bluuebunny/crossref_metadata_2025 huggingface dataset:
Gender Differences in Problem Drinking and Depression: Different “Vulnerabilities?”
Authors: Skaff Marilyn McKean , Finney John W. , Moos Rudolf H.
Published: April 2003

This study examines the relationship between stressors and resources and the functioning of a sample of 515 men and women who had a drinking problem. At a one‐year follow‐up, both women and men had improved on three functioning measures: alcohol consumption, days intoxicated, and depression. There were no gender differences at Time 2 on alcohol consumption, but men had more days intoxicated and women had more symptoms of depression. The impact of stressors and resources varied by life domain, functioning criterion, and gender. Although the predictors varied, the amount of variance in depression accounted for was the same for women and men. The most striking gender difference was the stronger impact of friendships for women on all aspects of functioning. This study provides support for reconsideration of the stress vulnerability of women and men.
A Simple, Unified Approach to Bayesian Risk Calculations
Authors: Hodge Susan E.
Published: April 2003

A simple, unified approach for calculating Bayesian risks is presented and illustrated with examples. Although new genetic tools have reduced the need for these risk calculations, situations still exist in which consultands need to know these kinds of risks (for example, when no direct test is available for a particular deleterious mutation, or when a consultand wants to know his/her risk before deciding whether to undergo a direct test). The “Unified Approach” presented here is straightforward and ensures calculating the correct risks. It can be applied to a wide variety of genetic counseling situations, including but not limited to: calculating recurrence or carrier risks for dominant and recessive diseases; incorporating false‐positive and false‐negative rates on genetic tests into risk calculations; and determining the probability that an isolated case in a family represents a new mutation. The method is based on basic principles of probability and likelihood theory but can be used without sophisticated knowledge of this theory. The method relies on two rules, the “Rule of All Configurations” and the “Rule of Fundamental Probabilities,” which are explained and illustrated. The Unified Approach does not represent new or original mathematics but should make it easier for users to calculate risks accurately. A warning is included that complex calculations should always be independently verified by another individual.
The mental health of crime victims: Impact of legal intervention
Authors: Herman Judith Lewis
Published: April 2003

In the aftermath of crime, victims must decide whether to seek justice. An encounter with the legal system offers major potential benefits to crime victims, but also exposes them to significant risks. Victims who file civil or criminal complaints are subject to the rules and procedures of a complex legal system, where their mental health and safety may be of marginal concern, and where the potential for retraumatization may be high. This paper reviews the social and psychological barriers that discourage victim participation in the legal system, and existing studies that document the impact of participation on victims' mental health. Prospective longitudinal research focusing on victims in the legal system is recommended.
Cancer Risk Assessment and Genetic Counseling in an Academic Medical Center: Consultands' Satisfaction, Knowledge, and Behavior in the First Year
Authors: Penles Stadler Mona , Mulvihill John J.
Published: April 2003

In 1995, we formally established a multifaceted cancer genetics program of clinical services, research, and education at a general academic medical center. In the first year, 58 families, mostly physician referred, received cancer risk assessment and genetic counseling for a family and/or medical history of cancer. The primary reasons for seeking consultation were to determine their risk or their offspring's risk for developing certain cancers and to inquire about the availability of DNA testing for predisposition to breast, ovarian, or colon cancers. To assess the level of satisfaction with program services, 51 consultands (22% with a personal history of cancer) were interviewed independently by telephone 3–12 months after the session. One goal of the survey was to improve program service. Ninety percent of respondents reported that the consultation was worth their time and money. Forty‐two percent stated that their anxiety related to their cancer risk had decreased following counseling and 56% indicated no change. Recall of exact numerical risk was poor and one‐third could not remember hearing any risk estimate. More respondents would recommend the service to friends (90%) than to family members (75%). Overall, the service was positively received by the majority of patients.
Multiple Mediators of the Effects of Acculturation Status on Delinquency for Mexican American Adolescents
Authors: Samaniego Roxana Y. , Gonzales Nancy A.
Published: April 2003

Research has shown that more acculturated Latino adolescents are at increased risk for delinquent behavior relative to their less acculturated counterparts. The present study examined the mediating effects of seven variables hypothesized to account for the empirical link between acculturation status and delinquent activity for a sample of Mexican American adolescents. Mediational analyses provided support for four of the putative mediators which included family conflict, maternal monitoring, inconsistent discipline, and negative peer hassles. Examined together, these variables totally mediated the effect of acculturation status on delinquent behavior. In addition, family conflict and maternal monitoring uniquely accounted for a significant proportion of the mediated variance above that explained by the other variables in the model. Adolescent's cultural identity, perceived discrimination, and maternal acceptance were not supported as mediators.
The Influence of American Urban Culture on the Development of Normative Beliefs About Aggression in Middle‐Eastern Immigrants
Authors: Souweidane Violet , Huesmann L. Rowell
Published: April 2003

The effects of a community's culture on children's and adolescents' normative beliefs about the appropriateness of aggression were examined. One hundred forty‐seven high school students and 103 fourth graders participated in a survey of normative beliefs; 69 high school and 44 elementary school students were of Middle‐Eastern background. Although there were no differences in the beliefs of immigrant and nonimmigrant fourth graders, adolescents born in the United States were more accepting of aggression than those who immigrated from the Middle East. Moreover, adolescents who immigrated to the U.S. at age 12 or later were less accepting of aggression than those who immigrated prior to age 12.
Legal interventions for child victims
Authors: Whitcomb Debra
Published: April 2003

Many commentators have expressed concern over the plight of children in the nation's court system, fearing that child victim/witnesses might suffer significant trauma. In efforts to alleviate this presumed trauma, new laws were passed and traditional procedures were modified. This paper synthesizes available research addressing 2 questions pertaining to the mental health needs of child victims: (1) To what extent are children traumatized by their involvement in the justice system, and (2) What interventions are effective in reducing children's trauma? The review concludes that most children can testify without suffering long‐term adverse effects. It also identifies elements of the justice system that appear to heighten stress for children. Finally, it suggests several strategies that might be effective in alleviating that stress.
Changes in the prevalence of disability pension in Iceland 1976-1996
Authors: Thorlacius Sigurður , Stefánsson Sigurjón B. , Ólafsson Stefán , Rafnsson Vilhjálmur
Published: April 2003

Aims: The objectives were to determine changes in the prevalence of disability pension in Iceland and its distribution according to gender, age, and main diagnoses. Methods : The study includes all persons receiving either full or partial disability pension in 1976 and 1996. The age-standardized risk ratio between the years 1976 and 1996 was calculated for all disability pensions and for full disability pension only. Results: The prevalence of all disability pensions decreased significantly among both men and women in 1996 as compared with 1976. When the figures were disaggregated, however, they revealed an increased risk of full disability pension and a decreased risk of partial disability pension. The prevalence of full disability pension had increased in most disease categories. Conclusion: The decreased prevalence of disability pension in 1996 as compared with 1976 is noteworthy, as unemployment was increasing during the years immediately preceding 1996. It seems likely, however, that the decrease of partial disability pension and increase of full disability pension is a reflection of increased competition for work in the labour market as well as increased attractiveness of full disability pension due to new supplementary sickness insurance benefits linked to full disability pension.
"I am allowed to be myself ' ' : women with chronic muscular pain being recognized
Authors: Steihaug Sissel , Ahlsen Birgitte , Malterud Kirsti
Published: April 2003

Aims: Since 1992, the authors have completed 11 treatment groups for women with chronic muscular pain. The programme includes movement training and group discussions. Qualitative data indicate that the participants valued the experience of being recognized in the groups as a crucial and beneficial effect of the treatment. In the present article, this finding is examined in more detail by studying the types of action and interaction that the women considered to have benefited from by participating in group treatment. Methods: Data are drawn from an action research project and the material originates from three treatment groups where 24 participants completed the programme. Qualitative data originating from five focus group interviews are analysed using Giorgi's principles of phenomenological analysis. Results: The women described different concrete aspects of interaction and awareness illustrating psychologist Løvlie Schibbye's theoretical perspectives of a recognizing attitude: listening, understanding, acceptance, tolerance, and confirmation. The women tell how they themselves have experienced these expressions of recognition from other group members and from the group leaders. Conclusions: The women confirmed that recognition had an important effect on how much they benefited from the treatment programme. The need for mutual recognition draws attention to the power and possible abuse of power inherent in human relationships, as exemplified by the relationship between the patient and healthcare providers. An explicit presentation of the human and moral value behind the treatment programme represents a challenge.
Science, consumerism and bureaucracy
Authors: Harrison Stephen , McDonald Ruth
Published: April 2003

This paper argues that the means by which the profession of medicine has to legitimise itself in the context of state‐provided health services is changing in a way that may be summarised in Weberian terms as a shift from substantive to formal rationality. The traditional model for such legitimations, evident in the UK over the last 50 years, relied heavily on professional interpretation of emergent patient needs, on professional pragmatism as a means of coping with resource limitations, on unsystematic empiricism and self‐critical reflections as sources of clinical knowledge, on professional self‐regulation, and on an empirical legal test of professional negligence. This seems to be in the process of being replaced by a neo‐bureaucratic model that relies on formalised assessments of patient need, explicit micro‐economic analysis, cumulative “scientific” evidence implemented through bureaucratic rules, increasingly external regulation, and possible shift to normative legal tests of professional negligence.
Competition policy and intra‐professional conflict: re‐regulating general practice
Authors: Dwan Kathryn , Boyce Rosalie A.
Published: April 2003

This paper investigates a case whereby the historical monopoly of a medical college was challenged by internal dissenters and also by external pressure in the form of national competition policy. The case is particularly notable in that the apparently private domain of medical training is now subject to explicit public involvement of a transparent and regulated nature. Based on in‐depth interviews and primary documents, the paper argues that in contributing to marketisation, the latent schism and tensions within Australian general practice have, consequently contributed to a decrease in professional autonomy and independence.
Variations of a circular-motion lab
Authors: Makous John L.
Published: April 2003

This article describes the use of a microcomputer-based laboratory force probe and a conventional circular motion apparatus to measure the centripetal force and period of an object undergoing circular motion.
The MCAT physics test
Authors: Blado Gardo Garnet
Published: April 2003

The present paper discusses the physics portion of the Medical College Admission Test (MCAT). Various methods of incorporating “MCAT-type” questions in introductory physics courses to help pre-medical students prepare for the MCAT, are carefully examined.
Color addition and alternating current
Authors: Saba Marcelo M. F. , Monteiro Daniel D.
Published: April 2003

This experiment illustrates both color addition and ac current concepts. It is a new version of an old experiment, but here a tri-colored LED is used. Some ideas on how to conduct the demonstration are also given.
Seeing the Moon
Authors: Bouffard Karen
Published: April 2003

The object of this challenge, which is “do-ahead” or onsite, is to construct a telescope that produces the clearest and largest image of the Moon using a variety of lenses.
Infrared radiation: Herschel revisited
Authors: Pursell Erin E. , Kozlowski Richard
Published: April 2003

The year 2000 marks the 200th anniversary of Herschel’s discovery of infrared radiation. Using a car light in place of the Sun and a liquid crystal sheet instead of thermometers, the experiment is an effective classroom demonstration of invisible light.
Aristarchus at your service
Authors: Derman Samuel
Published: April 2003

How to maintain student interest in class? Keep a collection of interesting diversionary topics on hand. One such topic: the surprising astronomical discoveries made more than 2000 years ago by the Greek mathematician, Artistarchus.
Fourteen things you can do with a stick
Authors: Greenslade Thomas B.
Published: April 2003

Some years back, Dick Zitto and I were teaching a week of mechanics to elementary school teachers in Canton, Ohio, city school system. Our mandate was to use simple materials and to be interesting. To start the session, I decided to have a discussion, partly prompted and partly free association on the ways one might use a stick to study physical phenomena.
Making Atwood’s machine “work”
Authors: Johnson Gordon O.
Published: April 2003

PASCO scientific’s Smart Pulley™, a lightweight, low-friction pulley and a photogate, begs to be used as an Atwood’s machine to determine the acceleration of gravity, g. Unfortunately ignoring the mass and friction of the pulley results in poor values of g. In this paper a procedure is outlined that includes the effects of the pulley’s inertia and friction. As a result, the value of g may be determined to an accuracy of 0.1%.
Modifying the inclined-plane experiment
Authors: Venable D. D. , Batra A. P. , Hubsch T.
Published: April 2003

We have modified our inclined plane experiment, for determining g, by adding a computer interface and utilizing a procedure that eliminates the need to know initial conditions of motion. Excellent results are obtained using either an air track or a PASCO dynamic cart system.
For the new teacher
Authors: Blanton Patricia
Published: April 2003

Here is the good news — through collaboration with peers, mentoring, and continual training we can all become better teachers. Those who begin to doubt they were really “born” to the profession can be reassured that teaching skills can be acquired and refined.
Bernoulli at the gas pump
Authors: Greene Nathaniel R. , Dworsak Matthew R.
Published: April 2003

Invented in the 1920s, the automatic shutoff valve incorporated into a gasoline-pump nozzle relies on the Bernoulli principle for its operation. The device’s history, underlying physics, and modern implementation are surveyed.
Physics measurements for sports
Authors: Haugland Ole Anton
Published: April 2003

Video analysis combined with simple equipment used for measuring force measures physical activities. Students make a simple force platform to measure the force an athlete exerts while touching it.
Dragging a Box: The representation of constraints and the constraint of representations
Authors: Leonard William J.
Published: April 2003

Using only geometry, trigonometry, and an alternative representation for the normal and static friction forces (i.e., without using calculus or algebra), we determine the “best” angle for dragging a box with a rope. We posit that the representation one uses to solve a problem can dictate and thus limit the approach.
A quantitative demonstration of the Doppler effect
Authors: Saba Marcelo M. F. , Rosa Rafael Antônio da S.
Published: April 2003

This experiment illustrates a new technique for studying the Doppler effect quantitatively. All that is needed is a tape recorder and software that generates spectrograms from digital sound files.
Alternative theoretical method for motion of a sand-filled funnel experiment
Authors: Byrd David , White Gary
Published: April 2003

In “Motion of a Sand-Filled Funnel,” Peter Sullivan and Anna McLoon described how to use numerical methods and a Microsoft Excel spreadsheet to predict the motion of a variant of Atwood’s machine with variable mass. They wrote for noncalculus-based physics classes, but we solve the same problem using the methods of calculus. Our method highlights the less-familiar but more accurate version of Newton’s second law, ∑F =dpdt. This can help introductory physics students understand a broader definition of Newton’s second law and enhance their calculus skills. It also teaches students how to solve a variable-mass problem.
Introductory thermal concept evaluation: assessing students' understanding
Authors: Yeo Shelley , Zadnik Marjan
Published: April 2003

We describe a pen and paper instrument designed to provide a measure of a range of student beliefs about thermal phenomena. The trial version, administered to 478 high school and university students aged 15–18 years, was able to distinguish belief changes in two populations, year 11 and first-year university physics students. We have used the revised instrument as a pre-test and post-test for evaluating students’ conceptual change following instruction. The instrument, called the Thermal Concept Evaluation, is appended.
A simple formula for the large-angle pendulum period
Authors: Kidd Richard B. , Fogg Stuart L.
Published: April 2003

An intuitively obvious formula allows the large-angle pendulum to be simply related to the small-angle period. The formula then allows laboratory measurements of the large-angle period to be compared with theoretical calculations.
Women in physics: A review
Authors: McCullough Laura
Published: April 2003

This paper reviews the current status of women in physics, and the current literature and programs available on this topic.
The broken-protractor prediction trick
Authors: Ellenstein Marshall
Published: April 2003

I like demonstrating physics principles in a “magical” way. One day while I was collecting protractors my students had used for a previous project, I stumbled on a remarkable effect. Every protractor that had broken broke in exactly the same place!
Demonstration of Newton's third law using a balloon helicopter
Authors: Ng Yee-kong , Mak Se-yuen , Chung Choi-man
Published: April 2003

In this note, we introduce a toy balloon helicopter for demonstrating Newton’s third law of motion. In contrast to the traditional balloon rocket, this toy can move up steadily to a much higher level and stay in air for a much longer time.
Improving Science Education for All Children
Authors: Ehlers Vernon
Published: April 2003

Last fall, in the midst of trying circumstances no one could have foreseen, Congress continued its intense work on improving K–12 education and eventually passed the President’s education reform bill. While these reforms will do much to improve our nation’s schools, they alone will not ensure that all of our students are adequately educated in science.
Cannon’s Recoil Against a Tree: How the Range Increases
Authors: Weinstock Robert
Published: April 2003

A rigorous proof is presented to show that a cannonball’s post-explosion velocity, and therefore its range, is increased by propping the rear of the cannon against a massive tree.
Using Undergraduate Students as Physics Lab Teaching Assistants
Authors: Harper Kathleen Andre , May David B. , Oliver Keith W.
Published: April 2003

We carefully selected several undergraduates to teach mechanics laboratories of a special course for honors engineering students. We share our experiences, including efforts to assess whether students taught by undergraduates were put at any disadvantage and whether the undergraduates we employed benefited from the experience.
A Playing-Card Soliton
Authors: Gardner Martin
Published: April 2003

A soliton is a wave that maintain itself by means of external restraints that prevent its collapse. You can model a soliton with a deck of playing cards.
Lightbulbs with a Memory
Authors: Greene Nathaniel R.
Published: April 2003

A series circuit of high-wattage incandescent lightbulbs exhibits memory effects based on whether the bulbs are still hot from previous use. Whereas the hot lightbulbs turn on immediately, the a series-connected cold bulb becomes luminous after a surprisingly long time delay.
Algebraic Treatment of Two-Slit Interference
Authors: Sobel Michael I.
Published: April 2003

Thomas Young’s two-slit interference experiment was one of the crucial experiments in the history of science, establishing the wave nature of light and determining the wavelength of light. Understanding this experiment should be a key point in any introductory course in physics. Yet the derivation of the equation for interference fringes, as found in most textbooks, and based on a geometrical argument, is seriously unconvincing. The purpose of this note is to show that an algebraic derivation produces the desired result much more cleanly, without ambiguous approximation, and at a level appropriate for an introductory course in physics.
An apparition
Authors: Gardner Martin
Published: April 2003

Stare at the center of the picture here while you count slowly to one hundred, then look at a white wall. You will see a startlingly real image of Jesus!
Correction: “Musical mastery of a Coke™ bottle” [Phys. Teach. 36(2) 70 (1998)]
Authors: Silverman Mark P. , Worthy Elizabeth R.
Published: April 2003

In February’s “Musical Mastery of a Coke Bottle” two lines above Eq. ( 1 ), the equation should read λ = 4 l, as shown correctly in Fig. 1.
Correction: “A student project on wind chimes: Tuning in to standing waves” [Phys. Teach. 36(4) 204 (1998)]
Authors: Baxter G. William , Hagenbuch Keith M.
Published: April 2003

In this article on wind chimes, the authors’ photos were accidently switched.
“Feel” the Difference Between Series and Parallel Circuits
Authors: Livelybrooks Dean
Published: April 2003

We all have our favorite curricular materials for teaching about current and voltage, and how they differ in series and parallel circuits. RealTime Physics Module 3: Electric Circuits,1 which addresses research about student difficulties with circuits noted by McDermott and Shaffer,2 is used at the University of Oregon, for example. This paper describes exercises in which students use a Genecon generator3 to supply power to series and parallel combinations of lightbulbs. They are able to “feel” the difference in how the generator is turned in producing equal power to the circuits.
Planar motion, complex numbers, and falling leaves: An intriguing minilab
Authors: Etkina Eugenia , Holton Brian , Horton George
Published: April 2003

We stress the importance of a hands-on component in intermediate-level physics instruction. The place of model building in mechanics is illustrated by studying planar motion using complex numbers instead of vectors. A related minilab is described and analyzed.
Musical mastery of a Coke™ bottle: Physical modeling by analogy
Authors: Silverman Mark P. , Worthy Elizabeth R.
Published: April 2003

A Coke™ bottle is modeled in analogy to a resonant LC circuit to obtain a theoretical prediction of the fundamental frequency as a function of the length of the air column. Experimental measurements are in excellent accord with our model.
Misconceptions for grown-ups
Authors: Swartz Clifford E.
Published: April 2003

We all know how hard it is to cure student misunderstandings. A mind convinced against its will is of the same conception still. Then there are the misconceptions that we adults have.
Whole vectors
Authors: Wheeler David , Charoenkul Niran
Published: April 2003

It’s about time vectors were taught more widely in their complete form, together with diagrams, to let students see how delightfully simple the world of motion is.
Steady-state forced-flow equations
Authors: O’Connell James
Published: April 2003

The flow of materials and energy is covered under a variety of topics in a first-year physics text. However, the underlying mathematical connection is seldom emphasized. In this note, the equations that describe steady flow opposed by a restrictive mechanism are compared.
Recollections of a first-year physics teacher
Authors: Stevenson Christopher
Published: April 2003

Author describes his experiences as a first-year physics teacher in the small town of Hardin, Montana.
Magic nails
Authors: Huhn James K.
Published: April 2003

Magnetism is one of the forgotten invisible forces unless its influence has affected one of our senses in some type of everyday use. The magnetic effects here confound our normal observations and conclusions in a seemingly practical application.
Covering lenses and covering images
Authors: Kwan A. M. , Wardle D. A.
Published: April 2003

Partially covering a converging lens can produce either vignetted or dimmed real images, depending on how the image is observed. A field lens captures non-paraxial rays, allowing the dimming effect to be observed directly, without using a screen.
An intuitive approach to collisions
Authors: Tindle C. T.
Published: April 2003

Momentum conservation and energy loss in collisions can be introduced intuitively by first considering the situation in which the total momentum is zero. Other cases, such as collision with a stationary object, are easily described by transforming the velocities of the zero momentum result. All two body, one-dimensional collisions can be easily treated this way without the need for solving simultaneous equations. Treatment of the general case leads immediately to conservation of momentum and to Newton’s law of elasticity.
Response time of a thermometer
Authors: Thomsen Volker
Published: April 2003

The response time of a thermometer is governed by Newton’s law of cooling. The time constant is analogous to that of electrical RC circuits. The response time of a thermometer is, however, critically dependent upon the coefficient of convective heat transfer of the (liquid) medium being measured. This places the thermometer in a unique category among measuring instruments.
Inexpensive demonstration of the magnetic properties of matter
Authors: Sawicki Charles A.
Published: April 2003

The magnetic properties of common materials such as wood, plastic, glass, and aluminum are demonstrated using small, inexpensive, surplus quadrupole magnets. Paramagnetic rods line up with the field above the magnet while diamagnetic samples line up perpendicular to the field.
Symbols and units in first-year physics
Authors: Bailey Kirk
Published: April 2003

Firs-year physics students are often bewildered by the fact that the symbol for one quantity is often the same as the unit for another quantity. And so, after a unit on measurement that begins our year, I emphasize that there is going to be some memorization required in the course, and I give each student this notation handout.
Inverse-square law of light with Airy’s disk
Authors: Narayanan V. Anantha , Narayanan Radha
Published: April 2003

We have verified the inverse-square law of light by forming the Airy’s discs when 6328 Å light wave from a He-Ne laser is diffracted by a circular hole. We moved the screen farther and farther from the hole and made the Airy’s discs larger and larger, measured areas (A) of the Airy's discs, illumination (E) of these discs, and the distances (x) of the screen to the hole.
How to quickly estimate the focal length of a diverging lens
Authors: Dudley Scott C.
Published: April 2003

To quickly estimate the focal length of a converging lens, we form a real image of a distant object. For a diverging lens, however, a quick estimate is not so easy because a diverging lens forms no real image.
Weight—Don’t use the word at all
Authors: Brown Ronald
Published: April 2003

I strongly agree with Richard Morrison that at the end of the twentieth century, the physics teaching community should at least agree on a definition of the word “weight.” That we do not is very strong evidence to me that the word should simply never appear in the literature or textbooks. It should be expunged from our vocabulary—except as a substitute for the word “object” as in “A weight was hanging from a string.”
Catenaries on the computer: A freshman physics assignment
Authors: Adler Charles L.
Published: April 2003

The shape of the catenary can be found by any student who knows freshman mechanics and has access to a computer.
Another surprise in mechanics: Styrofoam™ and toys
Authors: van den Berg Ed , Bonifacio Nestor , Embalzado Renante , Ravelo Mike
Published: April 2003

Here is a follow-up on an experiment described in this magazine in which bullets were shot into wooden blocks from below. We wondered if the experiment would work with toy guns, plastic arrows, and blocks cut from Styrofoam.
Can a west wind impede a cyclist’s northward motion?
Authors: Ward Gilbert H.
Published: April 2003

This paper explains why a wind at right angles to a cyclist’s motion does impede the motion. The situation is compared with that of a boat, where no constraining force is available to counter a sideward current.
Simple kinematics and traffic flow
Authors: Wörner C. H. , Romero S. , Romero A.
Published: April 2003

This note, prompted by recent papers, addresses the relationship between car speed and the safe distance between cars in a linear flow of traffic.
Reminder about Hooke’s Law and metal springs
Authors: Froehle Peter
Published: April 2003

When finding the spring constant for metal springs, it is not enough to measure the relationship between the stretch of the spring and the force (weight) applied to the spring.
A pencil-and-tape electricity experiment
Authors: Derman Samuel , Goykadosh Aron
Published: April 2003

An electrical experiment is described where students construct thin-film resistors by filling in with a graphite pencil, rectangles drawn on tape or drafting vellum. Rules of series and parallel circuits are verified, and industrial applications are discussed.
A radioactive tracer in medicine
Authors: Steiger Walter R.
Published: April 2003

Recently I had the opportunity to experience first-hand an example of the use of a radioactive tracer in medicine. A mole in an early stage of malignancy needed to be removed from above my left eyebrow.
The driven RLC circuit experiment
Authors: Backman Philip , Murley Chester , Williams P. J.
Published: April 2003

This article reports on a microcomputer-based laboratory (MBL) that explores the drive RLC circuit. In the experiment, students are able to measure both amplitude and phase relations while varying the frequency of the source. Details of the data acquisition and some typical results are presented.
New demonstration of photoelectric effect
Authors: Chen Chun Xiao , Zhang Chang Geng
Published: April 2003

One of the standard demonstrations of the photoelectric effect involves shining ultraviolet light on a zinc plate. Electrons are driven off the plate, leaving it charged positive.
Ideas for a magnetic field experiment
Authors: Molnar Michael R. , Martin Arthur J.
Published: April 2003

We show how to transform the Vernier Hall-effect sensor into a directional sensor useable in an Ampere’s law experiment. Moreover, the probe can be used as an economical device independent of an expensive computer interface. And students can be introduced to exploring the local geomagnetic field in calibrating this modified probe.
A pedagogical note on the relativistic velocity addition formula
Authors: Dibble William E. , Hart Grant W. , Stokes Harold T.
Published: April 2003

The velocity addition formula for special relativity in one dimension (along the direction of relative motion of the two coordinate systems) is easier to apply if written using the same subscript notation usually used with classical relative velocity vectors.
Beats on a vibrating string
Authors: Larson James H.
Published: April 2003

I showed Derrick Boucher’s acoustic demonstration of beats and interference to a colleague, and as we were talking I mentioned that the function generator could be hooked to mechanical wave drivers to obtain nice standing waves. Then it’s possible to verify that law of vibrating strings. However, we kept coming back to the concept of beats. Could we “see” beats on strings?
The energetics of a bouncing ball
Authors: Turner Warren A. , Ellis Glenn W.
Published: April 2003

Computer-based, real-time data collection is used to explore the energetics of a bouncing ball. Discussion centers around student comprehension and misconceptions surrounding interconversion of mechanical energy and the pedagogical use of this experiment.
Projectile motion in special relativity
Authors: Naddy Cory J. , Dudley Scott C. , Haaland Ryan K.
Published: April 2003

Two-dimensional projectile motion is solved using special relativity. Exact solutions are obtained using elementary algebra and calculus and interesting effects, such as acceleration along a component with no force, are shown.
Light polarization experiments with a diode laser pointer
Authors: Benenson Raymond E.
Published: April 2003

Polarized light has many uses: glare reduction, stress analysis, microscope image enhancement, thin-film characterization, astronomy, saccharimetry, and atomic spectroscopy. Here we discuss introductory polarized light measurements in which a diode laser pointer replaces the more frequently used polarized He-Ne laser. A diode laser has been used in introductory optics experiments, and in a more advanced polarization-reflection experiment. Its strong collimated beam is completely polarized and, being free of infrared radiation, it permits Polaroid sheets to be used successfully with semiconductor detectors.
Mediterranean Moisture Source for an Early-Holocene Humid Period in the Northern Red Sea
Authors: Arz Helge W. , Lamy Frank , Pätzold Jürgen , Müller Peter J. , Prins Maarten
Published: April 2003

Paleosalinity and terrigenous sediment input changes reconstructed on two sediment cores from the northernmost Red Sea were used to infer hydrological changes at the southern margin of the Mediterranean climate zone during the Holocene. Between approximately 9.25 and 7.25 thousand years ago, about 3‰ reduced surface water salinities and enhanced fluvial sediment input suggest substantially higher rainfall and freshwater runoff, which thereafter decreased to modern values. The northern Red Sea humid interval is best explained by enhancement and southward extension of rainfall from Mediterranean sources, possibly involving strengthened early-Holocene Arctic Oscillation patterns and a regional monsoon-type circulation induced by increased land-sea temperature contrasts. We conclude that Afro-Asian monsoonal rains did not cross the subtropical desert zone during the early to mid-Holocene.
BAX and BAK Regulation of Endoplasmic Reticulum Ca
2+
: A Control Point for Apoptosis
Authors: Scorrano Luca , Oakes Scott A. , Opferman Joseph T. , Cheng Emily H. , Sorcinelli Mia D. , Pozzan Tullio , Korsmeyer Stanley J.
Published: April 2003

BAX and BAK are “multidomain” proapoptotic proteins that initiate mitochondrial dysfunction but also localize to the endoplasmic reticulum (ER). Mouse embryonic fibroblasts deficient for BAX and BAK (DKO cells) were found to have a reduced resting concentration of calcium in the ER ([Ca
2+
]
er
) that results in decreased uptake of Ca
2+
by mitochondria after Ca
2+
release from the ER. Expression of SERCA (sarcoplasmic-endoplasmic reticulum Ca
2+
adenosine triphosphatase) corrected [Ca
2+
]
er
and mitochondrial Ca
2+
uptake in DKO cells, restoring apoptotic death in response to agents that release Ca
2+
from intracellular stores (such as arachidonic acid, C
2
-ceramide, and oxidative stress). In contrast, targeting of BAX to mitochondria selectively restored apoptosis to “BH3-only” signals. A third set of stimuli, including many intrinsic signals, required both ER-released Ca
2+
and the presence of mitochondrial BAX or BAK to fully restore apoptosis. Thus, BAX and BAK operate in both the ER and mitochondria as an essential gateway for selected apoptotic signals.
Light Microscopy Techniques for Live Cell Imaging
Authors: Stephens David J. , Allan Victoria J.
Published: April 2003

Since the earliest examination of cellular structures, biologists have been fascinated by observing cells using light microscopy. The advent of fluorescent labeling technologies plus the plethora of sophisticated light microscope techniques now available make studying dynamic processes in living cells almost commonplace. For anyone new to this area, however, it can be daunting to decide which techniques or equipment to try. Here, we aim to give a brief overview of the main approaches to live cell imaging, with some mention of their pros and cons.
The Demon of Determinism
Authors: Shermer Michael
Published: April 2003

Freedom Evolves
.
By Daniel C. Dennett
. Viking, New York, 2003. 363 pp. $24.95, C$37.50. ISBN 0-670-03186-0

Ranging through topics such as game theory, memes, and consciousness, Dennett argues for an evolutionary basis for human's free will in our deterministic world.
Role of Histone H3 Lysine 27 Methylation in X Inactivation
Authors: Plath Kathrin , Fang Jia , Mlynarczyk-Evans Susanna K. , Cao Ru , Worringer Kathleen A. , Wang Hengbin , de la Cruz Cecile C. , Otte Arie P. , Panning Barbara , Zhang Yi
Published: April 2003

The Polycomb group (PcG) protein Eed is implicated in regulation of imprinted X-chromosome inactivation in extraembryonic cells but not of random X inactivation in embryonic cells. The
Drosophila
homolog of the Eed-Ezh2 PcG protein complex achieves gene silencing through methylation of histone H3 on lysine 27 (H3-K27), which suggests a role for H3-K27 methylation in imprinted X inactivation. Here we demonstrate that transient recruitment of the Eed-Ezh2 complex to the inactive X chromosome (Xi) occurs during initiation of X inactivation in both extraembryonic and embryonic cells and is accompanied by H3-K27 methylation. Recruitment of the complex and methylation on the Xi depend on
Xist
RNA but are independent of its silencing function. Together, our results suggest a role for Eed-Ezh2–mediated H3-K27 methylation during initiation of both imprinted and random X inactivation and demonstrate that H3-K27 methylation is not sufficient for silencing of the Xi.
Effect of Particles on the Recovery of
Cryptosporidium
Oocysts from Source Water Samples of Various Turbidities
Authors: Feng Yao Yu , Ong Say Leong , Hu Jiang Yong , Song Lian Fa , Tan Xiao Lan , Ng Wun Jern
Published: April 2003

Cryptosporidium parvum
can be found in both source and drinking water and has been reported to cause serious waterborne outbreaks which threaten public health safety. The U.S. Environmental Protection Agency has developed method 1622 for detection of
Cryptosporidium
oocysts present in water. Method 1622 involves four key processing steps: filtration, immunomagnetic separation (IMS), fluorescent-antibody (FA) staining, and microscopic evaluation. The individual performance of each of these four steps was evaluated in this study. We found that the levels of recovery of
C. parvum
oocysts at the IMS-FA and FA staining stages were high, averaging more than 95%. In contrast, the level of recovery declined significantly, to 14.4%, when the filtration step was incorporated with tap water as a spiking medium. This observation suggested that a significant fraction of
C. parvum
oocysts was lost during the filtration step. When
C. parvum
oocysts were spiked into reclaimed water, tap water, microfiltration filtrate, and reservoir water, the highest mean level of recovery of (85.0% ± 5.2% [mean ± standard deviation]) was obtained for the relatively turbid reservoir water. Further studies indicated that it was the suspended particles present in the reservoir water that contributed to the enhanced
C. parvum
oocyst recovery. The levels of
C. parvum
oocyst recovery from spiked reservoir water with different turbidities indicated that particle size and concentration could affect oocyst recovery. Similar observations were also made when silica particles of different sizes and masses were added to seeded tap water. The optimal particle size was determined to be in the range from 5 to 40 μm, and the corresponding optimal concentration of suspended particles was 1.42 g for 10 liters of tap water.
Colonization of
Vitis vinifera
by a Green Fluorescence Protein-Labeled,
gfp
-Marked Strain of
Xylophilus ampelinus
, the Causal Agent of Bacterial Necrosis of Grapevine
Authors: Grall Sophie , Manceau Charles
Published: April 2003

The dynamics of
Xylophilus ampelinus
were studied in
Vitis vinifera
cv. Ugni blanc using
gfp
-marked bacterial strains to evaluate the relative importance of epiphytic and endophytic phases of plant colonization in disease development. Currently, bacterial necrosis of grapevine is of economic importance in vineyards in three regions in France: the Cognac, Armagnac, and Die areas. This disease is responsible for progressive destruction of vine shoots, leading to their death. We constructed
gfp
-marked strains of the CFBP2098 strain of
X. ampelinus
for histological studies. We studied the colonization of young plants of
V. vinifera
cv. Ugni blanc by
X. ampelinus
after three types of artificial contamination in a growth chamber and in a greenhouse. (i) After wounding of the stem and inoculation, the bacteria progressed down to the crown through the xylem vessels, where they organized into biofilms. (ii) When the bacteria were forced into woody cuttings, they rarely colonized the emerging plantlets. Xylem vessels could play a key role in the multiplication and conservation of the bacteria, rather than being a route for plant colonization. (iii) When bacterial suspensions were sprayed onto the plants, bacteria progressed in two directions: both in emerging organs and down to the crown, thus displaying the importance of epiphytic colonization in disease development.
Nondigestible Oligosaccharides Enhance Bacterial Colonization Resistance against
Clostridium difficile
In Vitro
Authors: Hopkins Mark J. , Macfarlane George T.
Published: April 2003

Clostridium difficile
is the principal etiologic agent of pseudomembranous colitis and is a major cause of nosocomial antibiotic-associated diarrhea. A limited degree of success in controlling
C. difficile
infection has been achieved by using probiotics; however, prebiotics can also be used to change bacterial community structure and metabolism in the large gut, although the effects of these carbohydrates on suppression of clostridial pathogens have not been well characterized. The aims of this study were to investigate the bifidogenicity of three nondigestible oligosaccharide (NDO) preparations in normal and antibiotic-treated fecal microbiotas in vitro and their abilities to increase barrier resistance against colonization by
C. difficile
by using cultural and molecular techniques. Fecal cultures from three healthy volunteers were challenged with a toxigenic strain of
C. difficile
, and molecular probes were used to monitor growth of the pathogen, together with growth of bifidobacterial and bacteroides populations, over a time course. Evidence of colonization resistance was assessed by determining viable bacterial counts, short-chain fatty acid formation, and cytotoxic activity. Chemostat studies were then performed to determine whether there was a direct correlation between bifidobacteria and
C. difficile
suppression. NDO were shown to stimulate bifidobacterial growth, and there were concomitant reductions in
C. difficile
populations. However, in the presence of clindamycin, activity against bifidobacteria was augmented in the presence of NDO, resulting in a further loss of colonization resistance. In the absence of clindamycin, NDO enhanced colonization resistance against
C. difficile
, although this could not be attributed to bifidobacterium-induced inhibitory phenomena.
Role of σBin Regulating the Compatible Solute Uptake Systems ofListeria monocytogenes: Osmotic Induction ofopuCIs σBDependent
Authors: Fraser Katy R. , Sue David , Wiedmann Martin , Boor Kathryn , O'Byrne Conor P.
Published: April 2003

The regulation of the compatible solute transport systems inListeria monocytogenesby the stress-inducible sigma factor σBwas investigated. Using wild-type strain 10403S and an otherwise isogenic strain carrying an in-frame deletion insigB, we have examined the role of σBin regulating the ability of cells to utilize betaine and carnitine during growth under conditions of hyperosmotic stress. Cells lacking σBwere defective for the utilization of carnitine but retained the ability to utilize betaine as an osmoprotectant. When compatible solute transport studies were performed, the initial rates of uptake of both betaine and carnitine were found to be reduced in thesigBmutant; carnitine transport was almost abolished, whereas betaine transport was reduced to approximately 50% of that of the parent strain. Analysis of the cytoplasmic pools of compatible solutes during balanced growth revealed that both carnitine and betaine steady-state pools were reduced in thesigBmutant. Transcriptional reporter fusions to theopuC(which encodes an ABC carnitine transporter) andbetL(which encodes an a secondary betaine transporter) operons were generated by using a promoterless copy of thegusgene fromEscherichia coli. Measurement of β-glucuronidase activities directed byopuC-gusandbetL-gusrevealed that transcription ofopuCis largely σBdependent, consistent with the existence of a potential σBconsensus promoter motif upstream fromopuCA. The transcription ofbetLwas found to besigBindependent. Reverse transcriptase PCR experiments confirmed these data and indicated that the transcription of all three known compatible solute uptake systems (opuC,betL, andgbu), as well as a gene that is predicted to encode a compatible solute transporter subunit (lmo1421) is induced in response to elevated osmolarity. The osmotic induction ofopuCAandlmo1421 was found to be strongly σBdependent. Together these observations suggest that σBplays a major role in the regulation of carnitine utilization byL. monocytogenesbut is not essential for betaine utilization by this pathogen.