Soil-Carbonate Genesis in the Pinacate Volcanic Field, Northwestern Sonora, Mexico

1991 ◽  
Vol 35 (3-Part1) ◽  
pp. 400-416 ◽  
Author(s):  
Janet L. Slate ◽  
William B. Bull ◽  
Teh-Lung Ku ◽  
Muhammad Shafiqullah ◽  
Daniel J. Lynch ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Laboratory Data ◽  
Clay Content ◽  
Volcanic Field ◽  
Soil Profiles ◽  
Soluble Salts ◽  
Pedogenic Carbonate ◽  
The Past ◽  
The Mean ◽  
Eolian Deposits

AbstractUranium-series methods were used to date and evaluate pedogenic CaCO3 genesis in the Pinacate volcanic field, northwestern Sonora, Mexico. Soils are developed in eolian deposits on lava flows. 230Th/234U dates of pedogenic carbonate are mininum soil ages because of (1) the time needed to yield clasts from flows and to accrete enough carbonate to sample, (2) subsequent additions of uranium, and (3) continued solution and reprecipitation of carbonate rinds. K-Ar dates of basalt flows are maximum soil ages. Maximum and minimum rates of CaCO3 accumulation are calculated from the Th/U dates and K-Ar dates, respectively. The mean maximum rate is 0.13 g CaCO3/cm2/1000 yr and the mean minimum rate is 0.05 g CaCO3/cm2/1000 yr. Least-squares regressions of pedogenic carbonate and clay content and of Th/U ages against K-Ar ages suggest additions to soils from atmospheric sources throughout the late Quaternary. Morphology of pedogenic carbonate and laboratory data for soluble salts indicate that the climate of the Pinacate has not changed significantly during the past 150,000 yr. Soil variability is influenced by proximity of the eolian source. Near the periphery of the Pinacate, carbonate and clay are evenly distributed throughout soil profiles. Within the volcanic field, carbonate and clay are concentrated in soil horizons, suggesting that additions from atmospheric sources are slow enough to allow translocation.

scholarly journals Radiocarbon and Stable Carbon Isotopes in Two Soil Profiles from Northeast India

Radiocarbon ◽  
2012 ◽  
Vol 54 (01) ◽  
pp. 81-89 ◽  
Author(s):  
Amzad H Laskar ◽  
M G Yadava ◽  
R Ramesh
Keyword(s):  
Organic Carbon ◽  
Stable Carbon Isotopes ◽  
Agricultural Land ◽  
Clay Content ◽  
Carbon Dynamics ◽  
Northeast India ◽  
Turnover Time ◽  
Soil Profiles ◽  
The Mean ◽  
Surface Vegetation

Two soil profiles from northeast India, one from Bakrihawar, an agricultural land, and the other from Chandipur, a virgin hilly area from Assam, are investigated to understand the organic carbon dynamics of the area. Due to frequent flooding, the Bakrihawar soil has accumulated a higher clay content than that of Chandipur. The carbon content is less than 1% by weight in both the sites. The higher clay content is responsible for relatively more soil organic carbon at Bakrihawar. The mean δ13C values at both sites reflect the values of the overlying vegetation. At Bakrihawar, both rice cultivation (C3) and natural C4grasses contribute to higher mean enriched values of13C relative to Chandipur, where the surface vegetation is mostly of C3type. The turnover time of organic carbon, estimated using the residual radiocarbon content, depends strongly on the soil particle size distribution, especially the clay content (i.e. it increases with clay content). To the best of our knowledge, this is the first soil carbon dynamics study of its kind from northeast India.

scholarly journals Radiocarbon and Stable Carbon Isotopes in Two Soil Profiles from Northeast India

Radiocarbon ◽  
2012 ◽  
Vol 54 (1) ◽  
pp. 81-89 ◽  
Author(s):  
Amzad H Laskar ◽  
M G Yadava ◽  
R Ramesh
Keyword(s):  
Organic Carbon ◽  
Stable Carbon Isotopes ◽  
Agricultural Land ◽  
Clay Content ◽  
Carbon Dynamics ◽  
Northeast India ◽  
Turnover Time ◽  
Soil Profiles ◽  
The Mean ◽  
Surface Vegetation

Two soil profiles from northeast India, one from Bakrihawar, an agricultural land, and the other from Chandipur, a virgin hilly area from Assam, are investigated to understand the organic carbon dynamics of the area. Due to frequent flooding, the Bakrihawar soil has accumulated a higher clay content than that of Chandipur. The carbon content is less than 1% by weight in both the sites. The higher clay content is responsible for relatively more soil organic carbon at Bakrihawar. The mean δ13C values at both sites reflect the values of the overlying vegetation. At Bakrihawar, both rice cultivation (C3) and natural C4 grasses contribute to higher mean enriched values of 13C relative to Chandipur, where the surface vegetation is mostly of C3 type. The turnover time of organic carbon, estimated using the residual radiocarbon content, depends strongly on the soil particle size distribution, especially the clay content (i.e. it increases with clay content). To the best of our knowledge, this is the first soil carbon dynamics study of its kind from northeast India.

Quantification of excess 231Pa in late Quaternary igneous baddeleyite

2020 ◽  
Vol 105 (12) ◽  
pp. 1830-1840 ◽  
Author(s):  
Yi Sun ◽  
Axel K. Schmitt ◽  
Lucia Pappalardo ◽  
Massimo Russo
Keyword(s):  
Late Quaternary ◽  
Central Italy ◽  
Direct Analysis ◽  
Weight Percent ◽  
Volcanic Field ◽  
Distribution Coefficients ◽  
Secular Equilibrium ◽  
Melt Distribution ◽  
D Values ◽  
Significant Figures

Abstract Initial excess protactinium (231Pa) is a frequently suspected source of discordance in baddeleyite (ZrO2) geochronology, which limits accurate U/Pb dating, but such excesses have never been directly demonstrated. In this study, Pa incorporation in late Holocene baddeleyite from Somma-Vesuvius (Campanian Volcanic Province, central Italy) and Laacher See (East Eifel Volcanic Field, western Germany) was quantified by U-Th-Pa measurements using a large-geometry ion microprobe. Baddeleyite crystals isolated from subvolcanic syenites have average U concentrations of ~200 ppm and are largely stoichiometric with minor abundances of Nb, Hf, Ti, and Fe up to a few weight percent. Measured (231Pa)/(235U) activity ratios are significantly above the secular equilibrium value of unity and range from 3.4(8) to 14.9(2.6) in Vesuvius baddeleyite and from 3.6(9) to 8.9(1.4) in Laacher See baddeleyite (values within parentheses represent uncertainties in the last significant figures reported as 1σ throughout the text). Crystallization ages of 5.12(56) ka (Vesuvius; MSWD = 0.96, n = 12) and 15.6(2.0) ka (Laacher See; MSWD = 0.91, n = 10) were obtained from (230Th)/(238U) disequilibria for the same crystals, which are close to the respective eruption ages. Applying a corresponding age correction indicates average initial (231Pa)/(235U)0 of 8.8(1.0) (Vesuvius) and 7.9(5) (Laacher See). For reasonable melt activities, model baddeleyite-melt distribution coefficients of DPa/DU = 5.8(2) and 4.1(2) are obtained for Vesuvius and Laacher See, respectively. Speciation-dependent (Pa4+ vs. Pa5+) partitioning coefficients (D values) from crystal lattice strain models for tetra- and pentavalent proxy ions significantly exceed DPa/DU inferred from direct analysis of 231Pa for Pa5+. This is consistent with predominantly reduced Pa4+ in the melt, for which D values similar to U4+ are expected. Contrary to common assumptions, baddeleyite-crystallizing melts from Vesuvius and Laacher See appear to be dominated by Pa4+ rather than Pa5+. An initial disequilibrium correction for baddeleyite geochronology using DPa/DU = 5 ± 1 is recommended for oxidized phonolitic melt compositions.

Scrub typhus (Orientia tsutsugamushi), A rapidly spreading epidemic in Chennai - A standalone lab experience

2016 ◽  
Vol 5 (09) ◽  
pp. 4896
Author(s):  
Sripriya C.S.* ◽  
Shanthi B. ◽  
Arockia Doss S. ◽  
Antonie Raj I. ◽  
Mohana Priya
Keyword(s):  
Scrub Typhus ◽  
Clinical Symptoms ◽  
Clinical Manifestations ◽  
Febrile Illness ◽  
Orientia Tsutsugamushi ◽  
The Past ◽  
Igm Elisa ◽  
The Mean ◽  
Specific Symptoms ◽  
Symptoms And Signs

Scrub typhus (Orientia tsutsugamushi), is a strict intracellular bacterium which is reported to be a recent threat to parts of southern India. There is re-emergence of scrub typhus during the past few years in Chennai. Scrub typhus is an acute febrile illness which generally causes non-specific symptoms and signs. The clinical manifestations of this disease range from sub-clinical disease to organ failure to fatal disease. This study documents our laboratory experience in diagnosis of scrub typhus in patients with fever and suspected clinical symptoms of scrub typhus infection for a period of two years from April 2014 to April 2016 using immunochromatography and IgM ELISA methods. The study was conducted on 648 patients out of whom 188 patients were found to be positive for scrub typhus. Results also showed that pediatric (0 -12 years) and young adults (20 – 39 years) were more exposed to scrub typhus infection and female patients were more infected compared to male. The study also showed that the rate of infection was higher between September to February which also suggested that the infection rate is proportional to the climatic condition. Statistical analysis showed that the mean age of the patients in this study was 37.6, standard deviation was 18.97, CV % was 50.45. 

scholarly journals AB0533 ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODY (ANCA) IN GENERAL POPULATION WITHOUT ANCA ASSOCIATED VASCULITIS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1563.3-1563
Author(s):  
H. Tamaki ◽  
S. Fukui ◽  
T. Nakai ◽  
G. Kidoguchi ◽  
S. Kawaai ◽  
...  
Keyword(s):  
Risk Factors ◽  
Autoimmune Disease ◽  
General Population ◽  
Granulomatosis With Polyangiitis ◽  
Dietary Habits ◽  
Laboratory Data ◽  
Clinical Manifestations ◽  
Anca Associated Vasculitis ◽  
The Mean

Background:Currently it is hypothesized that many systemic autoimmune diseases occur due to environmental risk factors in addition to genetic risk factors. Anti-Neutrophil Cytoplasmic Antibody (ANCA) is mainly associated with three systemic autoimmune disease including granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA). It is known that ANCA can be positive before clinical symptoms in patients with known diagnosis of GPA and ANCA titers rise before clinical manifestations appear. However, prevalence of ANCA among general population is not well known. It has not been described as well how many of people with positive ANCA eventually develop clinical manifestations of ANCA associated Vasculitis.Objectives:This study aims to estimate prevalence of ANCA in general population without ANCA associated Vasculitis. It also describes natural disease course of people with positive ANCA without ANCA associated Vasculitis. Risk factors for positive ANCA are also analyzed.Methods:This is a single center retrospective study at Center for Preventive Medicine of St. Luke’s International Hospital in Tokyo. ANCA was checked among the patients who wished to between 2018 and 2019. St. Luke’s Health Check-up Database (SLHCD) was utilized to collect the data. The patients whose serum was measured for ANCA were identified. The data for basic demographics, social habits, dietary habits and laboratory data were extracted. The charts of the patients with positive ANCA were reviewed.Results:Sera of total 1204 people were checked for ANCA. Of these 1204 people, 587 (48.8%) are male and the mean age was 55.8 years (32.6 to 79). There were total 11 patients with positive ANCA. Myeloperoxidase ANCA (MPO-ANCA) was positive for 3 patients and proteinase 3 ANCA (PR3-ANCA) was positive for 8 patients. Of these 11 patients, 5 were male (45.5%) and the mean age was 54.6 years. Two patients had history of autoimmune disease (primary biliary cirrhosis and ulcerative colitis). Five patients were evaluated by rheumatologists with the median follow-up period of 274 days. None of them developed clinical signs and symptoms of ANCA associated Vasculitis. Four out of five patients had ANCA checked later, two of which turned negative. The prevalence of ANCA in this cohort was 0.9% (95% confidence interval [95% CI]: 0.5% to 1.6%). Univariate analysis was performed to identify risk factors of positive ANCA. The variables analyzed include age, gender, body mass index (BMI), smoking habits, alcohol intake, dietary habits (fruits, fish, red meat), hypertension, dyslipidemia, and laboratory data. None of these variables demonstrated statistically significant differences except for positive rheumatoid factor (ANCA positive group: 33 % vs ANCA negative group: 9.1%, p value = 0.044).Conclusion:The prevalence of ANCA in this cohort was 0.9% (95% CI: 0.5% to 1.6%). None of them who had a follow-up developed ANCA associated Vasculitis during the follow-up period. Longer follow-up and more patients are necessary to determine natural course of people with positive ANCA.Disclosure of Interests:None declared

scholarly journals FRI0505 TOCILIZUMAB DISCONTINUATION AFTER REMISSION ACHIEVEMENT IN PATIENTS WITH ADULT STILL’S DISEASE

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 851.2-851
Author(s):  
H. Tamai ◽  
Y. Kaneko ◽  
T. Takeuchi
Keyword(s):  
Laboratory Data ◽  
Good Control ◽  
Still’S Disease ◽  
Median Dose ◽  
Chugai Pharmaceutical ◽  
Still's Disease ◽  
Adult Still's Disease ◽  
The Mean ◽  
Recurrence Group ◽  
Observation Period

Background:The efficacy of tocilizumab, an interleukin (IL)-6 receptor inhibitor, has been proved in patients with adult Still’s disease on suppressing systemic inflammation and decreasing glucocorticoid dose. However, whether tocilizumab can be discontinued after remission achievement is unclear.Objectives:To clarify the possibility of tocilizumab discontinuation in patients with adult Still’s disease who achieved remission with tocilizumab.Methods:Consecutive patients with adult Still’s disease diagnosed according to the Yamaguchi’s criteria in our hospital from April 2012 until September 2019 were retrospectively reviewed. Patients who were in good control with tocilizumab were included in the analysis, and their clinical courses were collected from their medical charts. Patients were divided according to the presence of recurrence after tocilizumab discontinuation and compared.Results:Among 42 patients with adult Still’s disease who had a history of intravenous tocilizumab of 8mg/kg use, 13 patients discontinued tocilizumab following a good disease control. During the mean observation period of 26.4 months, six patients (46%) remained in remission while seven patients (54%) developed recurrence after tocilizumab discontinuation. The sex and the mean observation period were not different between the patients with recurrence and those without (71% vs 50%, p=0.43; 27.3 months vs 25.4 months, p=0.93, respectively), but the age at tocilizumab discontinuation tended to be higher in the recurrence group than the non-recurrence group (64.0 years vs 46.5 years, p=0.08). The disease activity including swollen joint counts and laboratory data at tocilizumab discontinuation were comparable between the two groups (serum ferritin levels, 88 ng/mL vs 122 ng/mL, p=0.67). While the duration of tocilizumab use was not different between the two groups (29.4 months vs 39.5 months, p=0.40), the mean interval of tocilizumab infusion at tocilizumab discontinuation in the recurrence group was 3.6 weeks, shorter than the 6.7 weeks in the non-recurrence group (p=0.03). The median dose of prednisolone at tocilizumab discontinuation was 5.0 mg/day in the recurrence group and 0.0 mg/day in the non-recurrence group (p=0.06). In the recurrence group, the duration from the last tocilizumab administration to recurrence was 7.8 months, and the median dose of prednisolone at recurrence was 5.0 mg/day.Conclusion:Patients with adult Still’s disease remaining in remission with a longer interval of tocilizumab administration and a lower dose of prednisolone was likely to succeed in withdrawal of tocilizumab.Disclosure of Interests:Hiroya Tamai: None declared, Yuko Kaneko Speakers bureau: Dr. Kaneko reports personal fees from AbbVie, personal fees from Astellas, personal fees from Ayumi, personal fees from Bristol-Myers Squibb, personal fees from Chugai, personal fees from Eisai, personal fees from Eli Lilly, personal fees from Hisamitsu, personal fees from Jansen, personal fees from Kissei, personal fees from Pfizer, personal fees from Sanofi, personal fees from Takeda, personal fees from Tanabe-Mitsubishi, personal fees from UCB, Tsutomu Takeuchi Grant/research support from: Eisai Co., Ltd, Astellas Pharma Inc., AbbVie GK, Asahi Kasei Pharma Corporation, Nippon Kayaku Co., Ltd, Takeda Pharmaceutical Company Ltd, UCB Pharma, Shionogi & Co., Ltd., Mitsubishi-Tanabe Pharma Corp., Daiichi Sankyo Co., Ltd., Chugai Pharmaceutical Co. Ltd., Consultant of: Chugai Pharmaceutical Co Ltd, Astellas Pharma Inc., Eli Lilly Japan KK, Speakers bureau: AbbVie GK, Eisai Co., Ltd, Mitsubishi-Tanabe Pharma Corporation, Chugai Pharmaceutical Co Ltd, Bristol-Myers Squibb Company, AYUMI Pharmaceutical Corp., Eisai Co., Ltd, Daiichi Sankyo Co., Ltd., Gilead Sciences, Inc., Novartis Pharma K.K., Pfizer Japan Inc., Sanofi K.K., Dainippon Sumitomo Co., Ltd.

scholarly journals 797. Management of Patients with Multiple Clostridioides difficile Infection Recurrences using a Tapered-Pulsed Fidaxomicin Strategy

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S441-S442
Author(s):  
Xing Tan ◽  
Andrew M Skinner ◽  
Benjamin Sirbu ◽  
Larry H Danziger ◽  
Dale N Gerding ◽  
...  
Keyword(s):  
First Episode ◽  
Initial Symptom ◽  
Once Daily ◽  
The Past ◽  
Clostridioides Difficile ◽  
Time To Recurrence ◽  
Clostridioides Difficile Infection ◽  
The Mean ◽  
Systemic Antibiotics

Abstract Background There is a paucity of data assessing outcomes of alternate fidaxomicin strategies in patients with recurrent Clostridioides difficile infection (rCDI). The objective of our study is to evaluate a tapered-pulsed (T-P) fidaxomicin regimen that was administered immediately following a course of CDI treatment with initial symptom resolution in patients with multiple rCDI. Methods We reviewed the characteristics and outcomes of 46 consecutive patients who received T-P fidaxomicin between January 1, 2014-June 30, 2019 in a specialty CDI clinic. The first episode in which fidaxomicin T-P was administered was analyzed. Failure was defined as the persistence of diarrhea and/or the need for additional CDI treatment at any time on T-P fidaxomicin. Sustained clinical cure (SCC) was defined as resolution of diarrhea without recurrence. Recurrence was defined as the return of diarrhea requiring retreatment with CDI therapy after completion of T-P fidaxomicin. Both SCC and recurrence were evaluated at 30 and 90 days after completion of T-P fidaxomicin. Results The mean±SD age of the 46 patients was 63.2±19.9 years, 71.7% were female, and the mean±SD CDI episodes within the past year was 3±1.4 . Most patients (73.9%) had previously failed a vancomycin tapered and/or pulsed regimen. Prior to administering T-P fidaxomicin, a treatment regimen was given to ensure resolution of symptoms. The CDI treatment most commonly used (58.7%) was vancomycin. The T-P fidaxomicin regimen used consisted of 200 mg given once daily for 7 days followed by 200 mg every other day for a median (min-max) duration of 33 (6-120) days. Two patients (4%) failed to respond to T-P fidaxomicin; 34 (74%) and 28 (61%) achieved SCC at 30 and 90 days, respectively. Among the 44 patients that successfully completed the T-P fidaxomicin regimen, recurrence developed in 10 (22.7%) and 16 (36.4%) of patients at 30 and 90 days, respectively, with a median (min-max) time to recurrence of 20 (3-87) days (Figure 1). Four patients with recurrence had received subsequent systemic antibiotics. Figure 1. Course of CDI therapy and follow-up Conclusion A tapered-pulsed fidaxomicin strategy may be effective in patients with multiply rCDI who are refractory to other treatments, including a vancomycin tapered and pulsed regimen. Disclosures Larry H. Danziger, PharmD, Merck (Speaker’s Bureau)

scholarly journals Global nutrient transport in a world of giants

2015 ◽  
Vol 113 (4) ◽  
pp. 868-873 ◽  
Author(s):  
Christopher E. Doughty ◽  
Joe Roman ◽  
Søren Faurby ◽  
Adam Wolf ◽  
Alifa Haque ◽  
...  
Keyword(s):  
Surface Waters ◽  
Marine Mammals ◽  
Recent Literature ◽  
Late Quaternary ◽  
Nutrient Transport ◽  
Anadromous Fish ◽  
Upward Movement ◽  
The Past ◽  
Large Animals ◽  
Continental Interior

The past was a world of giants, with abundant whales in the sea and large animals roaming the land. However, that world came to an end following massive late-Quaternary megafauna extinctions on land and widespread population reductions in great whale populations over the past few centuries. These losses are likely to have had important consequences for broad-scale nutrient cycling, because recent literature suggests that large animals disproportionately drive nutrient movement. We estimate that the capacity of animals to move nutrients away from concentration patches has decreased to about 8% of the preextinction value on land and about 5% of historic values in oceans. For phosphorus (P), a key nutrient, upward movement in the ocean by marine mammals is about 23% of its former capacity (previously about 340 million kg of P per year). Movements by seabirds and anadromous fish provide important transfer of nutrients from the sea to land, totalling ∼150 million kg of P per year globally in the past, a transfer that has declined to less than 4% of this value as a result of the decimation of seabird colonies and anadromous fish populations. We propose that in the past, marine mammals, seabirds, anadromous fish, and terrestrial animals likely formed an interlinked system recycling nutrients from the ocean depths to the continental interiors, with marine mammals moving nutrients from the deep sea to surface waters, seabirds and anadromous fish moving nutrients from the ocean to land, and large animals moving nutrients away from hotspots into the continental interior.

scholarly journals Necrotizing Soft Tissue Infections in Intensive Care

2021 ◽  
pp. 088506662110101
Author(s):  
Alexandru Ogica ◽  
Christoph Burdelski ◽  
Holger Rohde ◽  
Stefan Kluge ◽  
Geraldine de Heer
Keyword(s):  
Septic Shock ◽  
Intensive Care ◽  
Soft Tissue ◽  
Sofa Score ◽  
Laboratory Data ◽  
Serum Lactate ◽  
Soft Tissue Infections ◽  
Necrotizing Soft Tissue Infections ◽  
The Mean ◽  
Organ Dysfunctions

Background: Necrotizing soft tissue infections (NSTIs) are typically characterized by extensive soft tissue destruction with systemic signs of toxicity, ranging from sepsis to septic shock. Our aim was to analyze the clinical characteristics, microbiological results, laboratory data, therapies, and outcome of patients with NSTIs admitted to an intensive care unit (ICU). Methods: A monocentric observational study of patients admitted to the ICU of a university hospital between January 2009 and December 2017. The demographic characteristics, comorbidities, clinical features, microbiology and laboratory results, organ dysfunctions, therapies, and outcome were retrospectively analyzed. Results: There were 59 patients and 70% males. The mean age (± SD) was 55 ± 18; type II (monomicrobial) NSTI was present in 36 patients (61%); the most common isolated pathogen was Streptococcus pyogenes in 28 patients (48%). Septic shock was diagnosed in 41 patients (70%). The most common organ dysfunctions were circulatory and renal in 42 (71%) and 38 patients (64%). The mean value (± SD) of serum lactate at admission to the ICU was 4.22 ± 5.42 mmol/l, the median SOFA score and SAPS II were 7 (IQR 4 - 10) and 46 (IQR 30.5 - 53). ICU mortality rate was 25%. Both SOFA score and serum lactate demonstrated a good prognostic value regarding ICU outcome (OR 1.29, 95%CI 1.07-1.57, P < 0.007 and OR 1.53, 95%CI 1.19-1.98, P < 0.001). A cut-off value for serum lactate of 6.55 mmol/L positively predicted mortality with 67% sensitivity and 97% specificity. Conclusion: NSTIs carry a high risk of septic shock and multiple organ dysfunction syndrome and thus are still associated with high mortality. In our study, the value of serum lactate at admission to the ICU correlated well with mortality. This easy-to-measure parameter could play a role in the decision-making process regarding prognosis and continuation of care.

Increasing author counts in neurosurgical journals from 1980 to 2020

2021 ◽  
pp. 1-5
Author(s):  
Tyler S. Cole ◽  
Mark A. Pacult ◽  
Michael T. Lawton
Keyword(s):  
Scientific Productivity ◽  
Academic Journals ◽  
Publication Type ◽  
Medical Specialties ◽  
The Past ◽  
The Mean ◽  
Scopus Database ◽  
Publication Volume ◽  
Over Time ◽  
Number Of Authors

OBJECTIVE Scientific productivity, as assessed by publication volume, is a common metric by which the academic neurosurgical field assesses its members. The number of authors per peer-reviewed article has been observed to increase over time across a broad range of medical specialties. This study provides an update to this trend in the neurosurgical literature. METHODS All publications from January 1, 1980, to April 30, 2020, were queried from four neurosurgical journals: Neurosurgery, Journal of Neurosurgery (JNS), JNS: Pediatrics, and JNS: Spine. Publication information was acquired from the National Center for Biotechnology Information Entrez database and reconciled with the Scopus database. Publication type was limited to articles and excluded editorials, letters, and reviews. The number of authors and affiliation counts were determined based on structured abstract fields provided in the two databases. RESULTS Between January 1, 1980, and April 30, 2020, the overall increase in author count for the four neurosurgical journals was 0.12 to 0.18 authors per year (p < 0.001). For Neurosurgery, the mean (SD) author count increased from 2.81 (1.4) in 1980–1985 to 7.97 (4.92) in 2016–2020 (p < 0.001). For the JNS, the mean (SD) author count increased from 2.82 (1.04) in 1980–1985 to 7.6 (3.65) in 2016–2020 (p < 0.001). The percentage of articles with more than 10 authors increased from 0.2% to 22.3% in Neurosurgery and from 1.9% to 17.5% in JNS. Only 28% of the author count variation was explained by an increasing number of institutional or departmental affiliations. CONCLUSIONS Author counts for peer-reviewed articles in neurosurgical academic journals have increased significantly during the past 4 decades, with large increases in the numbers of articles with more than 10 authors in the past 5 years. A total of 28% of the variation in this increase can be explained by an increase in multiinstitutional or multidepartmental studies.

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