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We investigated the influence of 6 morphometric and geographic factors on the structure and composition of plant communities in 56 temporary freshwater rockpools from 7 pool landscapes in the Malte...

This study characterizes the zonation of coastal vegetation in six coastal sites in Malta. The vegetation sequence on the coastal zone is predictable and displaces in response to changes in shoreline. The halophyte Limbarda crithmoides was used as an indicator species to ‘locate’ the position of the sequence. The vegetation surveys were used to construct a Gaussian distribution model for this species. Peak density and peak distance from the shore were positively correlated with exposure. The models were used to simulate the predicted shift of the vegetation in response to a modified shoreline

The study assesses consumer drone efficiency for surveying shallow-water benthic cover. We hypothesised that using a drone would reduce duration, and manpower requirements, while increasing accuracy, relative to manual surveys. Results obtained during this study clearly indicated that automated drone surveys were faster and more accurate than manual survey methods under most circumstances. This result has important implications for the scientific and economic aspects of the process and would have a multiplicative effect in monitoring programs that require regular surveys.

Bonnici, L.; Borg, J.A.; Evans, J.; Lanfranco, S., and Schembri, P.J., 2018. Of rocks and hard places: Comparing biotic assemblages on concrete jetties versus natural rock along a microtidal Mediterranean shore. The species composition and structure of littoral assemblages on concrete jetties were compared with those on natural rocky shores at two localities on the microtidal NE coast of Malta. Algal species richness and total algal biomass were significantly lower on jetties. Faunal species richness and faunal abundance were also lower on jetties, albeit not significantly so. Jetties and natural rocky shores differed in relative species composition. The algae Palisada perforata/Laurencia obtusa and several mobile animals, mostly crustaceans, molluscs, and polychaetes, were more abundant on rocky shores. In particular, the supralittoral gastropod Melarhaphe neritoides had a density ranging between 8 ind./m2 to 98 ind./m2 on rocky shores but was never recorded on jetties. Conversely, the algae Cla...

The saline marshlands of the Maltese Islands are coastal wetland biotopes defined by the presence of brackish water and a substratum of sandy/silty sediment. These habitats form at the mouth of valley systems where freshwater and sediment from inland sources interact with seawater. They are sparsely distributed round the Maltese coastline and often degraded by anthropogenic pressures. The natural hydrological cycles of the marshes follow the seasonal patterns of precipitation, where a wet phase, during which surface water is present, alternates with a dry phase. In managed marshes, the hydrological balance may be partly independent of climatic forcing and would depend more on specific management practices. The saline substratum supports halophytic vegetation whilst the water body is colonised by fauna typical of temporary waters or of brackish waters, depending on the duration of the hydroperiod. The substratum also functions as a repository for propagules, such as eggs, spores and seeds. This provides a ‘storage effect’, where reproductive failure in one year may be compensated for by germination or hatching of propagules deposited during previous seasons.

Temporary freshwater rockpools form in rocky depressions which accumulate surface water long enough to permit the development of specific aquatic vegetation and animal communities. These habitats alternate between periods of flooding during the wet season and sustained drought during the dry season. These pools are very small in size compared with other temporary pools present in the Mediterranean region, with surface areas ranging from a few tens of square centimetres to a few square metres. The pools are colonised by specialist fauna and flora characterised by compressed life cycles. The principal determinants of the biological cycles within pools are the frequency and duration of hydroperiods, and the water-retention properties of the sediment layer. Both factors act as environmental filters, excluding generalist species from the pool habitat.

We propose the use of phylogenetic patterns as a tool for monitoring long-term change in plant community structure in small temporary pools, as an alternative to the compilation of species lists across years. This was tested using forty temporary pools from four pool landscapes in Malta. These were followed between November 2014 and April 2015. Each pool was sectored into ‘Aquatic’, ‘Ecotone’ and ‘Terrestrial zones’ and the species present in each zone were recorded. All species data from a landscape were collated by zone, and the net relatedness index (NRI) for the species assemblages in each zone calculated using PHYLOCOM software. The NRI was positive in the ‘Terrestrial’ zones, and negative in the ‘Aquatic’ zones. The ‘Ecotone’ zones followed no discernible pattern. The results suggest that calculating the NRI of plant assemblages in different hydrological zones, and using these phylogenetic ‘signatures’ as a comparative baseline, would be a feasible addition to long-term monitoring programmes for the early detection of long-term environmental changes such as those arising from climatic changes.

We report a high efficiency sub-6GHz wideband Envelope-Tracking Power Amplifier (ET-PA) including a soft-switching buck-converter and a wideband RF-PA, used in conjunction with a digital front end (DFE) environment for signal generation and predistortion. Both buck-converter and RF-P A were fabricated using an 0.15um GaN HEMT process. The DFE can generate the input signals for both buck-converter and RF-P A, capture the output signal for feed-back and perform digital predistortion (DPD). The overall ET-P A achieves total efficiency of 39.5–46.7% and output power of 31.2–31.5dBm over 3.6–4.0GHz with 20MHz L TE signals. With DPD, ACLR was below −45dBc with total efficiency reaching 47% at 3.6GHz. This, to the best of the authors' knowledge, is the highest efficiency yet reported for an ET-PA at this carrier frequency.

Crace portrays diseased or decomposing human bodies as environments caught between the tended and the untameable. This chapter discusses Being Dead, Quarantine, and The Gift of Stones, to show how Crace’s narratives understand that the wilderness within humanity is always too close for comfort, both in life and in death. An interdisciplinary approach featuring perspectives from literary theory and biology informs a close reading of how decomposition is figured in Being Dead. Callus and Lanfranco situate Crace’s representations of death and decomposition against older traditions of memento mori within Western literature and culture, as well as broader discussions within posthumanist paradigms that turn on themes like morbidity, decay, regeneration, and anthropocentrism, and alongside which Being Dead offers a lyrically powerful fictive counterpart.

We report a high efficiency multi-band Envelope-Tracking Power Amplifier (ET-PA) that supports modulation bandwidth up to 80MHz using real-time digital predistortion (RT-DPD). The ET-PA consists of a broadband RF-PA and a singlephase buck-converter. The RF-PA has maximum PAE over 50% from 0.7 to 2.1GHz in CW measurements. The buck-converter operates at 245.76MHz switching frequency, and attains 78% PAE for modulated signals with 6.5dB PAPR. Both RF-PA and buckconverter were fabricated using a GaN HEMT process. The RT-DPD system can generate the input signals for both buck-converter and RF-PA, and capture the output signal for feedback. An FPGA is employed in the RT-DPD system to perform predistortion in a closed-loop fashion. The overall ET-PA achieves total efficiency of 32.1–35.5%, output power of 30–30.7dBm with 30V supply voltage over 0.9–2.15GHz. By using the RT-DPD, ACLR is improved to below −45dBc even under 80MHz modulated LTE signal with 6.5dB PAPR, maintaining high efficiency. To the authors' best knowledge, this is the widest modulation bandwidth yet reported for an efficient and multi-band ET-PA.

In this paper, co mprehensive design considerations for mult i-stage envelope tracking power amp lifier line-up design with a 10W GaN HEMT switch mode driver amp lifierwas presented to realized optimu m overall power added efficiency.Crest factor reduction algorith m and non-linear switch mode driver design for efficiency and linearization were studied. Also, a high efficiency inverse class-F amplifier was imp lemented with efficiency as 44.8% for LTE 20M Hz signaland characterized to provethe concept of applying linearizable inverse class-F amp lifierenvelope tracking driver purpose.

Rock pools are small eroded depressions that occur in a matrix of bedrock. Despite their size, they support diverse aquatic invertebrate communities. Hydroperiod is an important determinant of the species composition that can be found in a rock pool at a given moment. Species sorting, i.e., the distribution of species based on local environmental conditions, is a dominant structuring process in rock pool communities. Trade-offs between competition and predation tolerance are important underlying factors driving succession in these systems. As freshwater rock pools are unique habitats housing a surprisingly high diversity of specialist and endemic species, protection of these habitats is essential.

This paper presents a novel digitally assisted dual-switch envelope amplifier used for wideband high-efficiency envelope-tracking (ET) base-station power amplifiers (PAs). The proposed envelope amplifier comprises two switching buck converters to provide the high-power ET signal to the RF stage and a wideband linear stage to maintain the envelope signal accuracy. The control technique utilizes digital signal processing in conjunction with analog hysteretic feedback to separately control two high-efficiency switchers and thus successfully reduces power consumption of the linear stage, especially for applications requiring high peak-to-average ratio (PAPR) signals. The overall ET system was demonstrated using GaAs high-voltage HBT PAs. For a variety of signals ranging from 6.6- to 9.6-dB PAPR and up to 10-MHz RF bandwidth, the overall system power-added efficiency reached 50%-60%, with a normalized root-mean-square error below 1% and the first adjacent channel leakage power ratio of -55 dBc after digital predistortion with memory mitigation, at an average output power above 20 W and 10-dB gain. University of California Discovery Grant Program Nokia Siemens Networks

A high-efficiency wideband code-division multiple-access (W-CDMA) base-station amplifier is presented using high-performance GaN heterostructure field-effect transistors to achieve high gain and efficiency with good linearity. For high efficiency, class J/E operation was employed, which can attain up to 80% efficiency over a wide range of input powers and power supply voltages. For nonconstant envelope input, the average efficiency is further increased by employing the envelope-tracking architecture using a wide-bandwidth high-efficiency envelope amplifier. The linearity of overall system is enhanced by digital pre-distortion. The measured average power-added efficiency of the amplifier is as high as 50.7% for a W-CDMA modulated signal with peak-to-average power ratio of 7.67 dB at an average output power of 37.2 W and gain of 10.0 dB. We believe that this corresponds to the best efficiency performance among reported base-station power amplifiers for W-CDMA. The measured error vector magnitude is as low as 1.74% with adjacent channel leakage ratio of -51.0 dBc at an offset frequency of 5 MHz

Silene melitensis, a new species beonging to the sect. Dipterosperma, is described and illustrated from Maltese Archipelago. This therophyte occurs along the calcareous rocky coast of Malta and Gozo islands, where it grows within the ephemeral meadows together with many halophytes. Based on its prostrate-ascending habit and succulent leaves, S. melitensis shows some morphological similarities with S. nummica and S. crassiuscula, both included in the S. colorata group. S. melitensis differs from S. nummica in having inflorescence more flowered, petals smaller, claw on the back pubescent in the midrib, capsule bigger, carpophore shorter and seed with undulate wings, while it differs from S. crassiuscula in having scapes branched at the base, calyx tomentose-hirsute and shorter, petal limb shorter, coronal scales shorter and undulate, ovary shorter and seed larger. An diagnostic key of the taxa belonging to the sect. Dicterosperma is provided.

A pollen diagram was constructed for the early- to mid-Holocene transition (ca. 7350–5600 cal. B.P./5400–3650 B.C.) from the Burmarrad ria located in NW Malta. The vegetation at ca. 7350–6960 cal. B.P./5400–5010 B.C. was characterized by an almost tree-less steppe-like open landscape. Early Holocene dry climatic conditions were most probably due to intensification of the subtropical monsoon circulation that strengthened the subtropical anticyclonic descent over the central Mediterranean and blocked the penetration of humid air masses from the North Atlantic Ocean. At ca. 6950 cal. B.P./5000 B.C., the steppe-like vegetation was suddenly replaced by a Mediterranean evergreen forest or dense scrub dominated by Pistacia cf. lentiscus trees. This event, which has simultaneously been recorded in southern Sicily, was most probably caused by the southward shift of the ITCZ permitting the eastward movement of the North Atlantic cyclonic systems. Traces of human activities are evident in the pollen diagram since the beginning of the record but become more pronounced from the onset of the Temple Cultural Phase at ca. 6050 cal. B.P./4100 B.C. with a gradual decline of tree pollen. We suggest that the early- to mid-Holocene vegetation transformation was mainly controlled by a regional climatic change that occurred in a landscape only slightly impacted by human activities., peer-reviewed

In this paper, a novel supply modulator for envelope tracking power amplifier was presented, which boosts operation bandwidth capability to tracking up to LTE 60MHz by utilizing GaN MOSFET and compatible with feed forward loop to linearize the modulator for wideband, realizing high efficiency trading off linearity as well.

In this paper, comprehensive design considerations and conclusion for multi-stage envelope tracking power amplifier line-up was presented. Key aspects such as supply modulator, crest factor reduction algorithm and transistor technology with envelope tracking driver characterization were studied. Also, a test method was implemented to prove how envelope tracking trade off efficiency and linearity on various types of driver amplifiers.

In this work, a current-mode class-S RF power amplifier demonstrator working around 1 GHz has been designed and implemented following a partitioning design approach. Based on this approach, the entire class-S system has been systematically divided into several sub-modules; each sub-module is then separately designed, fabricated, and characterized. The unique advantages of this specialized design technique for implementing such complicated RF PA circuits have been presented. To our best knowledge, modulated signal with 80 MHz modulation bandwidth has been for the first time applied to test a class-S PA in the GHz range. Finally, the operating principles of the current-mode class-S power amplifier have been proven by the designed demonstrator with GaN HEMTs and key design considerations have been pointed out.

This paper presents a novel envelope amplifier architecture to improve the overall efficiency of wideband high linearity envelope tracking power amplifiers (PAs). We show here a technique to increase the efficiency of the envelope amplifier while maintaining the amplifier's bandwidth. The technique utilizes digital signal processing (DSP) control in conjunction with analog hysteretic feedback. Two high efficiency buck switching stages are coordinated to provide the wideband envelope power to the RF stage; a wide bandwidth linear regulator is also used at low power to maintain the envelope signal accuracy. The technique improves the efficiency of the envelope amplifier, especially for applications requiring high peak-to-average power ratio (PAPR) with wide bandwidth signals. The overall system was demonstrated using a GaAs high voltage HBT PA. For a variety of signals ranging from 6.6dB to 9.6dB PAR and up to 10MHz bandwidth, the overall system PAE reached above 50%, with a normalized power RMS error below 5% and ACLR1 of −50dBc with memory-less digital predistortion, at an average output power above 19W and gain of 10dB. The efficiencies obtained are the best ever reported, to our knowledge, for envelope tracking base station amplifiers for these signals.

A high performance W-CDMA base station power amplifier is presented, which uses an envelope tracking bias system along with an advanced 0.4mum gate length LDMOS transistor, to achieve high efficiency. High linearity is also achieved by employing digital predistortion. For a target WCDMA envelope with a peak-to-average power ratio of 7.6 dB, the measured overall power-added efficiency (PAE) is as high as 40.4 %. Within this system, the RF power amplifier has an average drain efficiency of approximately 64%, and the envelope amplifier has about 60% efficiency. After the memoryless digital predistortion the normalized power RMS error is 3.3%, at an average output power of 27 W and gain of 14.9 dB. After memory mitigation the normalized power RMS error drops to below 1.0%. The efficiency ranks among the highest reported for a single stage LDMOS W-CDMA base station amplifier

A high performance GaN HFET WCDMA basestation power amplifier is presented, which uses an envelope tracking bias system to achieve high linearity and efficiency. The measured overall power-added efficiency (PAE) reached 50.7%, with a normalized power RMS error of 0.7% and ACLR of -52dBc at an offset frequency of 5MHz, at an average output power of 37.2W and gain of 10.0dB for a single carrier WCDMA signal. To the authors' knowledge, this corresponds to the best efficiency reported for a single stage base station power amplifier. Digital predistortion (DPD) was used at two levels: memoryless DPD to compensate for the expected gain variation of the amplifier over the bias envelope trajectory, and deterministic memory mitigation, to further improve the linearity. The signal envelope had a peak-to-average power ratio of 7.67dB.

Four branchiopod species occur on the Maltese Islands, viz. Branchipus schaefferi, B. visnyai, Cyzicus tetracerus and Triops cancriformis. All four live in freshwater pools, but it is noteworthy that, beside B. schaefferi, T. cancriformis was recorded from a mesohaline, coast-fringing habitat.