Hyperfine and radiological characterization of soils of the province of Buenos Aires, Argentina

The depth profile concentration of both natural and anthropogenic gamma-ray-emitter nuclides were determined in soil samples collected in an area located at 34° 54.452′ S, 58° 8.365′ W, down to 50 cm in depth, using an hyper-pure Ge spectrometer. The soil samples were also characterized by means of Mössbauer spectrometry and X-ray diffraction. The activities of 238U and 232Th natural chains remain constant in depth at 41 Bq/kg and 46 Bq/kg, respectively, while the 40K activity increases from 531 Bq/kg to 618 Bq/kg between 2.5 cm y 25.5 cm of depth. The only anthropogenic detected nuclide is 137Cs, whose activity changes form 1.4 Bq/kg to values lower than the detection limit (LD) for depths below 25 cm, exhibiting a maximum at 10 cm beneath the surface. The Mössbauer spectra show two magnetic sextets associated with α-Fe2O3 and Fe3O4, as well as two Fe+3 Fe+2 doublets, probably originated in octahedral and tetrahedral sites of paramagnetic phases. The Fe3+ paramagnetic signal relative fraction increases up to 82% at the expense of the α-Fe2O3 one when de depth increases. No correlation between Fe3O4 and the 137Cs was identificated.Facultad de Ciencias ExactasInstituto de Física La Plat

Hyperfine and radiological characterization of soils of the province of Buenos Aires, Argentina

The depth profile concentration of both natural and anthropogenic gamma-ray-emitter nuclides were determined in soil samples collected in an area located at 34° 54.452′ S, 58° 8.365′ W, down to 50 cm in depth, using an hyper-pure Ge spectrometer. The soil samples were also characterized by means of Mössbauer spectrometry and X-ray diffraction. The activities of 238U and 232Th natural chains remain constant in depth at 41 Bq/kg and 46 Bq/kg, respectively, while the 40K activity increases from 531 Bq/kg to 618 Bq/kg between 2.5 cm y 25.5 cm of depth. The only anthropogenic detected nuclide is 137Cs, whose activity changes form 1.4 Bq/kg to values lower than the detection limit (LD) for depths below 25 cm, exhibiting a maximum at 10 cm beneath the surface. The Mössbauer spectra show two magnetic sextets associated with α-Fe2O3 and Fe3O4, as well as two Fe+3 Fe+2 doublets, probably originated in octahedral and tetrahedral sites of paramagnetic phases. The Fe3+ paramagnetic signal relative fraction increases up to 82% at the expense of the α-Fe2O3 one when de depth increases. No correlation between Fe3O4 and the 137Cs was identificated.Facultad de Ciencias ExactasInstituto de Física La Plat

Hyperfine and radiological characterization of soils of the province of Buenos Aires, Argentina

The depth profile concentration of both natural and anthropogenic gamma-ray-emitter nuclides were determined in soil samples collected in an area located at 34° 54.452′ S, 58° 8.365′ W, down to 50 cm in depth, using an hyper-pure Ge spectrometer. The soil samples were also characterized by means of Mössbauer spectrometry and X-ray diffraction. The activities of 238U and 232Th natural chains remain constant in depth at 41 Bq/kg and 46 Bq/kg, respectively, while the 40K activity increases from 531 Bq/kg to 618 Bq/kg between 2.5 cm y 25.5 cm of depth. The only anthropogenic detected nuclide is 137Cs, whose activity changes form 1.4 Bq/kg to values lower than the detection limit (LD) for depths below 25 cm, exhibiting a maximum at 10 cm beneath the surface. The Mössbauer spectra show two magnetic sextets associated with α-Fe2O3 and Fe3O4, as well as two Fe+3 Fe+2 doublets, probably originated in octahedral and tetrahedral sites of paramagnetic phases. The Fe3+ paramagnetic signal relative fraction increases up to 82% at the expense of the α-Fe2O3 one when de depth increases. No correlation between Fe3O4 and the 137Cs was identificated.Facultad de Ciencias ExactasInstituto de Física La Plat

The pest kill rate of thirteen natural enemies as aggregate evaluation criterion of their biological control potential of Tuta absoluta

Ecologists study how populations are regulated, while scientists studying biological pest control apply population regulation processes to reduce numbers of harmful organisms: an organism (a natural enemy) is used to reduce the population density of another organism (a pest). Finding an effective biological control agent among the tens to hundreds of natural enemies of a pest is a daunting task. Evaluation criteria help in a first selection to remove clearly ineffective or risky species from the list of candidates. Next, we propose to use an aggregate evaluation criterion, the pest kill rate, to compare the pest population reduction capacity of species not eliminated during the first selection. The pest kill rate is the average daily lifetime killing of the pest by the natural enemy under consideration. Pest kill rates of six species of predators and seven species of parasitoids of Tuta absoluta were calculated and compared. Several natural enemies had pest kill rates that were too low to be able to theoretically reduce the pest population below crop damaging densities. Other species showed a high pest reduction capacity and their potential for practical application can now be tested under commercial crop production conditions

The pest kill rate of thirteen natural enemies as aggregate evaluation criterion of their biological control potential of Tuta absoluta

Ecologists study how populations are regulated, while scientists studying biological pest control apply population regulation processes to reduce numbers of harmful organisms: an organism (a natural enemy) is used to reduce the population density of another organism (a pest). Finding an effective biological control agent among the tens to hundreds of natural enemies of a pest is a daunting task. Evaluation criteria help in a first selection to remove clearly ineffective or risky species from the list of candidates. Next, we propose to use an aggregate evaluation criterion, the pest kill rate, to compare the pest population reduction capacity of species not eliminated during the first selection. The pest kill rate is the average daily lifetime killing of the pest by the natural enemy under consideration. Pest kill rates of six species of predators and seven species of parasitoids of Tuta absoluta were calculated and compared. Several natural enemies had pest kill rates that were too low to be able to theoretically reduce the pest population below crop damaging densities. Other species showed a high pest reduction capacity and their potential for practical application can now be tested under commercial crop production conditions.Centro de Estudios Parasitológicos y de Vectore

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity > 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI

Population growth of three mirid predatory bugs feeding on eggs and larvae of Tuta absoluta on tomato

Tuta absoluta Meyrick quickly developed into a significant pest of tomatoes worldwide. While the mirid bugs Macrolophus basicornis (Stal), Engytatus varians (Distant) and Campyloneuropsis infumatus (Carvalho) prey on this tomato borer, their biology have not been well characterized. Using a mixture of T. absoluta eggs and larvae as food on tomato, mirid life histories were studied. Nymphs and adults successfully used T. absoluta as prey, although significant differences in biology of the species were observed. Campyloneuropsis infumatus and M. basicornis were quickest and slowest to become adult at 16 and 19 days, respectively. Nymphal survival was high and varied from 70 to 75 %. Female biased sex ratios were observed for C. infumatus (0.80) and M. basicornis (0.71), but not for E. varians (0.56). Intrinsic rates of increase for C. infumatus, E. varians and M. basicornis were 0.11, 0.10 and 0.11 respectively. Our results indicate rapid development and population increase of these three mirids, making them interesting candidates for biological control of T. absoluta on tomato

Comparative effectiveness and injury to tomato plants of three neotropical mirid predators of tuta absoluta (Lepidoptera : Gelechiidae)

Tuta absoluta (Meyrick; Lepidoptera: Gelechiidae) is a key pest of tomato and is quickly spreading over the world. We conducted an experiment aimed at evaluating the control capacity and risk for plant damage of three Neotropical mirid species, Campyloneuropsis infumatus (Carvalho; Hemiptera: Miridae), Engytatus varians (Distant; Hemiptera: Miridae) and Macrolophus basicornis (Stal; Hemiptera: Miridae) on T. absoluta infested tomato plants in large cages in an experimental greenhouse. During three successive periods of 9 wk each, we followed population development of the three mirids when exposed to T. absoluta, and of T. absoluta alone in separate cages in the greenhouse. We determined weekly the numbers of T. absoluta eggs and larvae per leaf, the number of mirid predators per leaf, the percentage of damaged leaves and fruits by T. absoluta, and the weight of fruits. Two of the mirid predators, C. infumatus and M. basicornis, successfully established on T. absoluta infested tomato plants and significantly reduced T. absoluta numbers, which ultimately resulted in an increased yield. These two mirid species hardly injured tomato plants or fruits as a result of plant feeding. Surprisingly, the species E. varians, which showed high predation rates in laboratory experiments, did not establish and reduce pest populations in any of the tests.</p

Adult lifetime predation of Tuta absoluta eggs by three Neotropical mirid predators on tomato

Tuta absoluta (Meyrick), a key pest of tomato, is quickly spreading over the world. Here we report lifetime predation of T. absoluta eggs by adults of three Neotropical mirid species [Campyloneuropsis infumatus (Carvalho), Engytatus varians (Distant) and Macrolophus basicornis (Stal)]. Prey eggs were offered ad libitum on a tomato leaflet at 24 ± 1 °C, 70 ± 10% RH and 12-h photophase. Daily, the number of eggs consumed by adults was noted. Observations were terminated after all adults had died. Total adult lifetime predation of T. absoluta eggs was 337, 313 and 339 for males, and 845, 668 and 934 for females of C. infumatus, E. varians and M. basicornis, respectively. Mean adult lifespan was 27 days for males and 24 for females of C. infumatus, 17 days for males and 14 for females of E. varians, and 30 days for males and 26 days for females of M. basicornis. Total and daily predation was significantly higher for females than for males, though lifespan was significantly longer for males than for females. The daily predation rates of C. infumatus and M. basicornis were similar, but were significantly lower than that of E. varians. Predation rates tended to decrease significantly with adult age for both sexes of all three species, except for males of M. basicornis, although proportions of explained variance were low (r2 < 0.24). Adult survival and egg predation data will later be combined with data about egg development time and survival, and nymphal development time, survival and egg predation to determine the pest kill rate of the three mirid species. The pest kill rate will then be used to predict which of the mirids might be best for control of T. absoluta on tomato. Eventually, experiments at practical tomato production conditions will show whether our predictions are correct.</p

Predation of Tuta absoluta eggs during the nymphal stages of three neotropical mirid predators on tomato

Tuta absoluta (Meyrick), a key pest of tomato, is quickly spreading over the world. We are evaluating the biology and pest control capacity of three Neotropical mirid species, Campyloneuropsis infumatus (Carvalho), Engytatus varians (Distant) and Macrolophus basicornis (Stal). Here we report about the predation of T. absoluta eggs by all nymphal stages of the three mirid species. A tomato leaflet with ad libitum prey was offered to a newly-emerged 1st instar nymph of a mirid predator and kept at 24 ± 1 °C, 70 ± 10% RH and 12-h photophase. Daily, the developmental stage of the nymph, as well as the number of eggs consumed was noted, and a new leaflet with eggs was added. Observations ended after nymphs had developed into adults and their sex had been determined. The average number of prey eaten by nymphs increased with nymphal age, and the 5th nymphal instar consumed higher numbers of prey than all earlier instars together. Total nymphal predation was 315, 393 and 331 T. absoluta eggs and total nymphal development took 16.9, 16.6 and 17.9 days for C. infumatus, E. varians and M. basicornis, respectively. Female nymphs of M. basicornis consumed significantly more prey than male nymphs. Nymphal survival of the three mirid species was 93%. The adult sex ratios of E. varians and M. basicornis did not deviate from a 1: 1 ratio, whereas the sex ratio of C. infumatus was significantly female biased. Nymphal predation of these three Neotropical mirids was higher than values reported for any other mirid predator, which, together with their earlier published positive characteristics, make them interesting candidates for biological control of T. absoluta