Sweet and sour synergy: exploring the antibacterial and antibiofilm activity of acetic acid and vinegar combined with medical-grade honeys.

Oxymel, a combination of honey and vinegar, has been used as a remedy for wounds and infections in historical and traditional medical settings. While honey is now clinically used to treat infected wounds, this use of a complex, raw natural product (NP) mixture is unusual in modern western medicine. Research into the antimicrobial activity of NPs more usually focuses on finding a single active compound. The acetic acid in vinegar is known to have antibacterial activity at low concentrations and is in clinical use to treat burn wound infections. Here, we investigated the potential for synergistic activity of different compounds present in a complex ingredient used in historical medicine (vinegar) and in an ingredient mixture (oxymel). We conducted a systematic review to investigate published evidence for antimicrobial effects of vinegars against human pathogenic bacteria and fungi. No published studies have explicitly compared the activity of vinegar with that of a comparable concentration of acetic acid. We then characterized selected vinegars by HPLC and assessed the antibacterial and antibiofilm activity of the vinegars and acetic acid, alone and in combination with medical-grade honeys, against Pseudomonas aeruginosa and Staphylococcus aureus. We found that some vinegars have antibacterial activity that exceeds that predicted by their acetic acid content alone, but that this depends on the bacterial species being investigated and the growth conditions (media type, planktonic vs. biofilm). Pomegranate vinegars may be particularly interesting candidates for further study. We also conclude that there is potential for acetic acid, and some vinegars, to show synergistic antibiofilm activity with manuka honey.

Preclinical transmission of prions by blood transfusion is influenced by donor genotype and route of infection.

Variant Creutzfeldt-Jakob disease (vCJD) is a human prion disease resulting from zoonotic transmission of bovine spongiform encephalopathy (BSE). Documented cases of vCJD transmission by blood transfusion necessitate on-going risk reduction measures to protect blood supplies, such as leucodepletion (removal of white blood cells, WBCs). This study set out to determine the risks of prion transmission by transfusion of labile blood components (red blood cells, platelets, plasma) commonly used in human medicine, and the effectiveness of leucodepletion in preventing infection, using BSE-infected sheep as a model. All components were capable of transmitting prion disease when donors were in the preclinical phase of infection, with the highest rates of infection in recipients of whole blood and buffy coat, and the lowest in recipients of plasma. Leucodepletion of components (<106 WBCs/unit) resulted in significantly lower transmission rates, but did not completely prevent transmission by any component. Donor PRNP genotype at codon 141, which is associated with variation in incubation period, also had a significant effect on transfusion transmission rates. A sensitive protein misfolding cyclic amplification (PMCA) assay, applied to longitudinal series of blood samples, identified infected sheep from 4 months post infection. However, in donor sheep (orally infected), the onset of detection of PrPSc in blood was much more variable, and generally later, compared to recipients (intravenous infection). This shows that the route and method of infection may profoundly affect the period during which an individual is infectious, and the test sensitivity required for reliable preclinical diagnosis, both of which have important implications for disease control. Our results emphasize that blood transfusion can be a highly efficient route of transmission for prion diseases. Given current uncertainties over the prevalence of asymptomatic vCJD carriers, this argues for the maintenance and improvement of current measures to reduce the risk of transmission by blood products.

Global forest loss disproportionately erodes biodiversity in intact landscapes.

Global biodiversity loss is a critical environmental crisis, yet the lack of spatial data on biodiversity threats has hindered conservation strategies. Theory predicts that abrupt biodiversity declines are most likely to occur when habitat availability is reduced to very low levels in the landscape (10-30%). Alternatively, recent evidence indicates that biodiversity is best conserved by minimizing human intrusion into intact and relatively unfragmented landscapes. Here we use recently available forest loss data to test deforestation effects on International Union for Conservation of Nature Red List categories of extinction risk for 19,432 vertebrate species worldwide. As expected, deforestation substantially increased the odds of a species being listed as threatened, undergoing recent upgrading to a higher threat category and exhibiting declining populations. More importantly, we show that these risks were disproportionately high in relatively intact landscapes; even minimal deforestation has had severe consequences for vertebrate biodiversity. We found little support for the alternative hypothesis that forest loss is most detrimental in already fragmented landscapes. Spatial analysis revealed high-risk hot spots in Borneo, the central Amazon and the Congo Basin. In these regions, our model predicts that 121-219 species will become threatened under current rates of forest loss over the next 30 years. Given that only 17.9% of these high-risk areas are formally protected and only 8.9% have strict protection, new large-scale conservation efforts to protect intact forests are necessary to slow deforestation rates and to avert a new wave of global extinctions.

Negative producer price differentials in Federal Milk Marketing Orders: Explanations, implications, and policy options.

In Federal Milk Marketing Orders (FMMO), which use multiple component pricing schemas, farmers are paid for delivered quantity of butterfat, protein, and other solids, plus a producer price differential (PPD). The PPD captures the difference between the total handler obligations to the pool and the total component value of milk. In 2020, record negative PPD caused widespread frustration among dairy farmers. The primary objective of this research was to provide a comprehensive analysis of factors that affect PPD and to quantify their relative importance. We examined FMMO data from the past 10 yr including prices, utilizations, and tests. By decomposing the PPD, we were able to isolate the drivers of negative values. We found that long-term trends in usage, most importantly declining beverage milk and rising component tests, including both butterfat and protein, have substantially reduced PPD over the past decade. Class I milk pricing reform of 2018 exacerbated negative PPD in 2020, but we found that the PPD would have been negative even without that reform. The greatest contributor to recent negative PPD was the spread between cheese and milk powder prices, caused by shifts in demand due to the COVID-19 pandemic and USDA intervention cheese purchases. A range of policy modifications proposed to address negative PPD was evaluated.

Zafirlukast Induces VHL- and HIF-2α-Dependent Oxidative Cell Death in 786-O Clear Cell Renal Carcinoma Cells.

Mutations in the Von Hippel-Lindau (VHL) gene are the driving force in many forms of clear cell renal cell carcinoma (ccRCC) and promote hypoxia-inducible factor (HIF)-dependent tumor proliferation, metastasis and angiogenesis. Despite the progress that has already been made, ccRCC generally remain resistant to conventional therapies and ccRCC patients suffer from metastasis and acquired resistance, highlighting the need for novel therapeutic options. Cysteinyl leukotriene receptor 1 (CysLTR1) antagonists, like zafirlukast, are administered in bronchial asthma to control eicosanoid signaling. Intriguingly, long-term use of zafirlukast decreases cancer risk and leukotriene receptor antagonists inhibit tumor growth, but the mechanisms still remain unexplored. Therefore, we aim to understand the mechanisms of zafirlukast-mediated cell death in ccRCC cells. We show that zafirlukast induces VHL-dependent and TNFα-independent non-apoptotic and non-necroptotic cell death in ccRCC cells. Cell death triggered by zafirlukast could be rescued with antioxidants and the PARP-1 inhibitor Olaparib, and additionally relies on HIF-2α. Finally, MG-132-mediated proteasome inhibition sensitized VHL wild-type cells to zafirlukast-induced cell death and inhibition of HIF-2α rescued zafirlukast- and MG-132-triggered cell death. Together, these results highlight the importance of VHL, HIF and proteasomal degradation in zafirlukast-induced oxidative cell death with potentially novel therapeutic implications for ccRCC.

Global reforestation and biodiversity conservation.

The loss of forest is a leading cause of species extinction, and reforestation is 1 of 2 established interventions for reversing this loss. However, the role of reforestation for biodiversity conservation remains debated, and lacking is an assessment of the potential contribution that reforestation could make to biodiversity conservation globally. We conducted a spatial analysis of overlap between 1,550 forest-obligate threatened species' ranges and land that could be reforested after accounting for socioeconomic and ecological constraints. Reforestation on at least 43% (∼369 million ha) of reforestable area was predicted to potentially benefit threatened vertebrates. This is approximately 15% of the total area where threatened vertebrates occur. The greatest opportunities for conserving threatened vertebrate species are in the tropics, particularly Brazil and Indonesia. Although reforestation is not a substitute for forest conservation, and most of the area containing threatened vertebrates remains forested, our results highlight the need for global conservation strategies to recognize the potentially significant contribution that reforestation could make to biodiversity conservation. If implemented, reforestation of ∼369 million ha would also contribute substantially to climate-change mitigation, offering a way to achieve multiple sustainability commitments at once. Countries must now work to overcome key barriers (e.g., unclear revenue streams, high transaction costs) to investment in reforestation.

Reforestación Mundial y Conservación de la Biodiversidad Resumen La pérdida de los bosques es una de las causas principales de la extinción de especies y la reforestación es una de las dos intervenciones establecidas para revertir esta pérdida. Sin embargo, el papel de la reforestación en la conservación de la biodiversidad todavía se debate, además de que hay una falta de evaluación de la contribución potencial que podría dar la reforestación a la conservación mundial de la biodiversidad. Realizamos un análisis espacial del traslape de la distribución de 1,550 especies obligadas de bosque que se encuentran amenazadas y el suelo que podría utilizarse para reforestar después de considerar las restricciones socioeconómicas y ecológicas. El análisis predijo que la reforestación en al menos el 43% (∼ 369 millones de ha) del área que se puede reforestar beneficiará potencialmente a los vertebrados amenazados. Esto es aproximadamente el 15% del área total en donde están presentes los vertebrados amenazados. Las oportunidades más grandes para conservar a las especies amenazadas de vertebrados se encuentran en los trópicos, particularmente en Brasil y en Indonesia. Aunque la reforestación no es un sustituto para la conservación de los bosques, y aunque la mayoría del área que contiene vertebrados amenazados todavía tiene flora original, nuestros resultados resaltan la necesidad de tener estrategias mundiales de conservación para reconocer la contribución potencialmente significativa que podría dar la reforestación a la conservación de la biodiversidad. Si se implementa, la reforestación de ∼369 millones de ha también contribuiría significativamente a la mitigación del cambio climático, ofreciendo así una manera de cumplir varios compromisos de sustentabilidad a la vez. Los países ahora deben trabajar para sobreponerse a las barreras importantes (p. ej.: flujos inciertos de ingresos, costos elevados de las transacciones) que enfrentan las inversiones para la reforestación.

Extinction risk is most acute for the world's largest and smallest vertebrates.

Extinction risk in vertebrates has been linked to large body size, but this putative relationship has only been explored for select taxa, with variable results. Using a newly assembled and taxonomically expansive database, we analyzed the relationships between extinction risk and body mass (27,647 species) and between extinction risk and range size (21,294 species) for vertebrates across six main classes. We found that the probability of being threatened was positively and significantly related to body mass for birds, cartilaginous fishes, and mammals. Bimodal relationships were evident for amphibians, reptiles, and bony fishes. Most importantly, a bimodal relationship was found across all vertebrates such that extinction risk changes around a body mass breakpoint of 0.035 kg, indicating that the lightest and heaviest vertebrates have elevated extinction risk. We also found range size to be an important predictor of the probability of being threatened, with strong negative relationships across nearly all taxa. A review of the drivers of extinction risk revealed that the heaviest vertebrates are most threatened by direct killing by humans. By contrast, the lightest vertebrates are most threatened by habitat loss and modification stemming especially from pollution, agricultural cropping, and logging. Our results offer insight into halting the ongoing wave of vertebrate extinctions by revealing the vulnerability of large and small taxa, and identifying size-specific threats. Moreover, they indicate that, without intervention, anthropogenic activities will soon precipitate a double truncation of the size distribution of the world's vertebrates, fundamentally reordering the structure of life on our planet.

Beverage milk consumption patterns in the United States: Who is substituting from dairy to plant-based beverages?

This research used a survey of 995 US households to explore how dairy milk and plant-based beverage substitutes were consumed. Long-term trends of declining beverage milk consumption have been exacerbated in recent years by increasing consumption of plant-based beverages. Although beverage milk consumption has been declining, total dairy consumption in the United States continues to increase, driven by growth in sales of cheese, butter, and yogurt. Using k-means cluster analysis, 3 consumption clusters for US households were identified. The largest cluster, consisting of 61.6% of households, consumed dairy milk with some regularity and consumed little or no plant-based beverages. A second cluster, flexitarian households, consisting of 15.6% of respondent households, frequently consumed both dairy milk and plant-based beverages. The third cluster, plant-based consumers, consisting of 22.8% of households, consumed almost exclusively plant-based beverages. Examining differences in demographics between clusters, flexitarian households were larger, more likely to include young children, more likely to include a vegetarian or vegan, and more liberal than traditional dairy-consuming households. Plant-based households had many similarities to flexitarian households. The flexitarian and plant-based clusters were willing to substitute plant-based beverages for dairy milk for almost all consumption uses.

US respondents' willingness to pay for Cheddar cheese from dairy cattle with different pasture access, antibiotic use, and dehorning practices.

Cheese is a widely consumed product in American diets and an important economic driver of US dairy markets. Given the widespread interest in credence attributes of fluid dairy products, the lack of knowledge of demand for animal welfare, environmental, and other credence attributes in cheeses is surprising. Increasing attention surrounding dairy cattle welfare has been placed on the disbudding or dehorning of dairy cattle, in addition to the longer term debates surrounding pasture access and antibiotic use. This work estimates willingness to pay for these attributes of dairy cattle management systems for Cheddar cheese in a nationally representative sample of 749 US household members. Ninety percent of respondents indicated they or someone in their household consumed cheese in the last year. Higher proportions of respondents with children in the household purchased cheese of any kind. Respondents had positive willingness to pay for Cheddar cheese that had the following attributes: USDA-, retailer-, and industry-verified antibiotic use not permitted, required pasture access, and dehorning with pain relief as well as polled (when compared with dehorning without pain relief). As dairy producers face tighter margins and shifting consumer preferences, increasing attention on consumer preferences for cheese may aid in increasing profitability if demanded attributes can be profitability provided.

Preexisting musculoskeletal burden and its development under letrozole treatment in early breast cancer patients.

One of the most common adverse events (AEs) occurring during treatment with aromatase inhibitors (AIs) is musculoskeletal pain. The aim of our study was to analyze the influence of preexisting muscle/limb pain and joint pain on the development of AI-induced musculoskeletal AEs. Women eligible for upfront adjuvant endocrine therapy with letrozole were included in the PreFace study, a multicenter phase IV trial. During the first treatment year, they were asked to record musculoskeletal AEs monthly by answering questions regarding pain symptoms and rating the pain intensity on a numeric rating scale from 0 (no pain) to 10 (very strong pain). Pain values were compared using nonparametric statistical tests. Overall, 1,416 patients were evaluable. The average pain value over all time points in women with preexisting muscle/limb pain was 4.3 (median 4.3); in those without preexisting pain, it was 2.0 (median 1.7). In patients without preexisting muscle/limb pain, pain levels increased relatively strongly within the first 6 months (mean increase +0.9, p < 0.00001) in comparison with those with preexisting pain (mean increase +0.3, p < 0.001), resulting in a statistically significant difference (p < 0.00001) between the two groups. The development of joint pain was similar in the two groups. Women without preexisting muscle/limb pain or joint pain have the greatest increase in pain after the start of adjuvant AI therapy. Women with preexisting pain have significantly higher pain values. The main increase in pain values takes place during the first 6 months of treatment.

Association between breast cancer risk factors and molecular type in postmenopausal patients with hormone receptor-positive early breast cancer.

PURPOSE: Evidence shows that genetic and non-genetic risk factors for breast cancer (BC) differ relative to the molecular subtype. This analysis aimed to investigate associations between epidemiological risk factors and immunohistochemical subtypes in a cohort of postmenopausal, hormone receptor-positive BC patients. METHODS: The prospective, single-arm, multicenter phase IV PreFace study (Evaluation of Predictive Factors Regarding the Effectivity of Aromatase Inhibitor Therapy) included 3529 postmenopausal patients with hormone receptor-positive early BC. Data on their epidemiological risk factors were obtained from patients' diaries and their medical histories. Data on estrogen receptor, progesterone receptor, and HER2 receptor status were obtained from pathology reports. Patients with incomplete information were excluded. Data were analyzed using conditional inference regression analysis, analysis of variance, and the chi-squared test. RESULTS: In a cohort of 3392 patients, the strongest association with the molecular subtypes of BC was found for hormone replacement therapy (HRT) before diagnosis of early BC. The analysis showed that patients who took HRT at diagnosis had luminal A-like BC more often (83.7%) than those who had never taken HRT or had stopped taking it (75.5%). Luminal B-like BC and HER2-positive BC were diagnosed more often in women who had never taken HRT or had stopped taking it (13.3% and 11.2%, respectively) than in women who were taking HRT at diagnosis of BC (8.3% and 8.0%, respectively). CONCLUSIONS: This analysis shows an association between HRT and the distribution of molecular subtypes of BC. However, no associations between other factors (e.g., age at diagnosis, body mass index, smoking status, age at menopause, number of deliveries, age at first delivery, breastfeeding history, or family history) were noted.

Eating plants and planting forests for the climate.

The IPCC's Special Report on Climate Change and Land addresses the closely coupled relationship between land use and climate change. The report notes the climate change mitigation potential of dietary shifts and afforestation. Here, we briefly discuss how decreases in ruminant meat consumption associated with dietary shifts have the potential to free up area for forests, allowing for greater CO2 sequestration and benefiting biodiversity, while simultaneously reducing anthropogenic CO2 emissions.

Influence of patient and tumor characteristics on therapy persistence with letrozole in postmenopausal women with advanced breast cancer: results of the prospective observational EvAluate-TM study.

BACKGROUND: Treatment of postmenopausal, hormone receptor-positive metastatic breast cancer (MBC) patients varies despite clear therapy guidelines, favoring endocrine treatment (ET). Aim of this study was to analyze persistence of palliative aromatase inhibitor (AI) monotherapy in MBC patients. METHODS: EvAluate-TM is a prospective, multicenter, noninterventional study to evaluate treatment with letrozole in postmenopausal women with hormone receptor-positive breast cancer. To assess therapy persistence, defined as the time from therapy start to the end of the therapy (TTEOT), two pre-specified study visits took place after 6 and 12 months. Competing risk survival analyses were performed to identify patient and tumor characteristics that predict TTEOT. RESULTS: Out of 200 patients, 66 patients terminated treatment prematurely, 26 (13%) of them due to causes other than disease progression. Persistence rate for reasons other than progression at 12 months was 77.7%. Persistence was lower in patients who reported any adverse event (AE) in the first 30 days of ET (89.5% with no AE and 56% with AE). Furthermore, patients had a lower persistence if they reported compliance problems in the past before letrozole treatment. CONCLUSIONS: Despite suffering from a life-threatening disease, AEs of an AI will result in a relevant number of treatment terminations that are not related to progression. Some subgroups of patients have very low persistence rates. Especially with regard to novel endocrine combination therapies, these data imply that some groups of patients will need special attention to guide them through the therapy process. TRIAL REGISTRATION: Clinical Trials Number: CFEM345DDE19.

Traditional attributes moo-ve over for some consumer segments: Relative ranking of fluid milk attributes.

Due to the decrease in fluid milk consumption as a beverage in the United States, the importance for dairy industry stakeholders to understand attribute preferences for consumer segments has increased. This paper uses a representative sample of U.S. residents to determine shopping behavior and a Best-Worst experimental design to examine consumer preferences for select milk attributes. The Random Parameters Logit model revealed the largest preference shares were for price (19.1%), fat content (17.6%), and humane handling (16.1%). Segmentation of the respondents was analyzed using a Latent Class Model, and the demographics of segments were analyzed by probabilistic assignment. This contribution, which may be applied to other products, allows for a detailed understanding of consumer preferences for fluid milk. Demographics such as gender and age were not statistically different across the five classes for this topic, unlike shopping behavior. Class 2 was named "The Balancing Act" due to respondents' balance between animal welfare aspects and the physical characteristics of milk. Class 5 was dubbed "Value and Volume" due to large preference shares for price and container size. A lower percentage of respondents in "The Balancing Act" (12.2%) reported purchasing fat-free skim milk when compared to the percentage of respondents in "Value and Volume" (18.6%). Due to the large preference shares for traditional milk attributes, Class 3 was named "Traditional Milk Shoppers." A higher percentage of respondents in "Value and Volume" also reported always reading the information on meat, egg, or milk products when compared to "Traditional Milk Shoppers" (12.2%). Although price is still important to many consumers, certain segments have preferences or demand for other attributes that may be satisfied by producers to increase market share or price premiums.

Optical and thermal analysis of the light-heat conversion process employing an antenna-based hybrid plasmonic waveguide for HAMR.

We investigate a tapered, hybrid plasmonic waveguide which has previously been proposed as an optically efficient near-field transducer (NFT), or component thereof, in several devices which aim to exploit nanofocused light. We numerically analyze how light is transported through the waveguide and ultimately focused via effective-mode coupling and taper optimization. Crucial dimensional parameters in this optimization process are identified that are not only necessary to achieve maximum optical throughput, but also optimum thermal performance with specific application towards heat-assisted magnetic recording (HAMR). It is shown that existing devices constructed on similar waveguides may benefit from a heat spreader to avoid deformation of the plasmonic element which we achieve with no cost to the optical efficiency. For HAMR, our design is able to surpass many industry requirements in regard to both optical and thermal efficiency using pertinent figure of merits like 8.5% optical efficiency.

Focusing element formed by scattering structures in a planar dielectric waveguide.

A design process for creating integrated diffractive focusing elements for use in planar waveguides is presented. The elements consist of a linear array of holes etched into the core layer of a planar dielectric waveguide. A complete element is a few micrometers in size, while the individual holes are sub-micrometer. The focusing element was designed using analytical Mie theory. The performance of the complete 3D structure was then evaluated using 3D finite difference time domain (FDTD) method. A focal spot width of 227 nm (full width at half maximum) was predicted by 3D FDTD simulations with a peak intensity more than 10x the incident intensity and back-reflections lower than 1%. The focusing elements were fabricated using electron beam lithography and plasma etching. Fluorescence imaging was used to map the intensity in the waveguide core. The experimentally measured intensity maps were in good agreement with the simulations when the finite spatial resolution of the imaging system was taken into account.

Quantifying predator dependence in the functional response of generalist predators.

A long-standing debate concerns how functional responses are best described. Theory suggests that ratio dependence is consistent with many food web patterns left unexplained by the simplest prey-dependent models. However, for logistical reasons, ratio dependence and predator dependence more generally have seen infrequent empirical evaluation and then only so in specialist predators, which are rare in nature. Here we develop an approach to simultaneously estimate the prey-specific attack rates and predator-specific interference (facilitation) rates of predators interacting with arbitrary numbers of prey and predator species in the field. We apply the approach to surveys and experiments involving two intertidal whelks and their full suite of potential prey. Our study provides strong evidence for predator dependence that is poorly described by the ratio dependent model over manipulated and natural ranges of species abundances. It also indicates how, for generalist predators, even the qualitative nature of predator dependence can be prey-specific.

Bayesian characterization of uncertainty in species interaction strengths.

Considerable effort has been devoted to the estimation of species interaction strengths. This effort has focused primarily on statistical significance testing and obtaining point estimates of parameters that contribute to interaction strength magnitudes, leaving the characterization of uncertainty associated with those estimates unconsidered. We consider a means of characterizing the uncertainty of a generalist predator's interaction strengths by formulating an observational method for estimating a predator's prey-specific per capita attack rates as a Bayesian statistical model. This formulation permits the explicit incorporation of multiple sources of uncertainty. A key insight is the informative nature of several so-called non-informative priors that have been used in modeling the sparse data typical of predator feeding surveys. We introduce to ecology a new neutral prior and provide evidence for its superior performance. We use a case study to consider the attack rates in a New Zealand intertidal whelk predator, and we illustrate not only that Bayesian point estimates can be made to correspond with those obtained by frequentist approaches, but also that estimation uncertainty as described by 95% intervals is more useful and biologically realistic using the Bayesian method. In particular, unlike in bootstrap confidence intervals, the lower bounds of the Bayesian posterior intervals for attack rates do not include zero when a predator-prey interaction is in fact observed. We conclude that the Bayesian framework provides a straightforward, probabilistic characterization of interaction strength uncertainty, enabling future considerations of both the deterministic and stochastic drivers of interaction strength and their impact on food webs.

Diffusion and nucleation in multilayer growth of PTCDI-C8 studied with in situ X-ray growth oscillations and real-time small angle X-ray scattering.

We study nucleation and multilayer growth of the perylene derivative PTCDI-C8 and find a persistent layer-by-layer growth, transformation of island shapes, and an enhancement of molecular diffusivity in upper monolayers (MLs). These findings result from the evaluation of the ML-dependent island densities, obtained by in situ real-time grazing incidence small angle X-ray scattering measurements and simultaneous X-ray growth oscillations. Complementary ex situ atomic force microscopy snapshots of different growth stages agree quantitatively with both X-ray techniques. The rate and temperature-dependent island density is analyzed using different mean-field nucleation models. Both a diffusion limited aggregation and an attachment limited aggregation model yield in the first two MLs the same critical nucleus size i, similar surface diffusion attempt frequencies in the 1019-1020 s-1 range, and a decrease of the diffusion barrier Ed in the 2nd ML by 140 meV.