bluuebunny/crossref_metadata_2025 huggingface dataset:
The Tyranny of Judicial Formalism: Oral Directives and the
Clear and Convincing Evidence Standard
Authors: RICH BEN A.
Published: November 2002

A decision by the Supreme Court of California in the case
Conservatorship of Wendland, issued in August 2001, forces
us once again to confront the all-too-common situation in which
an individual has, on multiple occasions, expressed strongly
held personal convictions about life-sustaining interventions
but failed to incorporate those convictions into a formal advance
directive. Many courts have recognized that lay citizens do
not consistently resort to written legal formalities in their
day-to-day lives, and reasonable accommodation must be made
to this fundamental fact about human nature. However, a small
but apparently growing minority of courts adamantly insist on
either formal written directives or prescience and prophetic
precision on the part of the patient before a surrogate can
direct the withdrawal of life-sustaining treatment. The chronology
of cases that comprise this minority position in American medical
jurisprudence raise important ethical issues.
Reflections
Authors: THOMASMA DAVID C.
Published: November 2002

Can it be already 30 years since the first days of modern,
secular bioethics? As those of us in the field for almost all
these years arrive near the end of our careers, we find that
time has truly flown and the challenges have not diminished
one bit. If anything, they are even greater than in the early
years. Along the way it was tempting to think that the broad
consensus reached on research ethics, on the four principles,
on the need for consent in clinical ethics, and then on rights
in reproduction and dying, would paint the picture rather well.
Only fill-in would be needed by the apprentices coming afterward.
Yet time and again new biological and medical discoveries continued
to challenge that painting. A new canvas had to be hung. Among
the major newer developments were the challenges of healthcare
reform, genetics, antifoundationalism, the certification of
ethics consultants, and now, the internationalization of bioethics,
its relationship to the environment and world politics, and
biotechnology.
Van Rensselaer Potter: A Memoriam
Authors: LOWER GERALD M.
Published: November 2002

I first met Van Potter nearly 40 years ago when I was 17 and
entering the University of Wisconsin as a new freshman. During
the summer of 1963, Van was a participant in a series of evening
seminars designed to familiarize premed students to the community
at the University of Wisconsin Medical School. I was immediately
struck by Van's unique ability to cut straight to the core
of virtually any issue having to do with biomedicine. As with
many of his students, I quickly found myself in a father-son
relationship of both our making. Van has been a source of
inspiration and guidance to me ever since.
Van Rensselaer Potter: An Intellectual Memoir
Authors: WHITEHOUSE PETER J.
Published: November 2002

Van Rensselaer Potter was the first voice to utter the word
“bioethics,” yet he is too little appreciated by
the bioethics community. My expectations for my first visit
with Professor Van Rensselaer Potter were primed by conversations
with leaders and historians of the field of biomedical ethics,
including Warren Reich, Al Jonsen, and David Thomasma. When
mentioning my interest in environmental ethics and my concerns
for the current state of biomedical ethics, I was told that
I must meet Van. On my first visit to Madison, Wisconsin, Van
met me at the McArdle Laboratories for Cancer Research at the
University of Wisconsin, where he spent essentially his entire
academic career as a basic oncological researcher. He was dressed
informally and driving a rusting1984 Subaru station wagon with
a license plate that read YES ZPG. We spent this first portion
of our visit at the Institute where he is an Emeritus Professor
and has contributed to understanding cancer metabolism as
recognized by his election to the National Academy of Sciences.
However, Van felt most at home in his shack located outside
Madison. This country retreat included a rather primitive hut
surrounded by acres of property owned by the family. I felt
at the heart of Van's world when I sat in one of a pair
of inexpensive plastic outdoor chairs in a particularly secluded
part of the woods on the property, the place where Van himself
communed with nature.
The Birth of Bioethics: Autobiographical Reflections of a
Patient Person
Authors: VEATCH ROBERT M.
Published: November 2002

The single most important intellectual event in my career in
medical ethics occurred the day I realized that the Hippocratic
ethic for medicine was not merely outdated and irrelevant but actually
in conflict with all the dominant religious and secular moral traditions
of our day. Whether one stood in any of the great modern religious
traditions or in any of the camps of secular philosophy—the
liberal tradition of political philosophy, Marxism, or more
recent feminist or communitarian views—the Hippocratic
ethic was wrong, both metaethically (epistemologically) and
normatively.
Harmless Error and Other Forays into Bioethics
Authors: PARIS JOHN J.
Published: November 2002

How does a self-described “simple teacher of religion”
at the College of the Holy Cross get involved in bioethics? Nothing in
my training or experience had prepared me for involvement in medicine.
Much like that of my moral theology professor and then mentor, Richard
McCormick, my training was in moral theology and social ethics. I also
had an abiding interest in the courts and constitutional law. That
interest led to a doctoral dissertation at the University of Southern
California's Program in Social Ethics on “The Supreme
Court's Understanding of Religion in Conscientious Objector
Cases.” Interestingly, doctoral work in the late 1960s on the
ethical dimension of war was the starting point for other ethicists
such as Leroy Walters and James Childress who subsequently became early
voices in bioethics.
The Accidental Bioethicist
Authors: McCULLOUGH LAURENCE B.
Published: November 2002

Albert Jonsen in The Birth of Bioethics notes that
his career in bioethics began with a phone call to him from
soon-to-be colleagues at the University of California at San
Francisco Medical Center. Bioethics didn't begin with a
bang but as an accident in the root sense—something that
happened, not by necessity, but rather by chance. Indeed, the opening
chapters of Jonsen's book chronicle a series of accidents that
helped to create the field of bioethics. Principal among these was
the fact that physicians and biomedical scientists who became puzzled
about the moral dimensions of their work and began to think about
these puzzles sought help in doing so from moral theologians
and philosophers. These physicians and scientists, for the most
part, were university people. They thought broadly, not just
deeply, about their work, but they just as well could have defined
themselves by their academic discipline and departments and
not reached beyond these familiar and comfortable intellectual
confines to the “culture” of the humanities disciplines
and departments. The theologians and philosophers whom these
physicians and scientists sought out were also university people
who also happened to have generous views of the intellectual
life in their disciplines—atypical of the time, especially
in philosophy. If C. P. Snow had been altogether right and if
ungenerous self-understanding of their work by physicians, scientists,
philosophers, and theologians had prevailed, bioethics might not have
happened at all.
From Metaethicist to Bioethicist
Authors: BAKER ROBERT
Published: November 2002

I was the graduate student that Albert Jonsen so aptly describes.
Bronx born and educated at the City College of New York, I
emigrated to the Midwest to study at the Minnesota Center for
the Philosophy of Science, where May Brodbeck, Herbert Feigl
and other “logical positivists” were engaging in
an ongoing dialogue with postpositivists like Paul Feyerabend
and Karl Popper. In this environment, I studied philosophy of
science, epistemology, and metaethics—the epistemology
and logic of ethical concepts and language. I even wrote my
thesis on the ur-text of the metaethical turn, G. E. Moore's
Principia Ethica. Then, like other epistemologists
and metaethicists, “a public disaster, the American military
involvement in Southeast Asia,” as well as the burgeoning civil
rights movement, drew me into the sphere of public debate.
As Time Goes By: Twenty-five Years of Bioethics
Authors: O'ROURKE KEVIN
Published: November 2002

Like Saint Paul, I was “born out of due time”
insofar as the study of bioethics is concerned. (Incidentally,
I prefer the term “healthcare ethics” to
“bioethics” because the discipline in question
addresses issues more far-reaching than medical issues, such
as downsizing access to healthcare.) I spent 15 years in teaching
and administration at the Aquinas Institute of Theology, then
in Dubuque, Iowa, now on the campus of Saint Louis University.
I was given a sabbatical study year in 1972–1973 to refresh
my mind and spirit. Though my major study and research emphasis
prior to the sabbatical study had been in the field of Church
law and religious government, I determined to direct my attention
to the study of moral theology and ethics, because at that time
there was confusion in this area of discipline, especially insofar
as the Catholic community was concerned. With this in mind,
I chose the University of Chicago as the locale for my study
and was awarded a postdoctoral fellowship.
Bioethics: Past, Present, and an Open Future
Authors: LOEWY ERICH H.
Published: November 2002

The history in which bioethics developed is well reviewed in
a recent book written by Al Jonsen. This superb little volume gives
a concise—even if a necessarily rather subjective—account
of the development of the field. A more objective history of the
contemporary development of the field cannot be expected from those
who helped craft it and awaits historians of the future. What I have
been asked to do here is to supply my own personal impressions of the
development of this field as I have experienced it. What I have been
asked to do here is to supply my own personal impressions of the
development of this field as I have experienced it.
Reproductive Technologies as Instruments of Meaningful
Parenting: Ethics in the Age of ARTs
Authors: HESTER D. MICAH
Published: November 2002

Since the decade of the 1970s, and particularly since the first
successful test-tube baby in 1978, the development and use of assisted
reproductive technologies (ARTs) have grown exponentially. Would-be
parents—including those in so-called traditional male-female
marriages, unmarried adults, postmenopausal women, and same-sex
partnerships—who just over 20 years ago had no recourse for
their (in)fertility issues can now pursue their desires to have children
with at least a partial, if not, total, genetic and/or biological
relationship. Ovulation-stimulating medications, artificial
insemination using the sperm of a husband or unrelated donor
(AIH or AID, respectively), in vitro fertilization with embryo
transfer (IVF-ET), intracytoplasmic sperm injection (ICS), and
gamete and zygote intrafallopian transfers (GIFT and ZIFT) are
but a few of a host of treatment options ranging in complexity,
invasiveness, and expense. And on the horizon are genetic techniques
such as cloning—which was once considered “pure”
science fiction but in 1997 became what some call an inevitability,
with the development of mammalian cloning in the form of the now-famous
(if not infamous) Dolly the sheep.
Of Terrorism and Healthcare: Jolting the Old Habits
Authors: TROTTER GRIFFIN
Published: November 2002

Old habits die slowly. Hence there is little surprise that
attorneys fashioning the Model State Emergency Health Powers
Act preserved much of their own standard operating procedure.
This model statute was designed for the worst of times—for
horrific scenarios in which terrorism, infectious disease, or
natural calamity threaten to derail the machinery of civilization
while snuffing out thousands or even millions of human lives.
Such grave threats seem to justify grave measures aimed at
restoring order and maximizing survival. So, the model statute
bestows sweeping power on state governors and public health
officials, allowing them to seize private property, obtain clinical
services through impressment, and enact quarantine and isolation
measures without the usual due process. Yet amid all these drastic
measures, certain standards persist.
Reflections on a Hospice Memorial Service
Authors: Heilig Steve
Published: November 2002

It's a chilly winter night outside, but very warm inside
the hospice guest house. All of the people gathered here have
wished one another “Happy New Year” and settled
on cushions in the big meeting hall. Both fireplaces are lit,
and the many little white cards with the names of each person
who died last year are arranged on the mantels over the fireplaces
and on a table in the center of the room. Paul, our teacher
for the evening, says a few simple and wise words about
impermanence and about being of service and then explains
tonight's process: we, the volunteers in attendance, will
pick up the cards, either by choosing a specific patient's
name or at random, and take them one by one to the fires, dropping
them in and saying something about each deceased person. The
idea is to hear a litany of names being remembered and honored
and sent onward as volunteers flow steadily to and from the
fireplaces.
Return to Reason, by Stephen Toulmin. Cambridge,
MA: Harvard University Press, 2001. 243 pp. $24.95.
Authors: Scofield Giles
Published: November 2002

If you buy and read only one book this year, make it this one.
Then, after you read and reread this book, buy and read, if
you have not done so already, it's prequel, Cosmopolis.
When you've done that you may find yourself wondering one
thing and worrying about another (at least, where medical ethics
is concerned). Why do we hear so little about Montaigne and
Wittgenstein? And why do we bother so much with Descartes and
his followers? Did philosophy take a wrong turn somewhere? Has
ethics gone in one direction, philosophy in another? Did we
moderns zig, when we could, and should, have zagged?
“Whose Bureaucracy Is This, Anyway?” Congress' 1946
Answer
Authors: Rosenbloom David H.
Published: November 2002

“Nor should we omit in our study [of public administration] the
problem of legislative-administrative relations, in view of the
increasing role of the public servant in the determination of
policy, through either the preparation of legislation or the making
of rules under which general legislative policy is given meaning and
application” (Gaus 1931, 123).

In the title of his 1993 Gaus Award Lecture, Francis Rourke posed the
deceptively simple question, “Whose Bureaucracy Is This, Anyway?”
His subtitle was “Congress, the President, and Public
Administration.” Rourke, a pioneer in the field of bureaucratic
politics, concluded that federal administration was constitutionally
and politically under the “joint custody” of Congress and the
president. Clearly, Congress has formidable constitutional authority
and responsibility for the structure and operation of the executive
branch. A great deal of political science research demonstrates that
the legislature and its committees are a major political force in
federal administration. Even as the older “iron triangle” model
gives way to newer approaches, no one (other than misguided
reformers) could reasonably answer Rourke's question and exclude
Congress. Its oversight, influence, and intervention in agency
operations on behalf of policy objectives and incumbency are central
features of contemporary federal administration.
“Area Studies” and the Discipline: Towards New
Interconnections
Authors: Harbeson John W. , McClintock Cynthia , Dubin Rachel
Published: November 2002

This collection of rich, provocative essays heralds a new opportunity
for the reinvigoration of political science. Our premise, and the
premise of our essayists, is that the term “area studies” is a
misnomer. The political scientists whose works have focused on
specific world regions have yielded significant theoretical and
conceptual contributions for the discipline, both in the past and in
the present.
Area and Regional Studies in the United
States
Authors: Katzenstein Peter J.
Published: November 2002

Area studies in the United States is under siege. Government and
foundations are turning their attention and funds elsewhere.
Although they operate from very diffrent quarters, critics are
taking area studies harshly to task for both alleged errors of
commission and omission. Yet mine is an optimistic message. These
difficulties must be seen within the context of a change in the
demographic composition of graduate studies in the U.S. An infusion
of intellectual energy from foreign graduate students and post-docs
is leading to a reinvention of traditional area studies as global
networks of scholarly engagement. Over the longer term these
networks, and the scholarship they will create and sustain, bode
well for the continued intellectual vitality of this field of
scholarship.
Africanists' Contributions to POlitical
Science
Authors: Hyden Goran
Published: November 2002

In this brief overview, I argue that Africanist contributions to the
study of politics have not been insignificant. While Africanists,
like many other comparativists, have felt uncomfortable about the
imperialist aspirations of rational choice, they increasingly see
the future as a time when theoretical and methodological pluralism
will prevail.
The Middle East
Authors: Hudson Michael C.
Published: November 2002

For political scientists studying the Middle East, the invitation to
discuss the possible relevance of their work to comparative politics
in general is a welcome and rare opportunity. There is, one senses,
a gap between the Middle East political science community and the
mainstream disciplinary generalists. To the extent that they even
care about being part of the field, some Middle East political
scientists feel ghettoized—their region and their work are ignored.
Some feel as well that mainstream comparative politics theorizing
has not offered much toward better understanding to Middle East
politics. Such concerns motivated the establishment of the
Conference Group on the Middle East, which organizes sessions in
conjunction with, yet separate from, the main program at the APSA
Annual Meeting. It is noteworthy that some of the most imaginative
recent work on Middle East politics draws from anthropology,
political economy, social history, and critical cultural and
literary theory. “The Middle East political science community” is
not populated exclusively by political scientists.
Asia Studies and the Discipline
Authors: Pye Lucian W.
Published: November 2002

I begin with three general points about the relationship of area
studies to political science, before turning to the specific
contributions that Asia and China studies have made in advancing
knowledge in political science.
Latin America
Authors: O'Donnell Guillermo
Published: November 2002

It took some gentle prodding from professors Cynthia McClintock and
John Harbeson, conveners of this session, to persuade me to
participate. The reason for my reluctance may be obvious,
considering the composition of this panel. My distinguished
colleagues can speak about “them” when referring to the
contributions of scholars from the regions on which they specialize.
This, I gather, allows them some degree of objectivity when
summarizing and assessing the works of their colleagues in the
respective regions; instead, when I analyze the contributions of
Latin Americans, I analyze “us.”
Census 2000–Epilogue
Authors: Brunell Thomas L.
Published: November 2002

Census 2000 is over; the debate over adjusting the census is not. In
this essay I respond to a number of points from Anderson and
Fienberg (2001) and report some of the results from Census 2000.
Active Learning in Comparative Politics: A Mock German
Election and Coalition-Formation Simulation
Authors: Shellman Stephen M.
Published: November 2002

Instructors constantly encourage students to learn and process
information. Brock and Cameron assert, “Individuals process
information, learn concepts, and solve problems in different ways”
(1999, 251). Some students learn by listening, others learn by
taking notes, more learn by seeing, and still others learn by doing
and saying. Yet in many college class-rooms, the dominant teaching
method is the traditional lecture. While lecturing may be a
necessary teaching technique, it is often insufficient for teaching
a large number of students with varying learning preferences.
Actions Do Speak Louder than Words:
Deterring Plagiarism with the Use of Plagiarism-Detection
Software
Authors: Braumoeller Bear F. , Gaines Brian J.
Published: November 2002

Introduction

In recent years, the availability of online source material and
online papers has increased instructors' concerns regarding
plagiarism in the classroom. Many instructors do not realize,
however, that the digital revolution has also created a niche for
fast and (at least somewhat) reliable plagiarism-detection
software.
Constructing the Prospectus
Authors: May Peter J.
Published: November 2002

I am struck by how similar the process of constructing a prospectus
is to developing plans for a new house. One starts with a desired
plot of land and an uncertain vision of an eventual home. The plot
of land is terrain to exploit. The vision is of something to be
comfortable with and, ideally, something of which to be proud.
Getting there, however, is a very bewildering process. An
architectural plan and specifications serve as the blueprint—the
prospectus—that provides the basis for approval for moving ahead.
The chief concerns on the part of the permit reviewers is whether
“it will stand up” and whether it meets appropriate planning and
construction criteria. The chief concerns of the prospective owner
are: “How much will it cost?” “Can it be built within a reasonable
amount of time?” and, “Will it look good enough when done?”
The “Rights” of Passage
Authors: Farrar-Myers Victoria A.
Published: November 2002

You are feeling relief that your coursework is drawing to a close.
You have become somewhat competent at going to class, discussing
materials, and passing tests. However, you have a sense of dread
that keeps creeping up on you every time you try to think of “the
topic” for your dissertation. You look to the senior graduate
students and even ask them questions about how they found their
topic. Divine revelation seems to have hit them and you wonder when
your turn will come. But they seem to be all-knowing, more like
budding faculty now than one of you. So you try to fight the notions
of self-doubt about whether you can actually find a topic and start
the quest of finding someone to help you. You naturally turn to the
professor whom you “know the best.” Is this the right choice? No one
seems to know; you just have this sense that you want to complete
the process as painlessly as possible. As questions swirl inside
your head—from how to choose an advisor to what might be the right
way to pick a dissertation topic—you may ask yourself what the
process of writing your dissertation proposal will really be
like.
Proposing a Dissertation with a Free Rein
Authors: den Dulk Kevin R.
Published: November 2002

Any Ph.D. knows that developing a basic statement of dissertation
ideas rarely begins or ends with the formal proposal. In a sense
dissertators never stop “proposing.” Throughout the process of data
gathering and writing, they must make sense of new ideas and
information, contend with theoretical and empirical dead ends,
address the suggestions (or demands!) of advisors and committees.
Nevertheless, the aspiring Ph.D. must start somewhere, and finding a
starting point depends on one's own aptitudes and interests and the
expectations of the scholars who will ultimately assess one's work.
All of these may vary widely.
Everything You Always Wanted to Know about Getting and
Keeping a Job at a Private Liberal Arts College, but Your Graduate
Advisor Didn't Tell You
Authors: Deardorff Michelle Donaldson , Githens Marianne , Halva-Neubauer Glen , Hudson William , Reeher Grant , Seyb Ronald
Published: November 2002

The irony was so striking that it could not be lost on anyone.
Sitting before us was a soon-to-be-minted Ph.D. candidate whom we
all liked tremendously, and who had an incredibly strong academic
record, both in research and teaching. Yet, as our panel read his
letter of application and CV, which were displayed on an overhead
projector, and as we discussed them in progressively greater detail
and honesty, we found several aspects of his materials off-putting.
Why did he phrase something THIS way, another THAT way, we asked
him? Sometimes his decisions were driven by a concern he need not
have had; other times he was being advised by his graduate
department. We ended by agreeing tat although he SHOULD have been
given a job interview, our hypothetical search process might have
passed him over for inclusion on our short list.
Nonlinear intensity dependence in the infrared multiphoton excitation and dissociation of methanol pre-excited to different energies
Authors: Boyarkin Oleg V. , Rizzo Thomas R. , Rueda David , Quack Martin , Seyfang Georg
Published: November 2002

We report quantitative dissociation yields for the reaction CH3OH (vOH)→ lim nhνCH3+OH induced by infrared multiphoton excitation of methanol pre-excited to various levels of the OH stretching vibration (vOH=0, 1, 3, 5). The yields are measured by detecting OH using laser induced fluorescence. It is demonstrated that for low levels of pre-excitation (vOH=0, 1, 3) there is a substantial nonlinear intensity dependence, as a higher yield is found for self mode-locked CO2 laser pulses (with higher peak intensity) as compared to single mode pulses of the same laser fluence, but lower peak intensity. In contrast, at high levels of preexcitation (vOH=5) this nonlinear intensity dependence is absent. Quantitative model calculations are carried out using a case B/case C master equation approach that takes nonlinear intensity dependence into account. The calculations are consistent with the experimental results and confirm the prediction that an important part of the selectivity of the CO2 laser excitation step in infrared laser assisted photofragment spectroscopy of CH3OH is due to this nonlinear intensity dependence. We discuss further consequences of these experimental observations and theoretical predictions, which are also extended to infrared multiphoton excitation of C2H5OH. Infrared (C–O) chromophore band strengths are reported for CH3OH and C2H5OH.
The behavior of an epoxy resin under one-dimensional shock loading
Authors: Millett J. C. F. , Bourne N. K. , Barnes N. R.
Published: November 2002

The response of an epoxy resin has been investigated using the methods of plate impact to generate planar shock waves. In particular, the Hugoniot, both in stress–particle velocity and shock velocity–particle velocity space, and the variation of shear strength with impact stress, have been investigated. Comparison of the results of this investigation with those of previous workers shows good agreement. Measurements of lateral stress, which have been used to determine the shear strength have indicated that shear strength increases with longitudinal stress in the range investigated. Further, lateral stresses have been shown to decrease behind the shock front, implying an increase of strength of this material during shock loading. It would seem possible that this is a manifestation of the viscoplastic nature of epoxy based resins.
Au-II 282 nm segmented hollow-cathode laser-parametric studies and modeling
Authors: Bánó G. , Szalai L. , Horváth P. , Kutasi K. , Donkó Z. , Rózsa K. , Adamowicz T. M.
Published: November 2002

Laser operation on the Au-II 282.3 nm ultraviolet transition is obtained using a high-voltage segmented hollow-cathode discharge tube. The metal vapor is produced by means of cathode sputtering. A small amount of argon is added to the helium buffer gas in order to achieve higher sputtering yield. Measurements of the laser power and small signal gain indicate that the optimal partial concentration of argon is in the range of 0.25%–0.75%. Quasi-continuous wave output power of 100 mW is obtained from a 34-cm-long active region while the highest small-signal gain is 52% m−1. To explain the basic features of the laser operation we present a model of the segmented hollow-cathode discharge. All the discharge characteristics are calculated in a self-consistent way except the temperature of slow electrons. The trajectories of fast electrons emitted from the cathode are followed by Monte Carlo simulation. Rate equations of ion, metastable and metal atom densities are solved in the negative glow, while another Monte Carlo code is applied for the fast heavy particles in the cathode sheath. The spatial distribution of the gas temperature and the thermalization of sputtered metal atoms are calculated as well. The laser characteristics predicted by the model are in reasonable agreement with the experimental results.
Room temperature optical gain in CdSe nanorod solutions
Authors: Link Stephan , El-Sayed Mostafa A.
Published: November 2002

We have performed femtosecond transient absorption measurements on CdSe nanorods in hexane solution as a function of pump wavelength and pump intensity. We found that although it is not possible to achieve optical gain when pumping at energies (400 nm) high above the band-gap energy, this problem can be circumvented by pumping the CdSe nanorods directly at the lowest 1S transition. We attribute the difference to alternative relaxation pathways and possibly trapping, resulting in a competing induced absorption below the band-gap energy when excitation is carried out at high energies. Our results suggest that it is possible to achieve stimulated emission from CdSe nanoparticles in solution at ambient temperature if the excitation wavelength is chosen properly.
Selective growth and associated faceting and lateral overgrowth of GaAs on a nanoscale limited area bounded by a SiO2 mask in molecular beam epitaxy
Authors: Lee S. C. , Malloy K. J. , Dawson L. R. , Brueck S. R. J.
Published: November 2002

We report homoepitaxial selective growth of GaAs on a 350 nm period two-dimensional SiO2-patterned substrate by molecular beam epitaxy. Ga atoms are largely desorbed from a SiO2 surface at high growth temperature (≳615 °C) when the Ga flux is about 0.1 monolayer/s. Under these conditions, a GaAs epilayer selectively grown in circular openings on GaAs(100) with a diameter of about 120–200 nm bounded by a 40 nm thick SiO2 mask shows faceting over its entire surface for 100 nm thick deposition. Lateral growth associated with faceting over the SiO2 mask in 〈100〉 is observed.
Depth profile study of ferroelectric PbZr0.2Ti0.8O3 films
Authors: Li Y. , Nagarajan V. , Aggarwal S. , Ramesh R. , Salamanca-Riba L. G. , Martı́nez-Miranda L. J.
Published: November 2002

We have performed depth profile studies of the structure of PbZr0.2Ti0.8O3 films of different thicknesses deposited on SrTiO3 substrates prepared by pulsed laser deposition, using grazing incident x-ray scattering (GIXS). The in-plane structure of the films reveals these consist of up to three domains, one c-axis domain, and two a-axis domains, denoted a1 and a2. GIXS measurements show the evolution of in-plane compression of the lattice parameter as a function of depth within the films, particularly in the a1 domains. This strain evolution is accompanied by the presence of twist grain boundaries in the plane in some films. The measured in-plane lattice parameters are asymmetric, which suggests an orthorhombic distortion of the lattice in the plane of the films.
Investigations into the fragmentation and ionization of highly excited La@C82
Authors: Lassesson A. , Mehlig K. , Gromov A. , Taninaka A. , Shinohara H. , Campbell E. E. B.
Published: November 2002

We report the first measurements of delayed ionization of the metallofullerene La@C82. When highly excited in laser desorption, La@C82 was found to ionize over several microseconds. The rate of delayed ionization of La@C82 was compared to C60 under the same extraction conditions, and found to be significantly different. A theoretical model was used for the fitting of the ion signal of the two fullerenes. The metallofullerene results can be fitted well over a time window <30 μs and are consistent with a low ionization potential (6.3 eV) and a high radiative cooling rate. The C60 data cannot be fitted over the same time window, indicative of an additional time-dependent competing decay channel.
Ferroelectricity of one-axis-preferred-oriented polycrystalline Pb(Zr,Ti)O3 films prepared by pulsed-metalorganic chemical vapor deposition
Authors: Funakubo Hiroshi , Aratani Masanori , Oikawa Takahiro , Tokita Kouji , Saito Keisuke
Published: November 2002

(100)- and/or (001)-preferred-oriented and (111)-preferred-oriented polycrystalline Pb(Zr,Ti)O3 (PZT) films with Zr/(Zr+Ti) ratios of 0.35 and 0.62, corresponding to tetragonal and rhombohedral PZT, respectively, were compared with that of epitaxially grown ones with the same composition and similar orientation from the viewpoint of crystal structure and ferroelectricity. (100)- and/or (001)-preferred-oriented and (111)-preferred-oriented polycrystalline PZT films were deposited on (111) Pt/Ti/SiO2/Si substrates at 580 and 415 °C, respectively, by pulsed-metalorganic chemical vapor deposition (pulsed MOCVD). On the other hand, epitaxially grown PZT films with the same composition and similar orientation were deposited on SrRuO3‖SrTiO3 substrates at 580 °C also by pulsed MOCVD. The difference in ferroelectricity between the polycrystalline and epitaxial films was found to be mainly due to the film composition rather than to the film orientation. Polycrystalline tetragonal PZT films deposited by pulsed MOCVD showed almost the same remanent and saturation polarizations (Pr and Ps) as the epitaxially grown ones corrected for film orientation even though the films were deposited at a low temperature of 415 °C. Moreover, the coercive field (Ec) values were almost the same. On the other hand, the polycrystalline rhombohedral films showed almost the same Ps value as the epitaxially grown ones, but their Pr value was smaller than that of the epitaxial ones. Moreover, the Ec value of the polycrystalline films was smaller than that of epitaxially grown ones. The difference in ferroelectricity between tetragonal and rhombohedral PZT is strongly related to the film composition’s dependence on the domain wall stability when the electric field is released.
Viscous modes in two-phase mixing layers
Authors: Yecko Philip , Zaleski Stéphane , Fullana Jose-Maria
Published: November 2002

The temporal instability of parallel viscous two-phase mixing layers is studied by adopting a composite error function flow profile such that boundary layers in each fluid sandwich the interface. Linear spectra and neutral stability curves are calculated numerically and the effects of varying the density ratio, viscosity ratio and Weber number are presented. In addition to the interfacial mode two Tollmien–Schlichting type modes are found and attributed to the presence of the two viscous boundary layers. This is important because it is shown that any of these three modes may be the most unstable, depending on parameter values. Mode multiplicity and competition has not yet been thoroughly explored for this problem even though it is essential to the analysis of experiments and to further stability study of flows relevant to breaking up of interfaces.
Multiple-quantum nuclear magnetic resonance spin dynamics in disordered rigid chains and rings
Authors: Doronin Serge I. , Fel’dman Edward B. , Lacelle Serge
Published: November 2002

Multiple-quantum (MQ) nuclear magnetic resonance (NMR) spin dynamics are investigated in rigid linear chains and rings with nearest neighbor dipole–dipole interactions with different coupling constants due to spatial disorder. It is shown that MQ NMR spectra, for such one-dimensional systems initially at thermal equilibrium followed by evolution under a 2-quantum/2-spin average dipolar Hamiltonian, only consist of 0- and 2-quantum coherences. A new constant of motion for the systems under consideration is found and used in the numerical analysis of MQ NMR spin dynamics to factorize the Hamiltonian into distinct blocks corresponding to different eigenvalues of the constant of motion. Only one of these blocks of dimension N×N (where N is the number of spins) completely determines the MQ NMR spin dynamics. Supercomputer calculations of MQ NMR spin dynamics in rigid linear chains containing up to 1000 spins are presented. The possibility to obtain structural information from the time evolution of MQ coherences is also discussed.
Subgrid-scale energy and pseudo pressure in large-eddy simulation
Authors: Knaepen B. , Debliquy O. , Carati D.
Published: November 2002

A dynamic model based on the Germano identity is proposed to evaluate the subgrid-scale energy in large-eddy simulations as a function of the large-scale velocity field only. The model is shown to allow the satisfactory reconstruction of the total energy contained in a direct numerical simulation from large-eddy simulations with different resolutions. The predicted subgrid-scale energy is given as a simple algebraic expression based on the Leonard tensor appearing in the dynamic procedure and does not require an additional transport equation. The model assumes a Kolmogorov spectrum and is implemented with and without the introduction of a dissipation cutoff in the high wave vector range.
A linear approach for the evolution of coherent structures in shallow mixing layers
Authors: van Prooijen Bram C. , Uijttewaal Wim S. J.
Published: November 2002

The development of large coherent structures in a shallow mixing layer is analyzed. The results are validated with experimental data obtained from particle tracking velocimetry. The mean flow field is modeled using the self-similarity of the velocity profiles. The characteristic features of the down-stream development of a shallow mixing layer flow, like the decrease of the velocity difference over the mixing layer, the decreasing growth of the mixing layer width, and the transverse shift of the center of the mixing layer layer are fairly well represented. It turned out that the entrainment coefficient could be taken constant, equal to a value obtained for unbounded mixing layers: α=0.085. Linearization of the shallow water equations leads to a modified Orr–Sommerfeld equation, with turbulence viscosity and bottom friction as dissipative terms. Growth rates are obtained for each position downstream, using the model for the mean flow field. For a given energy density spectrum at the inflow boundary, integration of the growth rates along the downstream direction yields the spectra at various downstream positions. These spectra provide a measure for the intensity and the length scale of the coherent structures (the dominant mode). The length scales found are in good agreement with the measured ones. The length scale of the most unstable mode appears much larger than the length scale of the dominant mode. Obviously, the longevity of the coherent structures plays a significant role. Three growth regimes can be distinguished: in the first regime the dominant mode is growing, in the second regime the dominant mode is dissipating, but other modes are still growing, and in the third regime all modes are dissipating. It is concluded that the development of the coherent structures in a shallow mixing layer can fairly well be described and interpreted by the proposed linear analysis.
The effects of wall proximity on vortex shedding from a square cylinder: Three-dimensional effects
Authors: Bailey S. C. C. , Martinuzzi R. J. , Kopp G. A.
Published: November 2002

The three-dimensional nature of turbulent vortex shedding from a square cylinder in the vicinity of a solid wall is investigated for a Reynolds number of 18 900 as a function of the gap height, S/D. Spanwise surface pressure measurements on the cylinder faces and on the solid wall are complemented by velocimetry data. It is observed that parallel and oblique shedding modes arise naturally. The number of vortex dislocations is clearly related to the variations in the oblique shedding angle. Dislocations occur with increasing probability as the gap height is decreased to S/D≈0.7. The dislocations are strongly associated with Type A instabilities and vortex splitting, which contribute significantly to phase-jitter. For gap heights close to that for vortex shedding suppression (0.5<S/D<0.7), dislocations occur less frequently. The vortex formation process is increasingly two-dimensional in this range, resulting in strong spanwise correlations and lower phase-jitter. These changes are observed as more sharply peaked frequency spectra, which have been interpreted as shedding frequency “tuning” in earlier studies.
Model equations in rarefied gas dynamics: Viscous-slip and thermal-slip coefficients
Authors: Siewert C. E. , Sharipov Felix
Published: November 2002

Various model equations are used to define the viscous-slip and the thermal-slip coefficients in rarefied gas dynamics. More specifically, the BGK model, the S model, the variable collision model and the CES model are used to establish the slip coefficients basic to Kramers’ problem and the half-space problem of thermal creep. While the most general results are developed from use of the Maxwell boundary condition, results for the BGK model and the S model as defined by the Cercignani–Lampis boundary condition are also reported. An analytical discrete-ordinates method is used to establish the reported numerical results, and when available results from a numerical solution of the linearized Boltzmann equation are used as reference values. In addition to the numerical work based on model equations, the important issue of how to define meaningful ways (appropriate mean-free paths) to compare the results for the various models is discussed.
Modeling of glow discharge-induced fluid dynamics
Authors: Shyy W. , Jayaraman B. , Andersson A.
Published: November 2002

Modeling of fluid dynamics and the associated heat transfer induced by plasma between two parallel electrodes is investigated. In particular, we consider a capacitvely coupled radio frequency discharge plasma generator, where the plasma is generated on the surface of a dielectric circuit board with electrode strips on the top and bottom. The electrodes have a thickness of 100 μm, which is comparable to the height of the boundary layer. The regime considered is that the electron component is in the non-equilibrium state, and the plasma is nonthermal. Overall, due to the ion and large fluid particle interaction, the pressure is higher in the downstream of the electrode, causing the velocity structure to resemble that of a wall jet. Parameters related to the electrode operation, including the voltage, frequency, and free stream speed are varied to investigate the characteristics of the plasma-induced flow. Consistent with the experimental observation, the model shows a clear dependence of the induced jet velocity on the applied voltage and frequency. The heat flux exhibited a similar dependence on the strength of the plasma. The present plasma-induced flow concept can be useful for thermal management and active flow control.
Electron-beam dissociation of the MgH complex in p-type GaN
Authors: Myers S. M. , Seager C. H. , Wright A. F. , Vaandrager B. L. , Nelson J. S.
Published: November 2002

The dissociation of the MgH complex in GaN under low-energy electron-beam irradiation (LEEBI) and its reassociation during postirradiation annealing were measured using infrared vibration spectroscopy. The dissociation rate exhibits a pronounced dependence on the H isotope, being about 4 times greater for protium than deuterium. Reassociation occurs at temperatures <200 °C, which may be problematic for device applications of LEEBI. We consider possible reaction paths based on atomic configurations from density-functional theory and bond-excitation mechanisms investigated in surface-desorption studies, thereby arriving at a model of the evolution consistent with the experimental results.
Hydrogen passivation of self assembled InAs quantum dots
Authors: Jacob A. P. , Zhao Q. X. , Willander M. , Ferdos F. , Sadeghi M. , Wang S. M.
Published: November 2002

A systematic study on the hydrogen passivation of nonradiative centers in InAs quantum dot’s grown on GaAs substrates is presented. The samples used in this study were grown by molecular beam epitaxy. The structures contain an InxGa1−xAs insertion layer between the InAs quantum dots layer and the GaAs cap layer. The thickness and In concentration of the InxGa1−xAs are varied to achieve the emission wavelength at 1.3 μm. The samples after the H2 plasma treatment show a significant increase of the photoluminescence intensity. The experimental results show that the quality of the InAs quantum dot structures does not degrade after the hydrogen (H2) plasma treatments. The enhancement of the photoluminescence intensity from the InAs quantum dots is thought to be due to the passivation of nonradiative centers like defects in the structures. High resolution x-ray diffraction rocking curves are used to correlate photoluminescence results.
Effects of ion irradiation on epitaxial Cu/Ni/Cu(001) with perpendicular magnetic anisotropy
Authors: Kim T. G. , Shin Y. H. , Song J. H. , Sung M. C. , Kim I. S. , You D. G. , Lee J. , Jeong K. , Jeon G. Y. , Whang C. N.
Published: November 2002

Epitaxial fcc Cu/Ni(t)/Cu(001) structures (t=20,30,60,90 Å) possessing perpendicular magnetic anisotropy were irradiated by 1 MeV C+ with a dose of 2×1016 ions/cm2. The spin reorientation transitions from perpendicular to in-plane magnetization occurred after ion irradiation. X-ray diffraction measurements showed that the crystal structures were conserved, the grain sizes of Cu in the Cu/Ni(60, 90 Å)/Cu(001) films increased by 38%, and the strain in the Ni layer was relaxed after irradiation when compared to the as-deposited samples. It is concluded that the spin reorientation transition is caused by the relaxation of the strain in Ni layer, which is initiated by ion irradiation.
Improvement in Al2O3 dielectric behavior by using ozone as an oxidant for the atomic layer deposition technique
Authors: Kim J. B. , Kwon D. R. , Chakrabarti K. , Lee Chongmu , Oh K. Y. , Lee J. H.
Published: November 2002

We have prepared Al2O3 films by the atomic layer deposition technique using trimethylaluminum as the precursor for aluminum and O3, instead of commonly used H2O, as an oxidant. We show that even without any postdeposition annealing or any preventive layer between the Al2O3 film and Si substrate to suppress the formation of metallic clusters, the Al2O3 films prepared using O3 have significantly less amount of defect states like Al–Al and OH bonds compared with those prepared by H2O. The films show device quality leakage characteristics, with Al2O3 film prepared with O3 showing a leakage current density one or two orders lower and a smaller flatband voltage shift than that of Al2O3 film prepared with H2O, demonstrating improved interface characteristics. The former also shows a very low wet etch rate.
Quantum dot formation by segregation enhanced CdSe reorganization
Authors: Passow T. , Leonardi K. , Heinke H. , Hommel D. , Litvinov D. , Rosenauer A. , Gerthsen D. , Seufert J. , Bacher G. , Forchel A.
Published: November 2002

The influence of the growth conditions during capping of CdSe/ZnSe quantum structures grown on GaAs(001) by molecular-beam epitaxy (MBE) were systematically investigated by high-resolution x-ray diffraction, transmission electron microscopy, and temperature dependent, partly time-resolved photoluminescence spectroscopy. The results clearly indicate formation of quantum wells with potential fluctuations if conventional MBE is used for capping the CdSe by ZnSe. In contrast, quantum dot formation occurs using migration enhanced epitaxy for this growth step. In the latter case, quantum dots can be obtained without formation of stacking faults.