The difference between primary and secondary sources is very important in the sciences, and distinguishing between the two is an important skill.
Primary articles mean that the authors of the article are reporting on their original experiment and results in the lab or field, etc. They have a literature review of what others have written about the topic, but then they have a methodology and results sections. They tend to have more jargon and they tend to be on a narrowly focused topic, but they represent the heart of how we know what we know in the sciences.
Secondary articles convey findings about library research on a topic. They are a literature review of what others have said and do not do their own experiments. They often have less jargon and cover a topic more broadly, often making them easier to read for novice scientists. They are also useful for experience scientists who want to see an overview of a topic so they have a better idea how specific individual studies fit into the broader picture.
Using the citations below, identify which article is primary and which is secondary.
1.Horseshoe crabs: biomedical importance and its potential use in developing health-care products
Horseshoe crabs have been a model for many biomedical science studies. Medicinal value of horseshoe crabs comes from its blue blood, eye and exoskeleton (chitin). Ability of blood to clot in the presence of bacteria, rendering the bacteria harmless has created its biomedical importance. Blood cells (amebocytes) carry Factor C, which binds lipopolysaccharide (LPS), undergoes a structural reorganization, then auto-proteolytically activates itself to initiate the clotting pathway that eventually results in a proteolytic modification of the zymogen, coagulogen, which then self-polymerizes into the insoluble fibrils of the extracellular blood clot. Blood-clotting ability of the horseshoe crab makes it very valuable in testing for injectable medicines, vaccines and sterile medical equipment. Secondly, the nerve pathways in the eyes of horseshoe crabs have led to many discoveries in human eye research. Furthermore, the outer shell of a horseshoe crab is made primarily of chitin and being used as a coating for suture material and burn dressings, rapidly increases the wound healing, cutting the time by half.
2. 2-PHENOXYETHANOL (2-PE) AND TRICAINE METHANESULFONATE (MS-222) IMMERSION ANESTHESIA OF AMERICAN HORSESHOE CRABS (LIMULUS POLYPHEMUS)
Despite extensive literature examining American horseshoe crab physiology, there are comparatively few publications addressing their medical care. Establishing anesthesia protocols for horseshoe crabs is integral to limiting the potential stress and pain associated with invasive procedures and for advancing euthanasia techniques. The objective of this study was to compare the effects of two immersion anesthetics, tricaine methanesulfonate (MS-222) at 1 g/L (buffered with sodium carbonate) and 2-phenoxyethanol (2-PE) at 2 mL/L, on horseshoe crabs. Twenty horseshoe crabs were assigned to one of two anesthetic treatment groups and individually anesthetized in natural seawater. Water quality, cardiac contractility, and hemolymph gas analytes were measured prior to anesthesia and at 30 min Animals were monitored via heart rate, gilling rate, and sedation score every 5 min until recovered. Transcarapacial ultrasonography was used to obtain heart rate, gilling rate, and percent fractional shortening. Light or surgical anesthesia was produced in 10/10 animals in the 2-PE group and 8/10 animals in the MS-222 group. There was no significant difference in sedation scores, induction time (median 15 min), or recovery time (median 20.5 min). Dining rate and cardiac contractility decreased during anesthesia, whereas heart rate did not. Hemolymph pH and pO(2) were not different among treatment groups or time points. Baseline pCO(2) was higher than pCO(2) at 30 min for both groups but significantly elevated only in the MS-222 group. This is attributed to increased activity during the handling of awake animals. Invasive blood pressure obtained via cardiac catheterization in two animals was markedly decreased during surgical anesthesia. In conclusion, 2-PE and MS-222 provided effective anesthesia with clinically useful induction and recovery times. 2PE provided a subjectively more reliable and smoother anesthesia compared to MS-222.
The history of the decline of the Ivory-billed Woodpecker is long and complex, but the status of the species since 1944, when the last widely accepted sighting in continental North America occurred, is particularly controversial. Reports of Ivory-billed Woodpeckers have continued, but none has reached the threshold of quality for general acceptance by ornithologists or the birdwatching public. In 2021, the U.S. Fish and Wildlife Service opened for public comment a proposal to declare the species extinct. Here, we present evidence suggesting the presence of the Ivory-billed Woodpecker at our study site, based on a variety of data collected over a 10-year search period, 2012-2022. These data are drawn from visual observations, similar to 70,000 h of recordings by 80-100 acoustic recording units, similar to 472,550 camera-hours by as many as 34 trail cameras, and similar to 1089 h of video drawn from similar to 3265 drone flights. Using multiple lines of evidence, the data suggest intermittent but repeated presence of multiple individual birds with field marks and behaviors consistent with those of Ivory-billed Woodpeckers. Data indicate repeated reuse of foraging sites and core habitat. Our findings, and the inferences drawn from them, suggest that not all is lost for the Ivory-billed Woodpecker, and that it is clearly premature for the species to be declared extinct.
The Ivory-billed Woodpecker (Campephilus principalis) is an elusive bird that has repeatedly been feared extinct only to be rediscovered during the past hundred years. The most recent rediscovery, which took place in Arkansas, was announced in an article that was featured on the cover of Science in 2005. Despite published reports of sightings in Florida and Louisiana in the years that followed, the issue became controversial when nobody managed to obtain a clear photo and critics attacked relatively weak video evidence that was presented in the original article. The issue began to develop into a science scandal when the critics used specious arguments to delay the publication of the strongest evidence, which consists of three videos that were obtained during encounters with birds that were identified in the field as Ivory-billed Woodpeckers and that show field marks, body proportions, flights, and other behaviors that are consistent with that species but no other species of the region. The scandal culminated in a decision by the U.S. Fish & Wildlife Service to declare the species extinct in 2021, which was made without addressing the strongest evidence. An update is given here on recent developments. The decision to declare the species extinct was based on a five-year review of evidence for persistence. During an interview, it came to light that the person who performed the review was unaware of basic facts about the strongest evidence. Evidence that was obtained at another site in Louisiana [Latta et al., "Multiple lines of evidence suggest the persistence of the Ivory-billed Woodpecker (Campephilus principalis) in Louisiana," Ecology and Evolution (2023)] is discussed and compared with the strongest evidence. Videos obtained with a drone on a sunny day often show white markings that do not correspond to actual field marks. It is demonstrated that a video that was purported to show an Ivory-billed Woodpecker on the basis of apparent white markings is apparently a Pileated Woodpecker (Dryocopus pileatus). The bird in that video appears to have black trailing edges on the dorsal surfaces of the wings, which are consistent with the Pileated Woodpecker, not the Ivory-billed Woodpecker. The wingbeat frequency and an upward swooping landing also seem to be consistent with the Pileated Woodpecker but are not consistent with historical accounts of the Ivory-billed Woodpecker or flights appearing in videos that contain the strongest evidence.