

In 1993, Muzychuk showed that the rational S-rings over a cyclic group Z_n are in one-to-one correspondence with sublattices of the divisor lattice of n, or equivalently, with sublattices of the lattice of subgroups of Z_n. This idea is easily extended to show that for any finite group G, sublattices of the lattice of characteristic subgroups of G give rise to rational S-rings over G in a natural way. Our main result is that any finite group may be represented as the automorphism group of such a rational S-ring over an abelian p-group. In order to show this, we first …

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Homomorphisms Into The Fundamental Group Of One-Dimensional And Planar Peano Continua, Curtis Andrew Kent Jul 2008

Homomorphisms Into The Fundamental Group Of One-Dimensional And Planar Peano Continua, Curtis Andrew Kent

Theses and Dissertations

Let X be a planar or one-dimensional Peano continuum. Let E be a Hawaiian Earring with fundamental group H. We show that every homomorphism from H to the fundamental group of X is conjugate to a homomorphism which is induced by a continuous function.

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Ordinal Regression To Evaluate Student Ratings Data, Emily Brooke Bell Jul 2008

Ordinal Regression To Evaluate Student Ratings Data, Emily Brooke Bell

Theses and Dissertations

Student evaluations are the most common and often the only method used to evaluate teachers. In these evaluations, which typically occur at the end of every term, students rate their instructors on criteria accepted as constituting exceptional instruction in addition to an overall assessment. This presentation explores factors that influence student evaluations using the teacher ratings data of Brigham Young University from Fall 2001 to Fall 2006. This project uses ordinal regression to model the probability of an instructor receiving a good, average, or poor rating. Student grade, instructor status, class level, student gender, total enrollment, term, GE class status, …

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Arbitrary Degree T-Splines, Gordon Thomas Finnigan Jul 2008

Arbitrary Degree T-Splines, Gordon Thomas Finnigan

Theses and Dissertations

T-Splines is a freeform surface type similar to NURBS, that allows partial rows of control points. Up until now, T-Splines have only been formally defined for the degree three case. This paper extends the definition to support all odd, even, and mixed degree T-Spline surfaces, making T-Splines a proper superset of all standard NURBS surfaces.

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A Review Of Fibroblast Populated Collagen Lattices, J. C. Dallon, Paul H. Ehrlich Jul 2008

A Review Of Fibroblast Populated Collagen Lattices, J. C. Dallon, Paul H. Ehrlich

Faculty Publications

Bellaes introduction of the fibroblast populated collagen lattice (FPCL) (1) has facilitated the study of collagen-cell interactions. As a result of the numerous modifications of the casting of FPCL's, the in vivo applications of these in vitro findings has been confusing. Here experimental FPCL contraction findings are viewed in regard to three proposed mechanisms responsible for lattice contraction. The cellular mechanisms responsible for generating FPCL contraction are: cell contraction, cell tractional forces related to cell locomotion, and initial cell elongation and spreading.

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Data-Driven Programming And Behavior For Autonomous Virtual Characters, Jonathan Dinerstein, Parris K. Egbert, Michael A. Goodrich, Dan A. Ventura Jul 2008

Data-Driven Programming And Behavior For Autonomous Virtual Characters, Jonathan Dinerstein, Parris K. Egbert, Michael A. Goodrich, Dan A. Ventura

Faculty Publications

In the creation of autonomous virtual characters, two levels of autonomy are common. They are often called motion synthesis (low-level autonomy) and behavior synthesis (high-level autonomy), where an action (i.e. motion) achieves a short-term goal and a behavior is a sequence of actions that achieves a long-term goal. There exists a rich literature addressing many aspects of this general problem (and it is discussed in the full paper). In this paper we present a novel technique for behavior (high-level) autonomy and utilize existing motion synthesis techniques. Creating an autonomous virtual character with behavior synthesis abilities frequently includes three stages: forming …

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Fusion Of Character Tables And Schur Rings Of Dihedral Groups, Long Pham Bao Nguyen Jun 2008

Fusion Of Character Tables And Schur Rings Of Dihedral Groups, Long Pham Bao Nguyen

Theses and Dissertations

A finite group H is said to fuse to a finite group G if the class algebra of G is isomorphic to an S-ring over H which is a subalgebra of the class algebra of H. We will also say that G fuses from H. In this case, the classes and characters of H can fuse to give the character table of G. We investigate the case where H is the dihedral group. In many cases, G can be completely determined. In general, G can be proven to have many interesting properties. The theory is developed in terms of S-ring …

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The Role Of Upstream Sequences In Selecting The Reading Frame On Tmrna, Allen R. Buskirk, Mickey R. Miller, David W. Healey, Jonathan D. Dewey, Stephen G. Robison Jun 2008

The Role Of Upstream Sequences In Selecting The Reading Frame On Tmrna, Allen R. Buskirk, Mickey R. Miller, David W. Healey, Jonathan D. Dewey, Stephen G. Robison

Faculty Publications

tmRNA acts first as a tRNA and then as an mRNA to rescue stalled ribosomes in eubacteria. Two unanswered questions about tmRNA function remain: how does tmRNA, lacking an anticodon, bypass the decoding machinery and enter the ribosome? Secondly, how does the ribosome choose the proper codon to resume translation on tmRNA? According to the -1 triplet hypothesis, the answer to both questions lies in the unique properties of the three nucleotides upstream of the first tmRNA codon. These nucleotides assume an A-form conformation that mimics the codon-anticodon interaction, leading to recognition by the decoding center and choice of the …

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Reducing Seed Load In The Bittorrent File Sharing System, Brian T. Sanderson Jun 2008

Reducing Seed Load In The Bittorrent File Sharing System, Brian T. Sanderson

Theses and Dissertations

BitTorrent is an attractive peer-to-peer technology that attempts to reduce load on file sharers by allowing downloaders to share content between themselves. BitTorrent's current focus is to provide users with a fast download, which requires the file sharer to serve a disproportionate amount of the file. We present a modification to the BitTorrent seeding algorithm that reduces the load on BitTorrent file sharers. Essentially, if a block of a file is already available from a significant number of peers, the file sharer refuses to share that block, forcing peers to get it from each other. Using this modification, we show …

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Algorithm For Generating Derivative Structures, Gus L. W. Hart, Rodney W. Forcade Jun 2008

Algorithm For Generating Derivative Structures, Gus L. W. Hart, Rodney W. Forcade

Faculty Publications

We present an algorithm for generating all derivative superstructures--for arbitrary parent structures and for any number of atom types. This algorithm enumerates superlattices and atomic configurations in a geometry-independent way. The key concept is to use the quotient group associated with each superlattice to determine all unique atomic configurations. The run time of the algorithm scales linearly with the number of unique structures found.

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Link Quality Prediction For Wireless Devices With Multiple Radios, Qiuyi Duan, Charles D. Knutson, Lei Wang, Daniel Zappala Jun 2008

Link Quality Prediction For Wireless Devices With Multiple Radios, Qiuyi Duan, Charles D. Knutson, Lei Wang, Daniel Zappala

Faculty Publications

Communication between wireless devices ought to be as simple as possible; they should be able to seamlessly switch between different radios and network stacks on the fly in order to better serve the user. To make this a possibility, we consider the challenging problem of predicting link quality in a changing mobile environment. In this paper we present an algorithm that uses Weighted Least Squares Regression to predict whether a given link can meet application requirements in terms of throughput, delay, and jitter. We use a simulation study to demonstrate that our algorithm is able to predict link quality accurately …

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A Naive, Robust And Stable State Estimate, Todd Gordon Remund Jun 2008

A Naive, Robust And Stable State Estimate, Todd Gordon Remund

Theses and Dissertations

A naive approach to filtering for feedback control of dynamic systems that is robust and stable is proposed. Simulations are run on the filters presented to investigate the robustness properties of each filter. Each simulation with the comparison of the filters is carried out using the usual mean squared error. The filters to be included are the classic Kalman filter, Krein space Kalman, two adjustments to the Krein filter with input modeling and a second uncertainty parameter, a newly developed filter called the Naive filter, bias corrected Naive, exponentially weighted moving average (EWMA) Naive, and bias corrected EWMA Naive filter.

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Geochemistry, Structure, And Tectonic Evolution Of The Eldivan Ophiolite, Ankara Melange, Central Turkey, Anne Dangerfield Jun 2008

Geochemistry, Structure, And Tectonic Evolution Of The Eldivan Ophiolite, Ankara Melange, Central Turkey, Anne Dangerfield

Theses and Dissertations

The Eldivan ophiolite, in the Ankara Mélange, represents the remnant of an ocean basin that developed in the İzmir-Ankara-Erzincan Ocean and collapsed the form the İzmir -Ankara-Erzincan suture zone (İAESZ) through continental block collision. Whole-rock and mineral geochemical evidence show supra-subduction zone tectonomagmatic affinity for the ophiolite, revealing this basin formed in the upper plate of an intra-oceanic subduction zone. Detrital zircon from the ophiolitic mélange sandstone and the overlying Karadağ Formation suggest the ophiolites maximum age is 143.2 (±2) Ma, and the overlying Karadağ Formation is 105.2 (±5) Ma. The angular unconformity between the ophiolite and Karadağ formation reveal …

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Interactive Part Selection For Mesh And Point Models Using Hierarchical Graph-Cut Partitioning, Steven W. Brown Jun 2008

Interactive Part Selection For Mesh And Point Models Using Hierarchical Graph-Cut Partitioning, Steven W. Brown

Theses and Dissertations

This thesis presents a method for interactive part selection for mesh and point set surface models that combines scribble-based selection methods with hierarchically accelerated graph-cut segmentation. Using graph-cut segmentation to determine optimal intuitive part boundaries enables easy part selection on complex geometries and allows for a simple, scribble-based interface that focuses on selecting within visible parts instead of precisely defining part boundaries that may be in difficult or occluded regions. Hierarchical acceleration is used to maintain interactive speeds with large models and to determine connectivity when extending the technique to point set models.

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Lifting Galois Representations In A Conjecture Of Figueiredo, Wayne Bennett Rosengren Jun 2008

Lifting Galois Representations In A Conjecture Of Figueiredo, Wayne Bennett Rosengren

Theses and Dissertations

In 1987, Jean-Pierre Serre gave a conjecture on the correspondence between degree 2 odd irreducible representations of the absolute Galois group of Q and modular forms. Letting M be an imaginary quadratic field, L.M. Figueiredo gave a related conjecture concerning degree 2 irreducible representations of the absolute Galois group of M and their correspondence to homology classes. He experimentally confirmed his conjecture for three representations arising from PSL(2,3)-polynomials, but only up to a sign because he did not lift them to SL(2,3)-polynomials. In this paper we compute explicit lifts and give further evidence that his conjecture is accurate.

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Application And Evaluation Of Spatiotemporal Enhancement Of Live Aerial Video Using Temporally Local Mosaics, Dennis Eggett, Cameron Engh, Damon Gerhardt, Michael A. Goodrich, Bryan S. Morse, Nathan Rasmussen, Daniel Thornton Jun 2008

Application And Evaluation Of Spatiotemporal Enhancement Of Live Aerial Video Using Temporally Local Mosaics, Dennis Eggett, Cameron Engh, Damon Gerhardt, Michael A. Goodrich, Bryan S. Morse, Nathan Rasmussen, Daniel Thornton

Faculty Publications

Camera-equipped mini-UAVs are popular for many applications, including search and surveillance, but video from them is commonly plagued with distracting jittery motions and disorienting rotations that make it difficult for human viewers to detect objects of interest and infer spatial relationships. For time-critical search situations there are also inherent tradeoffs between detection and search speed. These problems make the use of dynamic mosaics to expand the spatiotemporal properties of the video appealing. However, for many applications it may not be necessary to maintain full mosaics of all of the video but to mosaic and retain only a number of recent …

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Assessing The Costs Of Sampling Methods In Active Learning For Annotation, James Carroll, Robbie Haertel, Peter Mcclanahan, Eric K. Ringger, Kevin Seppi Jun 2008

Assessing The Costs Of Sampling Methods In Active Learning For Annotation, James Carroll, Robbie Haertel, Peter Mcclanahan, Eric K. Ringger, Kevin Seppi

Faculty Publications

Traditional Active Learning (AL) techniques assume that the annotation of each datum costs the same. This is not the case when annotating sequences; some sequences will take longer than others. We show that the AL technique which performs best depends on how cost is measured. Applying an hourly cost model based on the results of an annotation user study, we approximate the amount of time necessary to annotate a given sentence. This model allows us to evaluate the effectiveness of AL sampling methods in terms of time spent in annotation. We acheive a 77% reduction in hours from a random …

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Or Best Offer: A Privacy Policy Negotiation Protocol, Eric G. Mercer, Kent E. Seamons, Daniel D. Walker Jun 2008

Or Best Offer: A Privacy Policy Negotiation Protocol, Eric G. Mercer, Kent E. Seamons, Daniel D. Walker

Faculty Publications

Privacy policy languages, such as P3P, allow websites to publish their privacy practices and policies in machine readable form. Currently, software agents designed to protect users’ privacy follow a “take it or leave it” approach that is inflexible and gives the server ultimate control. Privacy policy negotiation is one approach to leveling the playing field by allowing a client to negotiate with a server to determine how that server collects and uses the client’s data. We present a privacy policy negotiation protocol, “Or Best Offer”, that includes a formal model for specifying privacy preferences and reasoning about privacy policies. The …

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Ranking Search Results For Translated Content, Brian Edwin Hawkins May 2008

Ranking Search Results For Translated Content, Brian Edwin Hawkins

Theses and Dissertations

Translation Memory (TM) is a valuable tool that helps human translators in doing their job. TM consists of a collection of previously translated texts, called translation units, that may prove useful in the translation of new text. The main problem faced by translators who wish to take advantage of TM is that, although search tools do exist, there is no standardized way of effectively ranking search results. This thesis proposes a method for ranking TM search results together with a novel approach to efficiently finding common substrings that is used in the ranking process.

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Optimal Interest Rate For A Borrower With Estimated Default And Prepayment Risk, Scott T. Howard May 2008

Optimal Interest Rate For A Borrower With Estimated Default And Prepayment Risk, Scott T. Howard

Theses and Dissertations

Today's mortgage industry is constantly changing, with adjustable rate mortgages (ARM), loans originated to the so-called "subprime" market, and volatile interest rates. Amid the changes and controversy, lenders continue to originate loans because the interest paid over the loan lifetime is profitable. Measuring the profitability of those loans, along with return on investment to the lender is assessed using Actuarial Present Value (APV), which incorporates the uncertainty that exists in the mortgage industry today, with many loans defaulting and prepaying. The hazard function, or instantaneous failure rate, is used as a measure of probability of failure to make a payment. …

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Modeling The Hydrolyzing Action Of Secretory Phospholipase A2 With Ordinary Differential Equations And Monte Carlo Methods, Zijun Lan Dozier May 2008

Modeling The Hydrolyzing Action Of Secretory Phospholipase A2 With Ordinary Differential Equations And Monte Carlo Methods, Zijun Lan Dozier

Theses and Dissertations

Although cell membranes normally resist the hydrolysis of secretory phospholipase A2, a series of current investigations demonstrated that the changes in lipid order caused by increased calcium has a relationship with the susceptibility to phospholipase A2. To further explore this relationship, we setup ordinary differential equations models, statistic models and stochastic models to compare the response of human erythrocytes to the hydrolyzing action of secretory phospholipase A2 and the relationship between the susceptibility of hydrolysis and the physical properties of secretory phospholipase A2. Furthermore, we use models to determine the ability of calcium ionophore to increased membrane susceptibility.

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Machine Code Verification Using The Bogor Framework, Joseph R. Edelman May 2008

Machine Code Verification Using The Bogor Framework, Joseph R. Edelman

Theses and Dissertations

Verification and validation of embedded systems software is tedious and time consuming. Software model checking uses a tool-based approach automating this process. In order to more accurately model software it is necessary to provide hardware support that enables the execution of software as it should run on native hardware. Hardware support often requires the creation of model checking tools specific to the instruction set architecture. The creation of software model checking tools is non-trivial. We present a strategy for using an "off-the-shelf" model checking tool, Bogor, to provide support for multiple instruction set architectures. Our strategy supports key hardware features …

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The Enigmatic Young Object: Walker 90/V590 Monocerotis, M. D. Joner, M. R. Perez, B. Mccollum, M. E. Van Dend Ancker May 2008

The Enigmatic Young Object: Walker 90/V590 Monocerotis, M. D. Joner, M. R. Perez, B. Mccollum, M. E. Van Dend Ancker

Faculty Publications

Aims. We assess the evolutionary status of the intriguing object Walker 90/V590 Mon, which is located about 20 arcmin northwest of the Cone Nebula near the center of the open cluster NGC 2264. This object, according to its most recent optical spectral type determination (B7), which we confirmed, is at least 3 mag too faint in V for the cluster distance, but it shows the classical signs of a young pre-main sequence object, such as highly variable H emission, Mg II emission, IR excess, UV continuum, and optical variability. Methods. We analyzed a collection of archival and original data on …

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