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The microclimate and cucumber crop response in a screenhouse and in an evaporatively cooled greenhouse were studied in Oman during winter/spring and spring/summer cultivation periods. Measurements were carried out in two similarly shaped structures: (1) a greenhouse equipped with a pad-and-fan system for evaporative cooling of the greenhouse environment and (2) a screenhouse with no cooling system. Analysis of the spring/summer period climate data showed that the evaporative cooling in the greenhouse reduced the mean air temperature by about 4.5°C compared to outside and maintained the leaf temperature close to the greenhouse air temperature. The 24 h mean leaf and air temperatures in the greenhouse reached 25.8°C ±1.3°C and 25.9°C ±0.8°C, respectively. On the other hand, the 24 h mean leaf and air temperatures in the screenhouse were higher by 1.0°C and 1.3°C, respectively, compared to outside. The 24 h mean leaf and air temperatures in the screenhouse reached 32.8°C ±1.2°C and 31.8°C ±1.5°C, respectively. Furthermore, the evaporative cooling in the greenhouse maintained the 24 h mean air vapor pressure deficit (VPD) values at levels lower than 1.1 kPa, while the 24 h mean air VPD in the screenhouse reached values up to 4.5 kPa. These differences resulted in a 50% decrease in crop fruit yield during the spring/summer period. The radiation and water use efficiency (WUE) values observed in the two structures were similar during the winter/spring period but were higher in the greenhouse during the spring/summer period. However, for the greenhouse, when the water evaporated in the wet pad was also considered, the overall WUE was at the same level in both structures during summer. Furthermore, the evaporative cooling applied in the greenhouse enhanced the mean values of fruit quality characteristics measured during the spring/summer, such as fruit dry matter content (5.6%), fruit firmness (5.0 kg cm-2), and chroma (18.6), compared to that of the screenhouse (5.0%, 4.9 kg cm-2 and 16.3, respectively), but did not significantly affect other fruit quality characteristics, such as mean fruit weight (128 g for greenhouse and 123 g for screenhouse), total soluble solids content (3.9 °Brix for both structures), and juice pH (5.7 for greenhouse and 5.6 for screenhouse). Overall, it can be concluded that under the weather conditions of Oman, although greenhouses are still needed during spring/summer, screenhouses can be used during winter without jeopardizing crop production quantity and quality. [ABSTRACT FROM AUTHOR]

The total amount of water consumption needed to irrigate the cultivated lands in the Sultanate Oman is 1487 Mm³. There are 7.6 million date palm trees currently planted in the farms in Oman covering an area of 23241 hectares or 35% of total agricultural area in the Sultanate in addition to 0.9 million palm trees planted in homes or for landscaping in public parks and beside the roads. Hence, among all cultivated crops in Oman, date palms are the major water consuming plants. They consume 558 Mm³ that is 38% of total irrigation water and 31% of groundwater recharge that suffers an annual water deficit estimated at 316 Mm Keywords: Water productivity; irrigation water; economical return; date palm trees; Oman. These findings framed the main objectives of this study: (1) to describe the current status of date palm tree cultivation in the Sultanate; (2) to suggest solutions to reduce high consumption of water while improve dates production; and (3) to explore how irrigation water can be saved through increasing water productivity through alternative date palm cultivation and irrigation practices. The water saving recommendation in this study was based on the collected from different sources in addition to the investigation on the water loss during irrigation practices. We found that it is possible to save a total of 396 Mm³ of irrigation water by for instance reducing the cultivation of low quality/value date palm varieties and switching to modern over traditional irrigation systems. It is also important to determine the quality and value of the date palm cultivars to be planted in the proposed reduced area which will then contribute to an increased financial return for the farmers and thus to the country through increasing the water productivity by 64% of these new plots. [ABSTRACT FROM AUTHOR]

Introduction. In a traditional curriculum, medical students are expected to acquire clinical competence through the apprenticeship model using the Halstedian 'see one, do one, and teach one' approach. The School of Medicine, University of Zambia, Lusaka, Zambia, used a traditional curriculum model from 1966 until 2011, when a competence-based curriculum was implemented. Objective. To explore medical students' clerkship experiences and self-perceived competence in clinical skills. Methods. A cross-sectional survey was conducted among 5th-, 6th-, and 7th-year medical students at the School of Medicine, University of Zambia, two months before the final examinations. Students were asked to rate their clerkship experiences with regard to specific skills on a scale of 1 - 4 and their level of self-perceived competence on a scale of 1 - 3. Skills evaluated were in four main domains: history-taking and communication, physical examination and procedural skills, professionalism, teamwork and medical decision-making. Using the Statistical Package for the Social Sciences (SPSS), correlations were performed between experiences and self-perceived competence of specific skills, within domains and overall. Results. Of clinical students (N=197), 138 (70%) participated in the survey. The results showed a significant increase in the proportion of students performing different skills and reporting feeling very competent with each additional clinical year. Overall correlations between experience and self-perceived competence were moderate (0.55). For individual skills, the highest correlation between experience and self-perceived competence was observed mainly with regard to medical- and surgical-related procedural skills, with the highest at 0.82 for nasogastric tube insertion and 0.76 for endotracheal intubation. Conclusion. Despite the general improvement in skills and self-perceived competence some deficiencies were noted, as significant numbers of final-year students had never attempted important common procedures, especially those performed in emergency situations. Deficiencies in certain skills may call for the incorporation of teaching/learning methods that broaden students' exposure to such skills. [ABSTRACT FROM AUTHOR]

Seedling emergence is a critical stage in wheat (Triticum aestivum L.) establishment, particularly in dryland agriculture. Soil temperature, water potential, and planting depth are important factors influencing emergence. These factors can have considerable spatio-temporal variation, making it difficult to predict the timing and percentage of wheat seedling emergence. Our objectives were to: (1) measure the effect of soil temperature, water potential, and planting depth on seedling emergence of winter wheat; and (2) develop a population-based hydrothermal model to estimate time and percentage of winter wheat emergence planted at a given soil depth. The experiment was a 3 (wheat cultivars) x 3 (planting depths) x5 (temperatures) x5 (water potentials) factorial in a randomized complete block design (RCBD) with three replicates. Decreasing soil water potential from 0 to -1 MPa delayed emergence of Moro, Buchanan, and Rod by 13, 14, and 18 days after planting and prolonged the time to reach maximum emergence by 19, 21, and 27 days after planting, respectively. Decreasing soil temperature from 25°C to 5°C delayed the average starting emergence of the three wheat cultivars by 19 days and delayed their average maximum emergence by 25 days after planting. Increasing soil planting depth from 5 to 10 cm delayed starting emergence time for Moro, Buchanan, andRod by 6, 4, and 7 days, while maximum emergence was delayed by 12, 16, and 9 days after planting, respectively. Increasing the planting depth from 5 to 15 cm hindered the three cultivars from reaching 50% emergence. A hydrothermal time emergence model was developed that estimated observed emergence with 154 out of 207 data points having a root mean square error (RMSE) of<15%, whereas 19% of the simulated results did not exceed 19% RMSE and only 7% of the simulated data had RMSE greater than 20%. The simulations of the emergence model for maximum percent seedling emergence (Emax) and number of days after planting to reach maximum emergence (DAPmax) were compared with field data for three years and two cultivars (Rod and Moro). The emergence model gave reasonably good simulations of Emax and DAPmax for both winter wheat cultivars and in the three years of sowing dates. [ABSTRACT FROM AUTHOR]

Transformation of 2′-deoxyuridine and uridine analogs to protected 2′-deoxycytidine and cytidine analogs has been investigated by two different methods. First, traditional triazolation protocol and second p-nitrophenoxylation method. Our studies conclude that the triazolation method is better and suitable for commercial scale--up. [ABSTRACT FROM AUTHOR]

Antibiotic resistance is often studied in vitro, limiting the understanding of in vivo mechanisms that affect antibiotic treatment. In this issue of Cell Host & Microbe, Rodrigues et al. show that specific mutations allow bacteria to invade intestinal cells in a mouse model, thereby evading antibiotic treatment., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Molecular catch bonds are ubiquitous in biology and essential for processes like leucocyte extravasion 1 and cellular mechanosensing 2 . Unlike normal (slip) bonds, catch bonds strengthen under tension. The current paradigm is that this feature provides 'strength on demand 3 ', thus enabling cells to increase rigidity under stress 1,4-6 . However, catch bonds are often weaker than slip bonds because they have cryptic binding sites that are usually buried 7,8 . Here we show that catch bonds render reconstituted cytoskeletal actin networks stronger than slip bonds, even though the individual bonds are weaker. Simulations show that slip bonds remain trapped in stress-free areas, whereas weak binding allows catch bonds to mitigate crack initiation by moving to high-tension areas. This 'dissociation on demand' explains how cells combine mechanical strength with the adaptability required for shape change, and is relevant to diseases where catch bonding is compromised 7,9 , including focal segmental glomerulosclerosis 10 caused by the α-actinin-4 mutant studied here. We surmise that catch bonds are the key to create life-like materials., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

We study the role of a biomimetic actin network during the application of electric pulses that induce electroporation or electropermeabilization, using giant unilamellar vesicles (GUVs) as a model system. The actin cortex, a subjacently attached interconnected network of actin filaments, regulates the shape and mechanical properties of the plasma membrane of mammalian cells, and is a major factor influencing the mechanical response of the cell to external physical cues. We demonstrate that the presence of an actin shell inhibits the formation of macropores in the electroporated GUVs. Additionally, experiments on the uptake of dye molecules after electroporation show that the actin network slows down the resealing process of the permeabilized membrane. We further analyze the stability of the actin network inside the GUVs exposed to high electric pulses. We find disruption of the actin layer that is likely due to the electrophoretic forces acting on the actin filaments during the permeabilization of the GUVs. Our findings on the GUVs containing a biomimetic network provide a step towards understanding the discrepancies between the electroporation mechanism of a living cell and its simplified model of the empty GUV.

Dynamically cross-linked semiflexible biopolymers such as the actin cytoskeleton govern the mechanical behavior of living cells. Semiflexible biopolymers nonlinearly stiffen in response to mechanical loads, whereas the cross-linker dynamics allow for stress relaxation over time. Here we show, through rheology and theoretical modeling, that the combined nonlinearity in time and stress leads to an unexpectedly slow stress relaxation, similar to the dynamics of disordered systems close to the glass transition. Our work suggests that transient cross-linking combined with internal stress can explain prior reports of soft glassy rheology of cells, in which the shear modulus increases weakly with frequency.

Transiently crosslinked actin filament networks allow cells to combine elastic rigidity with the ability to deform viscoelastically. Theoretical models of semiflexible polymer networks predict that the crosslinker unbinding rate governs the timescale beyond which viscoelastic flow occurs. However a direct comparison between network and crosslinker dynamics is lacking. Here we measure the network's stress relaxation timescale using rheology and the lifetime of bound crosslinkers using fluorescence recovery after photobleaching (FRAP). Intriguingly, we observe that the crosslinker unbinding rate measured by FRAP is more than an order of magnitude slower than the rate measured by rheology. We rationalize this difference with a three-state model where crosslinkers are bound to either 0, 1 or 2 filaments, which allows us to extract crosslinker transition rates that are otherwise difficult to access. We find that the unbinding rate of singly bound crosslinkers is nearly two orders of magnitude slower than for doubly bound ones. We attribute the increased unbinding rate of doubly bound crosslinkers to the high stiffness of biopolymers, which frustrates crosslinker binding.

In viscoelastic materials, individually short-lived bonds collectively result in a mechanical resistance which is long lived but finite as, ultimately, cracks appear. Here, we provide a microscopic mechanism by which a critical crack length emerges from the nonlinear local bond dynamics. Because of this emerging length scale, macroscopic viscoelastic materials fracture in a fundamentally different manner from microscopically small systems considered in previous models. We provide and numerically verify analytical equations for the dependence of the critical crack length on the bond kinetics and applied stress.

MEPI was a $130 million competitively awarded grant by President's Emergency Plan for AIDS Relief (PEPFAR) and National Institutes of Health (NIH) to 13 Medical Schools in 12 Sub-Saharan African countries and a Coordinating Centre (CC). Implementation was led by Principal investigators (PIs) from the grantee institutions supported by Health Resources and Services Administration (HRSA), NIH and the CC from September, 2010 to August, 2015. The goals were to increase the capacity of the awardees to produce more and better doctors, strengthen locally relevant research, promote retention of the graduates within their countries and ensure sustainability. MEPI ignited excitement and stimulated a broad range of improvements in the grantee schools and countries. Through in-country consortium arrangements African PIs expanded the programme from the 13 grantees to over 60 medical schools in Africa, creating vibrant South-South and South-North partnerships in medical education, and research. Grantees revised curricular to competency based models, created medical education units to upgrade the quality of education and established research support centres to promote institutional and collaborative research. MEPI stimulated the establishment of ten new schools, doubling of the students' intake, in some schools, a three-fold increase in post graduate student numbers, and faculty expansion and retention.Sustainability of the MEPI innovations was assured by enlisting the support of universities and ministries of education and health in the countries thus enabling integration of the new programs into the regular national budgets. The vibrant MEPI annual symposia are now the largest medical education events in Africa attracting global participation. These symposia and innovations will be carried forward by the successor of MEPI, the African Forum for Research and Education in Health (AFREhealth). AFREhealth promises to be more inclusive and transformative bringing together other health professionals including nurses, pharmacists, and dentists., Competing Interests: The authors have no competing interests to declare., (© 2018 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See http://creativecommons.org/licenses/by/4.0/.)

How do the cells in our body reconfigure their shape to achieve complex tasks like migration and mitosis, yet maintain their shape in response to forces exerted by, for instance, blood flow and muscle action? Cell shape control is defined by a delicate mechanical balance between active force generation and passive material properties of the plasma membrane and the cytoskeleton. The cytoskeleton forms a space-spanning fibrous network comprising three subsystems: actin, microtubules and intermediate filaments. Bottom-up reconstitution of minimal synthetic cells where these cytoskeletal subsystems are encapsulated inside a lipid vesicle provides a powerful avenue to dissect the force balance that governs cell shape control. Although encapsulation is technically demanding, a steady stream of advances in this technique has made the reconstitution of shape-changing minimal cells increasingly feasible. In this topical review we provide a route-map of the recent advances in cytoskeletal encapsulation techniques and outline recent reports that demonstrate shape change phenomena in simple biomimetic vesicle systems. We end with an outlook toward the next steps required to achieve more complex shape changes with the ultimate aim of building a fully functional synthetic cell with the capability to autonomously grow, divide and move.

Introduction: Zambia is facing a chronic shortage of health care workers. The paper aimed at understanding how the Medical Education Partnership Initiative (MEPI) program facilitated strengthening and expanding of the national capacity and quality of medical education as well as processes for retaining faculty in Zambia., Methods: Data generated through documentary review, key informant interviews and observations were analyzed using a thematic approach., Results: The MEPI program triggered the development of new postgraduate programs thereby increasing student enrollment. This was achieved by leveraging of existing and new partnerships with other universities and differentiating the old Master in Public Health into specialized curriculum. Furthermore, the MEPI program improved the capacity and quality of training by facilitating installation and integration of new technology such as the eGranary digital library, E-learning methods and clinical skills laboratory into the Schools. This technology enabled easy access to relevant data or information, quicker turn around of experiments and enhanced data recording, display and analysis features for experiments. The program also facilitated transforming of the academic environment into a more conducive work place through strengthening the Staff Development program and support towards research activities. These activities stimulated work motivation and interest in research by faculty. Meanwhile, these processes were inhibited by the inability to upload all courses on to Moodle as well as inadequate operating procedures and feedback mechanisms for the Moodle., Conclusion: Expansion and improvement in training processes for health care workers requires targeted investment within medical institutions and strengthening local and international partnerships.

Background: African medical schools have historically turned to northern partners for technical assistance and resources to strengthen their education and research programmes. In 2010, this paradigm shifted when the United States Government brought forward unprecedented resources to support African medical schools. The grant, entitled the Medical Education Partnership Initiative (MEPI) triggered a number of south-south collaborations between medical schools in Africa. This paper examines the goals of these partnerships and their impact on medical education and health workforce planning., Methods: Semi-structured interviews were conducted with the Principal Investigators of the first four MEPI programmes that formed an in-country consortium. These interviews were recorded, transcribed and coded to identify common themes., Results: All of the consortia have prioritized efforts to increase the quality of medical education, support new schools in-country and strengthen relations with government. These in-country partnerships have enabled schools to pool and mobilize limited resources creatively and generate locally-relevant curricula based on best-practices. The established schools are helping new schools by training faculty and using grant funds to purchase learning materials for their students. The consortia have strengthened the dialogue between academia and policy-makers enabling evidence-based health workforce planning. All of the partnerships are expected to last well beyond the MEPI grant as a result of local ownership and institutionalization of collaborative activities., Conclusions: The consortia described in this paper demonstrate a paradigm shift in the relationship between medical schools in four African countries. While schools in Africa have historically worked in silos, competing for limited resources, MEPI funding that was leveraged to form in-country partnerships has created a culture of collaboration, overriding the history of competition. The positive impact on the quality and efficiency of health workforce training suggests that future funding for global health education should prioritize such south-south collaborations.

Background: The effect of idiopathic intracranial hypertension (IIH) on quality of life (QOL) is poorly understood. Our objectives were to compare QOL in IIH to the normal UK population; to investigate QOL changes with treatment of IIH, using a weight loss intervention, and to determine which clinical factors influence QOL., Methods: This was a prospective cohort evaluation of QOL, using the 36-Item Short Form (SF-36) Health Survey questionnaire, before and after a therapeutic dietary intervention which resulted in significant reduction in body mass index (BMI), intracranial pressure (ICP), papilloedema, visual acuity, perimetric mean deviation (Humphrey 24-2) and headache (six-item headache impact test (HIT-6) and headache diary). Baseline QOL was compared to an age and gender matched population. The relationship between each clinical outcome and change in QOL was evaluated., Results: At baseline, QOL was significantly lower in IIH compared to an age and gender matched population in most domains, p < 0.001. Therapeutic weight loss led to a significant improvement in 10 out of 11 QOL domains in conjunction with the previously published data demonstrating significant improvement in papilloedema, visual acuity, perimetry and headache (p < 0.001) and large effect size. Despite significant improvement in clinical measures only headache correlated significantly (p < 0.001) with improving QOL domains., Conclusions: QOL in IIH patients is significantly reduced. It improved with weight loss alongside significant improvement in clinical measures and headache. However, headache was the only clinical outcome that correlated with enhanced QOL. Effective headache management is required to improve QOL in IIH.

Zambia is facing a crisis in its human resources for health, with deficits in the number and skill mix of health workers. The University of Zambia School of Medicine (UNZA SOM) was the only medical school in the country for decades, but recently it was joined by three new medical schools--two private and one public. In addition to expanding medical education, the government has also approved several allied health programs, including pharmacy, physiotherapy, biomedical sciences, and environmental health. This expansion has been constrained by insufficient numbers of faculty. Through a grant from the Medical Education Partnership Initiative (MEPI), UNZA SOM has been investing in ways to address faculty recruitment, training, and retention. The MEPI-funded strategy involves directly sponsoring a cohort of faculty at UNZA SOM during the five-year grant, as well as establishing more than a dozen new master's programs, with the goal that all sponsored faculty are locally trained and retained. Because the issue of limited basic science faculty plagues medical schools throughout Sub-Saharan Africa, this strategy of using seed funding to build sustainable local capacity to recruit, train, and retain faculty could be a model for the region.