Manifestasi kek lapis Sarawak dalam proses pemerkasaan psikologi pengusaha wanita di Kampung Gersik, Kuching

The manifestation of tourism food products is an expression of identity for a tourism destination. However, little attention had been given to the relationship between tourism food products and women entrepreneurs in tourism-based businesses in the context of psychological empowerment. This study explores the manifestation of the Sarawak layer cake as a psychological empowerment catalyst for women entrepreneurs in tourism-based businesses in Kampung Gersik. The objectives of this study are to examine the meaning behind the manifestation of Sarawak layer cake designs and the contribution towards women psychological empowerment as well as the impact on destination branding at Kampung Gersik, Kuching. Qualitative methods were used in this research. A total of ten women entrepreneurs of Sarawak layer cake were selected from the study area. Another five participants were chosen as community representatives as they were indirectly affected by this industry. The entrepreneurs and participants were interviewed using semi-structured interview and the collected data were then analysed using thematic analysis. The results of the analysis revealed that the Sarawak layer cake came in three basic types, which are ‘Traditional’, ‘Contemporary’, and ‘Fusion’. These manifestations have eventually led to the psychological empowerment of women entrepreneurs as they strive for ‘meaningfulness’ and ‘perfection’ in their final product. The findings also revealed that, the design and motifs of Sarawak layer cake symbolise the passion and identity of women entrepreneurs which is a critical component in the process of destination branding as an inspiration for future sustainable tourism development of Kampung Gersik

Assessing the impact of transient orbital resonances

One of the primary sources for the future space-based gravitational wave detector, the Laser Interferometer Space Antenna, are the inspirals of small compact objects into massive black holes in the centres of galaxies. The gravitational waveforms from such Extreme Mass Ratio Inspiral (EMRI) systems will provide measurements of their parameters with unprecedented precision, but only if the waveforms are accurately modeled. Here we explore the impact of transient orbital resonances which occur when the ratio of radial and polar frequencies is a rational number. We introduce a new Effective Resonance Model, which is an extension of the numerical kludge EMRI waveform approximation to include the effect of resonances, and use it to explore the impact of resonances on EMRI parameter estimation. For one-year inspirals, we find that the few cycle dephasings induced by 3:2 resonances can lead to systematic errors in parameter estimates, that are up to several times the typical measurement precision of the parameters. The bias is greatest for 3:2 resonances that occur closer to the central black hole. By regarding them as unknown model parameters, we further show that observations will be able to constrain the size of the changes in the orbital parameters across the resonance to a relative precision of 10% for a typical one-year EMRI observation with signal-to-noise ratio of 20. Such measurements can be regarded as tests of fundamental physics, by comparing the measured changes to those predicted in general relativity.Comment: 16 pages, 6 figure

Insights on microbial and biochemical aspects of retting for bast fiber plant processing in a bioreactor

La transizione ad un\u2019economia bio-sostenibile ha previsto politicamente la coltivazione di biomassa per la produzione di energia e per quanto riguarda l\u2019industria chimica l\u2019impiego di materie prime rinnovabili in seguito al protocollo di Kyoto per far fronte ai cambiamenti climatici globali (UN FCCC, 1997). Fortunatamente, anche a livello industriale \ue8 stato riconosciuta l\u2019importanza del concetto di \u201ceco-efficienza\u201d indispensabile per uno sviluppo sostenibile. Le fibre naturali di origine vegetale rappresentano la maggiore fonte di materia prima rinnovabile e potrebbero giocare un ruolo importante in questa transizione. La valenza economica del mercato di piante da fibra sub\uec un calo dopo la Seconda Guerra Mondiale in seguito all\u2019introduzione delle fibre sintetiche. Attualmente, la loro valenza ecologica ha implementato la ricerca e lo sviluppo di compositi contenti fibre rinforzate impiegate nell\u2019industria dell\u2019automobile, nella bio-edilizia e nella produzione di tessuti biodegradabili. Tuttavia, l\u2019aumento della domanda di fibre naturali non ha ancora trovato un\u2019offerta adeguata in grado di soddisfarla. Nell\u2019ultimo decennio si \ue8 registrato un aumento della coltivazione delle piante da fibra come canapa, lino, kenaf e lino non supportate da uno sviluppo di un processo di estrazione delle fibre che ad oggi si basa ancora su sistemi tradizionali di macerazione. Il processo di separazione ed estrazione delle fibre dagli altri tessuti non fibrosi e dal midollo legnoso presenti nello stelo attraverso il distacco, la dissoluzione e la decomposizione delle pectine, gomme e le altre sostanze mucillaginose \ue8 chiamato retting. L\u2019obbiettivo proncipale di questo studio, in collaborazione con K.E.F.I. S.p.a., \ue8 stato lo sviluppo del processo di estrazione delle fibre vegetali a livello industriale in bioreattore mediante ribbon retting del kenaf. Il lavoro sperimentale pu\uf2 essere diviso in tre parti: la prima parte ha riguardato l\u2019ottimizzazione del processo di ribbon retting nel bioreattore analizzando diverse tipologie di materie prime (i ribbons di kenaf) e differenti variet\ue0 di kenaf (Everglade e Tainung); la seconda parte si \ue8 occupata di decifrare e caratterizzare la microflora che naturalmente si \ue8 sviluppata ed \ue8 stata coinvolta nella macerazione delle piante; la terza parte \ue8 servita ad identificare un possibile inoculo starter capace di implementare e standardizzare il processo di retting in bioreattore. Il processo di ribbon retting \ue8 un metodo particolare di macerzione basato sul pretrattamento meccanico degli steli che permette di ridurre: la quantit\ue0 necessaria di acqua, il tempo di macerazione e l\u2019inquinamento ambientale di circa un quarto in confronto agli altri metodi di macerazione che trattano lo stelo intero. In particolare, nella prima fase dello studio, le condizioni ottimali testate hanno permesso di garantire una miglior qualit\ue0 di fibre di kenaf sia in termini di resistenza, finezza, colore e soprattutto hanno prodotto fibre libere da residui del midollo legnoso. L\u2019ottimizzazione dei parametri di macerazione in bioreattore \ue8 stata condotta analizzando diversi carichi del bioreattore e testando differenti variet\ue0 di kenaf. La particolare impostazione del bioreattore, dotato di sistema di insufflazione di aria forzata ed di ricircolo del liquor di macerazione ha permesso di ottenere una macerazione spinta che ha prodotto in soli 5-7 giorni fibre di ottima qualit\ue0 e perfettamente macerate. In particolare, la macerazione in bioreattore ha permesso di monitorare e controllare i principali parametri del processo (pH, RedOx, ossigeno disciolto e temperatura). Particolarmente utile si \ue8 dimostrata la regolazione dell\u2019insufflazione dell\u2019aria che ha permesso di mantenere il pH del liquor a livelli vicini alla neutralit\ue0 evitando l\u2019eccessiva acidificazione ed il rischio di over-retting con conseguente danneggiamento delle fibre di cellulosa, principali costituenti delle fibre vegetali. L\u2019analisi microbiologica del liquor di macerazione mediante conta su diversi terreni di crescita ha evidenziato che durante il processo di macerazione popolazioni microbiche con attivit\ue0 pectinolitica si sono sviluppate sin dalle prime fasi del processo e hanno preso il sopravvento sull\u2019iniziale microflora eterotrofa derivante dalla contaminazione naturalmente presente sugli steli delle piante e nell\u2019acqua impiegata per la macerazione. L\u2019analisi del liquido di macerazione ha evidenziato il rilascio di sostanze fenoliche probabilmente originatesi dalla lignina presente nei tessuti vegetali, che tuttavia si \ue8 stabilizzato nel corso della macerazione a valori che dipendevano dalla tipologia di kenaf e dal carico del bioreattore. Nella seconda fase lo studio della microflora batterica coinvolta nel processo di macerazione \ue8 stato condotto sul liquor attraverso due approcci differenti ma complementari: un approccio culture dependent ed un approccio culture independent. Durante lo studio microbiologico del liquor mediante l\u2019approccio culture dependent, lo screening degli isolati pectinolitici mediante la tecnica A.R.D.R.A. ha evidenziato che la maggior parte degli isolati appartenga al genere Bacillus ed al gruppo dei gamma-Proteobacteria. L\u2019approccio culture dependent mediante analisi D.G.G.E. condotta sulla regione ipervariabile V3 del gene 16S rDNA degli Eubatteri ha permesso l\u2019individuazione della quasi totalit\ue0 delle specie batteriche presenti nel liquor ed ha confermato la presenza di tali specie. In seguito, tra i batteri pectinolitici isolati dal liquor sono stati individuati 5 ceppi con spiccata attivit\ue0 pectinolitica: K2H1 B. pumilus, K2H2 B. subtilis, K2H3 B. pumilus, K2H7 B. licheniformis e K607 Enterobacter sp.. La maggiorparte degli isolati con spiccata attivit\ue0 pectinolitica appartiene a batteri sporigeni conosciuti in letteratura per la produzione di enzimi pectinolitici. Il saggio RDA con acido tannico ha dimostrato che tra gli isolati K607 Enterobacter sp non viene influenzato nella crescita dalla presenza di tali sostanze. La presenza di Enterobacteriaceae \ue8 stata riscontrata anche nelle acque reflue delle industrie cartarie suggerendo che questo ceppo possa essere legato alla regolazione del contenuto di sostanze fenoliche nel liquor. Nella terza fase, testando le capacit\ue0 tecnologiche dei singoli ceppi pectinolitici in prove di macerazione in mesocosmo, \ue8 emerso che il ceppo K2H1 B. pumilus ha ottenuto i migliori risultati paragonabili a quelli ottenuti in bioreattore e, considerando le condizioni stringenti del mesocosmo, \ue8 possibile prospettare che l\u2019inoculo massivo di tale ceppo possa accelerare la macerazione in bioreattore riducendo il tempo di macerazione senza comprometterne la qualit\ue0. Successivamente, dall\u2019analisi proteomica degli enzimi pectinolitici prodotti e dall\u2019attivit\ue0 enzimatica registrata durante la macerazione in mesocosmo dell\u2019isolato K2H1 B. pumilus \ue8 emerso che l\u2019attivit\ue0 pectinolitica principale \ue8 imputabile ad un esoenzima pectato liasi di tipo C che viene prodotto in elevate quantit\ue0 dal batterio quando indotto dalla pectina. La pectato liasi agisce sulla catena dell\u2019acido poligalatturonico che \ue8 il principale costituente della pectina solubilizzandola in molecole pi\uf9 piccole. Riassumendo, in questo studio \ue8 stato approntato un bioreattore su scala pilota in grado di estrarre in termini di quantit\ue0 e qualit\ue0 fibre vegetali di kenaf su scala industriale. Inoltre, il processo in bioreattore si \ue8 dimostrato un ambiente ideale per la ricerca e lo sviluppo del processo di macerazione mediante la caratterizzazione della microflora macerante e l\u2019individuazione di un inoculo starter. In futuro, la sperimentazione dell\u2019inoculo potrebbe ridurre i tempi di macerazione dai 5-7 giorni alle 48-72 ore. Inoltre, ulteriori studi delle propriet\ue0 enzimatiche dei batteri coinvolti nel processo di macerazione potrebbe permetter di implementare un processo enzimatico con ulteriori vantaggi in termini economici.Transition to a more sustainable bio-based economy, as a political consequence of the Kyoto protocol on global climate change (United Nations Framework Convention on Climate Change, 1997), includes a shift of feedstock for energy and chemical industries from petrochemical to renewable resources. It is a good sign that also industries have by now recognized that the concept of "eco-efficiency" is an important way for businesses to contribute to sustainable development. As a major renewable resource lignocellulosic fibers derived from the structural plant tissues will play an important role in this transition. The markets for fiber crops such as flax, hemp, jute and sisal have seen substantial erosion since the introduction of synthetic fibers after Second World War in textile industries. Actually, the ecological 'green' image of cellulosic fibers has been the driving argument for innovation and development of products in the past decade, such as fiber reinforced composites in automotive industries, building and construction materials, biodegradable geotextiles and horticultural products. But today the industrial demand of natural fiber didn\u2019t encountered yet an adequate offer able to soddisfying it. In fact, intensive cultivation of bast fiber crops as hemp, flax, kenaf and jute raised up while stalk processing for the extraction of bast fibers \u2013 the raw material for the industry - relied on traditional method of retting. The process of separation and extraction of fibers from non-fibrous tissues and woody part of the stem through separation, dissolution and decomposition of pectins, gums and other mucilaginous substances is called retting. The quality of the fiber is largely determined by the efficiency of the retting process. In retting, the most important aspect is that pectic materials are broken down and the fibers are liberated. Fiber quality is dependent on method of extraction applied in different natural conditions and duration of retting. The major aim of this study, in collaboration with K.E.F.I. S.p.a., was to develop a ribbon retting process in bioreactor in order to improve the extraction of bast fiber from kenaf plant to industrial scale. This study could be divided in three parts: the first part comprised the optimization of retting process in bioreactor by analyzing different kind raw materials (kenaf ribbons) and different variety of kenaf (Everglade and Tainung); in the second part the occurring bacterial microflora involved in plant maceration was deciphered and characterized; and in the third part a possible starter inoculum was identified in order to improve and standardize the retting process in bioreactor. Ribbon retting is a particular method of retting based on a mechanical pretreatment of plant stalks that allowed reducing: the requirement of water, the length of retting time and the level of environmental pollution to almost one-fourth in comparison to other method that processed the whole plant. In particular, in the first part of this study, the optimal tested conditions allowed assuring better quality kenaf fiber in terms of fiber strength, fineness, color, and overall absolutely barking free kenaf fiber. The optimization of main parameters of maceration in bioreactor was achieved analyzing different loadings of kenaf ribbons and different varieties of kenaf. The pilot plant was provided with air insufflation system and a retting liquor recycling apparatus which allowed processing perfectly kenaf ribbons in only 5-7 days. In particular, main parameters of bioreactor (pH, RedOx, oxygen content and temperature) were monitored and controlled during the process. The air insufflation system was very useful because controlled the excessive acidification of the liquor preventing over \u2013retting risk with consequent damaging of cellulose (principal bast fibers component). Microbiological analysis of retting liquor by enumerating on different culture media evidenced the development of pectinolytic bacteria versus heterotrophic bacterial populations occurring on plant stem and in water. Moreover, the analysis of retting liquor evidenced the solubilization of phenolic compounds during maceration probably originating from lignin present in plant tissues. However, the phenolic content registered in retting liquor stabilized - during the process - to values influenced only by the loading of kenaf ribbons and kenaf varieties. The presence of phenolic compounds influenced negatively the development of bacterial populations by limiting the growth but also by inhibiting the enzymatic activities involved in the retting process. In the second part of this work, the study of the bacterial populations responsible of the retting process was achieved in retting liquor by two distinct but complementary approaches: culture dependent and independent approaches. During culture dependent approach and after screening of pectinolytic isolates through A.R.D.R.A. technique, strains belonging prevalently to genera Bacillus and gamma-Proteobacteria were identified. On the other side, culture independent approach such as D.G.G.E. analysis conducted on hypervariable V3 region of 16S rDNA of Eubacterial species confirmed the presence of those species. Later on, five high pectinolytic bacteria were isolated among strains isolated from retting liquor: K2H1 B. pumilus, K2H2 B. subtilis, K2H3 B. pumilus, K2H7 B. licheniformis e K607 Enterobacter sp.. Most of high pectinolytic strains belonged to spore-formers bacteria which are well known in literature to produce pectinolytic esoenzymes. On the other hand, RDA assay with tannic acid revealed that high pectinolytic isolates belonging to spore-formers bacteria were susceptible to phenolic compounds that inhibited their growth. Differently, K607 Enterobacter sp.\u2019s growth was not affected by phenolic compounds. The presence of Enterobacteriaceae was normally encountered in wastewaters of pulp and paper industry suggesting that K607 Enterobacter sp. could be involved in the regulation of phenolic compounds content in retting liquor during the maceration. In the third part of this study, the five high pectinolytic strains were tested as massive inoculum for trial of maceration in mesocosms in order to identify a possible starter strain able to improve retting process in bioreactor. From the data obtained from trials of retting in mesocosms it was evident that K2H1 B. pumilus produced the best retted fibers in comparison to other strains and retted fibers from bioreactor. The conditions of retting applied in mesocosms could be considered as the worst retting conditions possible in bioreactor (no aeration, no recycle of retting liquor). For these reasons, it is possible to predict that K2H1 B. pumilus added as massive inoculum could improve the retting in bioreactor by reducing the time of retting without compromising the quality of retted fibers. Later on, proteomic analyses of pectinolytic enzymes produced by K2H1 B. pumilus evidenced that this strain when induced by pectin produce a pectate lyase type C. Pectate lyase acts preferentially on polygalacturonic acid that was the main component of pectin backbone, consequently pectin was disrupted in small soluble molecules. Summarizing, in this study a pilot plant bioreactor was built up able to extract bast fibers of kenaf at industrial level both in term of quality and quantity. Furthermore, the environment of bioreactor was suitable to develop the retting process and to study and characterize the bacterial populations that allowed isolating a starter inoculum. In the next future, the test of K2H1 B. pumilus as massive inoculum could improve the maceration by reducing time of retting from 5-7 days to 48-72 hours. Moreover, further studies on enzymatic activities of bacteria involved in retting of bast fiber crops could developed an enzymatic retting procedd that will be able to reduce time of retting from 48-72 hours to few hours

Impact of the noise knowledge uncertainty for the science exploitation of cosmological and astrophysical stochastic gravitational wave background with LISA

This paper investigates the impact of a lack of knowledge of the instrumental noise on the characterisation of stochastic gravitational wave backgrounds with the Laser Interferometer Space Antenna (LISA). We focus on constraints on modelled backgrounds that represent the possible backgrounds from the mergers of binary black holes of stellar origin, from primordial black hole generation, from non-standard inflation, and from sound wave production during cosmic fluid phase transitions. We use splines to model generic, slowly varying, uncertainties in the auto and cross-spectral densities of the LISA time delay interferometry channels. We find that allowing for noise knowledge uncertainty in this way leads to one to two orders of magnitude degradation in our ability to constrain stochastic backgrounds, and a corresponding increase in the background energy density required for a confident detection. We also find that to avoid this degradation, the LISA noise would have to be known at the sub-percent level, which is unlikely to be achievable in practice

Known unknowns: assessing the impact of instrumental calibration uncertainty on LISA science

The primary scientific results of the future space-based gravitational wave interferometer LISA will come from the parameter inference of a large variety of gravitational wave sources. However, the presence of calibration errors could potentially degrade the measurement precision of the system parameters. Here, we assess the impact of calibration uncertainties on parameter estimation for individual sources, focusing on massive black holes, extreme-mass-ratio inspirals (EMRIs), galactic binaries, and stellar origin black hole binaries. Using a Fisher matrix formalism, we investigate how the measurement precision of source parameters degrades as a function of the size of the assumed calibration uncertainties. If we require that parameter measurements are degraded by no more than a factor of two relative to their value in the absence of calibration error, we find that calibration errors should be smaller than a few tenths of a percent in amplitude and $10^{-3}$ in phase. We also investigate the possibility of using verification binaries and EMRIs to constrain calibration uncertainties. Verification binaries can constrain amplitude calibration uncertainties at the level of a few percent, while both source types can provide constrain phase calibration at the level of a few$\times10^{-2}$

Quality over Quantity: Optimizing pulsar timing array analysis for stochastic and continuous gravitational wave signals

The search for gravitational waves using Pulsar Timing Arrays (PTAs) is acomputationally expensive complex analysis that involves source-specific noisestudies. As more pulsars are added to the arrays, this stage of PTA analysiswill become increasingly challenging. Therefore, optimizing the number ofincluded pulsars is crucial to reduce the computational burden of dataanalysis. Here, we present a suite of methods to rank pulsars for use withinthe scope of PTA analysis. First, we use the maximization of thesignal-to-noise ratio as a proxy to select pulsars. With this method, we targetthe detection of stochastic and continuous gravitational wave signals. Next, wepresent a ranking that minimizes the coupling between spatial correlationsignatures, namely monopolar, dipolar, and Hellings & Downs correlations.Finally, we also explore how to combine these two methods. We test theseapproaches against mock data using frequentist and Bayesian hypothesis testing.For equal-noise pulsars, we find that an optimal selection leads to an increasein the log-Bayes factor two times steeper than a random selection for thehypothesis test of a gravitational wave background versus a common uncorrelatedred noise process. For the same test but for a realistic EPTA dataset, a subsetof 25 pulsars selected out of 40 can provide a log-likelihood ratio that is$89\%$ of the total, implying that an optimally selected subset of pulsars canyield results comparable to those obtained from the whole array. We expectthese selection methods to play a crucial role in future PTA data combinations.<br

FastEMRIWaveforms: New tools for millihertz gravitational-wave data analysis

We present the FastEMRIWaveforms (FEW) package, a collection of tools to build and analyze extreme mass ratio inspiral (EMRI) waveforms. Here, we expand on the Physical Review Letter that introduced the first fast and accurate fully-relativistic EMRI waveform template model. We discuss the construction of the overall framework; constituent modules; and the general methods used to accelerate EMRI waveforms. Because the fully relativistic FEW model waveforms are for now limited to eccentric orbits in the Schwarzschild spacetime, we also introduce an improved Augmented Analytic Kludge (AAK) model that describes generic Kerr inspirals. Both waveform models can be accelerated using graphics processing unit (GPU) hardware. With the GPU-accelerated waveforms in hand, a variety of studies are performed including an analysis of EMRI mode content, template mismatch, and fully Bayesian Markov Chain Monte Carlo-based EMRI parameter estimation. We find relativistic EMRI waveform templates can be generated with fewer harmonic modes ($\sim10-100$) without biasing signal extraction. However, we show for the first time that extraction of a relativistic injection with semi-relativistic amplitudes can lead to strong bias and anomalous structure in the posterior distribution for certain regions of parameter space.Comment: 26 pages, 12 Figures, FastEMRIWaveforms Package: bhptoolkit.org/FastEMRIWaveforms

Probing Accretion Physics with Gravitational Waves

Gravitational-wave observations of extreme mass ratio inspirals (EMRIs) offer the opportunity to probe the environments of active galactic nuclei (AGN) through the torques that accretion disks induce on the binary. Within a Bayesian framework, we study how well such environmental effects can be measured using gravitational wave observations from the Laser Interferometer Space Antenna (LISA). We focus on the torque induced by planetary-type migration on quasicircular inspirals, and use different prescriptions for geometrically thin and radiatively efficient disks. We find that LISA could detect migration for a wide range of disk viscosities and accretion rates, for both $\alpha$ and $\beta$ disk prescriptions. For a typical EMRI with masses $50M_\odot+10^6M_\odot$, we find that LISA could distinguish between migration in $\alpha$ and $\beta$ disks and measure the torque amplitude with $\sim 20\%$ relative precision. Provided an accurate torque model, we also show how to turn gravitational-wave measurements of the torque into constraints on the disk properties. Furthermore, we show that, if an electromagnetic counterpart is identified, the multimessenger observations of the AGN EMRI system will yield direct measurements of the disk viscosity. Finally, we investigate the impact of neglecting environmental effects in the analysis of the gravitational-wave signal, finding 3$\sigma$ biases in the primary mass and spin, and showing that ignoring such effects can lead to false detection of a deviation from general relativity. This work demonstrates the scientific potential of gravitational observations as probes of accretion-disk physics, accessible so far through electromagnetic observations only

Quality over Quantity: Optimizing pulsar timing array analysis for stochastic and continuous gravitational wave signals

The search for gravitational waves using Pulsar Timing Arrays (PTAs) is a computationally expensive complex analysis that involves source-specific noise studies. As more pulsars are added to the arrays, this stage of PTA analysis will become increasingly challenging. Therefore, optimizing the number of included pulsars is crucial to reduce the computational burden of data analysis. Here, we present a suite of methods to rank pulsars for use within the scope of PTA analysis. First, we use the maximization of the signal-to-noise ratio as a proxy to select pulsars. With this method, we target the detection of stochastic and continuous gravitational wave signals. Next, we present a ranking that minimizes the coupling between spatial correlation signatures, namely monopolar, dipolar, and Hellings & Downs correlations. Finally, we also explore how to combine these two methods. We test these approaches against mock data using frequentist and Bayesian hypothesis testing. For equal-noise pulsars, we find that an optimal selection leads to an increase in the log-Bayes factor two times steeper than a random selection for the hypothesis test of a gravitational wave background versus a common uncorrelated red noise process. For the same test but for a realistic EPTA dataset, a subset of 25 pulsars selected out of 40 can provide a log-likelihood ratio that is $89\%$ of the total, implying that an optimally selected subset of pulsars can yield results comparable to those obtained from the whole array. We expect these selection methods to play a crucial role in future PTA data combinations

Constraining the evolution of Newton's constant with slow inspirals observed from spaceborne gravitational-wave detectors

Spaceborne gravitational-wave (GW) detectors observing at milli-Hz and deci-Hz frequencies are expected to detect large numbers of quasi-monochromatic signals. The first and second time-derivative of the GW frequency ($\dot f_0$ and $\ddot f_0$) can be measured for the most favourable sources and used to look for negative post-Newtonian corrections, which can be induced by the source's environment or modifications of general relativity. We present an analytical, Fisher-matrix-based approach to estimate how precisely such corrections can be constrained. We use this method to estimate the bounds attainable on the time evolution of the gravitational constant $G(t)$ with different classes of quasi-monochromatic sources observable with LISA and DECIGO, two representative spaceborne detectors for milli-Hz and deci-Hz GW frequencies. We find that the most constraining source among a simulated population of LISA galactic binaries could yield $\dot G/G_0 \lesssim 10^{-6}\text{yr}^{-1}$, while the best currently known verification binary will reach $\dot G/G_0 \lesssim 10^{-4}\text{yr}^{-1}$. We also perform Monte-Carlo simulations using quasi-monochromatic waveforms to check the validity of our Fisher-matrix approach, as well as inspiralling waveforms to analyse binaries that do not satisfy the quasi-monochromatic assumption. We find that our analytical Fisher matrix produces good order-of-magnitude constraints even for sources well beyond its regime of validity. Monte-Carlo investigations also show that chirping stellar-mass compact binaries detected by DECIGO-like detectors at cosmological distances of tens of Mpc can yield constraints as tight as $\dot G/G_0 \lesssim 10^{-11}\text{yr}^{-1}$.Comment: 10 pages, 3 figure