Tag Archives: sample

CAN YOU PROVIDE MORE DETAILS ABOUT THE MARS SAMPLE RETURN CAMPAIGN AND HOW IT RELATES TO PERSEVERANCE’S MISSION?

Leave a reply

The Mars Sample Return (MSR) campaign is an ambitious multi-year collaborative effort between NASA and the European Space Agency (ESA) to return scientifically selected rock and soil samples from Mars to Earth. Bringing samples back from Mars has been a priority goal of the planetary science community for decades as samples would provide a wealth of scientific information that cannot be obtained by current robotic surface missions or remote sensing from orbit. Analyzing the samples in advanced laboratories here on Earth has the potential to revolutionize our understanding of Mars and help answer key questions about the potential for life beyond Earth.

Perseverance’s role in the MSR campaign is to collect scientifically worthy rock and soil samples from Jezero Crater using its drill and sample caching system. Jezero Crater is a 28-mile wide basin located on the western edge of Isidis Planitia, just north of the Martian equator. Billions of years ago, Jezero was the site of an ancient lake filled by a river delta. Scientists believe this location preserves a rich geological record that could provide vital clues about the early climate and potential for life on Mars.

Perseverance carries 43 sample tubes that can each store one core sample about the size of a piece of chalk. Using its 7-foot long robotic arm, drill, and other instruments like cameras and spectrometers, Perseverance will identify and study geologically interesting rock formations and sedimentary layers that could contain traces of ancient microbial life or preserve a record of past environments like a lake. Under careful sterile conditions, Perseverance’s drill will then take core samples from selected rocks and the rover will transfer them to sealed tubes.

The carefully cached samples will then remain on the surface of Mars until a future MSR mission can retrieve them for return to Earth, hopefully within the next 10 years. Leaving the samples on the surface minimizes the risk of contaminating Earth with any Martian material and allows the scientific study of samples to happen under optimal laboratory conditions here with sophisticated equipment far beyond the capabilities of any Mars surface mission.

Perseverance began caching samples in its first session at “Rochette” in October 2021 and as of March 2022 had already cached 9 samples. It plans to continue collecting samples at Jezero Crater through at least 2033 to ensure the most scientifically compelling samples are returned to Earth for detailed analysis. The tubes will be deposited in carefully documented “cache” locations along the rover’s route so future missions know where to retrieve them. In total, Perseverance has the capability to cache up to 38 samples by the end of its prime mission.

The ambitious MSR architectural plan currently envisions three complex separate missions to retrieve and return the cached Perseverance samples. The first mission, currently targeted for launch in 2028, is the Mars Ascent Vehicle/Orbiting Sample (MAV/OS). This rocket and spacecraft combo would land near Perseverance’s cached samples, lift off from the Martian surface, and deploy the Sample Retrieval Lander containing the Mars Orbiting Sample canister.

The Sample Retrieval Lander would then touch down, deploy a small rover to retrieve the cache tubes left by Perseverance at the designated cache location(s), and transfer the samples to the Sample Orbiting Sample canister. The MAV would then lift back into Martian orbit where it would rendezvous with the orbiter and transfer the Sample Orbiting canister into the secure containment orbiting Mars.

The next critical MSR mission is the Earth Return Orbiter (ERO) launch, targeted for 2030. The ERO spacecraft would travel to Mars and capture the orbiting sample container left by the MAV/OS mission. The ERO would then depart Mars and begin the seven-month 230-million-mile trip back to Earth carrying the priceless samples. To prevent terrestrial contamination, the samples would remain sealed in the containment orbiter for re-entry.

The third mission planned is the Earth Entry Vehicle (EEV) targeted to launch in 2031. This mission would capture the returning ERO spacecraft and utilizing a capsule, heat shield, and parachutes, would safely land the sample containers in Utah’s west desert where scientists can extract the Mars samples under strict planetary protection protocols in new laboratories built specifically for this purpose.

The unprecedented MSR campaign has the potential to revolutionize our understanding of Mars and address questions that have intrigued scientists for generations like whether Mars ever supported microbial life. Careful caching by Perseverance and meticulous retrieval and return by the future MSR elements provides the best opportunity for scientific discovery while ensuring planetary protections. Perseverance’s diligent efforts at Jezero Crater to select and cache compelling rock core samples in its ambitious multi-year exploration leaves promising potential for future scientists to examine Martian treasures from the safety of Earth.

HOW DID THE PROJECT ADDRESS THE LIMITATIONS OF SAMPLING FROM A SINGLE HOSPITAL AND SMALL SAMPLE SIZE

Leave a reply

The researchers acknowledged that sampling data from only one hospital and with a relatively small sample size of 250 patients were limitations of the study that could impact the generalizability and reliability of the results. To help address these limitations, the researchers took several steps in the design, data collection, and analysis phases of the project.

In the study design phase, the researchers chose the hospital purposely as it was a large, urban, academic medical center that served a racially, ethnically, and economically diverse patient population from both the local community as well as patient referrals from other areas. This helped make the sample more representative of the broader population beyond just the local community served by that single hospital. The researchers only included patients across all departments of the hospital rather than focusing on specific diagnosis or treatment areas to get a broad cross-section of overall hospital patients.

Regarding sample size, while 250 patients was not a massive sample, it was a sufficient size to conduct statistical analyses and identify meaningful trends according to power calculations conducted during the study design. Also, to supplement the quantitative survey data from patients, the researchers conducted in-depth qualitative interviews with 20 patients to gain deeper insights into experiences that larger-scale surveys alone may miss. Interviewing a subset of the sample allowed for a mixed-methods approach that provided richer contextual understanding to support the quantitative findings.

During data collection, the researchers took efforts to maximize the response rate and reduce non-response bias that are risks with smaller samples. For the patient surveys, research assistants were present on various hospital units at varying times of day to approach all eligible patients during their stays, rather than relying on mail-back surveys. Monetary incentives were also provided to encourage participation. The quantitative survey included demographic questions so the researchers could analyze response patterns and identify any subgroups that may have been underrepresented to help address missing data issues.

For analysis and reporting of results, the researchers were transparent about the limitations of sampling from a single site and small sample size. They did not overgeneralize or overstate the applicability of findings but rather framed results asexploratory and in need of replication. Statistical significance was set at a more stringent level of p<0.01 rather than the typical p<0.05 to increase confidence given the moderate sample. Qualitative interview data was used to provide context and nuanced explanation for quantitative results rather than being reported separately. The researchers also performed several supplementary analytical tests to evaluate potential sampling bias. They compared their participant demographics to hospital patient demographics overall as an indicator of representativeness. Response patterns by demographic group were examined for non-response bias. They randomly split the sample in half and ran parallel analyses on each half to verify consistency of identified associations and trends, rather than assuming results would replicate with an independent sample. In their write-up and discussion of limitations, the researchers clearly acknowledged the constraints of the single-site setting and sample size. They argued their intentional sampling approach, mixed-methods design, response maximization efforts, more rigorous analysis, and supplementary tests provided meaningful initial insights with results that lay the necessary groundwork for future replication studies with larger, multi-site samples before making conclusive generalizations. The transparency around limitations and implications for applicability of findings model best practices for rigorously addressing challenges inherent to pilot and feasibility studies. Through careful attention in their methodology and analysis, the researchers took important steps to offset the acknowledged issues that could arise from their relatively small, single-site sample. Their comprehensive approach set the stage to begin exploring meaningful trends while also recognizing the need for future replication. The study provides an example of how initial feasibility research can be conducted and reported responsibly despite inherent sampling constraints.

AP LIT SAMPLE ESSAYS 2023

Leave a reply

The literary works of William Shakespeare continue to be both deeply inspirational and profoundly relevant today. In his tragedy Hamlet, Shakespeare explores universal themes of madness, revenge, morality, and the complexity of human nature that resonate as powerfully now as they did over 400 years ago when the play was written. At its core, Hamlet examines how revenge can destroy one’s soul and humanity.

Hamlet is tragic hero who is trying to balance his desire for vengeance with his moral conscience. Upon learning of his father’s murder at the hands of his uncle Claudius, who has also married Hamlet’s mother Gertrude, Hamlet is thrown into a state of deep grief and anger. He is a thoughtful, introspective character who is reluctant to take violent action without being completely certain. He fears that acting on impulse for revenge may be morally wrong or make him no better than his uncle. As the play’s morality play unfolds, Hamlet’s delay in seeking revenge allows his madness and inner turmoil to grow, spiraling further out of control.

One of the most famous elements of Hamlet is the “To be or not to be” soliloquy, where Hamlet contemplates suicide as an escape from the pains and troubles of the world. On the surface, he questions whether it is better to live with life’s difficulties or take arms against them by ending his own life. On a deeper level Hamlet is grappling with the moral conflict between his desire for vengeance and his conscience telling him not to commit murder, even if justified. The soliloquy perfectly encapsulates Hamlet’s inner turmoil and indecision as he tries to decide what path is right versus what his emotions are pushing him toward. This exploration of morality versus vengeance remains extremely compelling as audiences continue to wrestle with similar questions about justice, ethics, and human nature.

While seeking certainty and justice for his father’s murder, Hamlet’s delay in acting allows his mental state and behavior to descend into madness. His “antic disposition” takes on a public performance as he tries both to uncover the truth and stall for time while deciding what to do. Hamlet’s madness serves the useful dramatic purpose of allowing him to openly express his inner turmoil, confusion, disgust and grief without suspicion while also moving the plot forward. It also shows the personal cost of prolonged inaction and inability to resolve his conflicted feelings. Shakespeare uses Hamlet to profoundly demonstrate how the desire for revenge can consume and destroy someone from within if left to fester for too long without resolution.

One of the most compelling scenes demonstrating Hamlet’s decline into suspected madness is the “mouse trap” play scene. By covertly observing Claudius’s reaction to a play mimicking the murder of his father, Hamlet believes he has gotten the proof he needs to enact revenge. His behavior during this pivotal scene, especially verbally abusing his former love Ophelia, shows the personal toll his obsession with vengeance has taken. While gaining clarity, Hamlet has lost sight of whom his actions may hurt as his madness grows. This is a warning about how focusing on external desires for retribution can cause someone to neglect their own humanity and relationships.

Hamlet serves as a brilliant meditation on humanity’s capacity for both good and evil, as well as the tragic consequences that can occur when morality becomes obscured by emotions like anger and the desire for vengeance. While seeming to resolve itself through various characters’ deaths, the play leaves the audience with unsettled questions about justice, fate, and whether any in the end truly achieved peace or redemption. Hamlet’s delay is both his tragic flaw and what allows the complex themes to fully develop and continue challenging new generations of audiences. Shakespeare uses the characters and Danish setting but taps into issues that remain timeless – showing his genius and relevance will surely continue for centuries more.