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Abstract: Long-term sensitivity of human cells to reduced gravity has been supposed since the first Apollo missions and was demonstrated during several space missions in the past. However, little information is available on primary and rapid gravi-responsive elements in mammalian cells. In search of rapid-responsive molecular alterations in mammalian cells, short-term microgravity provided by parabolic flight maneuvers is an ideal way to elucidate such initial and primary effects. Modern biomedical research at the cellular and molecular level requires frequent repetition of experiments that are usually performed in sequences of experiments and analyses. Therefore, a research platform on Earth providing frequent, easy and repeated access to real microgravity for cell culture experiments is strongly desired. For this reason, we developed a research platform onboard the military fighter jet aircraft Northrop F-5E “Tiger II”. The experimental system consists of a programmable and automatically operated system composed of six individual experiment modules, placed in the front compartment, which work completely independent of the aircraft systems. Signal transduction pathways in cultured human cells can be investigated after the addition of an activator solution at the onset of microgravity and a fixative or lysis buffer after termination of microgravity. Before the beginning of a regular military training flight, a parabolic maneuver was executed. After a 1g control phase, the parabolic maneuver starts at 13,000ft and at Mach 0.99 airspeed, where a 22s climb with an acceleration of 2.5g is initiated, following a free-fall ballistic Keplerian trajectory lasting 45s with an apogee of 27,000ft at Mach 0.4 airspeed. Temperature, pressure and acceleration are monitored constantly during the entire flight. Cells and activator solutions are kept at 37°C during the entire experiment until the fixative has been added. The parabolic flight profile provides up to 45s of microgravity at a quality of 0.05g in all axes. Access time is 30min before take-off; retrieval time is 30min after landing. We conclude that using military fighter jets for microgravity research is a valuable tool for frequent and repeated cell culture experiments and therefore for state-of-the art method of biomedical research. [Copyright &y& Elsevier]

Purpose: This article reports on 12 select findings from a sequential mixed-methods, empirical study of U.S. educational-context professional writers composing for the Web. The study explores the status of knowledge and understanding of U.S. copyright law, levels of chilled speech, and the use of rhetorical invention in such digital writing contexts. Method: Research methods include a digital survey receiving 334 responses from randomly selected students/teachers and discourse-based interviews with seven of these participants. Results: With respect to authorship, Web writers sometimes occupy conflicting positions. Empirical evidence challenges traditional ideas of authorship, i.e., a single author working alone in a garret, producing texts from his or her sole creative genius. The study finds digital writers' speech is not as "chilled" as one might expect, and while knowledge of copyright law is important to digital writers, they are fairly confident in the knowledge they have. Copyright law is not the primary concern of digital writers. As it turns out, ethics trumps the law in importance when considering digital composing choices. In the area of copyright knowledge, key misunderstandings appeared among writers. For example: confusion on (1) the difference between copyright and plagiarism, (2) unauthorized use and authorized use, (3) the government exception to copyright, and (4) the fact that U.S. copyright law protects "creative" work to a higher extent than it protects "factual" work. Conclusion: The study hopes to provide a methodology for further research, and a baseline in the area of knowledge and understanding of copyright law as it intersects with invention, among the professional writing population. [ABSTRACT FROM AUTHOR]

The article discusses a mathematical activity based on a concept called the multiplicative digital root of an integer conducted by a group of preservice and inservice mathematics teachers in the U.S. The activity focuses on generating and analyzing a possible next term in the mathematical sequence which leads to the successful multiplication of digits of each integer. During the activity, the students deployed their graphing calculators and created a table denoting the two-digit integers, their multiplicative digital roots and persistence.

The article presents a series of mathematical instructions intended for high school students in the U.S. These mathematical expressions give clearer presentation of the number systems expressed in a step-by-step series of mathematical computations ranging from the easiest to the most difficult mathematical computations. Life expectancy calculations were also presented in equations. The author also cited that finding the solution to the mathematical problems means finding and evaluating the solutions numerically.

The standard approach to flood frequency analysis (FFA) fits mathematical functions to sequences of historic flood data and extrapolates the tails of the distribution to estimate the magnitude and likelihood of extreme floods. Here, we identify the most exceptional floods in the United States as compared against other major floods at the same location, and evaluate how the flood‐of‐record (Qmax) influences FFA estimates. On average, floods‐of‐record are 20% larger by discharge than their second‐place counterparts (Q2), and 212 gages (7.3%) have Qmax:Q2 ratios greater than two. There is no clear correspondence between the Qmax:Q2 ratio and median instantaneous discharge, and exceptional floods do not become less likely with time. Excluding Qmax from the FFA causes the median 100‐year flood to decline by −10.5%, the 200‐year flood by −11.8%, and the 500‐year flood by −13.4%. Even when floods are modelled using a heavy tail distribution, the removal of Qmax yields significantly "lighter" tails and underestimates the risk of large floods. Despite the temporal extension of systematic hydrological observations in the United States, FFA is still sensitive to the presence of extreme events within the sample used to calculate the frequency curve. [ABSTRACT FROM AUTHOR]

The article discusses the important things that must be taught in the study of mathematics in different schools in the U.S. Under the new and improved method, numbers should be taught in the last third of the year. During his second year, the student should be carefully directed in making actual measurements to understand numerical relations. The student should be ready to perform the fundamental operations in small numbers at the end of his third year.