Explore the vast range of titles available.

Anaerobic digestion is the most successful bioenergy technology worldwide with, at its core, undefined microbial communities that have poorly understood dynamics. Here, we investigated the relationships of bacterial community structure (>400,000 16S rRNA gene sequences for 112 samples) with function (i.e., bioreactor performance) and environment (i.e., operating conditions) in a yearlong monthly time series of nine full-scale bioreactor facilities treating brewery wastewater (>20,000 measurements). Each of the nine facilities had a unique community structure with an unprecedented level of stability. Using machine learning, we identified a small subset of operational taxonomic units (OTUs; 145 out of 4,962), which predicted the location of the facility of origin for almost every sample (96.4% accuracy). Of these 145 OTUs, syntrophic bacteria were systematically overrepresented, demonstrating that syntrophs rebounded following disturbances. This indicates that resilience, rather than dynamic competition, played an important role in maintaining the necessary syntrophic populations. In addition, we explained the observed phylogenetic differences between all samples on the basis of a subset of environmental gradients (using constrained ordination) and found stronger relationships between community structure and its function rather than its environment. These relationships were strongest for two performance variables— methanogenic activity and substrate removal efficiency— both of which were also affected by microbial ecology because these variables were correlated with community evenness (at any given time) and variability in phylogenetic structure (over time), respectively. Thus, we quantified relationships between community structure and function, which opens the door to engineer communities with superior functions.

The objective of this work was to evaluate the effect of intermittent aeration on the removal of ammonium (NH4+), total nitrogen (TN) and chemical oxygen demand (COD) in a horizontal subsurface flow constructed wetland (HFCW). Two HFCWs were studied, one non-aerated and another aerated intermittently, and both cultivated with Typha latifolia. Each system received 8.6 L d-1 of synthetic wastewater, resulting in 3 days of hydraulic retention time. The two systems displayed high efficiencies in the removal of COD (>90%); however, the intermittently aerated HFCW showed a higher rate of COD removal. Additionally, the removal of TN (48.8%) and NH4+ (57.7%) in the non-aerated system was limited, while in the aerated system, the efficiencies of TN (81.2%) and NH4+ (98.6%) removal were satisfactory. Thus, the results indicate that via intermittent aeration, nitrification and denitrification occur simultaneously, improving the performance of HFCW in the removal of TN and NH4+.

Many beer breweries use high-rate anaerobic digestion (AD) systems to treat their soluble high-strength wastewater. Biogas from these AD systems is used to offset nonrenewable energy utilization in the brewery. With increasing nonrenewable energy costs, interest has mounted to also digest secondary residuals from the high-rate digester effluent, which consists of yeast cells, bacteria, methanogens, and small (hemi)cellulosic particles. Mesophilic (37 °C) and thermophilic (55 °C) lab-scale, low-rate continuously-stirred anaerobic digestion (CSAD) bioreactors were operated for 258 days by feeding secondary residuals at a volatile solids (VS) concentration of ~40 g l⁻¹. At a hydraulic retention time (HRT) of 15 days and a VS loading rate of 2.7 g VS l⁻¹ day⁻¹, the mesophilic bioreactor showed an average specific volumetric biogas production rate of 0.88 l CH₄ l⁻¹ day⁻¹ and an effluent VS concentration of 22.2 g VS l⁻¹ (43.0% VS removal efficiency) while the thermophilic bioreactor displayed similar performances. The overall methane yield for both systems was 0.21 l CH₄ g⁻¹ VS fed and 0.47-0.48 l CH₄ g⁻¹ VS removed. A primary limitation of thermophilic digestion of this protein-rich waste is the inhibition of methanogens due to higher nondissociated (free) ammonia (NH₃) concentrations under similar total ammonium (NH₄ ⁺) concentrations at equilibrium. Since thermophilic AD did not result in advantageous methane production rates or yields, mesophilic AD was, therefore, superior in treating secondary residuals from high-rate AD effluent. An additional digester to convert secondary residuals to methane may increase the total biogas generation at the brewery by 8% compared to just conventional high-rate digestion of brewery wastewater alone.

Designation of eVTOL Operators In Canada, the strategic decision of an eVTOL operator to become an airline for the purposes of providing international air services is subject to a national licensing process that requires, among other conditions, compliance with ownership and control requirements and liability insurance obligations.17 At the outset, access to foreign financing, aircraft, and experienced leadership may be limited for Canadian eVTOL operators in the early stages of development due to foreign ownership and control requirements.18 However, a recent decision issued by the Canadian Transportation Agency with regard to Flair Airlines19 suggests that some level of flexibility could be possible for new entrants. U.S.-certificated eVTOL operators must decide their intended corporate structure and types of operations, comply with stringent ownership and control rules, secure required Department of Transportation and Federal Aviation Administration (FAA) operating authorizations, and meet liability insurance obligations. The FAA has been working closely with new entrants in this space and very recently granted Joby Aviation its Part 135 Air Carrier Certificate, allowing it to begin on-demand commercial air taxi operations in advance of its type and production certificates for its eVTOL aircraft.20 Designation of Traffic Rights The U.S.-Canada ATA would allow eVTOL operators that have been designated as airlines21 to operate transborder scheduled services between any point or points in Canada and any point or points in the United States, including points in third countries using fifth freedom rights.22 Quite relevant for future eVTOL operators, a designated airline would be allowed to carry its own stopover passenger traffic between points in the territory of the other party and transfer traffic from any of its aircraft to any of its other aircraft at any point on the routes.23 The entry of eVTOL operations in the U.S.-Canada transborder market may be further strengthened by the operational flexibility provisions in the U.S.-Canada ATA, most of which are currently underutilized. [...]for the purposes of U.S.-Canada transborder eVTOL operations, the term point can be interpreted as any airport or vertiport, without the need to be designated as international or to be in compliance with any other capacity conditions (for example, a minimum number of passengers per year).

[...]Annex 11 requires states to coordinate with the appropriate air traffic services authorities when arranging activities that are potentially hazardous to civil aircraft over the high seas.38 In addition, Annex 15 sets forth specific notice39 and coordination requirements.40 In such circumstances, the state with responsibility for the relevant FIR must initiate this notice and coordination process.41 The coordination must occur early enough to permit timely promulgation of information regarding the activities in accordance with the provisions of Annex 15.42 Under Annex 15, states must provide at least seven days' advance notice through a notice to airmen (NOTAM)43 when establishing prohibited, restricted, or danger areas in airspace.44 Alternatively, Annex 15 allows for a greater lead-time of at least 28 days regarding the establishment and withdrawal of, and premeditated significant changes to, a danger area.45 For prohibited, restricted, and danger areas, the type of restriction or nature of hazard and risk of interception in the event of penetration must be indicated in the Aeronautical Information Publication (AIP).46 Establishing an airspace blockade, particularly involving international airspace within an FIR, without prior notice or coordination runs afoul of ICAO's procedural safeguards designed to mitigate the risk to and disruption of international civil aviation. Need for Provisional Measures As demonstrated by the airspace blockade against Qatar, some states are increasingly using airspace as a tool for coercive diplomacy in the context of regional disputes that are driven by larger, nonaviation agendas.47 However, the Chicago Convention provides a means of dispute resolution that can be used to address the legality of actions pertaining to civil aviation within the jurisdiction of the treaty.48 Pursuant to this dispute settlement process, if any disagreement between two or more contracting states relating to the interpretation or application of the Convention and its Annexes cannot be settled by negotiation, the ICAO Council may decide the matter based on the application of any state concerned in the disagreement.49 No member of the Council is permitted to vote in the consideration by the Council of any dispute to which it is a party.50 Appeal from the decision of the Council may be made to an ad hoc arbitral tribunal agreed upon with the other parties to the dispute or to the Permanent Court of International Justice (ICJ).51 The decisions of the ICJ and of an arbitral tribunal are final and binding.52 Penalties for noncomplying contracting states include the suspension of voting rights in the ICAO Council and Assembly.53 In the case of the airspace blockade, on June 8, 2017, Qatar requested that the ICAO Council convene a special session to consider the actions of Saudi Arabia, the United Arab Emirates, Bahrain, and Egypt.54 The Council held an extraordinary meeting on July 31, 2017, to consider this request.55 On October 30, 2017, Qatar submitted two applications and memorials, under Article 84 of the Chicago Convention and Article II, Section 2 of the International Air Services Transit Agreement (IASTA), respectively.56 In March 2018, Saudi Arabia, the United Arab Emirates, Bahrain, and Egypt filed their countermemorials and raised preliminary objections, contesting the jurisdiction of ICAO in the matter and in the alternative that the claims raised by Qatar were inadmissible.57 The Council suspended the proceedings on the merits of Qatar's claim pending the resolution of the preliminary objections. The process could be strengthened by amending the Chicago Convention to explicitly empower the Council to mandate provisional measures under special circumstances that are likely to cause irreparable harm,61 upon a basis similar to a grant of injunctive relief under U.S. law.62 The penalty for noncompliance with provisional measures can be the same as already provided for under the Chicago Convention: suspension of voting rights in the ICAO Council and Assembly.63 In the case of an airspace embargo or civil aviation blockade, the disruption to international air transport and related economic harm is immediate and potentially permanent-even in normal circumstances, commercial aviation is an extraordinarily competitive and turbulent industry. [...]there must be a prima facie basis for the court's jurisdiction.66 Second, the rights asserted by the applicant must be plausible with a link between such rights and the measures being requested.67 Third, there must be a real and imminent risk that irreparable prejudice will be caused to the rights at issue in the absence of the provisional measures.68 On October 3, 2018, the ICJ determined that Iran had met this standard, despite strenuous opposition from the United States, and ordered the United States to ensure that reimposed sanctions exempt, among other items, spare parts, equipment, and associated services (including warranty, maintenance, repair services, and inspections) necessary for the safety of civil aviation.69 In response, the United States announced that it will withdraw from the bilateral treaty with Iran that provided the basis for the ICJ's jurisdiction, but begrudgingly acknowledged compliance with the ICJ's provisional measures, including those addressing civil aviation safety.70 Amending the Chicago Convention may prove challenging, but it is not unprecedented-even when complex geopolitical issues are involved.

Anaerobic digestion is the most successful bioenergy technology worldwide with, at its core, undefined microbial communities that have poorly understood dynamics. Here, we investigated the relationships of bacterial community structure (>400,000 16S rRNA gene sequences for 112 samples) with function (i.e., bioreactor performance) and environment (i.e., operating conditions) in a yearlong monthly time series of nine full-scale bioreactor facilities treating brewery wastewater (>20,000 measurements). Each of the nine facilities had a unique community structure with an unprecedented level of stability. Using machine learning, we identified a small subset of operational taxonomic units (OTUs; 145 out of 4,962), which predicted the location of the facility of origin for almost every sample (96.4% accuracy). Of these 145 OTUs, syntrophic bacteria were systematically overrepresented, demonstrating that syntrophs rebounded following disturbances. This indicates that resilience, rather than dynamic competition, played an important role in maintaining the necessary syntrophic populations. In addition, we explained the observed phylogenetic differences between all samples on the basis of a subset of environmental gradients (using constrained ordination) and found stronger relationships between community structure and its function rather than its environment. These relationships were strongest for two performance variables—methanogenic activity and substrate removal efficiency—both of which were also affected by microbial ecology because these variables were correlated with community evenness (at any given time) and variability in phylogenetic structure (over time), respectively. Thus, we quantified relationships between community structure and function, which opens the door to engineer communities with superior functions.

In this study, the authors show that conditional deletion of leptin receptors from astrocytes alters their morphology and results in an increase in the number of synapses on POMC and AgRP neurons of the arcuate nucleus. In addition, they find that loss of leptin response in astrocytes modified leptin- and ghrelin-controlled food intake. We found that leptin receptors were expressed in hypothalamic astrocytes and that their conditional deletion led to altered glial morphology and synaptic inputs onto hypothalamic neurons involved in feeding control. Leptin-regulated feeding was diminished, whereas feeding after fasting or ghrelin administration was elevated in mice with astrocyte-specific leptin receptor deficiency. These data reveal an active role of glial cells in hypothalamic synaptic remodeling and control of feeding by leptin.