Shortened food chain length in a fished versus unfished coral reef.

Direct exploitation through fishing is driving dramatic declines of wildlife populations in ocean environments, particularly for predatory and large-bodied taxa. Despite wide recognition of this pattern and well-established consequences of such trophic downgrading on ecosystem function, there have been few empirical studies examining the effects of fishing on whole system trophic architecture. Understanding these kinds of structural impacts is especially important in coral reef ecosystems-often heavily fished and facing multiple stressors. Given the often high dietary flexibility and numerous functional redundancies in diverse ecosystems such as coral reefs, it is important to establish whether web architecture is strongly impacted by fishing pressure or whether it might be resilient, at least to moderate-intensity pressure. To examine this question, we used a combination of bulk and compound-specific stable isotope analyses measured across a range of predatory and low-trophic-level consumers between two coral reef ecosystems that differed with respect to fishing pressure but otherwise remained largely similar. We found that even in a high-diversity system with relatively modest fishing pressure, there were strong reductions in the trophic position (TP) of the three highest TP consumers examined in the fished system but no effects on the TP of lower-level consumers. We saw no evidence that this shortening of the affected food webs was being driven by changes in basal resource consumption, for example, through changes in the spatial location of foraging by consumers. Instead, this likely reflected internal changes in food web architecture, suggesting that even in diverse systems and with relatively modest pressure, human harvest causes significant compressions in food chain length. This observed shortening of these food webs may have many important emergent ecological consequences for the functioning of ecosystems impacted by fishing or hunting. Such important structural shifts may be widespread but unnoticed by traditional surveys. This insight may also be useful for applied ecosystem managers grappling with choices about the relative importance of protection for remote and pristine areas and the value of strict no-take areas to protect not just the raw constituents of systems affected by fishing and hunting but also the health and functionality of whole systems.

Zinc stimulation of coastal productivity in low carbon dioxide environments.

Zinc (Zn) is a key micronutrient used by phytoplankton for carbon (C) acquisition, yet there have been few observations of its influence on natural oceanic phytoplankton populations. In this study, we observed Zn limitation of growth in the natural phytoplankton community of Terra Nova Bay, Antarctica, due to low (~220 µatm) pCO2 conditions, in addition to primary iron (Fe) limitation. Shipboard incubation experiments amended with Zn and Fe resulted in significantly higher chlorophyll a content and dissolved inorganic carbon drawdown compared to Fe addition alone. Zn and Fe response proteins detected in incubation and environmental biomass provided independent verification of algal co-stress for these micronutrients. These observations of Zn limitation under low pCO2 conditions demonstrate Zn can influence coastal primary productivity. Yet, as surface ocean pCO2 rises with continued anthropogenic emissions, the occurrence of Zn/C co-limitation will become rarer, impacting the biogeochemical cycling of Zn and other trace metal micronutrients.

Orthopaedic trauma residency programs: Perspectives from different countries across the world.

The ability to manage the myriad of musculoskeletal conditions successfully requires multiple years of training. Access to and completion of orthopaedic surgical training entails an often grueling, highly regulated path to certification to practice. Although the world is more connected than ever, the question is whether the local certification criteria for medical specialists leads to a generic residency program and a similar training in all countries. This report from eight nations on five continents details the distinctive features of that training, including the number of positions available, the examinations required, the gender distribution of residents, and available possibilities once the residence period is complete. This analysis shows a wide variation in the orthopaedic trauma training program worldwide, with emphasis on different skills per country.

Postfasciotomy Classification System for Acute Compartment Syndrome of the Leg.

OBJECTIVE: Acute compartment syndrome (ACS) is a true emergency. Even with urgent fasciotomy, there is often muscle damage and need for further surgery. Although ACS is not uncommon, no validated classification system exists to aid in efficient and clear communication. The aim of this study was to establish and validate a classification system for the consequences of ACS treated with fasciotomy. METHODS: Using a modified Delphi method, an international panel of ACS experts was assembled to establish a grading scheme for the disease and then validate the classification system. The goal was to articulate discrete grades of ACS related to fasciotomy findings and associated costs. A pilot analysis was used to determine questions that were clear to the respondents. Discussion of this analysis resulted in another round of cases used for 24 other raters. The 24 individuals implemented the classification system 2 separate times to compare outcomes for 32 clinical cases. The accuracy and reproducibility of the classification system were subsequently calculated based on the providers' responses. RESULTS: The Fleiss Kappa of all raters was at 0.711, showing a strong agreement between the 24 raters. Secondary validation was performed for paired 276 raters and correlation was tested using the Kendall coefficient. The median correlation coefficient was 0.855. All 276 pairs had statistically significant correlation. Correlation coefficient between the first and second rating sessions was strong with the median pair scoring at 0.867. All surgeons had statistically significant internal consistency. CONCLUSION: This new ACS classification system may be applied to better understand the impact of ACS on patient outcomes and economic costs for leg ACS.

Locked Plating versus Nailing for Proximal Tibia Fractures: A Multicenter RCT.

OBJECTIVES: The main 2 forms of treatment for extraarticular proximal tibial fractures are intramedullary nailing (IMN) and locked lateral plating (LLP). The goal of this multicenter, randomized controlled trial was to determine whether there are significant differences in outcomes between these forms of treatment. DESIGN: Multicenter, randomized controlled trial. SETTING: 16 academic trauma centers. PATIENTS/PARTICIPANTS: 108 patients were enrolled. 99 patients were followed for 12 months. 52 patients were randomized to IMN, and 47 patients were randomized to LLP. INTERVENTION: IMN or lateral locked plating. MAIN OUTCOME MEASUREMENTS: Functional scoring including Short Musculoskeletal Functional Assessment, Bother Index, EQ-5Dindex and EQ-5DVAS. Secondary measures included alignment, operative time, range of motion, union rate, pain, walking ability, ability to manage stairs, need for ambulatory aid and number, and complications. RESULTS: Functional testing demonstrated no difference between the groups, but both groups were still significantly affected 12 months postinjury. Similarly, there was no difference in time of surgery, alignment, nonunion, pain, walking ability, ability to manage stairs, need for ambulatory support, or complications. CONCLUSIONS: Both IMN and LLP provide for similar outcomes after these fractures. Patients continue to improve over the course of the year after injury but remain impaired even 1 year later. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Locked Lateral Plating Versus Retrograde Nailing for Distal Femur Fractures: A Multicenter Randomized Trial.

OBJECTIVES: The 2 main forms of treatment for distal femur fractures are locked lateral plating and retrograde nailing. The goal of this trial was to determine whether there are significant differences in outcomes between these forms of treatment. DESIGN: Multicenter randomized controlled trial. SETTING: Twenty academic trauma centers. PATIENTS/PARTICIPANTS: One hundred sixty patients with distal femur fractures were enrolled. One hundred twenty-six patients were followed 12 months. Patients were randomized to plating in 62 cases and intramedullary nailing in 64 cases. INTERVENTION: Lateral locked plating or retrograde intramedullary nailing. MAIN OUTCOME MEASUREMENTS: Functional scoring including Short Musculoskeletal Functional Assessment, bother index, EQ Health, and EQ Index. Secondary measures included alignment, operative time, range of motion, union rate, walking ability, ability to manage stairs, and number and type of adverse events. RESULTS: Functional testing showed no difference between the groups. Both groups were still significantly affected by their fracture 12 months after injury. There was more coronal plane valgus in the plating group, which approached statistical significance. Range of motion, walking ability, and ability to manage stairs were similar between the groups. Rate and type of adverse events were not statistically different between the groups. CONCLUSIONS: Both lateral locked plating and retrograde intramedullary nailing are reasonable surgical options for these fractures. Patients continue to improve over the course of the year after injury but remain impaired 1 year postoperatively. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Long-term sequelae of septic arthritis after tibial plateau fracture fixation: does timing matter?

INTRODUCTION: Septic arthritis following surgical treatment of a tibial plateau fracture is a rare complication, but it does occur, and the impact on long-term function is relatively unknown. The purpose of this study was to determine the long-term sequelae of septic arthritis among patients treated with internal fixation for a tibial plateau fracture and to determine the effect of timing (early or late infection) on the rate of such sequela. MATERIALS AND METHODS: A retrospective comparative study was designed using the trauma database of a single level I academic trauma center. Patients who developed culture-positive septic knee arthritis after internal fixation of a tibial plateau fracture, with 1-year follow-up, were included in the study. The number of debridement procedures required was recorded. Rates of long-term complications and implant removal were identified. Complications rates were compared between patients who developed early (within 30 days of definitive fixation) and late (more than 30 days) septic arthritis. RESULTS: The mean number of debridement procedures per patient was six. Fourteen patients (88%) required implant removal, and thirteen (81%) developed knee arthritis. There was a significantly lower rate of complications in the early septic arthritis group compared to the late group (3 of 6 patients or 50%, vs 10 of 10 patients or 100%; p = 0.036). CONCLUSIONS: Patients who developed septic arthritis following internal fixation of a tibial plateau fracture were likely to endure long-term sequelae. Early infection and detection led to fewer complications. Surgeons treating infectious complications in tibial plateau fracture patients should specifically seek to rule out septic arthritis, anticipate that implant removal may be necessary, and counsel these patients appropriately regarding the anticipated natural history of their condition. LEVEL OF EVIDENCE: III.

Autonomous submersible multiport water sampler.

Oceanography and limnology projects often require the collection of water samples for chemical analysis. Manual water sample collection is labor-intensive and often difficult, especially in remote locations or during nighttime hours. Here we describe a compact and inexpensive autonomous submersible multiport water sampler (AutoSampler) that is largely fabricated with off-the-shelf parts making it easier to build and maintain. The system can collect up to 12 discrete samples at user controllable times or intervals and is operated using open source Arduino hardware and software that can be user modified to meet deployment requirements. While the underwater pressure housing presented here is custom built from readily available materials, there are many commercially available pressure case options that can be used as a substitute. The electronic mounting plates and battery pack are designed so that they can easily be adapted to fit into other pressure case housings. Samples can be collected into bags or syringes and sample volume is set by adjusting how long the peristaltic pump is actuated. This AutoSampler allows research that would otherwise be too labor-intensive or logistically difficult to conduct, especially in remote locations.

Autonomous underwater pumping system.

We present an inexpensive autonomous underwater pumping system that is lightweight, compact, independent, and versatile, making it easy to deploy in a multitude of settings. This system can be used to pump water into discrete and flow-through sensor systems. With the exception of the custom built pressure case housing, this system can be fabricated with off-the-shelf parts, making it easier to maintain. This system uses open source Arduino software code for easier customization and operations. The electronics and battery pack used to power this system can be adapted to fit into commercially available pressure case housings.

Automated multiport flow-through water pumping and sampling system.

Flow-through systems are often used in aquarium and aquaculture facilities, laboratories, and aboard research vessels and other mobile systems to collect, analyze, and monitor water properties as they vary across time and location. These systems most often intake water from a single source and deliver it to a suite of flow-through sensors after which waste water either exits the system or is recirculated back to the source. Here we describe a system that is designed to take water from multiple sources via a multiport valve manifold and deliver it to a common sample stream, facilitating analysis by a single suite of flow-through and probe type sensors. Build cost depends on the manifold design and the number of valves, but generally under $9000. The inclusion of a Free Surface Interface Cup (FSIC) allows probe type sensors or sample "sippers" that require unpressurized conditions to be utilized down-stream of the pumping system and manifold. With the exception of the multiport sampling manifold, all components of this system are available off-the-shelf, simplifying construction, service, and maintenance. The operating system code is open source and based on the Arduino platform, enabling users to customize the code to better fit their requirements.

Acute Exertional Compartment Syndrome of Bilateral Upper Extremities After a Push-up Contest.

Acute exertional compartment syndrome (AECS) involving the upper extremity is a rare form of compartment syndrome that occurs after physical activity. Despite its infrequent occurrence, AECS has devastating sequelae, including muscle necrosis and nerve injury. It is imperative to promptly evaluate for AECS in any patient who has notable pain and sensory changes in the context of recent physical activity because of the dire consequences of a missed diagnosis. A 34-year-old man presented to the emergency department with excruciating pain and diffuse paresthesias in his bilateral arms and forearms after participating in a push-up contest. He also had pain with passive stretch of his triceps. Because of these physical examination findings and uncontrollable pain, a clinical diagnosis of AECS was made and was managed with fasciotomies. Postoperatively, the patient's pain and paresthesias slowly resolved, and he was eventually able to return to work at full capacity as a construction worker. This example of AECS of bilateral upper extremities emphasizes that it is a condition that, although rare, is real and must be taken seriously. With appropriate clinical suspicion, a prompt diagnosis can be made, and potentially devastating consequences can be avoided.

Living coral tissue slows skeletal dissolution related to ocean acidification.

Climate change is causing major changes to marine ecosystems globally, with ocean acidification of particular concern for coral reefs. Using a 200 d in situ carbon dioxide enrichment study on Heron Island, Australia, we simulated future ocean acidification conditions, and found reduced pH led to a drastic decline in net calcification of living corals to no net growth, and accelerated disintegration of dead corals. Net calcification declined more severely than in previous studies due to exposure to the natural community of bioeroding organisms in this in situ study and to a longer experimental duration. Our data suggest that reef flat corals reach net dissolution at an aragonite saturation state (ΩAR) of 2.3 (95% confidence interval: 1.8-2.8) with 100% living coral cover and at ΩAR > 3.5 with 30% living coral cover. This model suggests that areas of the reef with relatively low coral mortality, where living coral cover is high, are likely to be resistant to carbon dioxide-induced reef dissolution.

Author Correction: Coral carbon isotope sensitivity to growth rate and water depth with paleo-sea level implications.

The original version of the Source Data associated with this Article included an error, in which the 'Fiji AB d13C-Suess' data point and the 'TNI2 d13C-Suess Effect' data point for the year '1950.5' where incorrectly omitted from the Figure 3 tab. The missing values are '-0.24' and '-0.64', respectively. The HTML has been updated to include a corrected version of Source Data.

Coral carbon isotope sensitivity to growth rate and water depth with paleo-sea level implications.

Although reef coral skeletal carbon isotopes (δ13C) are routinely measured, interpretation remains controversial. Here we show results of a consistent inverse relationship between coral δ13C and skeletal extension rate over the last several centuries in Porites corals at Fiji, Tonga, Rarotonga and American Samoa in the southwest Pacific. Beginning in the 1950s, this relationship breaks down as the atmospheric 13C Suess effect shifts skeletal δ13C > 1.0‰ lower. We also compiled coral δ13C from a global array of sites and find that mean coral δ13C decreases by -1.4‰ for every 5 m increase in water depth (R = 0.68, p < 0.01). This highlights the fundamental sensitivity of coral δ13C to endosymbiotic photosynthesis. Collectively, these results suggest that photosynthetic rate largely determines mean coral δ13C while changes in extension rate and metabolic effects over time modulate skeletal δ13C around this mean value. The newly quantified coral δ13C-water depth relationship may be an effective tool for improving the precision of paleo-sea level reconstruction using corals.

Recent history of persistent organic pollutants (PAHs, PCBs, PBDEs) in sediments from a large tropical lake.

210Pb-dated sediment cores and surface sediments from Lake Chapala (LC), Mexico, were analyzed to assess the temporal trends in concentrations and fluxes of persistent organic pollutants (POPs: PAHs, PCBs and PBDEs). Total sediment concentrations of PAHs (95-1,482 ng g-1), PCBs (9-27 ng g-1) and PBDEs (0.2-2.5 ng g-1) were indicative of moderate to intense contamination. The POP concentrations have progressively increased since the 1990s. The light molecular weight PAHs, and the prevalence of PCB congeners with low-chlorination levels (e.g., di- to tri-CB) and low-to medium-brominated (tri- to penta-BDE) PBDEs in most sections of the sediment profiles, suggested that these POPs have most likely reached these sediments by long-range atmospheric transport from distant sources; although the significant presence of heavier PAH, PCB and PBDE congeners in the topmost sediments, indicate that other nearby and local sources (soil erosion from the catchment, urban and industrial wastewaters discharges, as well as navigation) might have also contributed to the recent input of POPs to LC. Taking into account the relevance of LC as regional freshwater supply and commercial fishing ground, the potential risk posed by the organic contaminated sediments to the biota and human population should not be underestimated.

Binding of Divalent Metal Ions with Deprotonated Peptides: Do Gas-Phase Anions Parallel the Condensed Phase?

Chelation complexes of the histidine-containing tripeptides HisAlaAla, AlaHisAla, and AlaAlaHis with Ni(II) and Cu(II) having a -1 net charge are characterized in the gas phase by infrared multiple-photon dissociation (IRMPD) spectroscopy and density functional theory calculations. We address the question of whether the gas-phase complexes carry over characteristics from the corresponding condensed-phase species. We focus particularly on three aspects of their structure: (i) square-planar chelation by the deprotonated amide nitrogens around the metal ion (low-spin for the Ni case), (ii) metal-ion coordination of the imidazole side chain nitrogen, and (iii) the exceptional preference for metal-ion chelation by peptides with His in the third position from the N-terminus, as in the amino terminal Cu and Ni (ATCUN) motif. We find that square-planar binding around the metal ion, involving bonds to both deprotonated backbone nitrogens, one of the carboxylate oxygens and the N-terminal nitrogen, is the dominant binding motif for all three isomers. In contrast to the condensed-phase behavior, the dominant mode of binding for all three isomers does not involve the imidazole side chain, which is instead placed outside the coordination zone. Only for the AlaAlaHis isomer, the imidazole-bound structure is also detected as a minority population, as identified from a distinctive short-wavelength IR absorption. The observation that this conformation exists only for AlaAlaHis correlates with condensed-phase behavior at neutral-to-basic pH, in the sense that the isomer with His in the third position is exceptionally disposed to metal ion chelation by four nitrogen atoms (4N) when compared with the other isomers. These results also emphasize the divergence between the conformational stabilities in the gas phase and in solution or crystalline environments: in the gas phase, direct metal binding of the imidazole is overall less favorable than the alternative of a remote imidazole that can act as an intramolecular H-bond donor enhancing the gas-phase stability.

The art of talking about science: beginning to teach physiology students how to communicate with nonscientists.

The ability to clearly disseminate scientific knowledge is a skill that is necessary for any undergraduate student within the sciences. Traditionally, this is accomplished through the instruction of scientific presentation or writing with a focus on peer-to-peer communication at the expense of teaching communication aimed at a nonscientific audience. One of the ramifications of focusing on peer-to-peer communication has presented itself as an apprehension toward scientific knowledge within the general populace. This apprehension can be seen in a variety of venues, including the traditional media, popular culture, and education, which generally paint scientists as aloof and with an inability to discuss scientific issues to anyone other than other scientists. This paper describes a curriculum designed to teach Introduction to Anatomy and Physiology students the tools necessary for communicating complex concepts that were covered during the semester using approachable language. Students were assessed on their word usage in associated writing activities, the student's ability to reduce complexity of their statements, and performance in an informal scientific presentation to a lay audience. Results showed that this pedagogical approach has increased students' ability to reduce the complexity of their language in both a written and oral format. This, in turn, led to evaluators reporting greater levels of understanding of the topic presented following the presentation.

Infrared laser dissociation of single megadalton polymer ions in a gated electrostatic ion trap: the added value of statistical analysis of individual events.

In this study, we report the unimolecular dissociation mechanism of megadalton SO3-containing poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) polymer cations and anions with the aid of infrared multiphoton dissociation coupled to charge detection ion trap mass spectrometry. A gated electrostatic ion trap ("Benner trap") is used to store and detect single gaseous polymer ions generated by positive and negative polarity in an electrospray ionization source. The trapped ions are then fragmented due to the sequential absorption of multiple infrared photons produced from a continuous-wave CO2 laser. Several fragmentation pathways having distinct signatures are observed. Highly charged parent ions characteristically adopt a distinctive "stair-case" pattern (assigned to the "fission" process) whereas low charge species take on a "funnel like" shape (assigned to the "evaporation" process). Also, the log-log plot of the dissociation rate constants as a function of laser intensity between PAMPS positive and negative ions is significantly different.

Acetoclastic Methanosaeta are dominant methanogens in organic-rich Antarctic marine sediments.

Despite accounting for the majority of sedimentary methane, the physiology and relative abundance of subsurface methanogens remain poorly understood. We combined intact polar lipid and metagenome techniques to better constrain the presence and functions of methanogens within the highly reducing, organic-rich sediments of Antarctica's Adélie Basin. The assembly of metagenomic sequence data identified phylogenic and functional marker genes of methanogens and generated the first Methanosaeta sp. genome from a deep subsurface sedimentary environment. Based on structural and isotopic measurements, glycerol dialkyl glycerol tetraethers with diglycosyl phosphatidylglycerol head groups were classified as biomarkers for active methanogens. The stable carbon isotope (δ13C) values of these biomarkers and the Methanosaeta partial genome suggest that these organisms are acetoclastic methanogens and represent a relatively small (0.2%) but active population. Metagenomic and lipid analyses suggest that Thaumarchaeota and heterotrophic bacteria co-exist with Methanosaeta and together contribute to increasing concentrations and δ13C values of dissolved inorganic carbon with depth. This study presents the first functional insights of deep subsurface Methanosaeta organisms and highlights their role in methane production and overall carbon cycling within sedimentary environments.

Intramedullary Nailing for Pilon Nonunions.

Nonunions are uncommon sequelae of tibial pilon fractures, but they can present a challenging problem to the treating surgeon. Treatment strategies can range from isolated bone grafting to revision plating depending on the type of nonunion and patient factors. Here, we present our technique and clinical results for intramedullary nailing of tibial pilon nonunions.