Low student enrollment and high attrition rates in Science, Technology, Engineering, and Mathematics (STEM) education are major challenges in higher education. Many STEM entrants end-up switching their majors to non-STEM fields, perform poorly relative to their peers in other programs, and/or drop out of college without earning any academic qualification. Therefore, it is important to examine strategies for reducing attrition in STEM programs. This paper reviews the major factors impeding student interest, success, and persistence in STEM programs, and current institutional practices aimed at addressing these issues. Suggested institutional strategies to improve persistence in STEM programs and their implications that are discussed in this paper include: provision of orientation programs, adoption of early warning systems, Mathematics review sessions, creation of student learning communities, professional development of faculty, as well as collaborative and outreach programs. It is hoped that this review will encourage debate toward solving the major challenges facing STEM education.

Worldwide, breast cancer has become the second most common cancer in women. The disease has currently been named the most deadly cancer in women but little is known on what causes the disease. We present the effects of estrogen as a risk factor on the dynamics of breast cancer. We develop a deterministic mathematical model showing general dynamics of breast cancer with immune response. This is a four-population model that includes tumor cells, host cells, immune cells, and estrogen. The effects of estrogen are then incorporated in the model. The results show that the presence of extra estrogen increases the risk of developing breast cancer.

The spread and persistence of schistosomiasis are some of the more complex host parasite processes to model mathematically because of the different larval forms assumed by the parasite and the requirement of two hosts during the life cycle. We construct a deterministic mathematical model to study the transmission dynamics of schistosomiasis where the miracidia and cercariae dynamics are incorporated. The model is analyzed to gain insights into the qualitative features of the equilibrium which allows the determination of the basic reproductive number. Conditions for existence of the endemic equilibrium are discussed and its local stability is determined using the Center Manifold Theory. Analytical and numerical techniques are employed to assess the conditions of containment and persistence of schistosomiasis. Our results show that control strategies that target the transmission of the disease from the snail to man will be more effective in the control of the disease than those that block the transmission from man to snail.

Background Older adults aged 65 and over will make up more than 20% of U.S. residents by 2030, and in 2050, this population will reach 83.7 million. Depression among older adults is a major public health concern projected to be the second leading cause of disease burden. Despite having Medicare, and other employer supplements, the burden of out of pocket healthcare expenses may be an important predictor of depression. The current study aims to investigate whether delay in seeing a doctor when needed but could not because of medical cost is significantly associated with symptoms of current depression in older adults. Methods Cross-sectional data from the 2011 Behavioral Risk Factor Surveillance System (BFRSS) from 12 states and Puerto Rico were used for this study ( n = 24,018). Results The prevalence of symptoms of current depression among older adults who reported medical cost as a barrier to seeking health care was significantly higher (17.8%) when compared to older adults who reported medical cost not being a barrier to seeking health care (5.5%). Older adults who reported medical cost as a barrier to seeking health care were more likely to report current depressive symptoms compared to their counterparts [Adjusted Odds Ratio (AOR): 2.2 [95% CI: 1.5–3.3]). Conclusions Older adults (≥ 65 years of age) who experience the burden of medical cost for health care are significantly more likely to report symptoms of depression. Health care professionals and policymakers should consider effective interventions to improve access to health care among older adults. Electronic supplementary material The online version of this article (10.1186/s12877-019-1203-2) contains supplementary material, which is available to authorized users.