Digital Commons Network^™

Quantum Tunneling Of The Magnetic Moment In A Free Nanoparticle, Michael F. O'Keeffe, Eugene M. Chudnovsky, Dmitry A. Garanin

Publications and Research

We study tunneling of the magnetic moment in a particle that has full rotational freedom. Exact energy levels are obtained and the ground-state magnetic moment is computed for a symmetric rotor. The effect of the mechanical freedom on spin tunneling manifests itself in a strong dependence of the magnetic moment on the moments of inertia of the rotor. Energy of the particle exhibits quantum phase transitions between states with different values of the magnetic moment. Particles of various shapes are investigated and quantum phase diagram is obtained.

Quantum Deflagration And Supersonic Fronts Of Tunneling In Molecular Magnets, Dmitry A. Garanin, Saaber Shoyed

Publications and Research

Theory of magnetic deflagration taking into account dipolar-controlled spin tunneling has been applied to the realistic model of molecular magnet Mn_12 Ac. At small transverse field, the front speed v has tunneling maxima on the bias field B_z reflecting those of the molecular spin's relaxation rate calculated from the density-matrix equation. At high transverse field, spin tunneling directly out of the metastable ground state leads to front speeds that can exceed the speed of sound. Both for the weak and strong transverse field, the spatial profile of the deflagration front near tunneling resonances shows a front of tunneling that triggers …

Dipolar-Controlled Spin Tunneling And Relaxation In Molecular Magnets, Dmitry A. Garanin

Publications and Research

Spin tunneling in molecular magnets controlled by dipole-dipole interactions (DDI) in the disordered state has been considered numerically on the basis of the microscopic model using the quantum mean-field approximation. In the actual case of a strong DDI spin coherence is completely lost and there is a slow relaxation of magnetization, described by t^{3/4} at short times. Fast precessing nuclear spins, included in the model microscopically, only moderately speed up the relaxation.

Cosmic String Interactions Induced By Gauge And Scalar Fields, Daniel N. Kabat, Debajyoti Sarkar

Publications and Research

We study the interaction between two parallel cosmic strings induced by gauge fields and by scalar fields with non-minimal couplings to curvature. For small deficit angles the gauge field behaves like a collection of non-minimal scalars with a specific value for the non-minimal coupling. We check this equivalence by computing the interaction energy between strings at first order in the deficit angles. This result provides another physical context for the "contact terms" which play an important role in the renormalization of black hole entropy due to a spin-1 field.

Holographic Representation Of Bulk Fields With Spin In Ads/Cft, Daniel N. Kabat, Gilad Lifschytz, Shubho Roy, Debajyoti Sarkar

Publications and Research

We develop the representation of bulk fields with spin one and spin two in anti-de Sitter space, as non-local observables in the dual CFT. Working in holographic gauge in the bulk, at leading order in 1/N bulk gauge fields are obtained by smearing boundary currents over a sphere on the complexified boundary, while linearized metric fluctuations are obtained by smearing the boundary stress tensor over a ball. This representation respects AdS covariance up to a compensating gauge transformation. We also consider massive vector fields, where the bulk field is obtained by smearing a non-conserved current. We compute bulk two-point functions …

Casimir Effect: Edges And Diffraction, Dimitra Karabali

Publications and Research

The Casimir effect refers to the existence of a macroscopic force between conducting plates in vacuum due to quantum fluctuations of fields. These forces play an important role, among other things, in the design of nano-scale mechanical devices. Accurate experimental observations of this phenomenon have motivated the development of new theoretical approaches in dealing with the effects of different geometries, temperature etc. In this talk, I will focus on a new method we have developed in calculating the contribution to the Casimir effect due to diffraction from edges and holes in different geometries, at zero and at finite temperature.

Effects Of Video-Based Peer Modeling On The Question Asking, Reading Motivation And Text Comprehension Of Struggling Adolescent Readers, Kallen E. Tsikalas

Dissertations, Theses, and Capstone Projects

Struggling adolescent readers are distinct from others in two important ways: (1) They are adolescents; and (2) they have a history of struggle with reading.

Good pedagogy prescribes that effective programs "meet students where they are." For middle-school students, this means meeting them in adolescence. Adolescents are more concerned with social norms and more susceptible to peer influence than younger children. Additionally, the fact that these youth are still struggling after years of reading instruction suggests that their motivation to persist at reading is likely to have suffered. To fully support and engage such adolescents, reading programs must leverage social …

Geometric Graph Theory And Wireless Sensor Networks, Deniz Sarioz

Dissertations, Theses, and Capstone Projects

In this work, we apply geometric and combinatorial methods to explore a variety of problems motivated by wireless sensor networks. Imagine sensors capable of communicating along straight lines except through obstacles like buildings or barriers, such that the communication network topology of the sensors is their visibility graph. Using a standard distributed algorithm, the sensors can build common knowledge of their network topology.

We first study the following inverse visibility problem: What positions of sensors and obstacles define the computed visibility graph, with fewest obstacles? This is the problem of finding a minimum obstacle representation of a graph. This minimum …

Recollecting Turbulence: Catastrophe And Sacrifice In The "History Of My Life" By Henry Darger, Carl Watson

Dissertations, Theses, and Capstone Projects

This study of "The History of My Life" the 5,086 page autobiographical text by the outsider artist/author Henry Darger, uses non-linear modes of analysis, such as chaos and complexity theory, to explore the meaning of Darger's epic narrative. Beginning with the idea that turbulence, seemingly chaotic, actually comes about as a compensatory restructuring of inadequate or unstable system dynamics, this study goes on to show that, as both influence and effect, turbulence is found at every level of Darger's life and art, both in theme and structure. "My Life" is a prime example: an extended narrative describing a cataclysmic tornado, …

Beyond The Scores: Mathematics Identities Of African American And Hispanic Fifth Graders In An Urban Elementary Community School, Paula Jenniver Fleshman

Dissertations, Theses, and Capstone Projects

As mathematics identity affects students' learning and doing of mathematics, it is critical to understand the mathematics identities of African American and Hispanic students as the mathematical performance and pursuits of far too many continue to lag behind. Further, as community schools have been shown to positively impact students in urban communities, it is also critical to understand how mathematics identities are developed within community schools. This study explores the culture, structures, and processes of an urban elementary community school including its afterschool archery program relative to fifth grade students' mathematics identities. It also explores students' math positioning, enactment, and …

The Minimum Of The Maximum Rectilinear Crossing Numbers Of Small Cubic Graphs, Matthew Alpert, Jens-P. Bode, Elie Feder, Heiko Harborth

Publications and Research

Here we consider the minimum of the maximum rectilin­ear crossing numbers for all d-regular graphs of order n. The case of connected graphs only is investigated also. For d = 3 exact values are determined for n are less than or equal to 12 and some estimations are given in general.

Pltl In The Developmental Writing Classsroom, Aaron Barlow, A. E. Dreyfuss, Jennifer Sears, Amelise Bonhomme, Rennee Clarke, Sungsoo Moon, Jodi-Ann Young, Lori Younge

Publications and Research

Writing placement exam preparation can be broken down into small tasks overseen by Peer Leaders, following (though not precisely) patterns set out by Fred Keller in “Good-bye Teacher” in 1968. The mechanical aspect of writing, however, is never enough for the production of essays that communicate, something that requires audience and a desire to “speak.” Students in developmental classrooms often have problems beyond the writing itself: they may be test shy and may not be prepared to take on even college entry tasks without careful direction. Working with Peer Leaders, the developmental program can address the problems of mechanics and …

Where’S The Pedagogy? The Role Of Teaching And Learning In The Digital Humanities, Stephen Brier

Publications and Research

The Digital Humanities (DH) has focused narrowly on digital research methods and projects and digital publication efforts. Yet DH has also had a significant, if under recognized, impact on classroom pedagogy. This chapter evaluates the ways DH practices, embodied in a series of pedagogy projects at the City University of York (CUNY), have been used to reshape teaching and learning in college classrooms.

Critical Bifocality And Circuits Of Privilege: Expanding Critical Ethnographic Theory And Design, Lois Weis, Michelle Fine

Publications and Research

Almost 10 years ago, in Working Method (2004), we argued for a critical theory of method for educational studies, which would analyze lives in the context of history, structure, and institutions, across the power lines of privilege and marginalization.

Committee On Academic Standing Minutes December 7, 2011, Bronx Community College Committee On Academic Standing

BCC Governance Archives

Minutes for the meeting of the Committee on Academic Standing on December 7, 2011.

College Senate Minutes December 1, 2011, Bronx Community College Senate

BCC Governance Archives

Minutes for the meeting of the College Senate on December 1, 2011.

Impaired Structural Connectivity Of Socio-Emotional Circuits In Autism Spectrum Disorders: A Diffusion Tensor Imaging Study, Stephanie H. Ameis, Jin Fan, Conrad Rockel, Aristotle N. Voineskos, Nancy J. Lobaugh, Latha Soorya, A. Ting Wang, Eric Hollander, Evdokia Anagnostou

Publications and Research

Background Abnormal white matter development may disrupt integration within neural circuits, causing particular impairments in higher-order behaviours. In autism spectrum disorders (ASDs), white matter alterations may contribute to characteristic deficits in complex socio-emotional and communication domains. Here, we used diffusion tensor imaging (DTI) and tract based spatial statistics (TBSS) to evaluate white matter microstructure in ASD. Methods/Principal Findings DTI scans were acquired for 19 children and adolescents with ASD (∼8–18 years; mean 12.4±3.1) and 16 age and IQ matched controls (∼8–18 years; mean 12.3±3.6) on a 3T MRI system. DTI values for fractional anisotropy, mean diffusivity, radial diffusivity and axial …

State Of The College Address 2011, Jeremy Travis

Reports and Publications from John Jay College

No abstract provided.

The Communicator, November 10, 2011, Bronx Community College

The Communicator

The Communicator newspaper published on November 10, 2011.

Committee On Academic Standing Minutes November 9, 2011, Bronx Community College Committee On Academic Standing

BCC Governance Archives

Minutes for the meeting of the Committee on Academic Standing on November 9, 2011.

Wave-Function Functionals For The Density, Marlina Slamet, Xiao-Yin Pan, Viraht Sahni

Publications and Research

We extend the idea of the constrained-search variational method for the construction of wave-function functionals psi[chi] of functions chi. The search is constrained to those functions chi such that psi[chi] reproduces the density rho(r) while simultaneously leading to an upper bound to the energy. The functionals are thereby normalized and automatically satisfy the electron-nucleus coalescence condition. The functionals psi[chi] are also constructed to satisfy the electron-electron coalescence condition. The method is applied to the ground state of the helium atom to construct functionals psi[chi] that reproduce the density as given by the Kinoshita correlated wave function. The expectation of single-particle …

College Senate Minutes November 3, 2011, Bronx Community College Senate

BCC Governance Archives

Minutes for the meeting of the College Senate on November 3, 2011.

Migration And Invasion Of Brain Tumors, Richard A. Able, Jr., Veronica Dudu, Maribel Vazquez

Publications and Research

Recent advances in molecular biology have led to new insights in the development, growth and infiltrative behaviors of primary brain tumors (Demuth and Berens, 2004; Huse and Holland, 2010; Johnson et al., 2009; Kanu et al., 2009). These tumors are derived from various brain cell lineages and have been historically classified on the basis of morphological and, more recently, immunohistochemical features with less emphasis on their underlying molecular pathogenesis (Huse and Holland, 2010). The detailed molecular characterization of brain tumors has laid the groundwork for augmentation of standard treatment with patient-specific designed targeted therapies (Johnson et al., 2009; Kanu et …

Undergraduate Research Through Nasa Initiatives, Gaffar Gailani, Sidi Berri, Nieves Angulo

Publications and Research

There was a common belief that research should only be introduced at the graduate level or at least the senior undergraduate year. Research in the freshman year was not even a topic for discussion. Today, throughout the City University of New York, colleges are stepping forward and conducting research at all undergraduate levels and achieving good results. Conducting research as part of an internship or with a faculty member, proved to be one of the most effective ways to enhance the skills of the students in STEM by many authors. The department of Mechanical Engineering and Industrial Design Technology at …

Committee On Academic Standing Minutes October 26, 2011, Bronx Community College Committee On Academic Standing

BCC Governance Archives

Minutes for the meeting of the Committee on Academic Standing on October 26, 2011.

Fabrication Of Size-Tunable Metallic Nanoparticles Using Plasmid Dna As A Biomolecular Reactor, Jacopo Samson, Irene Piscopo, Alex Yampolski, Patrick Nahirney, Andrea Parpas, Amit Aggarwal, Raihan Saleh, Charles Michael Drain

Publications and Research

Plasmid DNA can be used as a template to yield gold, palladium, silver, and chromium nanoparticles of different sizes based on variations in incubation time at 70 °C with gold phosphine complexes, with the acetates of silver or palladium, or chromium acetylacetonate. The employment of mild synthetic conditions, minimal procedural steps, and aqueous solvents makes this method environmentally greener and ensures general feasibility. The use of plasmids exploits the capabilities of the biotechnology industry as a source of nanoreactor materials.

Committee On Academic Standing Minutes October 12, 2011, Bronx Community College Committee On Academic Standing

BCC Governance Archives

Minutes for the meeting of the Committee on Academic Standing on October 12, 2011.

The Communicator, October 10, 2011, Bronx Community College

The Communicator

The Communicator newspaper published on October 10, 2011.

Dissemination Of Geological Information In Avoiding Geotechnical Risks Associated With Tunnel Construction: Lessons Learned From Deep Voids In Marble In Lower Manhattan, New York City, Nazrul I. Khandaker, Stanley Schleifer, Masud Ahmed, Leah Scott

Publications and Research

Test boring associated with the recently accomplished City Water Tunnel # 3 in Manhattan, New York City revealed moderately to highly weathered marble with insoluble silicate residues composed mostly of phlogopite, chlorite, and tremolite. Apparent control on the weatherability of the marble was in response to original mineral constituents dominating this lithology. Encountered marble samples ranged between pure calcitic to mixed dolomitic/siliceous types. Fresh marble samples collected from adjacent boring locations revealed characteristic geochemical data: Lime (25-45%), Silica (4-7%), Alumina (1-3%), MgO (5-20%), and LOI (35-42%); compressive strength of unweathered marble varied between 2000-3000 Kg/cm². Relict foliations with …

Unbound (Bioavailable) Igf1 Enhances Somatic Growth, Sebastien Elis, Yingjie Wu, Hayden-William Courtland, Dara Cannata, Hui Sun, Mordechay Beth-On, Chengyu Liu, Hector Jasper, Horacio Domené, Liliana Karabatas, Clara Guida, Jelena Basta-Pljakic, Luis Cardoso, Clifford J. Rosen, Jan Frystyk, Shoshana Yakar

Publications and Research

SUMMARY Understanding insulin-like growth factor-1 (IGF1) biology is of particular importance because, apart from its role in mediating growth, it plays key roles in cellular transformation, organ regeneration, immune function, development of the musculoskeletal system and aging. IGF1 bioactivity is modulated by its binding to IGF-binding proteins (IGFBPs) and the acid labile subunit (ALS), which are present in serum and tissues. To determine whether IGF1 binding to IGFBPs is necessary to facilitate normal growth and development, we used a gene-targeting approach and generated two novel knock-in mouse models of mutated IGF1, in which the native Igf1 gene was replaced by …