THE SPACEFLIGHT ENVIRONMENT AND THE SKELETAL SYSTEM

The spaceflight environment presents many challenges to the human body. Bone loss in astronauts is a well known consequence of reduced loading in the weightless environment of low-earth orbit. Recent studies have also indicated that spaceflight relevant types of radiation (at relatively high doses) have deleterious effects on trabecular bone. Both of these represent potential skeletal challenges during long-duration spaceflight. The objective of these studies is to examine the response of bone to models of the spaceflight environment. Astronauts will likely absorb doses of protons and heavy ions during lengthy missions outside the Earth\u27s magnetosphere. Following exposure to a range of doses of proton radiation, mouse bones displayed deterioration after receiving doses of one and two Gray (Gy), but not at one-half Gy. A one Gy absorbed dose is a potential scenario during a solar particle event. Mixed radiation source exposure (e.g. neutrons, protons, iron ions) characterize galactic cosmic rays. Trabecular bone loss in mice occurred after receiving a dose modeling what an astronaut may absorb during a mission to Mars. Additionally, the same dose led to cortical bone loss, which has not previously been demonstrated at spaceflight-relevant doses. When mice were irradiated with protons (one Gy) followed by unloading using a ground-based model of microgravity, bone loss was again observed. The unloading-induced bone loss in this study was much more severe than that which occurs during long-duration spaceflight. Because of the severity of this bone loss, it is not clear if radiation leads to additional bone loss when combined with unloading. However, there are indications of an additive negative effect of radiation and unloading. These studies demonstrate that spaceflight-relevant doses and types of radiation have deleterious effects on the skeletal system. Further study is necessary to understand the mechanisms behind radiation-induced bone loss. Additionally, further examination of the combined effect of radiation and unloading is necessary in order to understand spaceflight-induced bone loss and effectively develop countermeasures

Effectiveness of Problem-Based Learning in Middle School Science

Middle school science students appear to lack motivation when learning under teaching methods which reduce the subject of science to a body of facts. This study attempted to examine the effectiveness of problem-based learning as an alternative teaching method in sixth grade science. The participants were generally homogeneous representing mostly Caucasian children, and the classrooms were typical classrooms containing the normal range of abilities. Three variables were tested in a quasi-experimental pre-test/post-test control group design: attitude toward science, problem-solving ability, and knowledge. Results showed no significant effect for any of the variable as a result of the intervention. However, certain factors in the methodology of the intervention may have played a large role in affecting the outcomes

Summer Online Courses Program

Hope College is a pioneer among its peers in offering summer online courses, and have been doing so since 2006. This station details the history of the program, the rationale, the process of online course development, and how you can get on board. Stop by to learn the possibilities for innovating your course

Professor Stoker on Campus (con\u27t.)

Stoker\u27s first lecture is discussed in Pro Rege 2:19-20, Dec 1973. The second lecture is discussed in Pro Rege 2:19-20, March 1974

Sites of Agency, Sites of Growth: Elements of Success for Formerly Incarcerated Adult Graduates of an Alternative High School

Students who leave high school before graduating run a high risk of becoming incarcerated, and adults with a record of incarceration and no high school diploma have difficulty maintaining legal employment and therefore remaining out of prison. For adults who lack high school diplomas, few options exist to earn that credential. Though standardized testing is still a point of controversy in education policy for juveniles, the GED exam is the assumed standard for adults in the United States to earn their high school credentials, and few alternatives exist for those who are ill-equipped to pass a demanding standardized test. This qualitative case study of two graduates of an alternative, non-test-based high school for formerly incarcerated adults in Chicago explores how the post-incarceration experiences and geographical locations of those graduates impact their lifestyle choices. The two research subjects interviewed are both formerly incarcerated adults who have beaten the odds of recidivism by remaining out of prison for more than three years and securing stable employment. Research was conducted via semistructured one-on-one interviews with the subjects over a period of 20 months. The study explores the effect of Bronfenbrenner’s ecological systems theory on low-income urban youth of color and the adults they eventually became. The study found that, while these students were negatively impacted by nested systems during their childhoods, some of the effect of these systems – poor schooling systems, lack of parental support and over-zealous policing – were ameliorated by an appropriate, supportive parole placement that emphasized education for the sake of personal transformation

Spectral Analysis of GRBs Measured by RHESSI

The Ge spectrometer of the RHESSI satellite is sensitive to Gamma Ray Bursts (GRBs) from about 40 keV up to 17 MeV, thus ideally complementing the Swift/BAT instrument whose sensitivity decreases above 150 keV. We present preliminary results of spectral fits of RHESSI GRB data. After describing our method, the RHESSI results are discussed and compared with Swift and Konus.Comment: 4 pages, 4 figures, conference proceedings, 'Swift and GRBs: Unveiling the Relativistic Universe', San Servolo, Venice, 5-9 June 2006, to appear in Il Nouvo Ciment

RHESSI Spectral Fits of Swift GRBs

One of the challenges of the Swift era has been accurately determining Epeak for the prompt GRB emission. RHESSI, which is sensitive from 30 keV to 17 MeV, can extend spectral coverage above the Swift-BAT bandpass. Using the public Swift data, we present results of joint spectral fits for 26 bursts co-observed by RHESSI and Swift-BAT through May 2007. We compare these fits to estimates of Epeak which rely on BAT data alone. A Bayesian Epeak estimator gives better correspondence with our measured results than an estimator relying on correlations with the Swift power law indices.Comment: 4 pages, 1 figure. To appear in the proceedings of Gamma Ray Bursts 2007, Santa Fe, New Mexico, November 5-9 200