RESUMEN
The rate of the final step in the astrophysical αp process, the ^{34}Ar(α,p)^{37}K reaction, suffers from large uncertainties due to a lack of experimental data, despite having a considerable impact on the observable light curves of x-ray bursts and the composition of the ashes of hydrogen and helium burning on accreting neutron stars. We present the first direct measurement constraining the ^{34}Ar(α,p)^{37}K reaction cross section, using the Jet Experiments in Nuclear Structure and Astrophysics gas jet target. The combined cross section for the ^{34}Ar,Cl(α,p)^{37}K,Ar reaction is found to agree well with Hauser-Feshbach predictions. The ^{34}Ar(α,2p)^{36}Ar cross section, which can be exclusively attributed to the ^{34}Ar beam component, also agrees to within the typical uncertainties quoted for statistical models. This indicates the applicability of the statistical model for predicting astrophysical (α,p) reaction rates in this part of the αp process, in contrast to earlier findings from indirect reaction studies indicating orders-of-magnitude discrepancies. This removes a significant uncertainty in models of hydrogen and helium burning on accreting neutron stars.
Asunto(s)
Helio , Hidrógeno , Modelos Estadísticos , NeutronesRESUMEN
Precise antineutrino measurements are very sensitive to proper background characterization. We present an improved measurement of the ^{13}C(α,n)^{16}O reaction cross section which constitutes significant background for large ν[over ¯] detectors. We greatly improve the precision and accuracy by utilizing a setup that is sensitive to the neutron energies while making measurements of the excited state transitions via secondary γ-ray detection. Our results shows a 54% reduction in the background contributions from the ^{16}O(3^{-},6.13 MeV) state used in the KamLAND analysis.
RESUMEN
The neutron-capture reaction plays a critical role in the synthesis of the elements in stars and is important for societal applications including nuclear power generation and stockpile-stewardship science. However, it is difficult-if not impossible-to directly measure neutron capture cross sections for the exotic, short-lived nuclei that participate in these processes. In this Letter we demonstrate a new technique which can be used to indirectly determine neutron-capture cross sections for exotic systems. This technique makes use of the (d,p) transfer reaction, which has long been used as a tool to study the structure of nuclei. Recent advances in reaction theory, together with data collected using this reaction, enable the determination of neutron-capture cross sections for short-lived nuclei. A benchmark study of the ^{95}Mo(d,p) reaction is presented, which illustrates the approach and provides guidance for future applications of the method with short-lived isotopes produced at rare isotope accelerators.
RESUMEN
Detection of nuclear-decay γ rays provides a sensitive thermometer of nova nucleosynthesis. The most intense γ-ray flux is thought to be annihilation radiation from the ß^{+} decay of ^{18}F, which is destroyed prior to decay by the ^{18}F(p,α)^{15}O reaction. Estimates of ^{18}F production had been uncertain, however, because key near-threshold levels in the compound nucleus, ^{19}Ne, had yet to be identified. We report the first measurement of the ^{19}F(^{3}He,tγ)^{19}Ne reaction, in which the placement of two long-sought 3/2^{+} levels is suggested via triton-γ-γ coincidences. The precise determination of their resonance energies reduces the upper limit of the rate by a factor of 1.5-17 at nova temperatures and reduces the average uncertainty on the nova detection probability by a factor of 2.1.
RESUMEN
Needle core biopsy is considered the histological diagnostic method of choice for screen-detected breast lesions. Although the majority are definitively diagnosed as normal, benign, or malignant, approximately 7% are categorised as B3, of uncertain malignant potential. These include a wide range of lesions with different risks of associated malignancy from <2% to approaching 40% from literature review in UK practice. Historically, these have typically been surgically excised as a diagnostic procedure but the majority are then proven to be benign. An alternative approach, for many of these lesions, is thorough sampling/excision by vacuum-assisted biopsy techniques to exclude the presence of co-existing carcinoma. This would potentially reduce the benign open biopsy rate whilst maintaining accuracy of cancer diagnosis. A group from the Radiology, Surgery, and Pathology NHS Breast Screening Programme Co-ordinating Committees and an additional co-opted expert were charged with review and development of guidelines for the clinical management of B3 lesions. The guidelines reflect suggested practice as stated by the NHS Breast Screening Programme and approved by the Royal College of Radiologists.
Asunto(s)
Biopsia con Aguja Gruesa , Neoplasias de la Mama/patología , Tamizaje Masivo , Neoplasias de la Mama/diagnóstico por imagen , Diagnóstico Diferencial , Detección Precoz del Cáncer , Femenino , Humanos , Clasificación del Tumor , Valor Predictivo de las Pruebas , Medicina Estatal , Reino UnidoRESUMEN
The thermonuclear ^{30}P(p,γ)^{31}S reaction rate is critical for modeling the final elemental and isotopic abundances of ONe nova nucleosynthesis, which affect the calibration of proposed nova thermometers and the identification of presolar nova grains, respectively. Unfortunately, the rate of this reaction is essentially unconstrained experimentally, because the strengths of key ^{31}S proton capture resonance states are not known, largely due to uncertainties in their spins and parities. Using the ß decay of ^{31}Cl, we have observed the ß-delayed γ decay of a ^{31}S state at E_{x}=6390.2(7) keV, with a ^{30}P(p,γ)^{31}S resonance energy of E_{r}=259.3(8) keV, in the middle of the ^{30}P(p,γ)^{31}S Gamow window for peak nova temperatures. This state exhibits isospin mixing with the nearby isobaric analog state at E_{x}=6279.0(6) keV, giving it an unambiguous spin and parity of 3/2^{+} and making it an important l=0 resonance for proton capture on ^{30}P.
RESUMEN
Atomic nuclei have a shell structure in which nuclei with 'magic numbers' of neutrons and protons are analogous to the noble gases in atomic physics. Only ten nuclei with the standard magic numbers of both neutrons and protons have so far been observed. The nuclear shell model is founded on the precept that neutrons and protons can move as independent particles in orbitals with discrete quantum numbers, subject to a mean field generated by all the other nucleons. Knowledge of the properties of single-particle states outside nuclear shell closures in exotic nuclei is important for a fundamental understanding of nuclear structure and nucleosynthesis (for example the r-process, which is responsible for the production of about half of the heavy elements). However, as a result of their short lifetimes, there is a paucity of knowledge about the nature of single-particle states outside exotic doubly magic nuclei. Here we measure the single-particle character of the levels in (133)Sn that lie outside the double shell closure present at the short-lived nucleus (132)Sn. We use an inverse kinematics technique that involves the transfer of a single nucleon to the nucleus. The purity of the measured single-particle states clearly illustrates the magic nature of (132)Sn.
RESUMEN
BACKGROUND: Heat-shock protein 990 (HSP990) is a potent and selective synthetic small-molecule HSP90 inhibitor. The primary objectives of this phase I first-in-human study were to determine dose-limiting toxicities (DLTs), maximum-tolerated dose (MTD) and recommended phase II dose (RP2D). Secondary objectives included characterisation of the safety profile, pharmacokinetics (PKs) and pharmacodynamics (PDs). METHODS: Heat-shock protein 990 was administered orally once or two times weekly on a 28-day cycle schedule in patients with advanced solid tumours. Dose escalation was guided by a Bayesian logistic regression model with overdose control. RESULTS: A total of 64 patients were enrolled. Fifty-three patients received HSP990 once weekly at 2.5, 5, 10, 20, 30, 50 or 60 mg, whereas 11 patients received HSP990 two times weekly at 25 mg. Median duration of exposure was 8 weeks (range 1-116 weeks) and 12 patients remained on treatment for >16 weeks. Dose-limiting toxicities occurred in seven patients and included diarrhoea, QTc prolongation, ALT/AST elevations and central neurological toxicities. The most common drug-related adverse events were diarrhoea, fatigue and decreased appetite. Further dose escalation beyond 60 mg once weekly was not possible owing to neurological toxicity. Rapid absorption, no drug accumulation and large interpatient variability in PK exposures were observed. No objective responses were seen; 25 patients had a best overall response of stable disease. CONCLUSIONS: Heat-shock protein 990 is relatively well tolerated, with neurological toxicity being the most relevant DLT. The single agent MTD/RP2D of HSP990 was declared at 50 mg once weekly.
Asunto(s)
Antineoplásicos/administración & dosificación , Proteínas de Choque Térmico Pequeñas/administración & dosificación , Neoplasias/tratamiento farmacológico , Piridonas/administración & dosificación , Pirimidinas/administración & dosificación , Administración Oral , Adulto , Anciano , Antineoplásicos/efectos adversos , Antineoplásicos/farmacocinética , Progresión de la Enfermedad , Relación Dosis-Respuesta a Droga , Femenino , Proteínas HSP90 de Choque Térmico/antagonistas & inhibidores , Proteínas de Choque Térmico Pequeñas/efectos adversos , Proteínas de Choque Térmico Pequeñas/farmacocinética , Humanos , Masculino , Dosis Máxima Tolerada , Persona de Mediana Edad , Neoplasias/patología , Piridonas/efectos adversos , Piridonas/farmacocinética , Pirimidinas/efectos adversos , Pirimidinas/farmacocinética , Resultado del TratamientoRESUMEN
The Galactic 1.809-MeV γ-ray signature from the ß decay of ^{26g}Al is a dominant target of γ-ray astronomy, of which a significant component is understood to originate from massive stars. The ^{26g}Al(p,γ)^{27}Si reaction is a major destruction pathway for ^{26g}Al at stellar temperatures, but the reaction rate is poorly constrained due to uncertainties in the strengths of low-lying resonances in ^{27}Si. The ^{26g}Al(d,p)^{27}Al reaction has been employed in inverse kinematics to determine the spectroscopic factors, and hence resonance strengths, of proton resonances in ^{27}Si via mirror symmetry. The strength of the 127-keV resonance is found to be a factor of 4 higher than the previously adopted upper limit, and the upper limit for the 68-keV resonance has been reduced by an order of magnitude, considerably constraining the ^{26g}Al destruction rate at stellar temperatures.
RESUMEN
The mammary gland is a complex tissue consisting of multiple cell types which, over the lifetime of an animal, go through repeated cycles of development associated with pregnancy, lactation and involution. The mammary gland is also known to be sensitive to maternal programming by environmental stimuli such as nutrition. The molecular basis of these adaptations is of significant interest, but requires robust methods to measure gene expression. Reverse-transcription quantitative PCR (RT-qPCR) is commonly used to measure gene expression, and is currently the method of choice for validating genome-wide expression studies. RT-qPCR requires the selection of reference genes that are stably expressed over physiological states and treatments. In this study we identify suitable reference genes to normalize RT-qPCR data for the ovine mammary gland in two physiological states; late pregnancy and lactation. Biopsies were collected from offspring of ewes that had been subjected to different nutritional paradigms during pregnancy to examine effects of maternal programming on the mammary gland of the offspring. We evaluated eight candidate reference genes and found that two reference genes (PRPF3 and CUL1) are required for normalising RT-qPCR data from pooled RNA samples, but five reference genes are required for analyzing gene expression in individual animals (SENP2, EIF6, MRPL39, ATP1A1, CUL1). Using these stable reference genes, we showed that TET1, a key regulator of DNA methylation, is responsive to maternal programming and physiological state. The identification of these novel reference genes will be of utility to future studies of gene expression in the ovine mammary gland.
Asunto(s)
Perfilación de la Expresión Génica , Lactancia/genética , Glándulas Mamarias Animales/metabolismo , Fenómenos Fisiologicos Nutricionales Maternos , Preñez , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Animales , Metilación de ADN , Femenino , Expresión Génica , Regulación de la Expresión Génica , Modelos Genéticos , Embarazo , Ovinos , Oveja Doméstica/genéticaRESUMEN
BACKGROUND: The aim of this review is to introduce the topic of next-generation DNA sequencing, a new technology that is being introduced into clinical practice, and to explain the potential impact for breast cancer surgeons and the wider breast cancer multidisciplinary team. METHODS: The PubMed database was used to identify relevant studies relating to breast cancer genetics. This evidence was then used to provide context and background information to demonstrate how next-generation sequencing (NGS) might change breast cancer practice. RESULTS: With NGS, breast cancer clinicians will know whether their patients carry high-risk mutations in genes, such as BRCA1 or BRCA2, before the start of treatment. This could alter treatment decisions; for instance, more women might opt for mastectomy instead of breast-conserving surgery, or for bilateral rather than unilateral surgery. CONCLUSION: The introduction of NGS will have a significant impact on breast cancer services in the near future. Speed of testing will improve in regions of the world where NGS is adopted in place of conventional sequencing, and, as costs decrease, genetic testing will also become accessible and realistic in less well funded health economies. This will create opportunities to improve patient treatment and challenges for the breast cancer multidisciplinary team.
Asunto(s)
Neoplasias de la Mama/genética , Análisis de Secuencia de ADN/tendencias , Neoplasias de la Mama/cirugía , Detección Precoz del Cáncer/métodos , Femenino , Genes BRCA1/fisiología , Genes BRCA2/fisiología , Pruebas Genéticas , Humanos , Mastectomía/métodos , Mutación/genética , Terapia Neoadyuvante/métodos , Medición de Riesgo , Factores de RiesgoRESUMEN
Single-neutron states in (133)Sn and (209)Pb, which are analogous to single-electron states outside of closed atomic shells in alkali metals, were populated by the ((9)Be, (8)Be) one-neutron transfer reaction in inverse kinematics using particle-γ coincidence spectroscopy. In addition, the s(1/2) single-neutron hole-state candidate in (131)Sn was populated by ((9)Be, (10)Be). Doubly closed-shell (132)Sn (radioactive) and (208)Pb (stable) beams were used at sub-Coulomb barrier energies of 3 MeV per nucleon. Level energies, γ-ray transitions, absolute cross sections, spectroscopic factors, asymptotic normalization coefficients, and excited-state lifetimes are reported and compared with shell-model expectations. The results include a new transition and precise level energy for the 3p(1/2) candidate in (133)Sn, new absolute cross sections for the 1h(9/2) candidate in (133)Sn and 3s(1/2) candidate in (131)Sn, and new lifetimes for excited states in (133)Sn and (209)Pb. This is the first report on excited-state lifetimes of (133)Sn, which allow for a unique test of the nuclear shell model and (132)Sn double-shell closure.
RESUMEN
Classical novae are expected to contribute to the 1809-keV Galactic γ-ray emission by producing its precursor 26Al, but the yield depends on the thermonuclear rate of the unmeasured 25Al(p,γ)26Si reaction. Using the ß decay of 26P to populate the key J(π)=3(+) resonance in this reaction, we report the first evidence for the observation of its exit channel via a 1741.6±0.6(stat)±0.3(syst) keV primary γ ray, where the uncertainties are statistical and systematic, respectively. By combining the measured γ-ray energy and intensity with other experimental data on 26Si, we find the center-of-mass energy and strength of the resonance to be E(r)=414.9±0.6(stat)±0.3(syst)±0.6(lit.) keV and ωγ=23±6(stat)(-10)(+11)(lit.) meV, respectively, where the last uncertainties are from adopted literature data. We use hydrodynamic nova simulations to model 26Al production showing that these measurements effectively eliminate the dominant experimental nuclear-physics uncertainty and we estimate that novae may contribute up to 30% of the Galactic 26Al.
RESUMEN
Recent calculations suggest that the rate of neutron capture by (130)Sn has a significant impact on late-time nucleosynthesis in the r process. Direct capture into low-lying bound states is expected to be significant in neutron capture near the N=82 closed shell, so r-process reaction rates may be strongly impacted by the properties of neutron single particle states in this region. In order to investigate these properties, the (d,p) reaction has been studied in inverse kinematics using a 630 MeV beam of (130)Sn (4.8 MeV/u) and a (CD(2))(n) target. An array of Si strip detectors, including the Silicon Detector Array and an early implementation of the Oak Ridge Rutgers University Barrel Array, was used to detect reaction products. Results for the (130)Sn(d, p)(131)Sn reaction are found to be very similar to those from the previously reported (132)Sn(d, p)(133)Sn reaction. Direct-semidirect (n,γ) cross section calculations, based for the first time on experimental data, are presented. The uncertainties in these cross sections are thus reduced by orders of magnitude from previous estimates.
RESUMEN
The best examples of halo nuclei, exotic systems with a diffuse nuclear cloud surrounding a tightly bound core, are found in the light, neutron-rich region, where the halo neutrons experience only weak binding and a weak, or no, potential barrier. Modern direct-reaction measurement techniques provide powerful probes of the structure of exotic nuclei. Despite more than four decades of these studies on the benchmark one-neutron halo nucleus 11Be, the spectroscopic factors for the two bound states remain poorly constrained. In the present work, the 10Be(d,âp) reaction has been used in inverse kinematics at four beam energies to study the structure of 11Be. The spectroscopic factors extracted using the adiabatic model were found to be consistent across the four measurements and were largely insensitive to the optical potential used. The extracted spectroscopic factor for a neutron in an nâj=2s(1/2) state coupled to the ground state of 10Be is 0.71(5). For the first excited state at 0.32 MeV, a spectroscopic factor of 0.62(4) is found for the halo neutron in a 1p(1/2) state.
RESUMEN
Proopiomelanocortin is a precursor peptide that gives rise to several neuropeptides including adrenocorticotrophic hormone (ACTH) and ß-endorphin. POMC-derived peptides have been shown to be synthesized in human epidermis where they modulate numerous skin functions. Because we previously observed that melanocortin receptor-2 and µ-opioid receptor 1, the respective receptors for ACTH and ß-endorphin decreased with ageing in human epidermis, we have selected an active ingredient (INCI name: Achillea millefolium extract) able to upregulate receptor expressions. The aim of the present work was first to evaluate the effect of A. millefolium extract on the expression pattern of various epidermal differentiation markers ex vivo in normal human skin biopsies using quantitative image analysis and second to evaluate its capacity to rejuvenate the appearance of skin surface in vivo. Results show an improved expression profile of cytokeratin 10, transglutaminase-1 and filaggrin in cultured skin biopsies as well as an increased epidermal thickness. In vivo, a 2-month treatment with A. millefolium extract at 2% significantly improved the appearance of wrinkles and pores compared with placebo. Results were also directionally better than those of glycolic acid that was chosen as reference resurfacing molecule.
Asunto(s)
Achillea/química , Extractos Vegetales/administración & dosificación , Receptor de Melanocortina Tipo 2/metabolismo , Receptores Opioides mu/metabolismo , Envejecimiento de la Piel/efectos de los fármacos , Anciano , Biopsia , Método Doble Ciego , Femenino , Proteínas Filagrina , Histocitoquímica , Humanos , Proteínas de Filamentos Intermediarios/metabolismo , Queratinas/metabolismo , Microscopía Confocal , Persona de Mediana Edad , Receptor de Melanocortina Tipo 2/genética , Receptores Opioides mu/genética , Piel/efectos de los fármacos , Piel/metabolismo , Estadísticas no Paramétricas , Transglutaminasas/metabolismoRESUMEN
Alzheimer's disease (AD), the most common form of dementia in the older people, is a multifactoral pathology, characterized by cognitive deficits, increase in cerebral deposition of the beta-amyloid (Abeta) peptide, neurofibrillary tangles, and neurodegeneration. Studies currently support a central role of neuroinflammation, through production of proinflammatory cytokines including excess tumor necrosis factor alpha (TNF-alpha) in the pathogenesis of AD, especially in Abeta-induced cognitive deficits. Imipramine, a tricyclic antidepressant, has potent anti-inflammatory and neuroprotective effects. This study investigates the effect of imipramine on alterations of long-term and short-term memories, TNF-alpha expression, and amyloid precursor protein (APP) processing induced by intracerebroventricular injection of Abeta25-35 in mice. Mice were treated with imipramine (10 mg/kg i.p. once a day for 13 days) from the day after the Abeta25-35 injection. Memory function was evaluated in the water-maze (days 10-14) and Y-maze (day 9) tests. TNF-alpha levels and APP processing were examined in the frontal cortex and the hippocampus (day 14). Imipramine significantly prevented memory deficits caused by Abeta25-35 in the water-maze and Y-maze tests, and inhibited the TNF-alpha increase in the frontal cortex. Moreover, imipramine decreased the elevated levels of Abeta both in frontal cortex and hippocampus with different modulations of APP and C-terminal fragments of APP. So, imipramine prevents memory impairment through its intrinsic property to inhibit TNF-alpha and Abeta accumulation and may represent a potential candidate for AD treatment.
Asunto(s)
Enfermedad de Alzheimer/tratamiento farmacológico , Imipramina/uso terapéutico , Trastornos de la Memoria/tratamiento farmacológico , Memoria/efectos de los fármacos , Fármacos Neuroprotectores/uso terapéutico , Factor de Necrosis Tumoral alfa/metabolismo , Péptidos beta-Amiloides/administración & dosificación , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/antagonistas & inhibidores , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Cognición/efectos de los fármacos , Modelos Animales de Enfermedad , Lóbulo Frontal/efectos de los fármacos , Lóbulo Frontal/metabolismo , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Imipramina/farmacología , Inyecciones Intraventriculares , Masculino , Trastornos de la Memoria/inducido químicamente , Ratones , Fármacos Neuroprotectores/farmacología , Fragmentos de Péptidos/antagonistas & inhibidores , Fragmentos de Péptidos/farmacologíaRESUMEN
The transfer of neutrons onto 24Ne has been measured using a reaccelerated radioactive beam of 24Ne to study the (d,p) reaction in inverse kinematics. The unusual raising of the first 3/2+ level in 25Ne and its significance in terms of the migration of the neutron magic number from N=20 to N=16 is put on a firm footing by confirmation of this state's identity. The raised 3/2+ level is observed simultaneously with the intruder negative parity 7/2- and 3/2- levels, providing evidence for the reduction in the N=20 gap. The coincident gamma-ray decays allowed the assignment of spins as well as the transferred orbital angular momentum. The excitation energy of the 3/2+ state shows that the established USD shell model breaks down well within the sd model space and requires a revised treatment of the proton-neutron monopole interaction.
RESUMEN
SYNOPSIS: Much effort has been placed in cosmetic research for better understanding of the effects of ageing on skin's appearance, structure, mechanical properties and function. It is now of common knowledge that UV radiations induce pre-mature skin ageing notably in the epidermis where UV radiations induce keratinocyte differentiation. As UV radiations have also been shown to regulate the pro-opiomelanocortin (POMC) peptide family in the skin and because no study has been conducted so far to investigate the age-related changes in POMC and related receptors, we analysed POMC, MC-1R, MC-2R and MOR-1 at mRNA level and MC-1R, MC-2R and MOR-1 at protein level too in primary cultures of normal human keratinocytes obtained from female donors aged from 17 to 75 years old. Regarding the gene expressions, we observed that MC-1R, MC-2R and MOR-1 suffered a dramatic decrease after 50 years of age, whereas POMC increased five-fold. Western blot analysis confirmed these results except for MOR-1 whose expression appeared to decrease at older age, around 70 years old. Immunostainings specific to MC-1R, MC-2R and MOR-1 performed on full-thickness skin biopsies also revealed an intense staining in the basal and spinous layers of a 30-year-old donor, whereas no reactivity could be observed in a 60-year-old one. We conclude that POMC and POMC-related receptors suffer a dramatically disturbed balance with ageing and that this may be implicated in the general process of skin ageing.
Asunto(s)
Envejecimiento/fisiología , Epidermis/fisiología , Queratinocitos/fisiología , Proopiomelanocortina/fisiología , Receptor de Melanocortina Tipo 1/fisiología , Receptor de Melanocortina Tipo 2/fisiología , Adolescente , Hormona Adrenocorticotrópica/genética , Hormona Adrenocorticotrópica/fisiología , Adulto , Anciano , Biopsia , Células Epidérmicas , Epidermis/química , Femenino , Humanos , Queratinocitos/química , Queratinocitos/citología , Persona de Mediana Edad , Proopiomelanocortina/genética , ARN/química , ARN/genética , Receptor de Melanocortina Tipo 1/genética , Receptor de Melanocortina Tipo 2/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Adulto Joven , alfa-MSH/genética , alfa-MSH/fisiología , betaendorfina/genética , betaendorfina/fisiologíaRESUMEN
Greater rates of genetic gain can be achieved by selecting animals born to younger parents. However, little is known about the lifetime performance of dual purpose ewes (Ovis aries) that are born to primiparous ewe lambs (8 to 9 months old at breeding). This experiment investigated the effect of being born from either a ewe lamb or mixed age dam as either a single or twin on the lifetime performance of ewe progeny. Lifetime performance was measured in terms of the life time live weights of the ewes, the weight and number of lambs born and weaned, the efficiency of production (kilograms of lamb weaned / predicted pasture intake (kgDM) of the ewes), and ewe survival. The study followed the lifetime production of 17 single and 41 twin female lambs born to mature ewes (M1 and M2, respectively), and 28 single and 29 twin lambs born to ewe lambs (L1 and L2, respectively). Over their lifetime L2 ewes were lighter (P<0.05) but had similar body condition scores to the other three ewe groups. There was no difference in average progeny weaning weight or total progeny litter weaning weights between groups. The M1 ewes had the greatest longevity (P<0.05) of the four groups. Even though L2 ewes were lighter than the other three groups, this was insufficient to increase their lifetime efficiency of production (kg lamb weaned/predicted pasture consumption), relative to the other groups. These results suggest farmers could select replacements born to ewe lambs without sacrificing animal production.