Application of Biotechnology to Solve Relevant Biological Problems Promotes Understanding of Underlying Concepts

Although some efforts have been made to modify the curriculum of the Introductory Biology laboratories from a passive to a more experimental form, the use of modern biotechnology had not been implemented at our institution. The need to understand the applications of modern technology to real-life situations seems imperative at the turn of the century [1,2]. Because several studies have shown that the study of biotechnology by itself does not increase conceptual understanding, the objective of this research was to determine if the use of biotechnology to solve relevant biological problems increased conceptual understanding among our students. We designed two complex problems: one on the conservation of an endangered Puerto Rican frog, and the other on tropical plant evolution. Two students majoring in Biology-Education participated as research assistants in the design and implementation of the laboratory activities. Graduate biology students who worked as teaching assistants in the laboratories were trained to use equipment and teach the activities. Assessment evidence indicated that students exposed to these experiences: (1) increased biological literacy by understanding the use and application of cutting-edge biotechnology; (2) were able to make connections between organismal and molecular biology; (3) decreased levels of anxiety and insecurity associated with the use of laboratory equipment; and, (4) were motivated to conduct research within and beyond the classroom setting

Elementary Excitations of Quantum Critical 2+1 D Antiferromagnets

It has been proposed that there are degrees of freedom intrinsic to quantum critical points that can contribute to quantum critical physics. We point out that this conclusion is quite general below the upper critical dimension. We show that in 2+1 D antiferromagnets skyrmion excitations are stable at criticality and identify them as the critical excitations. We found exact solutions composed of skyrmion and antiskyrmion superpositions, which we call topolons. We include the topolons in the partition function and renormalize by integrating out small size topolons and short wavelength spin waves. We obtain correlation length exponent nu=0.9297 and anomalous dimension eta=0.3381.Comment: 4 page

Comportamento da atividade canavieira nos Tabuleiros Costeiros da Bahia de 1990 a 2002.

bitstream/item/35097/1/doc-75.pd

Importância e evolução da dendeicultura na região dos Tabuleiros Costeiros da Bahia de 1990 a 2002.

bitstream/item/35099/1/doc-77.pd

Aspectos agroeconômicos da cultura do milho: características e evolução da cultura no Estado da Paraíba entre 1990 e 2003.

bitstream/item/35103/1/doc-80.pd

Caracterização agrossocioeconômica da atividade canavieira no Brasil, distribuição espacial na produção mundial entre 1961 e 2003: situação no Brasil entre 1990 e 2002.

bitstream/item/34634/1/doc-74.pd

Importância econômica e evolução da cultura do cacau no Brasil e na região dos tabuleiros costeiros da Bahia entre 1990 e 2002.

bitstream/item/26593/1/doc-72.pd

Heavy Fermion Quantum Criticality

During the last few years, investigations of Rare-Earth materials have made clear that not only the heavy fermion phase in these systems provides interesting physics, but the quantum criticality where such a phase dies exhibits novel phase transition physics not fully understood. Moreover, attempts to study the critical point numerically face the infamous fermion sign problem, which limits their accuracy. Effective action techniques and Callan-Symanzik equations have been very popular in high energy physics, where they enjoy a good record of success. Yet, they have been little exploited for fermionic systems in condensed matter physics. In this work, we apply the RG effective action and Callan-Symanzik techiques to the heavy fermion problem. We write for the first time the effective action describing the low energy physics of the system. The f-fermions are replaced by a dynamical scalar field whose nonzero expected value corresponds to the heavy fermion phase. This removes the fermion sign problem, making the effective action amenable to numerical studies as the effective theory is bosonic. Renormalization group studies of the effective action can be performed to extract approximations to nonperturbative effects at the transition. By performing one-loop renormalizations, resummed via Callan-Symanzik methods, we describe the heavy fermion criticality and predict the heavy fermion critical dynamical susceptibility and critical specific heat. The specific heat coefficient exponent we obtain (0.39) is in excellent agreement with the experimental result at low temperatures (0.4).Comment: 5 pages. In the replacement, the numerical value for the specific heat coefficient exponent has been included explicitly in decimal form, and has been compared with the experimental result