Students\u27 Understanding Of Quadratic Functions: Learning From Students\u27 Voices

The objective of this multiple case study was to examine how three pairs of high school students from a northern Vermont high school approached quadratic functions through traditional and multiple representation tasks. Four research questions were examined: 1) How do students think about the quadratic function as they work on a series of tasks? 2) What mathematical strategies do students employ when they work on a series of tasks related to the quadratic function? 3) How does the type of task, traditional versus multiple representation, impact students\u27 understanding of the quadratic function? 4) What kinds of knowledge (procedural or conceptual) do students utilize when completing a series of tasks about the quadratic function? Qualitative research methods that utilized think-aloud protocols while students were engaged in four tasks pertaining to the quadratic function were employed in this study. Results suggested that students tend to think about isolated parts of the problem when solving quadratic problems. Early on in their learning about quadratics, students primarily relied on procedural strategies such as think-alouds, gestures, algebraic formulas, converting equation forms, process of elimination, dissecting problems, backtracking, and drawing pictures. In addition, students preferred the standard form to the vertex form when solving quadratics and often confused the y-intercept of the standard form with the y-coordinate of the vertex when the function was in vertex form. Results also indicated that students preferred to algebraically solve a problem versus tabular or graphical strategies. By exploring how students approach the quadratic function through their own voices, this study offers some insight into the conceptions and strategies that students use for solving problems that involve the quadratic function as well as possibilities for how quadratics may be taught in high school

Shaping and transporting diamagnetic sessile drops

Electromagnetic fields are commonly used to control small quantities of fluids in microfluidics and digital microfluidics. Magnetic control techniques are less well studied than their electric counterparts, with only a few investigations into liquid diamagnetism. The ratio of magnetic to surface energy (magnetic Bond number B m) is an order of magnitude smaller for diamagnetic drops (B m ≈-0.3 at 1.2 T applied field) than for paramagnetic drops (B m ≈ 9.0 at 1.2 T applied field). This weaker interaction between the magnetic field and the diamagnetic drop has led to the phenomenon being overlooked in digital microfluidics. Here, we investigate shaping and transport of diamagnetic drops using magnetostatic fields. Our findings highlight how diamagnetic fluids can be used as a novel tool in the toolbox of microfluidics and digital microfluidics

A Single 10-Minute Vape Exposure Alters Ventilation in Adult Rats

E-cigarettes, also known as electronic nicotine delivery systems (ENDS), are an alternative to the traditional cigarette. ENDS function using a heating device (e.g. “vape pen”, such as JUUL) to heat liquids containing nicotine and other chemicals. Recent research in humans and animal models suggests that acute exposure (5 to 60 minutes) to e-cigarette vapor increases airway resistance and proinflammatory cytokine presence in lung tissue. These acute effects may lead to long term functional changes in the lung and tissue changes at the respiratory membrane. PURPOSE: The purpose of this study was to investigate the effects of an acute 10-minute e-cigarette vapor exposure on lung function and proinflammatory cytokine expression, specifically IL-1β in adult rats. METHODS: Adult male Long Evans rats (n=18) were randomly assigned to either the experimental vapor exposure group or the control air group. The vapor exposure group (n=9) was exposed once to 5% nicotine vapor for 10 minutes using whole-body exposure chambers. The air group (n=9) were placed in a chamber, but only exposed to room air. Ventilation recordings were completed the day before exposure (pre) and immediately after vapor or air exposure (post) using unrestrained whole-body plethysmography. Tidal volume/100g, breathing frequency, and minute ventilation/100g were assessed. Blood was collected at the end of the post-treatment day for all animals and processed to serum. Serum cotinine (a nicotine metabolite) and proinflammatory cytokine IL-1β were measured using enzyme linked immunosorbent assays (ELISA). RESULTS: The presence of cotinine was confirmed in the serum collected from the vapor exposed group (89.16 ± 31.16 ng/mL) compared to the air control group (0.054 ± 0.051 ng/mL). Baseline ventilation data (pre-) and post-treatment were compared between air and vapor exposed groups across three different parameters: tidal volume/100g, frequency, and minute ventilation/100g. These parameters were compared resulting in three distinct 2x2 (time x treatment) Mixed Model ANOVAs. A main effect of time (pre-treatment vs. post-treatment) on frequency (p = 0.036) and minute ventilation (p = 0.006) was observed. The main effect of time on breathing frequency was not due to the treatment group (p = 0.906). The minute ventilation for the vapor exposed group decreased from pre-treatment (83.2 ± 16.8 mL/min/100g) to post-treatment (59.5 ± 8.75 mL/min/100g; p = 0.007), while the minute ventilation of the air control group remained relatively constant pre-treatment (72.1 ± 8.6 mL/min/100g) to post-treatment (73.1 ± 15.1 mL/min/100g; p = 0.76). And while a main effect of time on tidal volume was not significant, there is a trend of a decrease in tidal volume for the vapor exposed group from pre- to post-treatment. There was no significant difference (unpaired student’s t-test, p = 0.44) in circulating proinflammatory IL-1β cytokine levels in the serum between the vapor exposed group (4.96 ± 5.98 pg/mL) and air group (8.05 ± 9.98 pg/mL). CONCLUSIONS: After an acute 10-minute e-cigarette vapor exposure, respiratory function was altered in that minute ventilation and possibly tidal volume were decreased in rats exposed to vape. Circulating levels of proinflammatory cytokine IL-1β did not differ between exposure groups. Taken together these results suggest that even a single bout of e-cigarette vapor exposure results in functional changes in the adult lungs. Future studies will investigate the duration of this functional change and additional cytokine presence

Field-induced shaping of sessile paramagnetic drops

We use the electromagnetic stress tensor to describe the elongation of paramagnetic drops in uniform magnetic fields. This approach implies a linear relationship between the shape of the drops and the square of the applied field, which we confirm experimentally. We show that this effect scales with the volume and susceptibility of the drops. By using this unified electromagnetic approach, we highlight the potential applications of combining electric and magnetic techniques for controlled shaping of drops in liquid displays, liquid lenses, and chemical mixing of drops in microfluidics

The introduction of the TMPG fails charge for U.S. Treasury securities

The TMPG fails charge for U.S. Treasury securities provides that a buyer of Treasury securities can claim monetary compensation from the seller if the seller fails to deliver the securities on a timely basis. The charge was introduced in May 2009 and replaced an existing market convention of simply postponing—without any explicit penalty and at an unchanged invoice price—a seller’s obligation to deliver Treasury securities if the seller fails to deliver the securities on a scheduled settlement date. This article explains how a proliferation of settlement fails following the insolvency of Lehman Brothers Holdings Inc. in September 2008 led the Treasury Market Practices Group (TMPG)—a group of market professionals committed to supporting the integrity and efficiency of the U.S. Treasury market—to promote a change in the existing market convention. The change—the introduction of the fails charge—was significant because it mitigated an important dysfunctionality in the secondary market for U.S. Treasury securities and because it stands as an example of the value of cooperation between the public and private sectors in responding to altered market conditions in a flexible, timely, and innovative fashion.Treasury bonds ; Government securities ; Clearing of securities ; Secondary markets

Seven Day E-cigarette Vapor Exposure Does Not Modify Ventilation Patterns in Long-Evans Rats

Electronic nicotine delivery systems or e-cigarettes are devices used to deliver aerosolized liquids often containing nicotine and other chemicals. These devices were originally created as a way to assist with smoking cessation in adults; however, use of these devices is increasing in adolescent and young adult populations. The long and short term effects of vaping are still under active investigation. PURPOSE: The purpose of this study was to investigate the effects of 7 days of e-cigarette vapor exposure in adult rats on lung function and lung tissue inflammatory cytokine expression, specifically IL-1. METHODS: Using random assignment, 10 adult male long-evans rats were assigned to vape (experimental) or air (control) groups. The animals were exposed to either air (n = 4) or 5% nicotine vapor (n=6) using a whole-body exposure chamber, twice a day for ten minutes for seven consecutive days. Ventilation recordings were completed on day 0 (before exposure) and day 8 (after exposure) using unrestrained whole-body plethysmography. Minute ventilation, tidal volume, and breathing frequency were assessed. Blood was collected on day 8 to look for the presence of cotinine (a nicotine metabolite). Whole lung tissue was also collected on day 8 for inflammatory cytokine assay, IL-1 ELISA. RESULTS: Cotinine was found to be present in the serum samples of the vape groups (86.6 ng/ml +/- 1.0 ng/mL) but not the air groups (0.0 ng/mL) confirming drug exposure. Baseline ventilation data collected on day 0 and post-exposure ventilation data collected on day 8 were compared between air and vape groups across three different parameters: minute ventilation, frequency, and tidal volume. These parameters were compared resulting in three distinct two-way ANOVAs comparing the variables time and treatment. No significant difference was found among any of the comparisons (p \u3e 0.05 for all). Similarly, no difference in lung inflammatory cytokine IL-1 was observed in the lung tissue of the air (85.6 pg/mL +/- 10.2 pg/mL) or vape (82.7 pg/mL +/- 14.9 pg/mL) exposure groups (p \u3e 0.05, t-test). CONCLUSIONS: In this study, 7 days of e-cigarette vapor exposure did not affect ventilation parameters or increase the presence of inflammatory cytokine, IL-1, in whole lung tissue. Limitations to this study include a small sample size (n = 10) and unreliable negative-pressure which were used to produce the vapor for the e-cigarette exposure. Future studies will modify the vape exposure system and include a larger sample size

Successful retrieval of competing spatial environments in humans involves hippocampal pattern separation mechanisms.

The rodent hippocampus represents different spatial environments distinctly via changes in the pattern of "place cell" firing. It remains unclear, though, how spatial remapping in rodents relates more generally to human memory. Here participants retrieved four virtual reality environments with repeating or novel landmarks and configurations during high-resolution functional magnetic resonance imaging (fMRI). Both neural decoding performance and neural pattern similarity measures revealed environment-specific hippocampal neural codes. Conversely, an interfering spatial environment did not elicit neural codes specific to that environment, with neural activity patterns instead resembling those of competing environments, an effect linked to lower retrieval performance. We find that orthogonalized neural patterns accompany successful disambiguation of spatial environments while erroneous reinstatement of competing patterns characterized interference errors. These results provide the first evidence for environment-specific neural codes in the human hippocampus, suggesting that pattern separation/completion mechanisms play an important role in how we successfully retrieve memories

Lifting the Burden of Addiction: Philanthropic Opportunities to Address Substance Use Disorders in the United States

Substance use disorders (SUDs), also known as substance abuse or addiction, affect an estimated 20 million or more adolescents and adults in the U.S. This guidance provides philanthropic funders with the tools & information to reduce immediate harm from substance use disorders and reduce the burden of the disorder over the long term. This includes reducing the damage the disorder causes to people with SUDs and their loved ones, reducing the overall incidence of SUDs, and reducing SUD-related costs to society. We present four strategies for philanthropic funders who want to help:- Save lives and reduce SUD-related illness and homelessness- Improve access to evidence-based treatment- Improve SUD care by changing systems and policies- Fund innovation to improve prevention and treatmen

Effects of 14 Day E-Cigarette Exposure on Ventilation and Circulating Pro-Inflammatory Cytokines in Adolescent Rats

Electronic nicotine delivery systems or e-cigarettes are devices used to deliver vaporized liquids often containing nicotine and other chemicals. These devices were originally created as a way to assist with smoking cessation in adults; however, use of these devices is increasing in adolescent and young adult populations. Recent research suggests that exposure to the chemicals in e-cigarette vapor may cause harm to adolescent lung tissue and promote a proinflammatory immune response in the lungs. These molecular changes may lead to functional changes in terms of lung volumes or gas exchange at the respiratory membrane. PURPOSE: The purpose of this study was to investigate the effects of 14 days of e-cigarette vapor exposure in adolescent rats on lung function and lung tissue proinflammatory cytokine expression, specifically IL-1β. METHODS: Using random assignment, 20 adolescent male Long Evans rats were assigned to vape (experimental) or air (control) groups. The animals were exposed to either air (n = 10) or 5% nicotine vapor (n=10) using a whole-body exposure chamber, once a day for ten minutes for fourteen consecutive days. Ventilation recordings were completed on day 0 (before exposure) and day 15 (after exposure) using unrestrained whole-body plethysmography. Minute ventilation/100g, tidal volume/100g, and breathing frequency were assessed. Blood was collected on day 15 and processed to serum. Serum samples were analyzed for circulating levels of the nicotine metabolite, cotinine, and the proinflammatory cytokine, IL-1β, using enzyme linked immunosorbent assays (ELISA). RESULTS: Cotinine was found to be present in the serum samples of the vape groups (20.71 ng/ml +/- 6.875 ng/mL) but not the air groups (0.007 +/- 0.019 ng/mL) confirming nicotine and vapor exposure. Baseline ventilation data collected on day 0 and post-exposure ventilation data collected on day 15 were compared between air and vape groups across three different parameters: minute ventilation/100g , frequency, and tidal volume/100 g. These parameters were compared resulting in three distinct 2x2 (time x treatment) Mixed Model ANOVAs. Between baseline and post-treatment measurements, for both groups, there was a significant decrease in values in minute ventilation (F(1,15) = 5.647, p = 0.0312) and tidal volume (F(1,15) = 12.38, p = 0.0031). Between treatment groups there was also a significant difference in minute ventilation (F(1,15) = 7.979, p = 0.0128) and frequency (F(1,15) = 11.35, p = 0.0042). There was also significantly lower levels observed in the inflammatory cytokine IL-1β (p \u3c 0.0136) for the vape group (22.13 +/- 19.96 pg/mL) in comparison to the air group (3.28 +/- 3.52 pg/mL). CONCLUSIONS: Following 14 days of e-cigarette vapor exposure, ventilation patterns were altered in the vapor exposed animals, specifically decreasing tidal volume and minute ventilation. Additionally, in these same vapor exposed animals, circulating levels of the pro-inflammatory cytokine, IL-1ꞵ, was decreased suggesting dysregulation of immune pathways. Taken together these results suggest that the use of e-cigarettes may lead to both functional and molecular changes in adolescent lungs, interfering with pulmonary function and affecting one’s quality of life